Eravacycline is a fully synthetic fluorocycline, structurally related to tigecycline but engineered with modifications that broaden its spectrum and improve its pharmacokinetic profile. It works by binding to the 30S ribosomal subunit, blocking protein synthesis in susceptible bacteria. Approved for use against complicated intra-abdominal infections, it has attracted growing interest as a potential salvage option for multidrug-resistant Gram-negative pathogens, including carbapenem-resistant Enterobacterales and, increasingly, S. maltophilia. Yet until now, clinical evidence evaluating eravacycline specifically against S. maltophilia has remained limited worldwide, leaving clinicians without solid guidance on whether the drug actually works in real patients.

The new study, led by researchers at Peking Union Medical College Hospital and published in BMC Infectious Diseases, set out to fill that gap. It analysed 103 adult patients who were treated with eravacycline-containing regimens for at least 72 hours for confirmed S. maltophilia infections between August 2023 and August 2024. The researchers tracked a battery of outcomes: overall clinical effectiveness at the end of treatment, clinical effectiveness 30 days after treatment ended, patient prognosis at discharge, microbiological clearance, and adverse events. This retrospective, multicentre design drew on de-identified medical records from multiple Chinese hospitals, giving the findings a breadth that single-centre reports cannot match.

The headline result is striking. The overall clinical effectiveness rate was 90.3 percent, or 93 out of 103 patients, at the end of treatment. Thirty days after treatment ended, the rate remained essentially stable at 88.3 percent, or 91 out of 103 patients. Furthermore, 88.3 percent of patients showed clinical improvement by the time of discharge. These figures suggest that eravacycline-containing regimens not only work in the short term but also produce durable results that hold up well beyond the treatment window, a critical consideration for infections that can relapse or persist in vulnerable hosts.

When the researchers broke down the results by infection type, the picture remained consistently favourable. Isolated pneumonia was the most common presentation, affecting 71 of 103 patients, or 68.9 percent of the cohort. Pneumonia with concomitant infection accounted for 21 patients, or 20.4 percent, while isolated extrapulmonary infection affected 11 patients, or 10.7 percent. At the end of treatment, clinical effectiveness rates were 87.3 percent for isolated pneumonia, 95.2 percent for pneumonia with concomitant infection, and 90.9 percent for isolated extrapulmonary infection. By day 30 after treatment ended, these rates remained stable across the respective subgroups, indicating that eravacycline performed well regardless of whether the infection was confined to the lungs or had spread elsewhere.

Microbiological clearance, a key secondary outcome, added further weight to the findings. Among 61 patients with evaluable follow-up cultures, S. maltophilia was cleared in 93.4 percent of cases, or 57 out of 61 patients. This high rate of bacterial eradication suggests that eravacycline-containing regimens are not merely masking symptoms but are genuinely eliminating the pathogen from infected sites. For a bacterium that can persist in biofilms and colonise immunocompromised hosts for extended periods, this level of microbiological efficacy is a meaningful signal.

Safety is often the Achilles heel of new antibiotics, but eravacycline fared well on this front too. Adverse events were minimal, affecting only 3 of 103 patients, or 2.9 percent of the cohort, and none were severe. This favourable safety profile is consistent with what has been observed in phase II and phase III trials of eravacycline for other indications, and it reinforces the drug’s potential as a tolerable option for patients who may already be dealing with a heavy burden of comorbidities and concurrent medications.

The authors are careful to temper enthusiasm with appropriate scientific caution. Because this was a retrospective observational study, baseline selection bias is an inherent limitation. Clinicians may have preferentially prescribed eravacycline to patients they believed would respond well, or to those who had failed other therapies, and these choices can skew the apparent effectiveness in either direction. The observed effectiveness, the researchers emphasise, must be interpreted cautiously for this reason. Without a randomised controlled trial, it is impossible to fully disentangle the drug’s true effect from the effects of patient selection and concurrent care.

Nevertheless, the study represents a significant step forward in the clinical evidence base for eravacycline against S. maltophilia. As multidrug resistance continues to erode the utility of older antibiotics, and as S. maltophilia infections become increasingly common in intensive care settings, the need for effective alternatives has never been greater. Eravacycline, with its broad spectrum, favourable pharmacokinetics, and now demonstrated real-world effectiveness, emerges as a potential alternative or salvage option for clinicians facing this difficult pathogen. The findings from this Chinese multicentre cohort provide a foundation upon which future prospective studies and randomised trials can build, ultimately clarifying the drug’s role in the standard of care for S. maltophilia infections worldwide.

Subject of Research: Clinical outcomes of eravacycline in Stenotrophomonas maltophilia infections

Article Title: Clinical outcomes of Eravacycline in patients with Stenotrophomonas maltophilia infections: a multicentre observational study in China

Article References: Zhai, X., Li, Y., Zhou, M., Xu, Y., & Yi, Q. (2026). Clinical outcomes of Eravacycline in patients with Stenotrophomonas maltophilia infections: a multicentre observational study in China. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14302-6

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14302-6

Keywords: Stenotrophomonas maltophilia, Eravacycline, Antibiotic resistance, Clinical outcomes, Multidrug resistance, Observational study, BMC Infectious Diseases, Clinical, outcomes, patients, Stenotrophomonas, maltophilia

The research team, led by Youjia Hao and colleagues in the Department of Critical Care Medicine at Beijing Jishuitan Hospital, Capital Medical University, systematically searched PubMed, EMBASE, Web of Science, and the Cochrane Library from inception to January 2025. They included prospective studies reporting resistin levels in relation to mortality or disease severity in sepsis. After rigorous screening, eighteen studies encompassing 2,197 sepsis patients made it into the final analysis. The review was registered with PROSPERO under CRD42025639277, ensuring methodological transparency from the outset.

Resistin itself has an intriguing biology. Originally named for its proposed role in insulin resistance, the molecule is now recognized as a potent driver of inflammation. Unlike adipose-derived resistin in rodents, human resistin circulates largely from immune cells, and it amplifies the release of tumor necrosis factor and interleukin-6 while promoting endothelial dysfunction. In the context of sepsis, where a dysregulated host response to infection cascades into organ failure, resistin’s rise seems to mirror the intensity of that inflammatory storm.

The meta-analysis quantified this relationship using standardized mean differences, a statistical measure that allows comparison across studies employing different laboratory assays. Resistin levels were significantly higher in non-survivors than in survivors, with a pooled standardized mean difference of 0.83 and a 95 percent confidence interval spanning 0.31 to 1.36. Patients with septic shock, the most severe form of sepsis characterized by profound circulatory collapse, showed even more striking elevations compared to those without shock, with a standardized mean difference of 1.34 and a confidence interval of 0.62 to 2.05. Compared with healthy controls, sepsis patients overall displayed substantially elevated resistin, yielding a standardized mean difference of 1.99 with a confidence interval of 1.63 to 2.35.

When the researchers arranged these findings along the spectrum of disease, a stepwise gradient emerged. Healthy controls occupied the lowest rung, followed by patients with non-shock sepsis, then those with septic shock, and finally non-survivors at the top. This ordered pattern suggests that resistin is not merely a binary flag of infection but a quantitative readout of inflammatory burden, potentially offering clinicians a way to gauge how far along the severity curve a patient sits at the moment of admission.

The team also assessed resistin’s diagnostic accuracy using areas under the receiver operating characteristic curve, a metric that ranges from 0.5, equivalent to random guessing, to 1.0, representing perfect discrimination. The pooled AUC for predicting mortality was 0.68 with a confidence interval of 0.64 to 0.73. In adult patients specifically, the pooled AUC rose to 0.70 with a confidence interval of 0.65 to 0.75. These values indicate moderate discriminatory power, meaning resistin alone cannot reliably sort survivors from non-survivors but may contribute meaningful prognostic information when combined with clinical scoring systems.

