Molecular detection of extended-spectrum beta-lactamase (ESβL)-encoding genes among clinical isolates of Enterobacteriaceae from Federal Teaching Hospital Gombe State Nigeria

Abstract

Beta-lactamase inhibitors, like clavulanic acid, inhibit extended-spectrum beta-lactamases (ESβLs), which are enzymes that impart resistance to penicillins, first-, second-, and third-generation cephalosporins, and aztreonam. The ESβLs are commonly found in Gram-negative bacteria particularly members of Enterobacteriaceae. The wide distribution of ESβL among Enterobacteriaceae has been attributed to the continuous misuse of these antibiotics. Global outbreaks have been linked to the genes producing the ESβLs enzymes that provide resistance to third-generation cephalosporins. This study was conducted to determine the prevalence and detect ESβLs genes among Enterobacteriaceae isolates from Federal Teaching Hospital, Gombe. A total of 420 clinical isolates of Enterobacteriaceae were collected and identified by using Gram staining and biochemical tests. As advised by CLSI, the isolates were screened using the disk diffusion method to check for the formation of ESβLs. Suspected ESβL producers based on the screening test were subjected to confirmatory test using double-disk-synergy test (DDST), while the presence of genes coding for the ESβL production was determined by Polymerase Chain Reaction (PCR). The organisms displayed high resistance to Ceftazidime, almost 90%, followed by Cefpodoxime with 75% and Cefotaxime with 74%. Among the 377 resistant isolates, 95(25.2%) were confirmed positive for ESβLs production. E. coli was the most common ESβL producer with 35.7%, followed by K. pneumoniae with 24.2%, K. oxytoca with 14.7% and Citrobacter spp. with 10.5%. Based on PCR analysis, 4 (20%) isolates had one type of ESβL gene, 11(55%) had two types and 5 (25%) isolates had three types of the genes. The most detected ESβL genes were blaCTX-M and blaSHV with equal occurrence of 63.7%, followed by blaTEM with 59.1%. The increased ESβL occurrence in clinical isolates of Enterobacteriaceae in our locality creates significant therapeutic problems prompting an immediate need for the establishment of local guidelines for ESβL screening and strengthening Infection Prevention and Control (IPC) and Antimicrobial Stewardship (AMS) practices in FTH Gombe, as well as other laboratories in the State.