Study Pinpoints Risk Factors Driving Central Line Infections in Adult ICUs

Central lines are lifelines for critically ill patients, delivering medications, nutrition, and fluids directly into major veins. But these same devices carry a serious risk: central line-associated bloodstream infection, or CLABSI, one of the most dangerous yet preventable healthcare-associated infections in intensive care units worldwide. A new retrospective matched case-control study conducted at a large tertiary referral center in Iran has now mapped out the specific patient characteristics and care-related factors that converge to drive this infection, offering clinicians a detailed empirical foundation for risk stratification and prevention.

The research, published in BMC Infectious Diseases, examined adult patients admitted to nine intensive care units at Namazi Hospital in Shiraz between January 2018 and December 2023. From 3,200 eligible records, the team identified 205 patients with confirmed CLABSI and compared them with 412 infection-free controls selected through 1:2 nearest-neighbor matching on age and sex. This design allowed investigators to isolate the factors that truly distinguish infected patients from otherwise similar critically ill individuals, rather than simply comparing them with the general ICU population.

Using multivariable binary logistic regression, the researchers identified seven independent risk factors for CLABSI. Medical hospitalization type nearly two-and-a-half-folded the odds of infection (adjusted odds ratio of 2.428, p < 0.001), while admission to a general ICU rather than a specialized unit nearly tripled the risk (adjusted OR of 3.068, p < 0.001). Invasive mechanical ventilation within the first 24 hours of ICU stay increased the odds nearly twofold (adjusted OR of 1.971, p = 0.013), reflecting the added vulnerability that comes with early invasive support.

Care received before the ICU also left a measurable imprint. Prior antibiotic use before ICU admission more than doubled the infection odds (adjusted OR of 2.768, p = 0.008), and each additional day spent hospitalized before reaching the ICU incrementally raised the risk (adjusted OR of 1.047 per day, p = 0.011). These findings point to pre-ICU healthcare exposure as a critical window during which patients may already be colonized with resistant organisms or depleted of protective microbiota before a central line is ever placed.

Patient physiology mattered as well. Each unit increase in body mass index raised the odds of CLABSI by roughly 5 percent (adjusted OR of 1.055 per kg/m², p = 0.008), and each degree Celsius of elevated core temperature increased the odds by about 66 percent (adjusted OR of 1.662, p = 0.012). Elevated body temperature, often a marker of systemic inflammation or early sepsis, may both reflect underlying illness severity and create conditions that favor microbial migration along the catheter tract.

Not all factors pointed toward danger. Several characteristics proved protective against CLABSI. Patients admitted directly from home had roughly 39 percent lower odds of infection (adjusted OR of 0.613, p = 0.021), and those arriving from the operating theatre or recovery room also showed reduced risk (adjusted OR of 0.647, p = 0.048). These patterns suggest that patients coming from controlled, relatively sterile environments carry fewer colonizing organisms than those funneled through emergency departments or general wards.

Neurological and hematological status also shaped the risk profile. Each point increase on the Glasgow Coma Scale, a standard measure of consciousness, modestly reduced the odds of CLABSI (adjusted OR of 0.950, p = 0.032), while higher platelet counts offered a small but statistically significant protective effect (adjusted OR of 0.998, p = 0.024). Better-preserved neurological function and intact hematological reserves likely reflect less severe illness overall, underscoring that CLABSI risk is deeply intertwined with the patient’s underlying trajectory rather than the catheter alone.

Microbiological analysis revealed the causative organisms behind these infections. Klebsiella species dominated, accounting for 22.2 percent of cases, followed by Acinetobacter species at 13.4 percent. Both genera are notorious for multidrug resistance in hospital settings, and their prominence in this cohort reinforces concerns about the growing threat of resistant Gram-negative pathogens in intensive care environments. The microbiological pattern also aligns with the finding that pre-ICU antibiotic exposure and prolonged pre-ICU hospitalization independently raise infection risk, since both factors select for resistant colonizing strains.

The study team took careful statistical precautions before building their model. Multicollinearity among predictor variables was assessed using the variance inflation factor and tolerance, ensuring that the adjusted odds ratios genuinely reflect each factor’s independent contribution rather than overlapping effects. The single-center design, while limiting generalizability, also provided consistency in diagnostic criteria, infection surveillance, and care protocols across the nine ICUs studied, strengthening the internal validity of the findings.

Taken together, the results paint CLABSI risk as a convergence of pre-ICU healthcare exposure, illness severity, invasive interventions, and patient physiology. The authors suggest these findings may inform future research on risk stratification and targeted prevention strategies, potentially allowing intensive care teams to identify high-risk patients early and intensify line-management precautions accordingly. As central venous catheters remain indispensable in modern critical care, understanding precisely who is most vulnerable to this preventable infection represents a meaningful step toward safer intensive care.

