Carbapenem (cfiA) resistance gene in Bacteroides fragilis group strains in Belgium

Abstract number: P912

Wybo I., Soetens O., Van Doorslaer K., Piérard D., Lauwers S.

Objectives: In a recent Belgian survey [1] 3% of the B. fragilis group strains were not susceptible to meropenem. In our university hospital a decrease in susceptibility to meropenem was observed from 97% in 2005 to 92% and 93% in 2006 and the first 8 months of 2007 respectively. In isolates belonging to other species of the B. fragilis group isolates susceptibility to meropenem was 97% in 2006 and 100% in the other years. The purpose of this study was to determine the prevalence of the cfiA carbapenem resistance gene in B. fragilis group isolates collected for a Belgian survey for resistance in anaerobes and to look for the presence of the cfiA gene in meropenem non-susceptible strains of this group isolated in our hospital.

Methods: From October 2003 to February 2005 238 B. fragilis group strains (135 B. fragilis and 103 other species) were collected in 9 Belgian hospitals. Also included in this study were 15 meropenem non-susceptible strains isolated in our hospital. Meropenem susceptibility was determined by Etest®. The following breakpoints were used for susceptible and resistant strains: leqslant R: less-than-or-eq, slant4 and geqslant R: gt-or-equal, slanted16 mg/L. The strains were screened for cfiA gene by PCR with specific primers.

Results: Of 135 B. fragilis collected for the survey three showed reduced susceptibility (MIC=8) and three were resistant (1 with MIC=16 and 2 with MIC=32). All these isolates and three of four isolates with a MIC of 4 were cfiA gene positive. All B. fragilis isolates with a MIC less than 4, one Bacteroides fragilis isolate with a MIC of 4 and the 103 isolates from other species were cfiA gene negative.

Fifteen meropenem non-susceptible strains (MIC>4; 12 B. fragilis, 1 B. thetaiotaomicron, 1 B. ovatus and 1 B. vulgatis) were detected in our hospital since 2005. Eleven B. fragilis isolates were cfiA gene positive. The cfiA gene was not detected in the remaining B. fragilis strain (MIC=8) and in the other species.

Conclusion: The prevalence of the cfiA resistance gene in Belgian survey isolates (2003–2005) was 6.7% (9/135) in Bacteroides fragilis isolates. All except one of meropenem non-susceptible B. fragilis strains isolated in our hospital since 2005 were cfiA gene positive. The cfiA gene was not detected in other species of the B. fragilis group.


1. Wybo. I. et al. Third Belgian multicentre survey of antibiotic susceptibility of anaerobic bacteria. Journal of Antimicrobial Chemotherapy 2007; 59: 132–9.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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