Faecal carriage of extended-spectrum beta-lactamase (ESBL)-producing commensal Klebsiella pneumoniae and Escherichia coli from hospital out-patients in Southern Nigeria

Normal intestinal microflora is the major source from which common hospital- and community-acquired infections originate. This study aimed to determine faecal carriage of extended-spectrum beta-lactam (ESBL) resistant genes from commensals of out-patients in Nigeria. Non-duplicateKlebsiella pneumoniae and Escherichia coli from different hospitals were investigated for susceptibility to a panel of antibiotics, carriage of plasmid mediated β-lactam resistance, andanalysis of plasmids present, including replicon typing. The minimum inhibitory concentrations (MICs) for β-lactam antibiotics showed MIC90 of ≥256 µg/ml for all antibiotics. CTX-M carriage was 36.8% for the 114 strains; 30 of these were CTX-M-15 and 12 carried CTX-M-2. TEM-1genes were present in 102 isolates (89.5%), SHV-1 genes in 24 (21.1%), OXA-1 in 36 (31.6%) and 10 (8.8%) in AmpC genes detected. There was no significant difference in the proportion of ESBL genes detected in E. coli and K. pneumoniae (t test; p = 0.64; p > 0.05) and between hospitals (c2 = 0.35; p = 0.84; p > 0.05). IncF was the common plasmid encoding β-lactamases. High faecal carriage of ESBL genes in commensals, importantly classical CTX-M-15 in out-patients is a reflection of the prevalence from clinical specimens in diseased conditions in Nigeria.