However, the analysis was not without caveats. Substantial heterogeneity pervaded the main pooled analyses, reaching an I-squared value of 89 percent, a statistical signal that the included studies varied considerably in their populations, assays, and timing of measurement. The 95 percent prediction intervals for sepsis-related mortality, 28-day mortality, and septic shock all included zero, indicating that the direction of the effect in future studies remains uncertain. Subgroup and meta-regression analyses were conducted to explore potential effect modifiers, but the authors acknowledge that these exploratory tools cannot fully resolve the underlying variability.

The authors conclude that admission resistin levels may be associated with disease severity and adverse outcomes in sepsis, but they are careful to emphasize that clinical utility remains unproven. Their recommendation is unambiguous: large, multicenter prospective studies are needed before resistin can be integrated into routine prognostic assessment. In the interim, the molecule joins a growing list of inflammatory biomarkers, including procalcitonin and interleukin-6, whose prognostic value in sepsis is promising but not yet definitive.

For a condition that kills swiftly and often silently, any tool that sharpens early risk stratification carries enormous clinical weight. Resistin’s stepwise rise across the sepsis spectrum offers a compelling biological narrative, one that aligns with the broader understanding of sepsis as a crescendo of immune dysregulation. Whether this cytokine will earn a place beside lactate and procalcitonin in the emergency department or intensive care unit remains to be seen, but this meta-analysis provides the strongest synthesis to date of its prognostic signal.

The study, published open access under a Creative Commons license, received no specific funding and involved no competing interests. As sepsis continues to challenge clinicians worldwide, biomarkers like resistin represent a frontier where laboratory science meets bedside decision-making, and the coming years of multicenter validation will determine whether this inflammatory messenger becomes a standard component of the sepsis prognostic toolkit.

Subject of Research: The prognostic value of resistin in patients with sepsis: a systematic review and meta-analysis

Article Title: The prognostic value of resistin in patients with sepsis: a systematic review and meta-analysis

Article References: Hao, Y., Bai, Y., Zhang, L., Cui, Z., Liu, C., & Wang, H. (2026). The prognostic value of resistin in patients with sepsis: a systematic review and meta-analysis. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14293-4

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14293-4

Keywords: resistin, sepsis, biomarker, meta-analysis, septic shock, mortality, inflammation, BMC Infectious Diseases, prognostic, value, patients, systematic

The researchers constructed what epidemiologists call an SEIQR model, an acronym that tracks individuals through five compartments: Susceptible, Exposed, Infected, Quarantined, and Recovered. What distinguishes their framework from classical single-population models is the explicit division into two behavioral groups, each with its own transmission dynamics and its own quarantine rate. The model is written as a system of ordinary differential equations, with cross-transmission terms capturing how infection flows between the groups. A susceptible individual in the high-risk group can be infected by infectious individuals in either group, and the same holds for the low-risk group, creating a transmission matrix whose entries encode the full pattern of contact and behavioral differences across the population.

Before any control strategy could be evaluated, the team established the mathematical foundations of the model. They proved that solutions remain positive and bounded, meaning the equations never produce negative numbers of people or unbounded populations, and they demonstrated global existence of solutions, ensuring the model is well-posed over time. These are not merely technical formalities; they guarantee that the model’s outputs are biologically meaningful and that numerical simulations rest on solid theoretical ground. The researchers then derived the basic reproduction number, R0, using the next-generation matrix method, a standard but powerful technique that computes the expected number of secondary infections produced by a single infected individual introduced into a wholly susceptible population.

The stability analysis forms the theoretical heart of the paper. The team identified two possible long-term outcomes of the epidemic: a disease-free equilibrium, where infection vanishes from the population, and an endemic equilibrium, where the disease persists at a steady level. Using a symmetry condition on the transmission rates, they established the global stability of both equilibria. In practical terms, this means that when R0 falls below one, the disease dies out regardless of initial conditions, and when R0 exceeds one, the infection persists in the population no matter how the outbreak begins. Such global results are considerably stronger than local stability findings, which only guarantee behavior near the equilibrium points, and they give public health modelers confidence that the qualitative predictions hold across a wide range of epidemic scenarios.

To understand which parameters matter most, the researchers performed a global sensitivity analysis using the Latin Hypercube Sampling and Partial Rank Correlation Coefficient method, commonly abbreviated as LHS-PRCC. Unlike one-at-a-time sensitivity tests, this approach varies all parameters simultaneously across their plausible ranges, revealing how uncertainty in each parameter propagates to uncertainty in R0. The analysis produced a clear and somewhat counterintuitive result: the transmission coefficient within the low-risk group, denoted beta-11, emerged as the strongest driver increasing R0, while the quarantine rate in the low-risk group, q1, had the greatest impact in reducing it. In other words, in this model, transmission among people who behave cautiously, perhaps because they mix widely while maintaining partial precautions, exerts an outsized influence on overall epidemic potential, and improving quarantine compliance in that same group offers the biggest lever for suppression.

The second major contribution of the study is its optimal control framework. The researchers formulated the problem of deploying two time-dependent interventions, vaccination and awareness campaigns, across the two behavioral groups, and they sought the intervention schedule that minimizes infections while keeping costs manageable. Solving such problems analytically requires Pontryagin’s Maximum Principle, a cornerstone of optimal control theory that converts the minimization problem into a system of adjoint equations coupled to the original epidemic dynamics. The resulting optimality system characterizes the intervention intensities that best balance the epidemiological benefit of reducing infections against the economic cost of implementing vaccination drives and awareness programs at each moment of the outbreak.

Numerical simulations brought the theoretical framework to life and yielded strategically important insights. The simulations showed that awareness-based interventions are highly effective in the early stages of an epidemic, when informing the public about risks and protective behaviors can rapidly bend the transmission curve before large numbers of people have been infected. As the epidemic progresses, however, the combined strategy of vaccination and awareness achieved the best overall performance, reducing both the cumulative number of infections and the total cost of the intervention program. This finding aligns with the intuitive logic of outbreak response: behavioral messaging works quickly but requires reinforcement, while vaccination builds durable protection that compounds over time, and the two tools complement each other when deployed in coordination.

Perhaps the most striking result concerns the allocation of intervention effort between the two groups. Under the specific transmission matrix, epidemiological parameters, and objective-function weights considered in the study, the optimal control solution directed greater intervention effort toward the low-risk group. This outcome may seem paradoxical, since high-risk individuals are typically prioritized in real-world vaccination campaigns. The authors are careful to address this directly: the greater allocation to the low-risk group is a model-dependent finding, arising from the particular parameter values and cost structure they examined, and it should not be interpreted as general public-health guidance to prioritize low-risk populations over clinically high-risk populations. The result instead illustrates a deeper principle, that heterogeneity in transmission can substantially influence the optimal allocation of interventions between population groups, and that control strategies optimized for one behavioral structure may be suboptimal for another.

The broader significance of this work lies in its demonstration that behavioral heterogeneity is not a nuisance to be averaged away but a structural feature that reshapes epidemic dynamics and control policy. When a population splits into groups with different contact patterns, quarantine compliance, and responsiveness to public health messaging, the single-number R0 of a homogeneous model gives way to a transmission matrix, and the levers that most effectively suppress the outbreak may sit in unexpected places. Sensitivity analysis becomes an essential tool for locating those levers, and optimal control theory provides a principled way to distribute finite resources, vaccines, funding, and public attention, across the groups where they will do the most good.

