Differences in the antibiotic susceptibility of human Escherichia coli with poultry-associated and non-poultry-associated extended-spectrum beta-lactamases.

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]