Cervical cancer remains one of the most significant threats to women’s health worldwide, ranking as the fourth most common malignancy among women globally. More than 600,000 new cases are diagnosed each year, and nearly 90 percent of them occur in resource-limited countries. In China, the disease is increasingly affecting younger women, intensifying the urgency of understanding why some HPV infections resolve quietly while others progress to precancerous lesions and cancer. Persistent infection with high-risk HPV is firmly established as the primary cause, yet only a small fraction of infected women ever develop invasive disease, a discrepancy that has long pointed to additional cofactors.

Among those cofactors, the microbial communities of the vagina and cervix have emerged as compelling suspects. In healthy women, the genus Lactobacillus typically dominates the reproductive tract, maintaining an acidic environment, competitively excluding pathogens, and modulating local immune responses. Epidemiological studies have consistently identified bacterial vaginosis, a condition marked by depletion of Lactobacillus and overgrowth of anaerobic bacteria, as a risk factor for cervical neoplasia. However, the molecular mechanisms linking microbial dysbiosis to carcinogenesis, and the specific functional gene programs expressed by cancer-associated bacteria, have remained poorly defined. Conventional culture-based methods, limited in sensitivity and coverage, have also hindered comprehensive characterization of these complex ecosystems.

To address these gaps, researchers recruited women visiting gynecology departments at Nanchong Hospital, Beijing Anzhen Hospital, and Capital Medical University between January and June 2024. After applying strict inclusion and exclusion criteria, 32 women aged 45 to 65 were enrolled and stratified by vaginal discharge microscopy and cervical biopsy histopathology into 16 cervical cancer patients and 16 healthy controls. Crucially, all cancer patients tested positive for high-risk HPV while all controls were HPV-negative, providing a clean contrast that allowed the team to attribute microbial shifts specifically to HPV-driven disease. Women with recent antibiotic use, vaginal douching, bacterial vaginosis, sexually transmitted infections, prior cervical lesions, or systemic diseases were excluded, minimizing confounding.

The team collected sterile swabs from both the vaginal wall and the cervical os during gynecological examinations, extracted genomic DNA, and amplified the hypervariable V3-V4 region of the bacterial 16S rRNA gene. Sequencing was performed on an Illumina MiSeq platform with paired-end 300-base reads, and the data were processed using the DADA2 algorithm within the QIIME 2 framework to denoise reads, merge pairs, remove chimeras, and construct amplicon sequence variants. Taxonomic annotation relied on a pre-trained Naive Bayes classifier against the Greengenes reference database. After quality filtering excluded three samples from each group, 13 participants per group formed the final analytical cohort, which was well matched for body mass index, pregnancies, menstrual characteristics, and other clinical variables.

The compositional results were striking. Healthy controls were uniformly dominated by Lactobacillus, with a median relative abundance of 72.5 percent and minimal variation between individuals. In cervical cancer patients, Lactobacillus abundance collapsed to a median of just 12.5 percent, a highly significant difference. In its place, anaerobic genera flourished: Prevotella rose from a median of 6.8 percent in controls to 28.3 percent in cancer patients, while Peptostreptococcus, Fusobacterium, Enterococcus, and Corynebacterium were also enriched. The cancer group showed higher overall microbial diversity, greater inter-individual variability, and, notably, site-specific heterogeneity between the vaginal wall and cervical os, whereas healthy women maintained stable communities across both anatomical sites.

Diversity metrics reinforced this picture of ecological disruption. Species richness indices such as Chao1 and observed species did not differ between groups, indicating that cancer samples did not simply gain or lose bacterial types but instead underwent a wholesale shift in community composition. Pielou’s evenness was significantly lower in cancer patients, while Shannon and Simpson indices and Faith’s phylogenetic diversity were all elevated, reflecting colonization by multiple opportunistic pathogens and a fragmented community structure following the collapse of the Lactobacillus-dominated stable state. Analysis of similarities based on Bray-Curtis distances confirmed a statistically significant, though moderate, separation between the groups, with an R-value of 0.218 and a p-value of 0.001. When the cancer patients were subdivided by HPV genotype into HPV16-positive and HPV-positive/non-16 subgroups, community structure remained comparable between the two, suggesting that high-risk HPV infection as a whole, rather than any particular subtype, exerts the dominant selective pressure on the cervical microenvironment.

Network analysis and functional prediction pushed the findings beyond taxonomy into mechanism. Co-occurrence networks built with the SparCC algorithm revealed that healthy samples centered on a stable Lactobacillus-driven network, whereas cancer samples displayed a more complex, Prevotella-centered pathogenic network, with Lactobacillus showing widespread negative associations with Prevotella that suggest competitive exclusion between a health-associated commensal and potential pathogens. Functional prediction using PICRUSt2 mapped gene families onto Kyoto Encyclopedia of Genes and Genomes pathways and revealed that glycolytic flux was significantly elevated in cancer samples, consistent with lactate accumulation and acidification of the tumor microenvironment, while oxidative phosphorylation was diminished, indicating a metabolic shift toward anaerobic fermentation. The aerobactin biosynthesis pathway, which enables bacteria to scavenge iron from the host, was markedly upregulated in the cancer cohort, hinting at a novel link between dysbiosis, iron acquisition, and tumor progression. Meanwhile, reduced representation of antigen-presentation and complement pathways suggested microbial strategies of immune evasion.

