Detection of erm(X)-mediated antibiotic resistance in Bifidobacterium longum subsp longum

Forty-six strains from a collection of human bifidobacteria stored in our lab, each belonging to Bifidobacterium longum subsp. longum species and displaying unique Multilocus sequencing typing (MLST) profiles, were chosen to assess an antibiotic resistance pattern. Three B. longum strains were found to be macrolide-lincosamide-streptogramin B (MLS)-resistant; erm(X) determinants were detected in genomic DNA, and two acquired erm(X) determinants by Tn5432 transposition. A complete sequence of Tn5432 in the bifidobacteria genome was obtained for the first time. The transposon Tn5432 in the Bifidobacterium longum subsp. longum SQS4-63 genome was located between the NTP pyrophosphatase and pyruvate kinase genes, and the insertion created an 8 bp duplication of the target sequence (GATAACGA).