New cfiA variant and novel insertion sequence elements in carbapenem-resistant Bacteroides fragilis isolates from Korea

Abstract

Of 276 nonduplicate Bacteroides fragilis clinical isolates recovered from 1997 to 2004, 3 were resistant to carbapenem. cepA and cfiA alleles were detected by polymerase chain reaction in 240 (87.0%) and 11 (4.0%) of the isolates, respectively. Insertion sequence (IS) elements were found only in the 3 carbapenem-resistant B. fragilis isolates, which produced metallo-beta-lactamase at a level detectable by UV spectrophotometry. Sequence analysis showed 1 new cfiA variant, cfiA(11), and 2 novel IS elements. The cfiA(11) gene revealed 5 amino acid substitutions compared to cfiA, with 97.6% amino acid identity. The transposase, terminal inverted repeat sequence, and target site duplication sequence of the 2 novel IS elements were unique. This study reconfirmed the correlation between ISs and carbapenem resistance in B. fragilis.