Mutations in rpoB and fusA cause resistance to rifampicin and fusidic acid in methicillin-resistant Staphylococcus aureus strains from a tertiary hospital in Malaysia

Lim, K.T. and Teh, C.S.J. and Mohd Yasim, M.Y. and Thong, Kwai Lin (2013) Mutations in rpoB and fusA cause resistance to rifampicin and fusidic acid in methicillin-resistant Staphylococcus aureus strains from a tertiary hospital in Malaysia. Transactions of the Royal Society of Tropical Medicine and Hygiene, 108 (2). pp. 112-118. ISSN 0035-9203,

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Abstract

Abstract Background The prevalence of resistance to rifampicin and fusidic acid among Malaysian strains of methicillin-resistant Staphylococcus aureus (MRSA) is increasing. This study aimed to determine the mechanisms of rifampicin and fusidic acid resistance and the genetic diversity of MRSA strains from a Malaysian tertiary hospital. Methods Minimum inhibitory concentrations (MIC) for 21 MRSA strains were determined by agar dilution test and Etest. The resistance genes, staphylococcal chromosome cassette mec (SCCmec) types, multilocus-sequence typing (MLST) types and spa types, were determined by PCR and DNA sequencing. Results MIC for rifampicin and fusidic acid resistance ranged from <1 to 8 µg/ml and from <1 to 256 µg/ml, respectively. A double mutation (484Arg/His and 517Glu/Gln) in rpoB causes high rifampicin resistance while a mutational change (461Leu/Lys) in fusA was observed in seven strains highly resistant to fusidic acid. Five of the seven were also resistant to rifampicin (MIC 8 µg/ml) and carried a mutated rpoB gene (484Arg/His). No other acquired fusidic acid resistance gene (fusB, fusC or fusD) was detected. Most (14/21) of the strains belonged to clone ST239-III-t037. Three belonged to ST22-IV-t1378 and the remaining four to ST239-III-t2029, ST239-III-t421, ST1178-IV-t1107 and ST241-III-t363, respectively. Conclusions The study showed that both rifampicin and fusidic acid resistance was associated with mutational change in rpoB and fusA, respectively. All rifampicin-resistant strains were from the same clone ST239-III-t037 whereas strains resistant to fusidic acid were genetically more diverse.

Item Type:	Article
Funders:	UNSPECIFIED
Uncontrolled Keywords:	MLST; mutation; rifampicin fusidic acid; spa; Staphylococcus aureus
Subjects:	Q Science > QR Microbiology
Divisions:	Faculty of Science > Institute of Biological Sciences
Depositing User:	Prof. Dr Kwai Lin Thong
Date Deposited:	25 Jun 2014 06:52
Last Modified:	18 Mar 2019 08:16
URI:	http://eprints.um.edu.my/id/eprint/10649

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