Prevalence of plasmid-mediated qnr determinants and gyrase alteration in Klebsiella pneumoniae isolated from a university teaching hospital in Malaysia

A.S. Saiful Anuar, M.Y. Mohd Yusof, S.T. Tay

Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. tayst@um.edu.my

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• Pharmacology

BACKGROUND AND OBJECTIVES: The ciprofloxacin resistance of Klebsiella (K.) pneumoniae is mediated primarily through alterations in type II topoisomerase (gyrA) gene and plasmid-mediated quinolone resistance-conferring genes (qnr).
This study aimed to define the prevalence of plasmid-mediated quinolone resistance-conferring genes (qnr) and type II topoisomerase (gyrA) alterations of a population of ciprofloxacin-resistant (n = 21), intermediate (n = 8), and sensitive (n = 18) K. pneumoniae isolates obtained from a teaching hospital at Kuala Lumpur, Malaysia.

MATERIALS AND METHODS: A multiplex PCR assay was performed for simultaneous detection of qnrA, qnrB and qnrS. Sequence analysis of the amplified gyrA and gyrB regions of the isolates were performed.

RESULTS: The findings in this study revealed the emergence of a high prevalence (48.9%) of qnr determinants in our isolates. Four variants of plasmid-mediated qnr determinants (qnrB1, qnrB6, qnrB10 and qnrS1) were detected from 11 (52.4%) ciprofloxacin-resistant, 5 (62.5%) intermediate and 7 (38.9%) sensitive isolates. gyrA alterations were detected from 18 (85.7%) ciprofloxacin-resistant isolates. Single gyrA alterations, Ser83→Tyr, Ser83→Ile, and Asp87→Gly, and double alterations, Ser83→Phe plus Asp87→Ala and Ser83→Tyr plus Asp87→Asn were detected. While ciprofloxacin resistance was significantly associated with gyrA alteration (Ser83, p = 0.003; Asp87, p = 0.005; double alteration, p = 0.016), no significant association of ciprofloxacin resistance was noted with the presence of qnr determinants (p = 0.283).

CONCLUSIONS: The findings in this study demonstrate the emergence of qnr determinants and gyrA alterations contributed to the development and spread of fluoroquinolone resistance in the Malaysian isolates.

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