For policymakers and modelers preparing for future epidemic threats, the study offers both a methodological template and a caution. The template is the combination of rigorous dynamical analysis, global sensitivity testing, and optimal control formulation, which together transform a descriptive model into a decision-support tool. The caution is that optimal allocations are contingent on the assumed parameters and objective weights, meaning that real-world deployment requires careful calibration to local epidemiological data and ethical constraints. As the authors emphasize, their finding on low-risk allocation is a property of their specific model configuration, not a prescription. What endures is the framework itself, which shows that acknowledging how differently people behave is not a complication of epidemic modeling but the very key to designing interventions that work.

Subject of Research: A two-group SEIQR epidemiological model of COVID-19 with heterogeneous behavior, analyzing stability, sensitivity, and optimal vaccination and awareness control strategies.

Article Title: Two-group SEIQR epidemiological model with heterogeneous behavior

Article References: Al-Arydah, M., Berhe, H. W., & Tridane, A. (2026). Two-group SEIQR epidemiological model with heterogeneous behavior. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14399-9

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14399-9

Keywords: COVID-19, SEIQR model, epidemiological modeling, behavioral heterogeneity, basic reproduction number, optimal control, vaccination, awareness campaigns, sensitivity analysis, Pontryagin's Maximum Principle, global stability, BMC Infectious Diseases

Omadacycline belongs to the aminomethylcycline subclass, the latest generation of tetracycline derivatives, engineered to overcome the two major resistance mechanisms that disable older tetracyclines: efflux pumps that expel the drug from bacterial cells and ribosomal protection proteins that shield the drug’s binding site. Because of these modifications, omadacycline retains activity against methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae, and many gram-negative pathogens, which is precisely why clinicians have been eager to see it deployed against difficult infections. Until now, however, its approved indications covered adults with community-acquired bacterial pneumonia and acute bacterial skin infections, leaving pediatric use essentially uncharted territory.

The research team, led by pharmacists at the First Affiliated Hospital of Nanchang University in Jiangxi, China, combed electronic medical records for patients aged 8 to 17 who received omadacycline for infectious diseases. The retrospective design means the drug was given at the discretion of treating physicians in real clinical practice, not under the controlled conditions of a randomized trial. Clinical effectiveness was assessed on the day before discharge and graded on a four-point scale: cured, markedly effective, improved, or ineffective. Effective outcomes were defined as complete resolution or significant improvement of infection-related symptoms and signs without the need for additional antimicrobial therapy.

The headline result was striking. Of the 267 patients, 20, or 7.5 percent, were cured, 109, or 40.8 percent, were markedly effective, and 115, or 43.1 percent, were improved, adding up to a clinical effective rate of 91.4 percent. Only 23 patients, or 8.6 percent, failed to respond. In other words, roughly nine out of ten children and adolescents treated with omadacycline left the hospital with their infections resolved or substantially improved, without needing rescue antibiotics. For a drug never before documented in this age group, the aggregate outcome pattern closely mirrors what adult trials and real-world adult series have reported.

Statistical analysis revealed which factors tipped the balance toward success. Patients with pulmonary infection were significantly more likely to achieve effective outcomes than those with infections at other sites, with the difference reaching statistical significance at P equal to 0.012. A longer duration of combination therapy, in which omadacycline was given alongside other antibiotics, was also associated with a greater probability of effectiveness, at P equal to 0.030. The authors suggest that the drug’s strong lung penetration, a hallmark of the aminomethylcyclines, may partly explain the pulmonary advantage, while combination regimens may have provided broader initial coverage in severely ill children until pathogens were identified.

One of the most clinically useful findings concerned fever. Body temperature declined continuously after the medication was started, a trend that was highly significant across the treatment period at P less than 0.001. When the researchers compared the effective group with the ineffective group, the children who ultimately responded had significantly lower body temperatures on day 3, at P equal to 0.035, and day 4, at P equal to 0.002, after the medication began. This defervescence pattern could eventually serve as an early bedside signal, allowing clinicians to distinguish responders from non-responders within the first few days of therapy and adjust treatment before the infection gains further ground.

Safety was the other half of the equation, and here the short-term picture was reassuring. Only 5 patients developed mild liver injury after receiving the drug, and no moderate or severe liver injury was recorded anywhere in the cohort. Laboratory indices from routine blood examinations, including white blood cells, neutrophils, lymphocytes, and platelets, as well as liver function markers such as alanine transaminase, aspartate aminotransferase, total bilirubin, and direct bilirubin, and renal function measures including uric acid, all remained within normal ranges before and after treatment, and the observed changes lacked clinical significance. For a tetracycline-class drug, a class historically associated with photosensitivity, tooth discoloration, and gastrointestinal upset in children, this laboratory profile is a notable point in the drug’s favor.

The study was conducted in accordance with the Declaration of Helsinki, approved by the Ethics Committee of the First Affiliated Hospital of Nanchang University, and carried out with a waiver of informed consent given its retrospective design. Funding came from the National Natural Science Foundation of China and the Natural Science Foundation of Jiangxi Province. The authors declared no competing interests, and the article is published open access under a Creative Commons license, making the full dataset description and supplementary materials freely available to clinicians and researchers worldwide.

Yet the authors are careful about what these results can and cannot prove. A retrospective cohort cannot eliminate selection bias, since physicians chose omadacycline for particular patients for particular reasons, and the absence of a control group means the outcomes cannot be attributed to the drug with certainty. The pediatric population studied was also limited to children aged 8 and above, leaving younger children entirely unstudied. The authors explicitly state that prospective controlled studies are needed to confirm the findings before omadacycline can be considered an evidence-based option for pediatric infections.

Even with those caveats, the study marks a meaningful step in pediatric antimicrobial therapy. As multidrug-resistant bacteria continue to erode the utility of older antibiotics, every new agent that can be safely extended to children expands the therapeutic arsenal for the most vulnerable patients. If prospective trials bear out the 91.4 percent effective rate and the clean short-term safety profile reported here, omadacycline could become a valuable option for children with pneumonia caused by resistant pathogens, and the defervescence signature identified in this cohort may give clinicians an early, practical tool for judging whether the drug is working. For now, the message is one of cautious optimism: the newest tetracycline has taken its first documented steps in pediatric medicine, and the early results look promising.

Subject of Research: Infectious Diseases

Article Title: Omadacycline in pediatric patients with predominantly pulmonary infections: a retrospective, real-world study

Article References: Liu, J., Liu, J., Zhang, Z., Huang, J., Liu, J., & Ouyang, A. (2026). Omadacycline in pediatric patients with predominantly pulmonary infections: a retrospective, real-world study. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14317-z

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14317-z

Keywords: omadacycline, tetracycline, pediatrics, pulmonary infection, antibiotics, antimicrobial resistance, BMC Infectious Diseases, pediatric, patients, predominantly, pulmonary, infections

Tuberculous meningitis is the most severe form of central nervous system tuberculosis. Mycobacterium tuberculosis reaches the meninges through the bloodstream and sets up a chronic inflammatory process concentrated at the base of the brain, where the basal cisterns become filled with thick, gelatinous exudate. This basal meningitis can compress cranial nerves, obstruct cerebrospinal fluid flow and damage blood vessels, producing hydrocephalus, infarction and a wide range of neurological deficits. Even with modern anti-tuberculous drugs and corticosteroids, mortality and disability remain high, particularly when diagnosis is delayed.

Paradoxical reactions add a cruel twist to this already difficult disease. In a paradoxical reaction, a patient initially improves on anti-tuberculous therapy, then deteriorates neurologically despite the drugs continuing to kill the bacteria. The prevailing explanation is immunological: as anti-tuberculous drugs reduce the bacterial load, they also strip away antigens that had been dampening the immune response, allowing a rebound of cell-mediated immunity directed at residual mycobacterial antigens. Tumor necrosis factor-alpha and other inflammatory mediators surge, granulomatous inflammation flares, and lesions that had been shrinking can enlarge or appear at new sites. Paradoxical worsening is well documented in HIV-negative patients and in HIV-positive patients after starting antiretroviral therapy, a related phenomenon known as immune reconstitution inflammatory syndrome.

