title: Occurrence of extended-spectrum and AmpC β-lactamases in multiple drug resistantSalmonellaisolates from clinical samples in Lagos, Nigeria.
abstract: OBJECTIVE
  Salmonellaspp. 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-resistantSalmonellaspp. from Lagos, Nigeria.
  
  
  METHODS
  FortySalmonellaspp. from clinical samples (S. typhi= 13;S. typhimurium= 10;S. enteritidis= 8;S. choleraesuis= 5;S. paratyphi= 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 AmpCfoxgene was carried out by polymerase chain reaction.
  
  
  RESULTS
  Thirty-two (80%) of theSalmonellaisolates were cefoxitin resistant. Plasmid-mediated AmpC β-lactamase and ESBL enzymes were recorded in 10/40 (25%) and 16/40 (40%) of theSalmonellaisolates, respectively. Specifically, 16/40 (40%) of theSalmonellaisolates possessed 380 bp AmpCfoxgene, with the highest occurrence found inS.typhistrains (43.8%) followed byS. typhimurium(25%). There was no AmpCfoxgene detected inS. paratyphistrains. 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.
  
  
  CONCLUSIONS
  Emergence of AmpC β-lactamase-producingSalmonellaisolates in our environment was recorded for the first time, raising concern on increased antibiotic resistance among strains ofSalmonellaserovars in Lagos. Further genotypic study of the isolates could answer the questions on strain sources, clonal relatedness, and mechanism of spread.
authors.affiliation: Department of Microbiology, Lagos State University, Ojo.
authors.forename: K O
authors.initials: KO
authors.lastname: Akinyemi
authors.affiliation: Molecular Biology and Biotechnology Division, Nigerian Institute of Medical Research, Yaba, Lagos, Nigeria.
authors.forename: Bamidele Abiodun
authors.initials: BA
authors.lastname: Iwalokun
authors.affiliation: Department of Microbiology, Lagos State University, Ojo.
authors.forename: Akeeb O Bola
authors.initials: AO
authors.lastname: Oyefolu
authors.affiliation: Department of Microbiology, Lagos State University, Ojo.
authors.forename: C O
authors.initials: CO
authors.lastname: Fakorede
keywords: Salmonella; fox gene; minimum inhibitory concentration; plasmid; resistance