Fluoroquinolone resistance in clinical isolates of Klebsiella oxytoca.
BACKGROUND
Prevalence of fluoroquinolone-resistant Klebsiella oxytoca has been reported worldwide.


METHODS
We recovered ten clinical K. oxytoca isolates from patients with acute cystitis, asymptomatic bacteriuria or acute bacillary diarrhea in Japan. Out of ten isolates, one fluoroquinolone-susceptible isolate was included as a control. Fluoroquinolone resistance was characterized genetically by PCR and DNA sequencing methods. Outer membrane protein (OMP) profiles were determined by SDS-PAGE.


RESULTS
In nine clinical isolates of levofloxacin-resistant K. oxytoca, nucleotide sequences in the quinolone-resistance-determining regions showed amino acid mutations such as Thr83Ile and Asp87Gly in GyrA and Ser80Ile in ParC. Combined effects of reduced 36-kDa OMP production and amino acid mutations in GyrA and ParC were shown by two K. oxytoca isolates exhibiting higher minimum inhibitory concentrations for fluoroquinolones than other fluoroquinolone-resistant isolates.


CONCLUSIONS
In clinical K. oxytoca isolates, the various mechanisms of fluoroquinolone resistance may include reduced 36-kDa OMP production as well as GyrA and ParC mutations.
Horii
Toshinobu
T
Division of Bacteriology, Department of Microbiology and Immunology, Tottori University Faculty of Medicine, Yonago, Japan. horii@med.tottori-u.ac.jp
Osaki
Mai
M
Muramatsu
Hideaki
H
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004198:Disease Susceptibility; D024881:Drug Resistance, Bacterial; D005243:Feces / Q000382:microbiology; D024841:Fluoroquinolones / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007710:Klebsiella Infections / Q000188:drug therapy / Q000382:microbiology* / Q000635:transmission / Q000652:urine; D041121:Klebsiella oxytoca / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase