Multi-drug resistant ESBL-producing Enterobacteriaceae isolates from retail raw meats in markets of Singapore

Enterobacteriaceae isolates from retail raw meats in a supermarket in Singapore were acquired during 2017-2018. Ten grams of sample was homogenized with 90 grams of Universal Pre- enrichment Broth (UPB) by stomacher at 230rpm for 1 minute. Homogenate was incubated at 37? overnight and then streaked on Brilliance TM ESBL Agar (Thermo Scientific). A single colony was picked after 24h incubation. Double-disk synergy test (DDST) was performed to confirm the production of extended-spectrum beta-lactamase as previously described (6). Antimicrobial susceptibility testing (AST) was performed by broth microdilution method to determine the minimum inhibitory concentration (MIC). MicroScan Neg MIC Panel Type 44 (Beckman Coulter, Inc., Brea, CA, USA) was used following manufacturer's instruction. The genomic DNA was extracted using QIAamp® DNA Mini Kit following manufacturer's instructions(Qiagen, Germany). Illumina Hiseq2500 sequencer was used for whole genome sequencing. The raw reads were assembled by Assembler 1.2. The species and antimicrobial resistance genes were determined by KmerFinder3.1 and ResFinder, respectively.