The Sri Lankan team, led by Shanindra de Alwis of the University of Sri Jayewardenepura with colleagues from the University of Colombo and the Institute of Neurology at the National Hospital of Sri Lanka, focused on one of the most destructive forms this rebound can take. Optochiasmatic arachnoiditis involves the optic nerves and the chiasmatic cisterns, the fluid-filled spaces surrounding the optic chiasm where fibers from both eyes cross. Inflammation and fibrosis in this region entrap the optic pathways, causing progressive, often irreversible loss of vision. Because the optic chiasm sits directly above the suprasellar cistern and within reach of the basal inflammatory exudate of tuberculous meningitis, it is uniquely vulnerable when paradoxical inflammation flares at the base of the brain.

All three patients in the series followed the same ominous trajectory. Each initially improved after starting anti-tuberculous therapy, consistent with the drugs doing their job. Then, during the course of treatment, they developed new neurological deterioration and radiological changes consistent with a paradoxical reaction. Neuroimaging revealed suprasellar tuberculomas, granulomatous masses in the region above the pituitary fossa, together with basal cisternal involvement affecting the optic pathways in every case. The pattern of optochiasmatic arachnoiditis was thus visible on magnetic resonance imaging as inflammatory disease encasing the structures that carry visual signals from the eyes to the brain.

Managing these patients proved extraordinarily difficult. Treatment required prolonged high-dose corticosteroid therapy to suppress the runaway inflammatory response, an approach that carries its own substantial risks when maintained for months. In selected cases, the team added adjunctive immunomodulatory therapy, including thalidomide, a drug with potent anti-tumor necrosis factor-alpha activity that has been used experimentally in severe central nervous system tuberculosis and in refractory paradoxical reactions. Thalidomide’s mechanism is relevant here: by inhibiting tumor necrosis factor-alpha, it aims to blunt the very cytokine driving the granulomatous flare, offering a targeted way to calm inflammation that corticosteroids alone could not control.

The outcomes were grim. Despite intensive immunosuppressive therapy, two patients died from complications related to prolonged immunosuppression. The surviving patient experienced persistent visual deficits, a lasting reminder that even when life is saved, the optic pathways damaged by optochiasmatic arachnoiditis may never fully recover. The authors emphasize that optochiasmatic arachnoiditis represents a rare but catastrophic paradoxical complication of tuberculous meningitis in HIV-negative patients, a population in whom paradoxical reactions are less commonly anticipated than in patients with HIV who begin antiretroviral therapy.

The series carries important lessons for clinicians worldwide. First, deterioration during anti-tuberculous therapy is not always treatment failure. Distinguishing paradoxical reactions from drug resistance, inadequate dosing or alternative diagnoses is essential, because the management strategies differ fundamentally: paradoxical worsening calls for intensified immunosuppression, not for changing anti-tuberculous drugs. Second, new visual symptoms in a patient being treated for tuberculous meningitis should prompt urgent neuroimaging of the suprasellar and chiasmatic regions, because early recognition of optochiasmatic arachnoiditis may allow intervention before irreversible fibrosis entombs the optic nerves. Third, the fatal complications of prolonged immunosuppression in two patients highlight the double-edged nature of the available therapies, which must suppress a destructive immune flare without leaving the patient defenseless against infection and other steroid-related harms.

The immunopathology underlying paradoxical reactions remains incompletely understood, and the authors argue that improved understanding is essential to guide targeted adjunctive therapies and improve outcomes. The interplay between mycobacterial antigen load, cell-mediated immunity, tumor necrosis factor-alpha and other cytokines determines whether residual disease smolders quietly or erupts into granulomatous inflammation around the optic chiasm. Better biomarkers to predict which patients will flare, and immunomodulatory agents that can be deployed with precision rather than through prolonged blunt immunosuppression, are the goals the field must pursue. For now, this Sri Lankan case series stands as a stark warning: the very success of anti-tuberculous therapy can ignite an inflammatory backlash capable of stealing a patient’s sight, and in the most severe cases, their life.

Published as an open access case report in BMC Infectious Diseases, the study adds to the growing recognition that central nervous system tuberculosis is not merely an infectious disease but an immunological battleground. As tuberculosis continues to affect millions globally, and as drug-resistant strains prolong treatment courses and expand the window for paradoxical events, awareness of optochiasmatic arachnoiditis among neurologists, infectious disease specialists and ophthalmologists could make the difference between timely intervention and permanent blindness. The Sri Lankan experience shows that vigilance during the treatment of tuberculous meningitis must extend beyond bacterial cure to the immune consequences of that cure itself.

Subject of Research: Health & Medicine

Article Title: Optochiasmatic arachnoiditis as a paradoxical reaction in tuberculous meningitis: a case series from Sri Lanka

Article References: de Alwis, S., Chandrasiri, D., Ruwanpathirana, P., Fernando, A., & Senanayake, B. (2026). Optochiasmatic arachnoiditis as a paradoxical reaction in tuberculous meningitis: a case series from Sri Lanka. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14471-4

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14471-4

Keywords: tuberculous meningitis, optochiasmatic arachnoiditis, paradoxical reaction, central nervous system tuberculosis, thalidomide, corticosteroids, Sri Lanka, BMC Infectious Diseases, Optochiasmatic, arachnoiditis, paradoxical, reaction

The study’s design was straightforward but rigorous. The researchers collected clinical data and contrast-enhanced cranial MRI images from all patients admitted with intracranial tuberculosis between January 2018 and March 2026. Each patient underwent follow-up lasting at least 12 months, after which outcomes were graded using the modified Rankin Scale, a standard clinical measure of functional disability. Patients scoring 0 to 2, meaning little to no disability, formed the favorable prognosis group of 67 individuals, while those scoring 3 to 6, ranging from moderate disability to death, formed the poor prognosis group of 52 patients.

Contrast-enhanced MRI was central to the investigation because it reveals pathological changes that plain CT and non-contrast imaging often miss. Gadolinium-based contrast agents leak across disrupted blood-brain barriers, highlighting thickened, inflamed meninges, tuberculomas, abscesses, and the characteristic basal enhancement pattern of tuberculous meningitis. This technique allowed the team to classify patients into imaging subtypes and to document complications such as cerebral infarction, hydrocephalus, and cerebral arteritis with far greater sensitivity than conventional approaches.

When the two prognosis groups were compared, striking differences emerged. Patients in the poor prognosis group were older and more frequently male. They more often presented with meningeal-type or mixed-type intracranial tuberculosis rather than the parenchymal form, and they showed significantly higher rates of meningeal thickening, involvement of the basal and pericallosal cisterns, multi-site meningeal involvement, acute cerebral infarction, hydrocephalus, and cerebral arteritis. Conversely, parenchymal-type disease and tuberculomas were less common in the poor outcome group, suggesting that disease confined to brain tissue with discrete granulomas may carry a better outlook than diffuse meningeal inflammation.

To move beyond simple associations, the researchers performed multivariate logistic regression, a statistical technique that isolates the independent contribution of each variable while controlling for all others. Three factors emerged as independent risk factors for poor long-term prognosis: age, acute cerebral infarction, and hydrocephalus. This finding is clinically meaningful because it separates true prognostic drivers from markers that merely travel alongside them. Meningeal thickening and arteritis, for example, were more common in poor-outcome patients but did not retain independent predictive value once infarction and hydrocephalus were accounted for.

