Abstract:
Extended-spectrum beta-lactamase (ESBL)-producing bacteria have increasingly been reported to be widespread in various environments. In the Philippines, limited studies have been made on the presence of ESBL-producers particularly on bacteria isolated from caves. This study screened ESBL production and genotyped the beta-lactamase genes of 28 bacterial strains from bat guano in Cabalyorisa Cave, Mabini, Pangasinan, Philippines. The strains were found to belong to the family Enterobacteriaceae and were identified to be either Enterobacter cloacae, Enterobacter xiangfengensis, Escherichia coli, and Salmonella spp. Antimicrobial susceptibility testing of these strains against four 3rd generation cephalosporins and a monobactam showed that 18 (64%) out of the 28 strains were found to be resistant to at least one of four antibiotics. ESBL-production was then confirmed using the Phenotypic Confirmatory Disk Diffusion Test (PCDDT) and 15 (83%) out of 18 strains that were initially tested antibiotic resistant were also positive for ESBL production. Lastly, the type of beta-lactamase genes that the phenotypically identified ESBL-producing strains possessed was determined by the amplification and sequencing of the blaCTX-M, blaOXA, blaAmpC genes through Polymerase Chain Reaction (PCR). Results showed that 12 (80%) and 14 (93%) out of the 15 strains were detected to harbor the blaOXA and blaAmpC genes, respectively. Meanwhile, the blaCTX-M gene was detected in all of the strains tested making it the most predominant bla gene present among the strains. Alarmingly, 11 (73%) of the strains harbored all the three bla genes tested which may indicate higher resistance to antibiotics. This study therefore confirmed presence of ESBLproducers with multiple genes indicative of the spread of antibiotic resistant bacteria in the Philippine wildlife and other isolated environments. Further studies therefore are necessary to determine the distribution and prevalence of ESBL-producers in various environments.
