Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae in Tertiary Hospitals in Lagos State

The dissemination of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in hospital settings constitutes a critical antimicrobial resistance threat, yet molecular epidemiological data characterizing resistance gene types and clonal relationships among Nigerian isolates remain sparse. This study applied molecular epidemiological tools to characterize ESBL-producing Enterobacteriaceae from three tertiary hospitals in Lagos State, South West Nigeria. A total of 180 Enterobacteriaceae isolates from blood cultures, urinary tract infection specimens, and wound swabs were screened for ESBL production by combined disk test. ESBL genotype was determined by multiplex PCR targeting blaCTX-M, blaTEM, and blaSHV gene families. Clonal relatedness of CTX-M-positive E. coli and Klebsiella pneumoniae was assessed by pulsed-field gel electrophoresis (PFGE). Results showed ESBL prevalence of 54.4 percent across isolates. blaCTX-M-15 was the dominant gene (73.5%), followed by blaTEM-1 (48.0%) and blaSHV-12 (22.4%). PFGE analysis revealed the presence of epidemic clones circulating across all three hospitals, indicating inter-hospital transmission. E. coli sequence type 131 (ST131), a globally dominant MDR lineage, was identified by PCR-based typing. The research fills an important epidemiological gap by demonstrating the presence of international high-risk clones in Lagos tertiary settings and urges the implementation of whole-genome sequencing-based AMR surveillance to track clonal dissemination across Nigeria's healthcare networks. Keywords: ESBL, CTX-M-15, Enterobacteriaceae, molecular epidemiology, Lagos.