The predictive model built from these three variables performed impressively well. Evaluated with receiver operating characteristic analysis, it achieved an area under the curve of 0.861, sensitivity of 70.1 percent, specificity of 89.6 percent, and overall accuracy of 80.7 percent. In practical terms, the model correctly identified nearly nine out of ten patients who would ultimately do well, while capturing seven out of ten of those destined for poor outcomes. An AUC above 0.85 is generally considered strong discrimination for a clinical prediction model, particularly one built on routinely available imaging and demographic data.

Each of the three predictors tells a coherent biological story. Older patients have less physiological reserve, more comorbidities, and blunted immune responses that impair clearance of infection and repair of tissue damage. Acute cerebral infarction in tuberculous meningitis typically results from inflammatory occlusion of small perforating arteries at the base of the brain, where exudate accumulates in the subarachnoid space and triggers vasculitis. Once brain tissue is lost to infarction, recovery is limited, and the infarct itself serves as a proxy for both disease severity and vascular involvement. Hydrocephalus, meanwhile, arises when inflammatory debris obstructs cerebrospinal fluid flow through the ventricular system or impairs its resorption at the arachnoid granulations, raising intracranial pressure and compressing neural tissue.

The Evans index, a ratio comparing the width of the frontal horns of the lateral ventricles to the maximal internal diameter of the skull, was among the imaging variables recorded, providing a quantitative measure of ventricular enlargement. Its inclusion alongside direct assessments of hydrocephalus reflects the study’s effort to capture both qualitative radiological judgments and reproducible morphometric markers. Similarly, the initial Glasgow Coma Scale score was documented for each patient, anchoring the clinical assessment at admission and allowing the investigators to account for baseline neurological status.

The implications for clinical practice are substantial. Patients with intracranial tuberculosis who present with advanced age, evidence of acute infarction on contrast-enhanced MRI, or ventricular enlargement can now be flagged early as high risk, prompting intensified monitoring, earlier consideration of surgical intervention for hydrocephalus such as ventriculoperitoneal shunting, and closer attention to antitubercular therapy optimization. Conversely, patients with parenchymal-type disease and tuberculomas, who showed more favorable outcomes in this cohort, may be candidates for less intensive follow-up protocols, though the authors caution that individualized assessment remains essential.

Limitations of the study are worth noting. As a single-center retrospective analysis, its findings require validation in larger, multicenter cohorts before widespread adoption of the risk model. The retrospective design also means that imaging protocols and clinical management may have varied over the eight-year enrollment period. Nevertheless, the study demonstrates that contrast-enhanced cranial MRI, already a mainstay of diagnosis in intracranial tuberculosis, can be repurposed as a prognostic tool, transforming a routine diagnostic scan into a roadmap for risk stratification and early intervention. As tuberculosis continues to pose a global burden, particularly in regions with limited neurosurgical resources, simple imaging-based predictors of outcome could help clinicians allocate intensive care where it matters most.

Subject of Research: Risk stratification of intracranial tuberculosis patients using contrast-enhanced MRI predictors of long-term prognosis

Article Title: Risk stratification in intracranial tuberculosis patients based on contrast-enhanced MRI

Article References: Wang, Y.-J., Qiu, X.-W., Wang, A.-L., Hu, Y.-N., Li, W.-Q., & Huang, X.-S. (2026). Risk stratification in intracranial tuberculosis patients based on contrast-enhanced MRI. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14479-w

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14479-w

Keywords: intracranial tuberculosis, contrast-enhanced MRI, hydrocephalus, cerebral infarction, tuberculous meningitis, prognosis, risk stratification, neuroradiology, modified Rankin Scale, cerebral arteritis, BMC Infectious Diseases, Risk

The research team, led by Ran Li and Zhancheng Gao of Peking University People’s Hospital together with collaborators across 24 Chinese hospitals, compared two regimens in patients treated for pneumonia caused by carbapenem-resistant Gram-negative bacilli, a group of pathogens that includes carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Klebsiella pneumoniae (CRKP), and carbapenem-resistant Pseudomonas aeruginosa (CRPA). All patients in the analysis received nebulized CMS, delivered as an inhaled aerosol intended to concentrate the drug at the site of infection in the lung. The study group additionally received intravenous CMS, while the control group received intravenous antibiotics that did not contain CMS.

Among 427 eligible patients, 215 were assigned to the study group and 212 to the control group. Because this was a retrospective cohort study, the investigators used propensity score matching in a 1:1 ratio for the primary analysis, a statistical technique that pairs patients from the two groups who have similar baseline characteristics, thereby reducing the influence of confounding factors such as age, illness severity, and underlying conditions. The matched analysis included 130 pairs. The median age was 69 years in the study group versus 71 years in the control group, and the proportion of male patients was 73.9 percent versus 85.4 percent. Most patients in both groups had no prior Gram-negative bacilli infection, at 86.9 percent and 88.5 percent respectively.

The pathogen mix differed between the matched groups in ways that matter for interpretation. Carbapenem-resistant Acinetobacter baumannii was the predominant organism in both arms but was more frequent in the study group, at 72.9 percent versus 55.3 percent. Carbapenem-resistant Klebsiella pneumoniae accounted for 9.3 percent versus 19.5 percent, and carbapenem-resistant Pseudomonas aeruginosa for 7.8 percent versus 12.2 percent. CRAB is notoriously difficult to eradicate and is a leading cause of hospital-acquired pneumonia in intensive care units, so the higher proportion of CRAB in the intravenous CMS arm makes the observed advantage in that arm particularly notable.

The results favored the intravenous CMS regimen on both effectiveness endpoints. Patients in the study group had a shorter duration of nebulized CMS, a median of 9 days versus 11 days in the control group, a difference that reached statistical significance at p = 0.02. The clinical response rate, a measure of whether the pneumonia improved under treatment, was 82.3 percent in the study group versus 70.8 percent in the control group, at p = 0.03. Bacterial eradication, meaning clearance of the resistant organism, was likewise better with intravenous CMS, at 80.6 percent versus 68.5 percent, again at p = 0.03.

To test whether these findings would hold beyond the matched sample, the researchers ran a supportive multivariable logistic regression using the entire cohort of 427 patients. This approach controls for potential confounding factors by including them as covariates in the regression model. The adjusted odds ratio for clinical response with the intravenous CMS regimen was 2.60, with a 95 percent confidence interval of 1.48 to 4.57 and p = 0.001. In plain terms, after accounting for baseline differences, patients receiving intravenous CMS plus nebulized CMS had roughly two and a half times the odds of clinical response compared with those receiving nebulized CMS plus intravenous non-CMS antibiotics.

Safety was a central concern, because colistin is known for nephrotoxicity, the potential to cause kidney injury, particularly when given systemically. The study found no significant difference in mortality between the two groups, and no significant difference in kidney injury. The absence of additional adverse events in the intravenous CMS arm is an important part of the message, since a regimen that improved effectiveness while adding new safety concerns would be a harder sell for clinicians already managing fragile, critically ill patients.

The technical rationale for combining inhaled and intravenous colistin is rooted in pharmacology. Colistimethate sodium is an inactive prodrug that is converted to the active antibiotic colistin in the body. Intravenous dosing of colistin has well-documented limitations in the lung: the drug penetrates poorly into lung tissue and epithelial lining fluid, which can leave the site of infection underdosed even when plasma concentrations are adequate. Nebulized delivery bypasses this barrier by depositing the aerosolized drug directly into the airways, achieving high local concentrations. The open question addressed by this study is whether the intravenous partner should also be CMS, providing systemic coverage with the same agent, or whether a different intravenous antibiotic with activity against the resistant organism can serve as the systemic component while nebulized CMS handles the local component.

