title: Dissemination of IncF plasmids carrying beta-lactamase genes in Gram-negative bacteria from Nigerian hospitals.
abstract: BACKGROUND
  Production of beta-lactamases is the predominant cause of resistance to beta-lactam antibiotics in Gram-negative bacteria. We investigated the diversity of plasmid-borne beta-lactamase genes and replicon type of the plasmids carrying the respective genes in Gram-negative bacteria recovered from clinical infection in Nigerian hospitals.
  
  
  METHODS
  A total of 134 Gram-negative bacteria of 13 species were analyzed for antimicrobial susceptibility, phenotypic and genotypic detection of various beta-lactamases, and plasmid analysis, including replicon typing.
  
  
  RESULTS
  Of the 134 isolates, 111 (82.8%) contained beta-lactamases, while 28 (20.9%) carried extended-spectrum beta-lactamases. PCR and sequencing identified TEM-1 in 109 isolates (81.3%), SHV-1 in 33 isolates (24.6%), OXA-1 in 15 isolates (11.2%) and CTX-M enzymes (24 CTX-M-15 and 1 CTX-M-3) in 25 isolates (18.7%). Multiplex PCR showed that 6 isolates carried plasmidic AmpCs (ACT-1, DHA-1 and CMY-2); these enzymes were detected only in isolates possessing CTX-M beta-lactamases. Of 13 (76.9%) representative plasmids investigated in detail, 9 (69.2%) were self-transferable when selected by a beta-lactam and the plasmids once transferred coded for beta-lactam resistance. Replicon typing indicated IncF as the common vector encoding for beta-lactamases.
  
  
  CONCLUSIONS
  The study showed a diversity of beta-lactamase genes disseminated by conjugative IncF plasmids in Gram-negative bacteria; TEM-1, SHV-1, OXA-1, CTX-M-15, CTX-M-3 and plasmidic AmpC enzymes are in common circulation in Nigeria.
authors.affiliation: Ladoke Akintola University of Technology, Ogbomoso, Osogbo Campus, Nigeria. olusogadave@yahoo.com
authors.forename: David Olusoga
authors.initials: DO
authors.lastname: Ogbolu
authors.forename: Oluwole Adebayo
authors.initials: OA
authors.lastname: Daini
authors.forename: Afolabi
authors.initials: A
authors.lastname: Ogunledun
authors.forename: Oyebode Armstrong
authors.initials: OA
authors.lastname: Terry Alli
authors.forename: Mark Alexander
authors.initials: MA
authors.lastname: Webber
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003227:Conjugation, Genetic; D003428:Cross Infection / Q000453:epidemiology*; D004269:DNA, Bacterial / Q000235:genetics; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D014644:Genetic Variation; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology*; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D060885:Multiplex Polymerase Chain Reaction; D009549:Nigeria; D010957:Plasmids / Q000145:classification / Q000302:isolation & purification*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D001618:beta-Lactamases