First Occurrence of a <i>Pseudomonas aeruginosa</i> Isolate in the United States Producing an IMP Metallo-β-Lactamase, IMP-18
Bibliographic record
Abstract
First Occurrence of a Pseudomonas aeruginosa Isolate in the United StatesProducing an IMP Metallo--Lactamase, IMP-18Metallo--lactamases hydrolyze most -lactam antibiotics except aztreonam.Therefore, many pathogens that produce these enzymes at high levels are resistant to the majority of -lactam antibiotics, including the carbapenems.The first report of an imported metallo--lactamase described a Pseudomonas aeruginosa isolate obtained from a Japanese patient in 1988 (6).Since then, the occurrence of mobile genetic elements encoding metallo--lactamases has extended beyond P. aeruginosa to include many types of gram-negative organisms distributed throughout the world (5).Areas which have reported these types of isolates include several countries in Asia and Europe; the Americas, including Brazil, Canada, and the United States; and Australia (5).Based on recent reports, there are two major families of imported metallo--lactamases, IMP and VIM, that are carried on mobile gene cassettes inserted into integrons (5).Including those in this report, there are 18 variants of IMP metallo--lactamases and 11 variants of VIM metallo--lactamases (5).The only two published reports on metallo--lactamases from the United States identified VIM-2 and VIM-7 (1, 4).In this study, we investigated a carbapenem-resistant P. aeruginosa isolate for metallo--lactamase production.The isolate was recovered from the tracheal aspirate of a motorcycle accident victim in the southwestern United States.It was found to produce a new member of the IMP family of metallo--lactamases.The isolate was identified by the Phoenix system (BD Diagnostic Systems, Sparks, Md.).Antibiotic susceptibility was determined by broth microdilution and interpreted by using CLSI criteria (2).These data are presented in Table 1.Metallo-lactamase production was phenotypically investigated by using the Etest metallo--lactamase strip (AB BIODISK, Solna, Sweden).By Etest there was a Ն32-fold reduction in the MIC of imipenem in the presence of EDTA (Ն256 to 8 g/ml).The bla IMP-1-like gene was detected by PCR as previously described (3), using IMP-1-family-specific primers internal to the gene.Amplification of the full-length product of 781 bp was obtained by PCR, using an annealing temperature of 42°C, a magnesium concentration of 2 mM, and primers which flanked the gene.The forward primer was 5Ј-GTTAGAAAA GGAAAAGTATG-3Ј, and the reverse primer was 5Ј-TGCT GCAACGACTTGTTAG-3Ј.PCR products were generated on at least two separate occasions and sequenced by automated cycle sequencing, using an ABI Prism 3100-Avant Genetic analyzer.Sequence alignments and analyses were performed online using the BLAST program (www.ncbi.nlm.nih.gov).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".