Polyphasic Characterization Reveals that the Human Pathogen Mycobacterium peregrinum Type II Belongs to the Bovine Pathogen Species Mycobacterium senegalense

Mycobacterium peregrinum consists of two taxa: types I and II. We evaluated 43 clinical type II strains from throughout the United States. They were responsible for soft-tissue and bone infections, catheter-related infections, and possible pneumonitis. By carbohydrate utilization, they were indistinguishable from type I strains, beingd -mannitol and trehalose positive. However, they had a distinct susceptibility pattern that included intermediate ciprofloxacin MICs but low clarithromycin and doxycycline MICs of ≤1 μg/ml. These features were also shared by reference isolates ofMycobacterium senegalense from African bovine cases of “farcy.” By 16S rRNA gene sequencing, the type II isolates shared 100% sequence identity withM. senegalense . Partial sequencing of the type IIhsp65 gene (441 bp) revealed four sequevars showing ≥98.4% identity with each other and ≥98.6% identity with the sequence of five bovine strains ofM. senegalense . There was ≤97.1% identity withM. peregrinum type I isolates and otherMycobacterium fortuitum group species. Sequencing of additional gene targets including the 16S-23S rDNA internal transcribed spacer region and therpoB gene (partial sequence) revealed a similar phylogenetic grouping. DNA-DNA hybridization showed 76 to 99% relatedness between the bovine and human strains. These studies demonstrate that type II isolates are not isolates ofM. peregrinum but represent human strains ofM. senegalense . This study is the first to demonstrate this species as a human pathogen. Representative humanM. senegalense strains include ATCC 35755 and newly submitted strains ATCC BAA-849, ATCC BAA-850, and ATCC BAA-851.