Molecular epidemiology and clinical features of <i>Klebsiella variicola</i> bloodstream infection compared with infection with other <i>Klebsiella pneumoniae</i> species complex strains
Bibliographic record
Abstract
ABSTRACT Klebsiella variicola is an emerging pathogen within the Klebsiella pneumoniae species complex, and its clinical and microbiological characteristics remain poorly understood. This retrospective case-control study analyzed 252 patients with bloodstream infections caused by K. pneumoniae species complex, including 60 with K. variicola infection, to elucidate these characteristics. Our study showed no significant differences in clinical outcomes, such as 30-day mortality, between K. variicola and K. pneumoniae . However, a significant difference was found in the rate of harboring [ peg-344 , iucA , and rmpA ] genes, which are associated with virulence in K. pneumoniae , suggesting that K. variicola may be generally less virulent. Notably, we identified two patients with community-acquired liver abscess caused by hypervirulent K. variicola , representing the first genetically analyzed case of this phenomenon in Japan and highlighting the potential virulence of this species. While there have been several reports on K. variicola carrying hypervirulence genes, this is the first report in Japan, to our knowledge, to genetically characterize a hypervirulent K. variicola isolated from a patient with disseminated liver abscesses using whole-genome sequencing. Multilocus sequence typing revealed high diversity among K. variicola isolates, with 49 distinct sequence types identified, 30 of which were newly registered, highlighting the genetic heterogeneity of this pathogen. No significant clinical differences were observed between K. variicola and other Klebsiella spp. The emergence of hypervirulent K. variicola strains with the potential to cause severe complications warrants further surveillance and research. IMPORTANCE Klebsiella variicola is increasingly recognized as an emerging pathogen commonly found in the environment and human gut. However, its clinical and microbiological characteristics remain poorly understood. This study provides a comprehensive analysis of K. variicola bloodstream infections (BSIs), comparing clinical and genetic features with the closely related K. pneumoniae . We identified significant differences in the prevalence of virulence genes between the two species. Notably, we observed K. variicola causing disseminated liver abscesses, similar to hypervirulent K. pneumoniae strains. These findings have important implications for accurate species identification, informing treatment strategies, and improving patient outcomes in the face of this emerging infectious threat.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".