The answer from this cohort favors keeping CMS in the intravenous component as well. One possible explanation is that the non-CMS intravenous antibiotics used in the control group may have had weaker or less reliable activity against the specific resistant pathogens involved, particularly CRAB, for which few alternatives exist. Another is that the dual CMS approach provides a higher total colistin exposure, both systemically and locally, which could translate into faster bacterial killing and shorter treatment courses, consistent with the shorter nebulized CMS duration observed in the study group.

As a retrospective cohort study, the analysis carries inherent limitations that the authors and readers must weigh. Treatment assignment was not randomized, and despite propensity score matching and multivariable adjustment, unmeasured confounding cannot be excluded. The pathogen distribution differed between groups, with more CRAB in the intravenous CMS arm, and the generalizability of findings from 24 Chinese hospitals to other settings remains to be established. The study was approved by the Ethical Review Committee of Peking University People’s Hospital and conducted in compliance with the Declaration of Helsinki, with informed consent waived for the retrospective design. The research received no specific grant from funding agencies, and the authors declare no competing interests. Published as open access on 18 September 2026, the article is citable under DOI 10.1186/s12879-026-14462-5 and is subject to further editorial edits before the final Version of Record replaces it. For clinicians confronting carbapenem-resistant Gram-negative bacilli pneumonia, the study adds evidence that when nebulized CMS is part of the regimen, pairing it with intravenous CMS rather than intravenous non-CMS antibiotics is associated with improved clinical response and bacterial eradication, without additional safety concerns.

Subject of Research: Antimicrobial Resistance

Article Title: Compare intravenous colistimethate sodium (CMS) with non-CMS antibiotics in combination with nebulized CMS for treating Carbapenem-resistant Gram-negative Bacilli (CR-GNB) pneumonia: a multicenter retrospective cohort study

Article References: Li, R., Fu, Y., Mu, G., Cheng, C., Zhao, M., Gu, Y., Zhang, C., Tao, Y., Yi, Y., Xu, H., Li, D., Wang, G., Chai, S., Dai, B., Xu, Y., Deng, S., Dou, L., Wang, Z., Zhang, Y., & Gao, Z. (2026). Compare intravenous colistimethate sodium (CMS) with non-CMS antibiotics in combination with nebulized CMS for treating Carbapenem-resistant Gram-negative Bacilli (CR-GNB) pneumonia: a multicenter retrospective cohort study. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14462-5

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14462-5

Keywords: colistimethate sodium, nebulized colistin, carbapenem-resistant Gram-negative bacilli, CRAB, CRKP, CRPA, pneumonia, antimicrobial resistance, BMC Infectious Diseases, propensity score matching, Compare, intravenous

The research team, led by João Paulo Cola and Thiago Nascimento do Prado and spanning institutions including the State Department of Health of Espírito Santo, the Federal University of Espírito Santo, the Federal University of Rio de Janeiro, and the Oswaldo Cruz Institute, analyzed notifications recorded in Brazil’s national tuberculosis database between 2018 and 2023. Their focus was a cohort of children and young adolescents aged 0 to 15 years who had been prescribed tuberculosis preventive treatment, commonly abbreviated TPT. Out of 31,121 notified cases, 24,903 carried complete outcome information — a substantial analytical sample that allowed the investigators to model completion patterns with statistical rigor using a robust variance Poisson regression approach, reporting relative risks with 95 percent confidence intervals.

The headline finding is both encouraging and sobering. Completion rates were modestly higher among children aged 5 to 9 years, with a relative risk of 1.02 (95 percent CI 1.01–1.04), and among adolescents aged 10 to 15, with a relative risk of 1.03 (95 percent CI 1.02–1.05). Children of white skin color showed slightly higher completion (RR 1.02; 95 percent CI 1.01–1.03), as did those vaccinated with BCG (RR 1.05; 95 percent CI 1.02–1.08) and those using immunosuppressive therapy (RR 1.07; 95 percent CI 1.03–1.19). But the strongest signals belonged to the treatment regimens themselves: shorter courses of four months of rifampicin (RR 1.10; 95 percent CI 1.08–1.12) and three months of isoniazid plus rifapentine (RR 1.13; 95 percent CI 1.12–1.15) were associated with meaningfully better completion than the traditional long-course alternatives.

To appreciate why these numbers matter, it helps to understand the pharmacological landscape of preventive therapy. For decades, the global standard for treating latent tuberculosis infection has been six to nine months of daily isoniazid — regimens designated 6H and 9H in the study’s nomenclature, involving 180 to 270 doses taken over six to twelve months. Adherence to such prolonged schedules is notoriously difficult for anyone, let alone a toddler or a teenager juggling school, family dynamics, and the general impatience of youth. Each additional month of daily pills multiplies the opportunities for missed doses, side effects, caregiver fatigue, and eventual dropout. The alternative regimens examined in this study flip that equation: 4R consists of 120 doses of rifampicin taken over four to six months, while 3HP — the regimen combining rifapentine with isoniazid — requires only 12 weekly doses administered over 12 to 15 weeks. The 3HP scheme, in particular, represents a paradigm shift, compressing what was once nearly a year of daily compliance into roughly three months of weekly visits.

The Brazilian health system context amplifies the significance of these findings. Brazil’s Unified Health System, known locally as SUS, provides tuberculosis care free of charge across a vast and geographically diverse country, and the national surveillance infrastructure — including the Information System for Notification of People on Tuberculosis Preventive Treatment, or IL-TB — captures granular data on who is prescribed preventive therapy and how their courses conclude. This study leveraged that infrastructure to assemble one of the most comprehensive pictures to date of pediatric preventive treatment in a high-burden, middle-income setting. The cohort period, 2018 to 2023, also straddles an important policy transition: the gradual introduction of shorter regimens, including 3HP, into Brazilian clinical practice following World Health Organization recommendations.

Notably, the association between 3HP and completion held even after the researchers adjusted for demographic and clinical confounders in their multivariate model. A relative risk of 1.13 may sound incremental, but when applied across tens of thousands of treatment courses, it translates into thousands of additional children who finish therapy and thereby gain durable protection against future active disease. The 4-month rifampicin regimen showed a similar magnitude of benefit at RR 1.10. These effect sizes are consistent with the broader international literature, which has repeatedly demonstrated that shorter preventive regimens outperform longer ones on adherence, though direct comparisons across health systems are complicated by differences in drug availability, cost, and clinical guidelines.

One of the more intriguing findings concerns the youngest children. Those under 5 years of age did not show the modest completion advantage observed in older age bands — and this matters enormously from a public health standpoint, because children under 5 who are household contacts of infectious tuberculosis cases face the highest risks of rapid progression from infection to severe, disseminated disease such as tuberculous meningitis. Pediatric guidelines therefore prioritize this age group for preventive treatment, often without requiring confirmation of infection through a tuberculin skin test or interferon gamma release assay. Yet the very factors that make young children a priority — their dependence on caregivers for every dose, the challenges of administering medications formulated for adults, and the frequency of intercurrent childhood illnesses that interrupt treatment — also make them the most vulnerable to incomplete courses. The study’s authors conclude that targeted strategies to improve adherence among children younger than 5 years may be essential to enhancing overall completion in Brazil.

The associations with BCG vaccination status and skin color deserve careful interpretation. The finding that BCG-vaccinated children showed higher completion (RR 1.05) likely reflects underlying differences in healthcare access and surveillance rather than any direct pharmacological effect of the vaccine on adherence. Similarly, the modest completion advantage among children recorded as having white skin color (RR 1.02) echoes well-documented patterns of health inequity in Brazil, where structural factors — including socioeconomic status, geographic proximity to clinics, and the quality of patient-provider interactions — shape treatment trajectories long before a prescription is written. The researchers were careful to characterize these associations as modest, and the confidence intervals, while statistically significant, indicate effects that are real but small in absolute terms. The clinical and policy implications therefore hinge less on any single demographic factor and more on the systemic levers — regimen choice above all — that can be pulled at scale.

