Characterization of extended spectrum beta-lactamases in enterobacteriaceae from foods using molecular method

Clinical and community-related resistant bacteria are widely found in the present time. This new type of biohazard is a growing health concern of Global significance for human health. That's why, international authorities, including WHO, FAO and EFSA, are enhancing the researchers to focus on this issue. Extended spectrum beta-lactamases (ESBL) are the enzymes that are encoded by plasmid-mediated bla-genes. inactivate beta-lactam antibiotics through a mechanism of resistance, so-called enzymatic inactivation, and lead to failure of treatment of bacterial infections. The bla-genes are easily transferable among the same and/or different bacterial species. Not only clinical and community settings, foods are also under suspicion for development and transmission of antibiotic resistance in bacteria. In Turkey, clinical and community-related ESBL-producers were examined well, whereas foodborne dissemination was not questioned seriously. The objective of this study was to characterize blaTEM, blaSHV and blaCTX-M genes and blaCTX-M subtypes in 55 ESBL-producing Enterobacteriaceae isolated from foods of animal origin after identification by mass spectrometer. DNA materials from each ESBL-positive isolate were initially amplified by Polymerase Chain Reaction (PCR), and subsequently visualised by gel-electrophoresis. Within them, 1 blaTEM positive amplicon, 1 blaSHV positive amplicon and 1 blaCTX-M positive amplicon were purified, sequenced, and confirmed using BLAST Program. SPSS 19 was used for statistical analysis. Kruskal-Wallis H-test was performed for qualitative-comparison of frequency rate of each bla-genes with respect to their sampling groups. P<0.05 was considered to be significant. Genotypic results showed that frequency rates of blaTEM, blaCTX-M and blaSHV were determined to be 96.4%, 65.5%, and 34.5%, respectively. The co-existence of bla-genes were found as 57.8% blaTEM+blaCTX-M, 22.2% blaTEM+blaSHV, 17.8% blaTEM+blaCTX-M+blaSHV, and 2.2% blaTEM+blaCTX-M. Subtyping CTX-M-positive amplicons revealed that the most common subtype of blaCTX-M was 97.2% blaCTX-M-1, followed by 2.8% blaCTX-M-8. Sequencing and BLAST analysis also confirmed blaTEM, blaSHV and blaCTX-M genes. The statistical evaluation provided that foods of animal-origin were potential sources for ESBL-encoding bla-genes regardless type of food. To conclude, we found that Enterobacteriaceae from foods of animal orgin harboured ESBL-encoding bla-genes in some foods of animal origin, indicated a multiresistance pattern, and leaded to the colonization of the consumers with these spreadable genetic materials.