Beyond the headline findings, the study’s design choices deserve attention because they shape how confidently the results can be interpreted. By matching each CLABSI case to two controls on age and sex, the investigators controlled for two of the most pervasive confounders in infection research: older patients generally face higher infection risk, and sex can influence both immune responses and patterns of healthcare utilization. Nearest-neighbor matching, a technique that pairs each case with the most similar available controls, helped ensure that the comparison groups were balanced on these dimensions before any other variables entered the regression model. This approach is particularly valuable in retrospective studies, where randomization is impossible and selection bias can otherwise distort the apparent effect of care-related exposures.

The choice of a matched case-control design also reflects the practical realities of studying CLABSI. Because the infection is relatively uncommon even among patients with central lines, following a large cohort prospectively to accumulate enough cases would require years of surveillance and considerable resources. By starting with confirmed cases and working backward to identify comparable controls, the researchers could efficiently examine a six-year window of ICU admissions. The trade-off is that case-control studies can establish association but not definitive causation, and unmeasured factors—such as catheter insertion site, dressing type, line maintenance practices, or individual clinician behavior—may have differed between cases and controls in ways the available records could not capture.

The dominance of Klebsiella and Acinetobacter species in this cohort fits within a broader epidemiological pattern recognized across intensive care units in many regions. These Gram-negative organisms are equipped with efficient mechanisms for acquiring antibiotic resistance, including extended-spectrum beta-lactamases in Klebsiella and a wide repertoire of resistance determinants in Acinetobacter. Their capacity to survive on inanimate surfaces and medical equipment for extended periods makes them formidable opponents in the ICU environment, where catheters, ventilator circuits, and other devices create multiple pathways for bloodstream invasion. The finding that nearly one in four CLABSI cases in this study involved Klebsiella species underscores how the microbiology of device-associated infections has shifted in settings where Gram-negative organisms predominate, in contrast to older surveillance data from some regions where coagulase-negative staphylococci were more frequently reported.

The protective effect of admission from the operating theatre or recovery room offers an interesting window into how the trajectory of care influences infection risk. Patients arriving from the surgical suite have typically undergone recent preoperative preparation, including skin antisepsis, and their hospital stay before ICU arrival is often brief and tightly controlled. In contrast, patients transferred from general wards or emergency departments may have spent days in environments where resistant organisms circulate more freely, accumulating healthcare exposure that the study found to be independently associated with infection. This gradient of risk along the admission pathway suggests that the moments before ICU arrival are not merely logistical details but biologically meaningful exposures that shape the microbial landscape a patient carries when a central line is placed.

The relationship between fever and CLABSI risk also merits careful interpretation. Elevated core temperature was measured as a continuous variable, with each additional degree Celsius raising the odds by roughly two-thirds. While fever may simply mark more severe underlying illness, it is also plausible that febrile patients undergo more frequent line manipulations, blood draws, and diagnostic evaluations, each of which creates opportunities for catheter contamination. Disentangling whether fever is a cause, a consequence, or a correlate of infection risk remains a challenge for future prospective work.

Similarly, the modest per-unit effects of BMI, Glasgow Coma Scale score, and platelet count should be understood in context. Individually, each point or unit change shifts risk only slightly, but critically ill patients often differ substantially across these measures, so the cumulative impact across a population can be considerable. The combination of higher BMI, lower consciousness scores, and thrombocytopenia may identify a phenotype of vulnerability—patients whose adiposity complicates line insertion and dressing adherence, whose impaired consciousness increases aspiration and colonization risk, and whose falling platelets signal worsening physiology.

For clinicians, the practical implication is that CLABSI prevention cannot rely on catheter care alone. The study suggests that risk accumulates before the ICU is ever reached, shaped by prior antibiotic exposure, length of pre-ICU hospitalization, and the route by which a patient arrives. Integrating admission source, recent care history, and baseline physiological status into bedside risk assessment could help intensive care teams decide which patients warrant the most rigorous line-avoidance strategies, earliest possible catheter removal, and heightened surveillance. As antimicrobial resistance continues to reshape the microbiology of healthcare-associated infections, studies like this one provide the granular, locally grounded evidence needed to target prevention where it matters most.

Subject of Research: Infectious Diseases

Article Title: Patient- and care-related factors associated with central line-associated bloodstream infection in adult intensive care units: a retrospective matched case-control study at a tertiary referral center

Article References: Homayoun, B., Zand, F., Asmarian, N., Rosenthal, V. D., Abrishamifar, K., Niakan Kalhori, S. R., Shafiee, E., & Banifatemi, M. (2026). Patient- and care-related factors associated with central line-associated bloodstream infection in adult intensive care units: a retrospective matched case-control study at a tertiary referral center. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14435-8

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14435-8

Keywords: Patient-, care-related, factors, associated, central, line-associated, bloodstream, infection, adult, intensive, care, units