The study’s authors caution that several limitations temper these conclusions. The cross-sectional design precludes causal inference, precancerous cases were excluded so microbiota dynamics during lesion progression could not be traced, and 16S rRNA sequencing lacks the species-level resolution needed to fully resolve functional heterogeneity, making metagenomic validation essential. Nevertheless, the results align closely with international findings, including a 2025 meta-analysis confirming elevated Prevotella in cervical cancer patients and cohort studies linking non-Lactobacillus-dominated community state types to persistent high-risk HPV infection and lesion progression. The researchers propose that future work should employ metagenomics to confirm aerobactin genes in enriched taxa, establish HPV-transgenic mouse models colonized with patient-derived Prevotella strains, and test probiotic interventions with Lactobacillus crispatus to restore acidic pH and inhibit pathobionts. If validated in longitudinal cohorts, the microbial signatures identified here, particularly the depletion of Lactobacillus, the enrichment of Prevotella, and the activation of iron-acquisition and inflammatory pathways, could serve as auxiliary biomarkers for early risk prediction and open the door to precision interventions based on microecological remodeling.

Subject of Research: Vaginal and cervical microbiota dysbiosis associated with cervical cancer, characterized by 16S rRNA gene sequencing

Article Title: Exploring Cervical Cancer‐Associated Vaginal and Cervical Microbiota via 16S rRNA Sequencing

Article References: Wang, G., Liu, X., Wang, Z., Tian, H., Li, Y., & Luo, Y. (2026). Exploring Cervical Cancer‐Associated Vaginal and Cervical Microbiota via 16S rRNA Sequencing. MicrobiologyOpen, 15(5), Article e70412. https://doi.org/10.1002/mbo3.70412

Image Credits: AI Generated

DOI: 10.1002/mbo3.70412

Keywords: cervical cancer, microbiome, 16S rRNA sequencing, Lactobacillus, Prevotella, HPV, dysbiosis, PICRUSt2, bacterial vaginosis, aerobactin, QIIME 2, women's health

Klebsiella pneumoniae has long been divided into two epidemiological personalities. Classical strains colonize hospitals, infecting newborns, elderly patients and the immunocompromised, and are a leading cause of hospital-acquired infections and neonatal septicemia. Hypervirulent strains, by contrast, strike healthy people in the community, causing devastating syndromes such as pyogenic liver abscess, endophthalmitis and meningitis. For years these two worlds barely overlapped: hospital strains were resistant but relatively tame, while community strains were virulent but broadly susceptible to antibiotics. The US Centers for Disease Control and Prevention and the World Health Organization have both flagged carbapenem-resistant K. pneumoniae, or CRKP, as one of the most urgent threats in medicine, with new antimicrobials desperately needed.

That tidy separation collapsed in 2016, when strains of the ST11 lineage began acquiring pLVPK-like virulence plasmids, the mobile genetic elements that carry the genes behind hypervirulence. The resulting carbapenem-resistant hypervirulent K. pneumoniae, or CR-hvKP, fuses the worst features of both worlds. A fatal hospital outbreak in China described in 2018 first sounded the alarm, and the new study now provides a global, decade-scale accounting of what happened next. Within the ST11 lineage, two capsular subtypes, KL64 and KL47, emerged as the principal vehicles of CRKP, and their fortunes diverged dramatically.

The data show that KL47 was the dominant subtype from 2011 to 2015, after which its numbers plateaued. KL64, by contrast, entered a phase of explosive growth beginning in 2016 and overtook KL47 to become China’s predominant CRKP subtype, accounting for 40.5 percent of ST11-CRKP strains versus 28.9 percent for KL47. Regional patterns were stark: KL64 dominated Zhejiang province with 62.3 percent of strains and Sichuan with 58.7 percent, while KL47 held sway in Beijing, Jiangsu and Anhui. Globally, the picture was equally uneven, with KL24 dominant in Spain, Poland, Russia and Pakistan, KL105 predominant in the United Kingdom, and KL64 leading in Brazil and Uruguay. Of the ST11-CRKP strains examined, 89.7 percent carried carbapenemase genes, most commonly KPC-2 at 77.8 percent, followed by OXA-48 and NDM-1.

The decisive difference between the two subclones lay in how faithfully they maintained the virulence plasmid. Among 2,390 KL64 isolates, 60.5 percent carried the aerobactin gene, a key iron-scavenging virulence factor typically housed on pLVPK-like plasmids, compared with just 27.3 percent of 1,706 KL47 isolates. Detection of the RmpADC genes, which enhance capsular expression, showed an even wider gap: 40.7 percent in KL64 against 2.1 percent in KL47. The trajectory of aerobactin carriage tracked KL64’s rise almost perfectly. From 2015 to 2020, aerobactin-positive KL64 strains climbed from 58.9 percent to 86.6 percent of that subclone, while KL47’s aerobactin rate stayed flat in single digits. Patients infected with aerobactin-carrying strains faced significantly worse outcomes, with an odds ratio of 2.34 for severe disease.

