title: Distribution of plasmid-mediated quinolone resistance in Gram-negative bacteria from a tertiary hospital in Nigeria.
abstract: BACKGROUND
  Until recently, mechanisms of resistance to quinolones in Gram-negative bacteria were believed to be only chromosome encoded. However, emergence of plasmid-mediated quinolone resistance (PMQR) has been reported worldwide.
  
  
  OBJECTIVE
  This study investigated distribution of PMQR in Gram-negative bacteria from a tertiary hospital in eastern part of Nigeria.
  
  
  METHODS
  Seventy-one nonduplicate Gram-negative bacterial isolates of eight species were analyzed for antimicrobial susceptibility, genotypic detection of various PMQRs, typed by random amplified polymorphic DNA (RAPD) and analysis of plasmids present, including replicon typing.
  
  
  RESULTS
  The minimum inhibitory concentrations showed MIC90values as high as 256 μg/ml for fluoroquinolones. Carriage of PMQR was found to be 35.2%. Twenty (28.2%) isolates carried various qnr genes, of which seven (9.9%) qnrA1; four (5.6%) qnrB1; eight (11.3%) qnrS1 while one (1.4%) encoded qnrD1. Eighteen (25.4%) isolates were positive for aac(6')-Ib-cr while carriage of multiple genes exists in some strains. Similarly, 13 isolates (18.7%) were found to carry PMQR efflux pump gene, qepA. Conjugation experiments revealed that the plasmids once transferred coded for fluoroquinolone resistance. The transconjugant strains carried a common plasmid estimated to be 65 kb. These plasmids were untypable for replicon/incompatibility. Typing revealed high diversity among all species tested with no identical RAPD pattern seen.
  
  
  CONCLUSIONS
  This study further confirms high level resistance to many antimicrobials in different species of Gram-negative bacteria including fluoroquinolones and spread of PMQR genes in Southern Nigeria.
authors: Department of Biomedical Sciences, Molecular Biology Unit, Ladoke Akintola University of Technology, Osogbo Campus, Ogbomoso, Nigeria; Antimicrobials Research Group, Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom, .
authors: David Olusoga
authors: DO
authors: Ogbolu
authors: Department of Biomedical Sciences, Molecular Biology Unit, Ladoke Akintola University of Technology, Osogbo Campus, Ogbomoso, Nigeria.
authors: Armstrong Oyebode
authors: AO
authors: Alli
authors: Department of Medical Microbiology and Parasitology, Federal Medical Centre, Ebonyi; Department of Medical Microbiology and Parasitology, Olabisi Onabanjo University, Remo Campus, Ago Iwoye, Nigeria.
authors: Michael C
authors: MC
authors: Anorue
authors: Department of Biochemistry, Kampala International University, Kampala, Uganda.
authors: Oluwole Adebayo
authors: OA
authors: Daini
authors: Department of Medical Microbiology and Parasitology, Olabisi Onabanjo University, Remo Campus, Ago Iwoye, Nigeria.
authors: Afolabi
authors: A
authors: Oluwadun
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D014644:Genetic Variation; D006090:Gram-Negative Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D009549:Nigeria / Q000453:epidemiology; D010957:Plasmids / Q000032:analysis*; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D019105:Random Amplified Polymorphic DNA Technique; D062606:Tertiary Care Centers
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones