Characterization of Mycobacterium fortuitum isolates from sternotomy wounds by antimicrobial susceptibilities, plasmid profiles, and ribosomal ribonucleic acid gene restriction patterns.

An outbreak of sternotomy infections due to Mycobacterium fortuitum in patients who had received cardiovascular surgery occurred in a cardiothoracic hospital in Hong Kong, and 21 such isolates from different patients had antimicrobial susceptibility studies against 14 drugs in vitro. These isolates were also studied for plasmid profiles and ribosomal ribonucleic acid gene restriction patterns. The latter method proved valuable in categorization of these isolates into two groups (comprising of nine and seven isolates, respectively) and five other sporadic strains. When the plasmid profiles and ribotyping are matched against the clinical and epidemiologic data, multisource contamination is suspected to be responsible for the outbreak. The organisms were probably derived from the environment rather than contaminated surgical equipments and materials.