Identification of chicken-related enterobacteriaceae resistant to extended spectrum beta-lactam antibiotics and determination of resistance profiles

IDENTIFICATION OF CHICKEN-RELATED ENTEROBACTERIACEAE RESISTANT TO EXTENDED SPECTRUM BETA-LACTAM ANTIBIOTICS AND DETERMINATION OF RESISTANCE PROFILES Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae associated infectious diseases as well as higher rates of mortality are becoming a problem in the World. ESBLs are the enzymes that inactivate a broad range of antibiotics, including penicillins, cephalosporins, and monobactams through hydrolysis. GSBL-positive enterobacteria can disseminate through foods of animal origin, not only in clinical and community settings. This situation is, therefore, considered to be a severe issue for both food safety and public health policies. Intensive and overuse of modern beta-lactam antibiotics are one of the major factors for the wide spread of ESBL-producing bacteria worldwide. In the poultry sector, the antibiotics are widely and extensively used in preventive medicine and disease-treatment. The sensitivity and specificity of disc-approximation testing methods are relatively low. Thus, the findings need to be verified by disc-diffusion testing, including MIC determination for ESBL determination. In this study, ESBL-producing Enterobacteriaceae from the raw chicken meat samples was phenotypically analyzed according to the Guidelines by Clinical and Laboratory Standards Institute. A total of 109 samples, including carcass and offal parts, was collected from markets, public bazaars, and chicken farms located in the region of Marmara, including İstanbul district during the year 2014. After pre-enrichment, the suspensions were selectively enriched in chromogen ESBL agar. The presumptive isolates were exposed to oxidase testing, and the oxidase negative ones were identified by Vitek MS (bioMeriux). After that, the isolates were initially subjected to disc diffusion testing, then subsequently to disc diffusion confirmation using ceftazidim (CAZ), cefotaxime (CTX), and cefpodoxime (CPD) with/without clavulanate (CLA) discs. The suspected isolates were confirmed for ESBL production by Merlin Micronaut-S beta-lactamase VII Kit. The MIC readings were obtained by a multiscan spectrometer, and the data were automatically analyzed by Sifin MIC software. All the phenotypic testing was performed according to the Guidelines by Clinical and Laboratory Standards Institute. The results showed that 33 ESBL-suspected isolates were confirmed as positive ESBL-producers according to disc diffusion confirmation and MIC determination testing. Based on disc-diffusion testing, the phenotypic resistances against CPD, CTX, and CAZ were found as 96.6%, 87.8%, and 45.4%, respectively. The disc diffusion confirmation revealed that the resistances were determined to be 93% in CPD±CLA, 90% in CTX±CLA, and 72% CAZ±CLA. Of 33 ESBL-positive isolates, the most common phenotype was 84,8% E. coli, followed by 6.1% K. pneumoniae, 6.1% E. cloacae, and 3.0% C. werkmanii. Two E. coli strains of 33 isolates was also detected to be simultaneously positive for ESBL and Amp-C production. The MIC values revealed that 63.6% of the isolates were resistant to CAZ (16-128 µg/mL), and 72.7% to CTX (≥128 µg/mL). The tested samples of raw chicken meat harboring ESBL-producing Enterobacteriaceae presented a severe risk, with a major role for the dissemination and transfer of ESBL-encoding genes among the identical and/or different species through specific mechanism of plasmid mediated. To conclude, this study suggested that the foods of animal origin may possibly potential reservoirs for the spread of antibiotic resistance.