Occurrence of CTX-M, SHV and TEM β-lactamase genes in Extended Spectrum Beta-Lactamase (ESBL)- producing bacteria recovered from wastewater of a privately-owned hospital in Nigeria and a hand-dug well within its vicinity

Abstract

BackgroundThe possibility of the dissemination of resistant bacteria and antimicrobials from healthcare facilities into shared environment is a threat to human health. This study investigated the occurrence of ESBL and AmpC β-lactamase genes in ESBL- producing bacteria isolated from wastewater of a privately-owned hospital in South-western Nigeria and underground water sources within its vicinity. MethodsHospital wastewater and water samples from borehole and hand-dug well, were collected over three months for the isolation of gram-negative bacteria. Phenotypic detection of ESBL production was done using the double disc synergy test (DDST), while characterization of positive isolates was done using API 20E identification kit. Susceptibility to antibiotics and detection of resistance genes were done using the disc diffusion method and Real-Time PCR respectively. Pulse field gel electrophoresis was used to determine the relationship between the isolates. ResultsSixteen ESBL- producing bacteria identified as Serratia fonticola (14), Enterobacter cloacae (1) and Pantoea agglomerans (1) were recovered. Resistance to ampicillin was 100%, ceftazidime (93.75%), amoxicillin-clavulanate (75.0%), trimethoprim-sulfamethoxazole (68.75%), gentamicin (50%), cefotaxime (43.75%), cefpodoxime (31.25%), ceftriaxone (18.75%) and 56.25% each to tetracycline and ciprofloxacin. No resistance was observed to cefoxitin. All the ESBL positive bacteria carried blaSHV, six carried blaSHV + blaTEM, while blaCTX-M-2, blaCTX-M-8 and blaCTX-M-25 were detected in three isolates. No isolate carried blaCTX-M-1, blaCTX-M-9, blaKPC, blaNDM-1, blaCMY-1 and ampC. All the ESBL- producing Serratia fonticola showed a high degree of genetic relatedness. ConclusionHospital wastewater and hand-dug wells in proximity to hospitals could be important reservoirs of ESBL- producing bacteria.