Vol.54 No.5 September 2006

Susceptibility testing of antimicrobial agents against CTX-M-2 group β-lactamase producing Proteus mirabilis isolated from clinical specimens

Atsushi Wakamatsu, Hiroshi Kurokawa, Ayako Serizawa, Takashi Ishimatsu and Akiyoshi Nagata

Health Sciences Research Institute, Inc. Center for Infectious Disease Testing,
106 Godo-cho, Hodogaya-ku, Yokohama, Kanagawa, Japan

Abstract

MICs of antimicrobial agents were tested against CTX-M-2 group β-lactamase producing ESBL Proteus mirabilis isolated from 148 clinical specimens gathered from May to July 2005.
MIC₉₀s of ceftibuten (1 μg/mL), ceftazidime (0.5 μg/mL), cefmetazole (4 μg/mL), latamoxef (≤0.25 μg/mL), imipenem (2 μg/mL), meropenem (≤0.25 μg/mL), and aztreonam (2 μg/mL) indicated high susceptibility toward these agents. Ampicillin, piperacillin, cefazolin, and cefotaxime showed very high MIC₉₀s (≥256 μg/mL).
MIC₉₀ of minocycline was high (128 μg/mL), whereas those of aminoglycosides amikacin, tobramycin, and gentamicin were 8, 16, and 16 μg/mL. MICs of quinolones levofloxacin, ciprofloxacin, and gatifloxacin fluctuated widely from ≤0.25-≥256 μg/mL, ≤0.25-≥256 μg/mL, and ≤0.25-128 μg/mL for each agent.
Infection control of ESBL producing gram-negative rods is very important at a medical institution. Furthermore, susceptibility tests play an important role in the implementation of effective control measures.

Key word

extended spectrum β-lactamase, Proteus mirabilis, drug susceptibility

Received

March 28, 2006

Accepted

June 15, 2006

Jpn. J. Chemother. 54 (5): 447-452, 2006