Phenotypic characterization of ESBL- and AmpC- type beta lactamases in Enterobacteriaceae from chicken meat and dairy products

Abstract

The excess and off-label use of antibiotics results in development of antibiotic resistance among microorganisms. Although microbiological criteria have been appropriately considered in the Food Codex, an inspection for antibiotic-resistant bacteria has not come into force yet. Beta-lactamase producing Enterobacteriaceae adversely affects the human health by leading to therapeutic failures against infections. The objective of this study was to characterize ESBL- and/or AmpC- type beta-lactamases in Enterobacteriaceae isolated from chicken meat, raw milk and unpacked-fresh cheese samples phenotypically. In this study, a total of 327 samples (109 chicken meat, 135 raw milk and 83 unpacked fresh cheese) was examined microbiologically by performing pre-enrichment, enrichment on selective media, and oxidase test according to the Criteria by ISO/DIS21528-2. Overall, 80 ESBL- and/or AmpC positive isolates were identified by mass spectrometer. The most prevalent strain was Escherichia coli (68.8%), followed by Klebsiella pneumoniae (8.8%), Enterobacter cloacae (7.5%), Citrobacter spp. (6.2%), Hafnia alvei (6.2%), and Klebsiella oxytoca (2.5%). The beta-lactamases were screened by disc diffusion, disc diffusion confirmation, and MIC determination according to the Guidelines of Clinical and Laboratory Standards Institute. The most common beta-lactamase type was found as ESBL in 75 isolates, followed by a combination of ESBL & AmpC in 10 isolates, and AmpC in five isolates, respectively. In conclusion, our study showed that ESBL- and/or AmpC-type beta-lactamases were the most common enzymes in Enterobacteriaceae in the analyzed foods.