The finding that children on immunosuppressive therapy showed higher completion (RR 1.07; 95 percent CI 1.03–1.19) is also worth unpacking. These are children whose underlying conditions — perhaps autoimmune diseases, oncologic diagnoses, or pre-transplant preparation — require medications that dampen the immune system, dramatically raising the stakes of untreated latent tuberculosis infection, which can reactivate catastrophically under immunosuppression. In such cases, families and clinicians alike have powerful, immediate motivations to see preventive therapy through to completion, and the data suggest that this heightened vigilance translates into measurable adherence gains. It is a reminder that perceived risk is one of the strongest drivers of health behavior, and that communicating the seriousness of latent infection to families of otherwise healthy children remains an ongoing challenge.

As the world pursues the End TB Strategy’s goals of drastic reductions in tuberculosis incidence and mortality, the study’s message is clear: the tools to prevent disease in children already exist, and the frontier now lies in delivery. Shorter regimens like 3HP and 4-month rifampicin offer a pharmacological shortcut to adherence, but their impact will be realized only if health systems can reliably identify eligible children, initiate treatment promptly after exposure, and support families through the full course. Brazil’s experience, documented across more than 31,000 pediatric notifications over six years, provides both a warning — that the youngest and most vulnerable remain the hardest to reach with complete preventive courses — and a roadmap, showing that regimen simplification is among the most effective levers available. For a disease that has coexisted with humanity for millennia, the quiet arithmetic of pill counts and completed courses may prove as consequential as any laboratory breakthrough.

Subject of Research: Completion of tuberculosis preventive treatment among children and adolescents aged 0 to 15 years in Brazil

Article Title: Completion of tuberculosis preventive treatment in children and adolescents aged 0 to 15 in Brazil: analysis of a retrospective cohort

Article References: Cola, J. P., da Conceição Costa, L., de Souza, F. M., Caetano, C. L., dos Santos, G. S., Sales, C. M. M., Carvalho, A. C. C., Maciel, E. L. N., & do Prado, T. N. (2026). Completion of tuberculosis preventive treatment in children and adolescents aged 0 to 15 in Brazil: analysis of a retrospective cohort. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14204-7

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14204-7

Keywords: tuberculosis, preventive treatment, children, adolescents, Brazil, 3HP regimen, isoniazid, rifapentine, rifampicin, treatment adherence, public health, BMC Infectious Diseases

The study included 3,586 patients who had been tested with a multiplex real-time PCR respiratory panel after initially testing negative for SARS-CoV-2. This design choice is important: because the COVID-19 pandemic dominated respiratory diagnostics from 2020 onward, patients negative for the coronavirus were typically then screened with broader panels capable of detecting a wide range of viruses and bacteria simultaneously. Multiplex PCR works by amplifying genetic material from multiple target organisms in a single reaction, allowing laboratories to identify pathogens such as influenza viruses, respiratory syncytial virus, rhinoviruses, adenoviruses, and bacterial species like Streptococcus pneumoniae and Haemophilus influenzae from one sample. The technique has become a cornerstone of modern respiratory surveillance, particularly in settings where clinical symptoms alone cannot distinguish between viral and bacterial causes of infection. In this cohort, 62.4 percent of the patients were children, reflecting the fact that young people bear a disproportionate burden of acute respiratory tract infections and are tested more frequently with these panels.

Overall, at least one pathogen was detected in 52.6 percent of the samples, but the identity of those pathogens was striking. The most frequently detected organism was Streptococcus pneumoniae, found in 36.7 percent of samples, followed by Haemophilus influenzae at 8.2 percent, rhinovirus at 6.1 percent, and human bocavirus and influenza A, each at 2.8 percent. The dominance of bacterial detections, particularly pneumococcus, is notable because multiplex PCR detects genetic material rather than viable organisms, and colonizing bacteria can be present in the airways without causing disease. Nevertheless, the pattern provides a snapshot of what was circulating in the population’s respiratory tracts during the study window. Positivity rates were dramatically higher in children than in adults, at 64.5 percent versus 33.0 percent, a difference that was highly statistically significant. Detection also peaked in autumn and winter, consistent with the well-documented seasonality of respiratory infections in temperate climates, where indoor crowding and lower humidity favor transmission.

The temporal trends across the four years were equally revealing. Overall positivity declined from 57.5 percent in 2021 to 34.8 percent in 2023, and then rebounded sharply to 60.7 percent in 2024. This trajectory mirrors patterns observed globally after the COVID-19 pandemic, when widespread masking, distancing, and lockdowns suppressed transmission of many common respiratory pathogens, only for them to return with unusual intensity once restrictions lifted. The dip in 2023 is particularly interesting because it coincides with the year of the earthquakes, which struck in February and upended daily life across the region. Yet the researchers found that the overall rate of pathogen detection was almost identical before and after the earthquakes, at 52.5 percent versus 52.7 percent. On the surface, the disaster appeared to have left the total burden of detectable respiratory pathogens essentially unchanged.

Beneath that stable overall figure, however, the composition of detected pathogens shifted in ways that initially seemed alarming. In unadjusted comparisons, bacterial positivity rose from 34.2 percent before the earthquakes to 44.9 percent afterward, while viral positivity fell from 31.2 percent to 19.8 percent. This pattern would be consistent with what disaster epidemiologists might predict: displacement into crowded shelters, interruption of routine healthcare, and stress-induced immune suppression could plausibly increase bacterial carriage and transmission, while reduced social mixing in some settings or altered testing patterns might suppress viral detection. When the researchers built multivariable logistic regression models adjusting for age group, sex, season, clinical setting, year of sampling, and PCR platform, the signal persisted in some analyses. Compared with 2021, the adjusted odds of bacterial detection in 2024 were 5.50 times higher, with a 95 percent confidence interval of 3.51 to 8.63, a substantial and statistically robust increase.

But the story took a decisive turn when the team applied sensitivity analyses designed to test the robustness of the earthquake association. When they restricted the post-earthquake period to just the first 12 months after the disaster, the increases in bacterial and pneumococcal detection disappeared. When they restricted the analysis to samples tested only with the Bio-Speedy platform, one of the PCR systems used in the laboratory during the study period, the increases were not reproduced either. These findings matter because they suggest that the apparent post-earthquake bacterial surge may have been an artifact of how the comparison windows were defined or of changes in testing platforms and laboratory workflows over time, rather than a genuine biological effect of the earthquakes. The authors explicitly state that the differences between pre- and post-earthquake periods varied according to the time window and analytic subset examined, and that the data do not support attributing these differences specifically to the earthquakes.

This methodological caution is one of the study’s most valuable contributions. Natural experiments like earthquakes generate enormous public health interest, and observational data from affected regions are often the only evidence available in the chaotic aftermath of disaster. Yet such data are vulnerable to confounding by indication, changes in who gets tested, shifts in laboratory capacity, and the simple passage of time. A patient tested in late 2024 differs from one tested in 2021 not only in earthquake exposure but also in pandemic-era immune history, vaccination status, healthcare access, and the diagnostic technology applied to their sample. By showing that a seemingly compelling association dissolved under alternative analytic choices, the study offers a template for how respiratory surveillance data should be interrogated before dramatic conclusions are drawn about disaster-driven outbreaks.

The findings also carry practical implications for laboratories and public health agencies. Multiplex PCR panels are powerful tools, but their results depend on the specific platform, the panel composition, and the clinical context in which testing is ordered. The fact that restricting the analysis to a single PCR platform changed the results underscores how technical factors can shape epidemiological signals. The authors argue that multiplex PCR-based surveillance may be valuable for monitoring respiratory pathogen dynamics during periods of epidemiological disruption, precisely because such periods are when conventional assumptions about seasonality and pathogen distribution break down. Continuous, standardized surveillance, they suggest, is the best defense against both missed outbreaks and false alarms.

