High Level Plasmid-Mediated Quinolone Resistance in Clinical Infections at a Tertiary Healthcare Institution in South-West Nigeria

Abstract

Background Plasmid-mediated quinolone resistance (PMQR) has become a growing clinical concern worldwide. Recent reports from Nigeria revealed that qunolone resistant clinical isolates have become commomplace. However, few reports regarding the prevalence of PMQR are available. Hence, this study aimed to determine the prevalence of PMQR genes in qunolone resistant clinical isolates from a tertiary care hospital in Nigeria. Methods This was a cross-sectional hospital based study involving 390 non-repetitive Gram negative bacilli from diverse clinical infections. The isolates were characterized by the MicrobactTM identification kit and their susceptibility patterns determined by the Kirby-Bauer disc diffusion technique. All quinolone resistant isolates were investigated for the carriage of PMQR genes by multiplex polymerase chain reaction (PCR). Data analysis was with appropriate descriptive and inferential statistics.Results The isolates were distributed as Escherichia coli (n=121; 31.0%), Klebsiella species (n= 112;28.7%), Pseudomonas aeruginosa (n=59;15.1%), Proteus species (n=43;11.0%), Salmonella species (n=6;1.3%) and others. They were commonly resistant to nalidixic (62.6%), co-amoxiclav (57.7%); norfloxacin (52.3%), ofloxacin(52.1%) and ciprofloxacin(51.0%), but were least resistant to imipenem; (n=36; 9.2%). Out of 244 isolates that were resistant to at least one quinolone, 180 (73.8%) harboured one or more PMQR gene with a high prevalence of efflux-mediating determinants (qepA, 22.5%; oqxAB, 21.1%), and the aminoglycoside acetyltransferase (aac(6’)-Ib-cr, 19.7%). Proportionately low level of target-protecting determinants; qnrB, 13.2%; qnrS, 8.7%; qnrA, 5.9%; qnrD, 4.5% and qnrC, 4.2% were found in these isolates.Conclusion There is high level quinolone resistance and wide distribution of PMQR genes in clinical isolates in Nigeria with a preponderance of Efflux-mediating determinants and the aminoglycoside acetyltransferase. This emphasizes the need for regular resistance surveillance and antimicrobial stewardship to guide the appropriate and judicious use of antibiotics.