Clinical isolates of Streptococcus pneumoniae resistant to levofloxacin contain mutations in both gyrA and parC genes

Citation
Xt. Zheng et al., Clinical isolates of Streptococcus pneumoniae resistant to levofloxacin contain mutations in both gyrA and parC genes, INT J ANT A, 18(4), 2001, pp. 373-378
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS
ISSN journal
0924-8579 → ACNP
Volume
18
Issue
4
Year of publication
2001
Pages
373 - 378
Database
ISI
SICI code
0924-8579(2001)18:4<373:CIOSPR>2.0.ZU;2-8
Abstract
Thirty Streptococcus pneumoniae clinical isolates resistant to levofloxacin were analyzed for the quinolone resistance-determining DNA sequences to id entify point mutations and were tested for in vitro susceptibility to multi ple drug classes. Of these isolates, 29 had mutations in both gyrA and parC genes of DNA gyrase and topoisomerase IV. respectively. In GyrA, an amino acid change from Ser-81 --> Phe was detected in 27 isolates and a Glu-85 -- > Lys change was found in the remaining three. Of the 29 isolates for which ParC data were available, Ser-79 --> Tyr or Phe were the predominant mutat ions observed. MICs for levofloxacin were 4-16 mg/l. whereas those for moxi floxacin were 1-2 mg/l. Twenty-four (80%) isolates were susceptible to eryt hromycin, 25 (83%) to azithromycin, 26 (87%) to clarithromycin, 27 (90%) to clindamycin, 20 (67%) to penicillin, 21 (70%) to ceftriaxone and 30 (100%) to amoxycillin/clavulanate. These results confirm the presence of double m utations among clinical isolates of S. pneumoniae from diverse geographical regions of North America and also suggest that quinolone resistance may de velop independently of resistance to other drug classes. (C) 2001 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved .