Characterization of extended-spectrum beta-lactamases (ESBLs) in North America
Bibliographic record
Abstract
Extended-spectrum beta-lactamases (ESBLs) are a growing concern both in the hospital and community settings.These ESBLs have frequently been repofted among Escherichia coliand K/ebsiel/a spp.but have also been described in Salmonel/a spp.Many isolates that harbour ESBLs are multi-drug resistant and can therefore limit therapeutic options.This reporl describes ESBLs in three different studies, ESBLs identified from Canadian Sa/monella isolates, ESBLs produced by E. coli in a long term care facility, and ESBLs identified in fluoroquinolone resistant strains o'f E. coliin a North American study.The methodologies from all three projects are described below.Susceptibilities were determined using the automated Sensititer System and ESBLs were confirmed using disk diffusion (CLSI).PCR and sequence analysis was used to identify blalç¡¡, b/asHv, and blaçyy-n¡.Strains were subtyped using pulsed-field gel electrophoresis and analysed for similarity using BioNumerics v3.5.Plasmid DNA was transferred to E. coliDH10B using electroporation and plasmid fingerprinting and size estimation was carried out using Bglll and Hpal.Salmonella strains from human cases were identified from the Canadian lntegrated Program for Antimicrobial Resistance Surveillance (CIPARS) over a 2.5 year period beginning January 2003.Twenty-five (0.33%) of 7618 Salmonella isolates were identified among ten different serovars over the 2.5 year period as ESBL-producers.ESBL rates per year were: 2003, 0.26% (n=B/3056); 2004, 032% (n=10/31 47); January 2005 to June 30, 2005, 0.49% (n=711415).Genotype distribution included blas¡v-zu1t"ì=13, 52o/o), blasnv-tz(n=2, Bo/o), blactx-M-14 (n=2, Bo/o), blactx-M-1s (n=1 , 4%) and seven (28%) strains contained unknown resistance mechanisms.Plasmid fingerprinting suggested an indistinguishable SHV-2a containing plasmid may have spread between serovars.Over a two year period, starting January 2002 and ending April 20O4, all E. coli displaying reduced susceptibility to CLS I recommended beta-lactams isolated from a long term care facility (LTCF) in Manitoba were submitted to Cadham Provincial Laboratory.Sequence analysis of the 40 confirmed ESBLproducers revealed 29 (72.5%)CTX-M-1 4, 10 (25%) CTX-M-15, and one (2.5%)SHV-S gene.PFGE subtyping revealed two major clusters distributed among the LTCF.Majority of isolates were multidrug resistant and were resistant to ciprofloxacin (n=39, 97 .5o/o),naladixic acid (n=39 , 97 .5o/o),tetracycline (n=39, 97 .5%),trimethoprim/sulfamethoxazole (n=15, 37 .5%),kanamycin (n=9, 22.5%) and gentamicin (n=11 ,27.5%).Statistical analysis revealed patients with multiple isolates were more likely to have had multiple courses of antibiotics.As well patients harbouring CTX-M-14 were more likely to have had a gastrostomy. As paft of the North American Urinary Tract lnfection CollaborativeAlliance Quinolone Resistant (NAUTICA-QR) study 30 medical centres in the United States and 10 medical centres in Canada collected consecutive outpatient QR-E coli mid-stream urine (MSU) isolates.ESBL distribution of the 59 confirmed ESBl-producers included 31 (52.5%)b/acrx-rr¡-rs, 21 (35.6o/o)blactx-r¡- 14, ore (1 .7%)blactx-¡t-zq, three (5.1%)blasnv-tz, one (1 .7%)blarc¡4-1 and one (1.7%)blaqx-t¿-zs.A total of 66% of the isolates were multidrug resistant.The three studies presented here have shown very different results among ESBL-producing bacteria.For instance SHVtype ESBLs were frequently seen
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".