JAC Advance Access published online on April 29, 2004
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkh225
© 2004 by The British Society for Antimicrobial Chemotherapy
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1 Departamento de Microbiología,
Facultad de Medicina, Universidad de Zaragoza, 50009 Zaragoza;
* To whom correspondence should be addressed. E-mail: vila{at}medicina.ub.es.
Objectives: The aim of this study
was to determine the roles of mutations in the gyrA and parC genes and the overexpression of efflux pump(s)
as mechanisms of resistance to quinolones. Forty-five Yersinia
enterocolitica O:3 clinical isolates (41 nalidixic acid-resistant,
three nalidixic acid-susceptible and one nalidixic acid-resistant
strain obtained in vitro) were analysed. Results: All the nalidixic acid-resistant strains
showed mutations in the gyrA gene and none in the parC gene. The presence of the inhibitor produced
decreases in the MIC values of nalidixic acid by two to six serial dilution
steps in 37 of the 41 nalidixic acid-resistant strains. Meanwhile,
the MIC value of ciprofloxacin was affected in two strains whose
values diminished three serial dilution steps. The nalidixic acid-resistant mutant
obtained in vitro was also affected by the inhibitor
decreasing the MIC value of nalidixic acid three serial dilutions
steps whereas the MICs for the nalidixic acid-susceptible strains
were not affected. Conclusions: Our results show that the high
level of resistance to nalidixic acid is likely due to an overexpression
of an efflux pump plus a mutation in the gyrA gene,
whereas decreased susceptibility to ciprofloxacin is only associated
with the presence of a mutation in the gyrA gene.
Revised March 1, 2004
Accepted March 5, 2004
Brief report
Characterization of the molecular mechanisms of
quinolone resistance in Yersinia enterocolitica O:3
clinical isolates
2 Secció de Medicina Tropical,
C.S.I., U.A.S.P., IDIBAPS, Hospital Clínic, Villarroel
170, 08036 Barcelona;
3 Servei de Microbiologia, Institut
Clínic Infeccions i Inmunología, IDIBAPS, Facultad
de Medicina,
Universitat de Barcelona, Villarroel 170, 08036 Barcelona, Spain
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Abstract
-naphthylamide, quinolones
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