Article in Japanese

Antimicrobial susceptibility of Moraxella catarrhalis isolated from children during 2013-2014: comparison with two previous surveys

Shuta KITO¹⁾, Takao OZAKI¹⁾, Mako HASEGAWA¹⁾, Takuya AKANO¹⁾, Ayami YOSHIKANE¹⁾, Hiroki TAKAO¹⁾, Yuto FUKUDA¹⁾, Tomoyasu NOGUCHI¹⁾, Kensei GOTOH¹⁾, Koji TAKEMOTO¹⁾, Naoko NISHIMURA¹⁾

A total of 75 strains of Moraxella catarrhalis were isolated from 75 children with respiratory tract infections (aged 25 days-13.1 years) who attended this pediatric department from April 2013 to March 2015. Regarding the isolated strains, the β-lactamase test was conducted and the minimum inhibitory concentrations (MICs) for 13 different antimicrobials were measured. M. catarrhalis was isolated most frequently from children aged <1 year and 1 year old (21, and 21 patients, respectively). Overall, 80% of M. catarrhalis were isolated from patients <4 years old. Twelve patients (16%) also had other pathogenic bacteria.
Similar to the results of two previous surveys conducted by the authors in 2000 and 2006, all 75 strains in this study produced β-lactamase. When resistance was defined as intermediate and resistant according to the Clinical and Laboratory Standards Institute (CLSI) criteria, no strain was resistant to CVA/AMPC or LVFX. Resistance to CLDM was noted in 99%. The MIC₅₀/MIC₉₀ values (μg/mL) of the 13 antimicrobials were as follows: ABPC 4/16, CVA/AMPC 0.25/0.25, CCL 1/4, CPDX 1/2, CDTR 0.5/1, CFDN 0.25/0.5, CFTM 1/2, EM 0.25/0.5, CAM ≤0.12/0.5, AZM ≤0.12/≤0.12, MINO ≤0.12/0.25, CLDM 4/8, and LVFX ≤0.12/≤0.12. These data were comparable to results of the previous two surveys. However, high MIC values (>16μg/mL) for EM, CAM, and AZM were seen with 2 strains(3%). This high resistance to macrolides was not observed in the two previous surveys. Therefore, antimicrobial susceptibility to M. catarrhalis should be monitored closely in the future.

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1) Department of Pediatrics, Konan Kosei Hospital

Key words	Moraxella catarrhalis, antimicrobial susceptibility, β-lactamase, macrolides-resistant strain
Received	June 13, 2019
Accepted	November 21, 2019

32 (1)：11─18,2020