The frequency of BRO β-lactamase and its relationship to antimicrobial susceptibility and serum resistance in Moraxella catarrhalis.
We investigated the frequency of BRO β-lactamase and its relationship to antibiotic susceptibility profiles and serum susceptibility. Moraxella catarrhalis clinical isolates (n = 197) were collected from patients with respiratory tract infections in Tokyo between November 2004 and April 2005. Phenotypic and genotypic detection of β-lactamases was performed. The MICs of 6 antibiotics were determined by Etest, and the serum bactericidal assay was conducted by using the culture-and-spot test. Nearly all (192; 97%) of the clinical isolates were β-lactamase producers; of these, 182 (95%) were bro-1 and 10 (5%) were bro-2 positive. MIC50, MIC90, and geometric mean MICs of penicillin, amoxicillin, cefixime, and clarithromycin for BRO-1 isolates were significantly higher than for BRO-2 isolates. The frequency of intermediate and full serum resistance was significantly higher in BRO-1 isolates than in BRO-2 isolates (P = 0.0056), but not BRO-negative isolates (P = 0.1333). We provide the first evidence that the presence of BRO-1 in M. catarrhalis is associated with reduced susceptibility to clarithromycin and β-lactam antibiotics, as well as serum non-sensitive (intermediate and resistant).
Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan. Electronic address: r-saito.mi@tmd.ac.jp.
Ryoichi
R
Saito
Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Shotaro
S
Nonaka
Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Yuji
Y
Fujinami
Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Shiho
S
Matsuoka
Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Shinichi
S
Nakajima
Clinical Laboratory Department, Surugadai Nihon University Hospital, 1-8-13 Kandasurugadai, Chiyoda-Ku, Tokyo 101-8309, Japan.
Hiroyuki
H
Nishiyama
Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Noboru
N
Okamura
D000890:Anti-Infective Agents / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D001936:Moraxella catarrhalis / Q000187:drug effects* / Q000201:enzymology* / Q000302:isolation & purification; D045828:Moraxellaceae Infections / Q000188:drug therapy / Q000382:microbiology*; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000382:microbiology; D001618:beta-Lactamases / Q000032:analysis / Q000096:biosynthesis*
D000890:Anti-Infective Agents; C408134:BRO beta-lactamase; D001618:beta-Lactamases
Macrolide; Moraxella catarrhalis; Serum resistance; β-Lactam; β-Lactamase