Characterization of Beta-Lactamase Producing Enterobacteriaceae in Clinical Samples at University of Calabar Teaching Hospital

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are increasingly recognized as significant drivers of treatment failure in hospital-acquired infections worldwide. This study characterized ESBL-producing members of the Enterobacteriaceae family from clinical samples received at the University of Calabar Teaching Hospital, Cross River State, in the South South geopolitical zone of Nigeria. Clinical samples including urine, wound swabs, blood cultures, and stool collected between April and September 2024 were processed by standard microbiological methods. ESBL production was confirmed by the combined disk diffusion test using cefotaxime and cefotaxime plus clavulanic acid. A total of 280 Enterobacteriaceae isolates were recovered, of which 41.4 percent were confirmed ESBL producers. Escherichia coli and Klebsiella pneumoniae accounted for 78 percent of ESBL-positive isolates. Multi-drug resistance was documented in 89 percent of ESBL-producing strains, with retained susceptibility primarily to carbapenems and colistin. Urine samples from the urology ward had the highest proportion of ESBL producers. These results highlight the alarming dissemination of ESBL-producing organisms within UCTH and the urgent need for stewardship programs, contact precautions, and periodic surveillance cultures in high-risk wards. Molecular typing of strains is advocated as a future research priority. Keywords: ESBL, Enterobacteriaceae, Calabar, antibiotic resistance, nosocomial infection.