Novel allelic variants of blaOXA-48-like carried on IncN2 and IncC2 plasmids isolated from clinical cases in Argentina: In vivo emergence of blaOXA-567
Bibliographic record
Abstract
• Carbapenem-resistant Escherichia coli ST1196 and Klebsiella pneumoniae ST6838 were isolated from paediatric patients. • OXA-438 and OXA-567 were found to be novel variants derived from the OXA-48-like group of enzymes. • The new oxa enzymes were located in IncN 2 and IncC 2 conjugative plasmids. • The close genetic environment of bla OXA-438 and bla OXA-567 suggests a common origin. • bla OXA-567 emerged during co-colonisation in vivo with bla OXA-163 K. pneumoniae. The OXA-48-like enzymes have the capacity to hydrolyse carbapenems and are members of class D β-lactamases that are primarily detected in Enterobacterales . The allelic variant bla OXA-163 , which has low hydrolytic activity towards carbapenems, was detected in Argentina in 2011 and has spread successfully since then, giving sporadic origin to novel local variants. The aim of this study was to analyse the phenotypic profile and dissemination strategies of two novel OXA enzymes, bla OXA-438 and bla OXA-567 , located in Escherichia coli M17224 and Klebsiella pneumoniae M21014, respectively, isolated from two paediatric patients. Minimum inhibitory concentration measurements were performed to determine the phenotypic profile of the clinical isolates, transconjugants and transformant cells. Biparental conjugation, PCR, Sanger and whole-genome sequencing were performed to determine the complete genetic characteristics of the plasmids. Both isolates were found to be resistant to carbapenems and susceptible to ceftriaxone. bla OXA-438 was located on a 69-kb IncN 2 plasmid, while bla OXA-567 was found on a 175-Kb IncC 2 plasmid, both transferable by biparental conjugation. The close genetic environment of the bla OXA genes suggests a common origin likely involving mobile genetic elements. Finally, the clinical case of M21014 revealed that the patient had previous infections with two genetically related K. pneumoniae ST6838 that carried bla OXA-163 on an IncC 2 plasmid with equal size and genetic hallmarks to that of M21014, providing strong evidence for the intra-patient emergence of bla OXA-567. This research underscores the need for ongoing surveillance and integral studies to understand the emergence, biochemistry and dissemination capacity of OXA enzymes with the overarching aim to halt their spread.
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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 | 0.001 | 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 | 0.000 |
| 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".