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Prevalence and genetic background of fluoroquinolone resistance in clinical isolates of Proteus mirabilis

Abstract number: 1733_391

Nakano R., Abe M., Inoue M., Okamoto R.

Objectives: Fluoroquinolone (FQ) resistance among Enterobacteriaceae was reported increasingly. It occurs primarily through mutation in the QRDRs of the DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE). In this study, we carried out a survey to assess the prevalence of the FQ resistant P. mirabilis and investigate the mechanism of the resistance.

Methods: 1855 isolates of P. mirabilis were collected from 7 different hospitals in Kanagawa Prefecture, Japan in 2000–2005. The susceptibility of levofloxacin (LVFX) was determined by the agar dilution method according to the CLSI guidelines. DNA sequences of the QRDRs of gyrA, gyrB, parC, and parE in 50 clinical isolates with susceptibility or resistance to LVFX were determined by PCR and sequencing.

Results: Of the 297 strains were found to resistant to LVFX (MIC > 2 mg/mL). It was gradually increase the incidence in 2000–2004 and was significantly increased 45.9% in 2005. The DNA sequences of the QRDRs of P. mirabilis were identified. Susceptibility strains (MIC, 0.125 to 2 mg/mL) and MIC 4mg/mL strains showed change in gyrA (S83I) and parC (S80I). Low-level resistant strains (MIC, 8 to 16 mg/mL) showed change in gyrA (S83I), gyrB (S464Y or E467D), and parC (S80I). High-level resistant strains (MIC, 32 to 256 mg/mL) showed change in gyrA (S83I+E87K), parC (S80I), and parE (D420N). Highest-level resistant strains (MIC, 512 mg/mL) strains showed change in gyrA (S83I+E87G), gyrB (S464F), parC (S80I), and parE (D420N).

Conclusion: The prevalence of LVFX resistant P. mirabilis was steadily increasing in Japan. Susceptibility profiles for LVFX were correlated with amino acid changes in QRDRs. Low-level resistant strains (MIC, 8 to 16 mg/mL) were associated with mutation in gyrB (S464Y or E467D). High-level resistant strains (MIC, 32 to 256 mg/mL) were associated with mutations in gyrA (E87K) and parE (D420N). Highest-level resistant strains (MIC, 512 mg/mL) were associated with mutations in gyrA (E87G), gyrB (S464F), and parE (D420N).

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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