Distribution of plasmid‑mediated quinolone resistance in Gram‑negative bacteria from a tertiary hospital in Nigeria.
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Date
2016-07
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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. Aim: This study investigated distribution of PMQR
in Gram‑negative bacteria from a tertiary hospital in eastern part of Nigeria.
Materials and 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 MIC90 values 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. Conclusion: 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.
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Keywords
Gram‑negative bacteria, Nigeria, plasmid‑mediated quinolone resistance, quinolone, resistance
Citation
Ogbolu David Olusoga, Alli Armstrong Oyebode, Anorue Michael C, Daini Oluwole Adebayo, Oluwadun Afolabi. Distribution of plasmid‑mediated quinolone resistance in Gram‑negative bacteria from a tertiary hospital in Nigeria. Indian Journal of Pathology & Microbiology. 2016 July-Sept 59(3): 322-326.