Molecular Detection of Extended-Spectrum Beta-Lactamase (ESBL) Genes in Escherichia coli Isolated From Vegetables and Environmental Samples in Selected Urban Farms and Wet Markets in Metro Manila, Philippines.

Escherichia coli (E. coli) is a facultative anaerobic Gram-negative bacterium that is not only commensal, inhabiting the intestinal tract of humans and warm-blooded animals, but also a major opportunistic pathogen causing several diseases, mainly foodborne. E. coli is also involved in a wide range of niches including plant surfaces and tissues. Some strains of E. coli produce extended-spectrum β-lactamases (ESBL), which reduces the efficacy of β-lactam antibiotics which is one of the most commonly used antibiotics. Therefore, contamination of fresh produce with E. coli, potentially carrying ESBL, can pose a significant health risk. This study aims to detect ESBL genes in E. coli isolated from raw vegetables, using in-house designed primers for polymerase chain reaction (PCR). A total of 117 fresh produce and environmental samples was obtained from selected urban gardens, along with 348 fresh produce from selected wet markets in Metro Manila, Philippines. Using culture in mTEC agar and confirmation by uidA gene detection using conventional PCR, a total of 74 samples tested positive for E. coli. These were subjected to phenotypic and molecular detection of ESBL genes, using primer pairs for three ESBL genes blaCTX-M, blaTEM, and blaSHV designed in this study. Overall, the prevalence of ESBL-producing E. coli in this study was 5.41%. The primers designed successfully amplified the desired amplicon sizes, demonstrating potential utility in PCR-based detection of ESBL genes in E. coli isolates. The results of the research may be used to improve the current detection methods of ESBL-producing bacteria thereby contributing to the current knowledge on antimicrobial resistance in foodborne pathogens.