Intrinsic fluoroquinolone resistance in Orientia tsutsugamushi

Title
Intrinsic fluoroquinolone resistance in Orientia tsutsugamushi
Authors
Nair, S; Miller, B; Barends, M; Jaidee, A; Patel, J; Mayxay, M; Newton, P; Nosten, F; Ferdig, MT; Anderson, TJC
Keywords
SCRUB TYPHUS; ANTIBIOTIC SUSCEPTIBILITY; RICKETTSIA-TSUTSUGAMUSHI; CIPROFLOXACIN; THAILAND; HUMANS; INDIA; ASSAY; LAOS; GENE
Issue Date
2010
Publisher
INT J ANTIMICROB AG
Citation
Int. J. Antimicrob. Agents;APR;2010;35;4
Abstract
Scrub typhus is a public health concern for a population of over a billion humans, with an estimated incidence of one million cases/year in endemic areas. Although doxycycline remains the standard therapy, fluoroquinolones have been used successfully in a few patients. However, there is also clinical evidence that fluoroquinolones are ineffective in the treatment of scrub typhus. To clarify this matter, we determined the in vitro susceptibility of Orientia tsutsugamushi strain Kato to ciprofloxacin and ofloxacin and sequenced the quinolone resistance-determining region (QRDR) of the gyrA gene, the target of fluoroquinolones, of 18 fresh isolates from the Lao PDR. Orientia tsutsugamushi strain Kato was resistant to ciprofloxacin and ofloxacin in vitro (minimum inhibitory concentration = 8 mu g/mL). All sequences obtained, including those from the two available genomes of O. tsutsugamushi (strains Boryong and Ikeda), had a Ser83Leu mutation in their QRDR domain that is known to be associated with fluoroquinolone resistance. These findings re-emphasise the usefulness of in silico analysis for the prediction of antibiotic resistance and suggest that fluoroquinolones should not be used in the treatment of scrub typhus. (C) 2009 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.
URI
http://hdl.handle.net/11267/2402
ISSN
0924-8579
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5.Mahosot Hospital > Journal articles
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