Complete genome sequencing of 125 KL64 and 87 KL47 isolates exposed the molecular mechanism. Among aerobactin-positive strains, 98.7 percent of KL64 carried the gene on a plasmid, and 94.8 percent of those plasmids were intact and highly similar to the canonical pLVPK plasmid. In KL47, by contrast, only 41.2 percent of plasmids were intact; 58.8 percent had fused with IncFIB(pNDM-Mar)-like plasmids, leaving behind truncated remnants retaining little more than aerobactin and tellurium-resistance genes, and 41.4 percent of KL47 strains had lost the plasmid entirely, with virulence genes scattered onto the chromosome. Genome-wide comparison confirmed the disparity in gene retention: 71.2 percent of KL64 plasmids preserved the bulk of pLVPK genes, while most KL47 plasmids showed deletions exceeding 30 percent of the reference genome, with half losing more than 45 percent.

The fusion events themselves revealed a fascinating evolutionary intermediate. Twelve of fourteen truncated plasmids arose when pLVPK recombined with IncFIB(pNDM-Mar), a replicon type so rare it appeared almost exclusively in these hybrids. In thirteen strains, the recombination went further: genes from both parent plasmids, including aerobactin and type IV secretion system components, were transferred into the chromosome at a highly conserved insertion site marked by IS26 sequences. These chromosomal integrations appeared in hospitals across multiple regions, hinting that the instability of pLVPK in the KL47 background pushes the plasmid toward destructive recombination, while the KL64 genomic environment accommodates it intact. The researchers suggest this reflects classic plasmid fitness economics: acquiring a large virulence plasmid imposes metabolic costs that vary with host background, and KL47 appears to resolve those costs by shedding or chopping up the plasmid, whereas KL64 tolerates it stably enough to reap the full virulence benefit.

Geography and ecology help explain why ST11, rather than its American counterpart ST258, became the CR-hvKP powerhouse. Only 15 of 3,726 ST258-CRKP strains, a mere 0.4 percent, had acquired pLVPK-like plasmids, versus 33.9 percent of ST11-CRKP strains. The likely reason is proximity: hypervirulent KL1 and KL2 strains, the natural reservoirs of pLVPK, are concentrated in Asia, where intestinal colonization rates of K. pneumoniae in healthy Chinese adults reach 62.1 percent. In China, 48.4 percent of ST11-CRKP strains carry pLVPK-like plasmids, while in the United States only 0.5 percent of ST258-CRKP strains do. Intensive care units appear to be critical mixing vessels. In Sichuan, only 7.7 percent of human ST11-CRKP strains had acquired pLVPK-like plasmids, but 40 percent of environmental strains from neuro-intensive care and respiratory ICU surfaces had, underscoring the role of hospital environments in catalyzing plasmid transfer.

The evolutionary stakes are high. Strains carrying pLVPK-like plasmids survive environmental stress better, establish intestinal colonization more effectively and are associated with higher mortality than ordinary CRKP infections, and the loss of pLVPK sharply reduces extraintestinal spread. The authors acknowledge limitations, including geographic sampling bias toward well-resourced Chinese provinces and reduced data availability after 2020 due to sequencing submission lag. Even so, the message for surveillance is unambiguous. Monitoring plasmid-mediated virulence, not just resistance genes, may be essential to anticipate which CRKP clones will explode next, particularly in critical care settings where horizontal gene transfer can rewrite a pathogen’s arsenal within a single hospital ward. As the ST11-KL64 story demonstrates, in the arms race between antibiotics and bacteria, the plasmid is the engine of conquest.

Subject of Research: Plasmid-mediated fitness advantages underlying the global spread of carbapenem-resistant hypervirulent Klebsiella pneumoniae ST11-KL64.

Article Title: A fitness advantage from the pLVPK plasmid fuels the global spread of a carbapenem-resistant hypervirulent Klebsiella pneumoniae high-risk clone: ST11-KL64

Article References: Ren, Y., Li, X., Ju, L., Yao, Y., Chen, X., & Wang, X. (2026). A fitness advantage from the pLVPK plasmid fuels the global spread of a carbapenem-resistant hypervirulent Klebsiella pneumoniae high-risk clone: ST11-KL64. International Microbiology. https://doi.org/10.1007/s10123-026-00888-z

Image Credits: AI Generated

DOI: 10.1007/s10123-026-00888-z

Keywords: Klebsiella pneumoniae, pLVPK plasmid, carbapenem resistance, hypervirulence, ST11-KL64, aerobactin, genomic surveillance, horizontal gene transfer, CR-hvKP, plasmid stability, antimicrobial resistance, public health