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The concurrent presence of bla and bla genes on similar plasmids of Escherichia coli isolated from poultry, chicken meat and humans supports the occurrence of food-borne transmission of extended-spectrum beta-lactamase (ESBL) genes. ESBL-producing E. coli (ESBL- E. coli) are most frequently detected in hospitalised patients and are known to spread in healthcare settings. We hypothesised that poultry-associated (PA) ESBL genes are predominant in the community, where acquisition is fuelled by food contamination, whereas non-PA ESBL genes are predominant in hospitals, with acquisition fuelled by cross-transmission. Then, differences in antimicrobial selective pressure in hospitals and poultry would create differences in co-resistance between PA and non-PA ESBL- E. coli. We, therefore, determined the prevalence and co-resistance of PA and non-PA ESBL- E. coli in community-acquired and nosocomial urinary tract infections in humans and bla and bla isolates from poultry. A total of 134 human ESBL- E. coli urine isolates were included in this study. Isolates containing bla or bla were considered to be PA, with the remainder being non-PA. Also, 72 poultry ESBL- E. coli were included. Minimum inhibitory concentration (MIC) values were determined by broth microdilution. The prevalence of PA ESBL genes in isolates obtained in general practice and hospitals was 28 % versus 30 % (n.s.). Human PA ESBL- E. coli were more frequently susceptible to ciprofloxacin (51 % vs. 25 %; p = 0.0056), gentamicin (86 % vs. 63 %; p = .0.0082), tobramycin (91 % vs. 34 %; p = 0.0001) and amikacin (98 % vs. 67 %; p = 0.0001) compared to human non-PA ESBL- E. coli. PA ESBL- E. coli are not more prevalent in community acquired than nosocomial urine samples, but are more often susceptible to ciprofloxacin and aminoglycosides than non-PA ESBL- E. coli. This does not support the existence of different reservoirs of ESBL genes. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the routine setting performance of a guideline for phenotypic detection of extended spectrum β-lactamases (ESBLs) in Enterobacteriaceae, recommending ESBL confirmation with Etest or combination disc for isolates with a positive ESBL screen test (i.e. cefotaxime and/or ceftazidime MIC >1 mg/L or an automated system ESBL warning). Twenty laboratories submitted 443 Enterobacteriaceae with a positive ESBL screen test and their confirmation test result (74% Escherichia coli, 12% Enterobacter cloacae, 8% Klebsiella pneumoniae, 3% Proteus mirabilis, 2% Klebsiella oxytoca). Presence of ESBL genes was used as reference test. Accuracy of local phenotypic ESBL detection was 88%. The positive predictive value (PPV) of local screen tests was 70%, and differed per method (Vitek-2: 69%, Phoenix: 68%, disc diffusion: 92%), and species (95% K. pneumoniae-27% K. oxytoca). A low PPV (3%) was observed for isolates with automated system alarm but third-generation cephalosporin MICs <2 mg/L. Local ESBL confirmation had a PPV and negative predictive value (NPV) of 93% and 90%, respectively. Compared with centrally performed confirmation tests, 7% of local tests were misinterpreted. Combination disc was more specific than Etest (91% versus 61%). Confirmation tests were not reliable for P. mirabilis and K. oxytoca (PPV 33% and 38%, respectively, although NPVs were 100%). In conclusion, performance of Etests could be enhanced by education of technicians to improve their interpretation, by genotypic ESBL confirmation of P. mirabilis and K. oxytoca isolates with positive phenotypic ESBL confirmation, and by interpreting isolates with a positive ESBL alarm but an MIC <2 mg/L for cefotaxime and ceftazidime as ESBL-negative. [ABSTRACT FROM AUTHOR]

Clin Microbiol Infect 2011; 17: 1435-1438 Abstract Since the diagnostic characteristics of the Check-KPC ESBL microarray as a confirmation test on isolates obtained in a routine clinical setting have not been determined, we evaluated the microarray in a random selection of 346 clinical isolates with a positive ESBL screen test (MIC >1 mg/L for cefotaxime or ceftazidime or an ESBL alarm from the Phoenix or Vitek-2 expert system) collected from 31 clinical microbiology laboratories in the Netherlands in 2009. Using sequencing as the reference method the sensitivity of the microarray was 97% (237/245), the specificity 98% (97/99), the positive predictive value 99% (237/239) and the negative predictive value 92% (97/105). [ABSTRACT FROM AUTHOR]

Intestinal carriage of extended-spectrum beta-lactamase (ESBL) -producing bacteria in food-producing animals and contamination of retail meat may contribute to increased incidences of infections with ESBL-producing bacteria in humans. Therefore, distribution of ESBL genes, plasmids and strain genotypes in Escherichia coli obtained from poultry and retail chicken meat in the Netherlands was determined and defined as ‘poultry-associated’ (PA). Subsequently, the proportion of E. coli isolates with PA ESBL genes, plasmids and strains was quantified in a representative sample of clinical isolates. The E. coli were derived from 98 retail chicken meat samples, a prevalence survey among poultry, and 516 human clinical samples from 31 laboratories collected during a 3-month period in 2009. Isolates were analysed using an ESBL-specific microarray, sequencing of ESBL genes, PCR-based replicon typing of plasmids, plasmid multi-locus sequence typing (pMLST) and strain genotyping (MLST). Six ESBL genes were defined as PA (blaCTX-M-1, blaCTX-M-2, blaSHV-2, blaSHV-12, blaTEM-20, blaTEM-52): 35% of the human isolates contained PA ESBL genes and 19% contained PA ESBL genes located on IncI1 plasmids that were genetically indistinguishable from those obtained from poultry (meat). Of these ESBL genes, 86% were blaCTX-M-1 and blaTEM-52 genes, which were also the predominant genes in poultry (78%) and retail chicken meat (75%). Of the retail meat samples, 94% contained ESBL-producing isolates of which 39% belonged to E. coli genotypes also present in human samples. These findings are suggestive for transmission of ESBL genes, plasmids and E. coli isolates from poultry to humans, most likely through the food chain. [ABSTRACT FROM AUTHOR]