Occurrence of extended-spectrum and AmpC β-lactamases in multiple drug resistant isolates from clinical samples in Lagos, Nigeria.

Purpose: spp. are important foodborne pathogens exhibiting increasing resistance to antimicrobial drugs. Resistance to broad-spectrum β-lactams, mediated by extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase enzymes is fast spreading and has had negative impacts on the clinical outcomes, particularly on third-generation cephalosporins. This study investigated the carriage of AmpC gene among multidrug-resistant spp. from Lagos, Nigeria.

Methods: Forty spp. from clinical samples ( = 13; = 10; = 8; = 5; = 4) were subjected to in vitro susceptibility test by disk diffusion methods. Isolates that were resistant to cefoxitin and third-generation cephalosporins were screened for ESBL (Double Disk Synergy Test Method) and AmpC enzyme (AmpC disk test) production. Detection of AmpC gene was carried out by polymerase chain reaction.

Results: Thirty-two (80%) of the isolates were cefoxitin resistant. Plasmid-mediated AmpC β-lactamase and ESBL enzymes were recorded in 10/40 (25%) and 16/40 (40%) of the isolates, respectively. Specifically, 16/40 (40%) of the isolates possessed 380 bp AmpC gene, with the highest occurrence found in . strains (43.8%) followed by (25%). There was no AmpC gene detected in strains. Interestingly, coproduction of enzymes occurred in some of the isolates, raising fears of resistance to a multitude of antibiotics in the treatment of bacterial infections.

Conclusion: Emergence of AmpC β-lactamase-producing isolates in our environment was recorded for the first time, raising concern on increased antibiotic resistance among strains of serovars in Lagos. Further genotypic study of the isolates could answer the questions on strain sources, clonal relatedness, and mechanism of spread.