Original Article

Ann Lab Med 2015; 35(1): 94-98

Published online January 1, 2015

Copyright © Korean Society for Laboratory Medicine.

Antimicrobial Susceptibility of Clinical Isolates of Bacteroides fragilis Group Organisms Recovered from 2009 to 2012 in a Korean Hospital

Jisook Yim, M.D.1, Yangsoon Lee, M.D.2, Myungsook Kim, M.T.1, Young Hee Seo, B.S.1, Wan Hee Kim, B.S.1, Dongeun Yong, M.D.1, Seok Hoon Jeong, M.D.1, Kyungwon Lee, M.D.1, and Yunsop Chong, Ph.D.1

Department of Laboratory Medicine and Research Institute of Bacterial Resistance1, Yonsei University College of Medicine, Seoul; Department of Laboratory Medicine2, Hanyang University College of Medicine, Seoul, Korea

Correspondence to: Kyungwon Lee
Department of Laboratory Medicine, Research Institute of Bacterial Resistance, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Korea
Tel: +82-2-2228-2446
Fax: +82-2-313-0956

Received: July 25, 2014; Revised: September 16, 2014; Accepted: October 30, 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: Periodic monitoring of antimicrobial resistance trends of clinically important anaerobic bacteria such as Bacteroides fragilis group organisms is required. We determined the antimicrobial susceptibilities of clinical isolates of B. fragilis group organisms recovered from 2009 to 2012 in a tertiary-care hospital in Korea. Methods: A total of 180 nonduplicate clinical isolates of B. fragilis group organisms were collected in a tertiary care hospital. The species were identified by conventional methods: the ATB 32A rapid identification system (bioMérieux, France) and the Vitek MS matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (bioMérieux). Antimicrobial susceptibility was determined by the CLSI agar dilution method. Results: Imipenem and meropenem resistance rates were 0-6% for B. fragilis group isolates. The rate of resistance to piperacillin-tazobactam was 2% for B. fragilis and 0% for other Bacteroides species, but 17% for B. thetaiotaomicron isolates. High resistance rates to piperacillin (72% and 69%), cefotetan (89% and 58%), and clindamycin (83% and 69%) were observed for B. thetaiotaomicron and other Bacteroides spp. The moxifloxacin resistance rate was 27% for other Bacteroides spp. The MIC50 and MIC90 of tigecycline were 2-4 μg/mL and 8-16 μg/mL, respectively. No isolates were resistant to chloramphenicol or metronidazole. Conclusions: Imipenem, meropenem, chloramphenicol, and metronidazole remain active against B. fragilis group isolates. Moxifloxacin and tigecycline resistance rates are 2-27% and 8-15% for B. fragilis group isolates, respectively.

Keywords: Bacteroides fragilis group, Antimicrobial resistance, Tigecycline, Moxifloxacin