The research was supported by the Scientific Research Projects Coordination Unit of Mersin University and approved by the university’s Health Sciences Research Ethics Committee, which waived the requirement for informed consent given the retrospective design and use of anonymized routine clinical data. As the region continues to recover from one of the deadliest earthquakes in modern history, the study provides reassurance that the disaster did not produce a measurable, sustained shift in the overall burden of detectable respiratory pathogens, while simultaneously demonstrating how much careful statistical work is required to separate genuine epidemiological change from the noise of a health system in upheaval. For infectious disease watchers, the message is twofold: respiratory pathogens in southern Türkiye followed their own temporal rhythms through pandemic and earthquake alike, and the tools we use to watch them must be scrutinized as rigorously as the pathogens themselves.

Subject of Research: Temporal patterns of respiratory pathogen detection by multiplex PCR in southern Türkiye before and after the 2023 earthquakes

Article Title: Temporal patterns of respiratory pathogen detection in southern Türkiye: a retrospective multiplex PCR study with pre- and post-earthquake comparisons

Article References: Gülbudak, H., Bozok, T., Bekci, A., Ülger, S. T., & Aslan, G. (2026). Temporal patterns of respiratory pathogen detection in southern Türkiye: a retrospective multiplex PCR study with pre- and post-earthquake comparisons. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14638-z

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14638-z

Keywords: respiratory pathogens, multiplex PCR, Streptococcus pneumoniae, earthquakes, Türkiye, epidemiology, respiratory tract infections, post-pandemic, surveillance, BMC Infectious Diseases, bacterial detection, rhinovirus

Peptoniphilus harei belongs to a family of microbes that most physicians will never encounter by name. It is a gram-positive anaerobic coccus, meaning it stains purple under the Gram stain, thrives in the absence of oxygen, and grows as spherical cells. These organisms normally live quietly among the diverse bacterial communities of human skin and mucosal surfaces. According to the report, P. harei invades soft tissues and causes suppurative infections, abscess-forming, pus-producing disease, when the skin or mucosal barrier is compromised. In other words, the bacterium is an opportunist: it waits for a break in the body’s defenses and then establishes a foothold in the tissue beneath.

The patient’s story began at a local hospital, where she presented with pain and swelling in the region beside her left ear, the paraauricular region. When initial evaluation suggested a collection of pus rather than a simple cellulitis, she was referred to the Liaocheng team. Upon admission, the clinicians aspirated pus from the swelling, a step that served both to relieve pressure and to obtain the specimen that would ultimately identify the culprit. The aspirated material was sent for culture, and the laboratory’s analysis identified the growing organism as P. harei using matrix-assisted laser desorption ionization-time of flight mass spectrometry, a technique known in the trade as MALDI-TOF MS.

MALDI-TOF MS has transformed clinical bacteriology over the past two decades, and this case illustrates why. The method works by firing a laser at the organism’s proteins embedded in a crystal matrix, ionizing them, and measuring the time the ions take to fly through a vacuum tube toward a detector. The resulting spectrum acts as a proteomic fingerprint that can be matched against reference databases. For anaerobic bacteria like P. harei, which are slow-growing, fastidious, and difficult to characterize by traditional biochemical tests, mass spectrometry often provides in minutes an identification that once required days of laborious manual work. The technology’s accuracy depends on the completeness of the reference library, and the successful identification in this case reflects how thoroughly these databases now cover even uncommon anaerobes.

Once the culture confirmed the identity of the organism, the clinical team moved to definitive treatment. The abscess was debrided and drained, the surgical cornerstone of managing any walled-off collection of pus, and the patient received antibiotics targeted at the recovered organism. She made a gradual recovery. This combination of source control and antimicrobial therapy remains the standard approach for soft-tissue abscesses, and the case demonstrates that infections involving unusual anaerobes respond to the same principles that govern more familiar pathogens.

To place their patient in context, the authors conducted a literature review of prior P. harei infections. The organism has previously been associated with a range of suppurative and invasive conditions at other anatomical sites, and the new report is, to the best of the authors’ knowledge, the first documented case of P. harei infection presenting as a paraauricular soft-tissue abscess. That distinction matters for clinicians working in otorhinolaryngology and head and neck surgery, because the differential diagnosis for swelling near the ear typically centers on more common entities, including parotid gland disease, odontogenic infections spreading from the teeth, and infections of overlying skin. An anaerobic coccus from the Peptoniphilus genus would rarely appear high on that list.

The diagnostic workup described in the report also highlights the layered approach modern laboratories take to anaerobic infections. Alongside culture on blood agar plates and anaerobic blood agar plates, the evaluation referenced in the case includes routine inflammatory markers such as the complete blood count, C-reactive protein, and the erythrocyte sedimentation rate, together with imaging by computed tomography when deeper extension needs to be excluded. For definitive identification, the field increasingly relies on MALDI-TOF MS and, when spectra are ambiguous, 16S rRNA gene sequencing, which reads a conserved stretch of the bacterial genome to place an organism on the tree of life. Each layer narrows the uncertainty until a precise species-level answer emerges.

Why does a single case report deserve attention? The authors argue that documenting rare presentations improves the efficiency of diagnosis and treatment. When clinicians read that P. harei can produce an abscess beside the ear, the organism enters their mental library of possibilities, and the next patient with a similar picture may be diagnosed faster. Anaerobic cultures are frequently discarded or reported as mixed flora when laboratories lack the tools or the persistence to identify every isolate, so published cases also signal to microbiology departments that these organisms are worth pursuing. The report, the team writes, enhances clinicians’ understanding of the clinical sites of infection, manifestations, diagnostic methods, and surgical and antimicrobial treatments for P. harei.

The biology of Peptoniphilus species adds further interest. These gram-positive anaerobic cocci were once lumped among the so-called Peptostreptococcus group before genomic analysis scattered them into separate genera. They are among the organisms that flourish in polymicrobial infections, where several bacterial species cooperate to overcome host defenses, and they are increasingly recognized in abscesses, diabetic foot wounds, prosthetic joint infections, and other settings where tissue oxygen levels are low. The paraauricular case fits this pattern: a barrier breach, a low-oxygen niche, and an opportunist ready to exploit it.

For the patient, the outcome was a gradual recovery after drainage and antibiotics. For the wider clinical community, the case is a reminder that the paraauricular region, like every anatomical site, can host infections caused by organisms far outside the usual suspects, and that mass spectrometry has made identifying such organisms routine rather than exceptional. The study was approved by the Clinical Research Ethics Committee of Liaocheng People’s Hospital and conducted with the patient’s written informed consent, and the article is published open access so that clinicians anywhere can add this rare presentation to their diagnostic repertoire.

Subject of Research: First documented case of a paraauricular soft-tissue abscess caused by the anaerobic bacterium Peptoniphilus harei

Article Title: Paraauricular soft-tissue abscess associated with Peptoniphilus harei: a case report and literature review

Article References: Lv, Y., Xu, J., Shi, G., Gong, L., Li, L., Song, P., & Huang, Q. (2026). Paraauricular soft-tissue abscess associated with Peptoniphilus harei: a case report and literature review. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14659-8

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14659-8

Keywords: Peptoniphilus harei, anaerobic bacterial infection, soft tissue abscess, paraauricular region, MALDI-TOF MS, case report, BMC Infectious Diseases, gram-positive anaerobic coccus, abscess drainage, antimicrobial therapy, clinical microbiology, head and neck infection