Restriction fragment length polymorphism analysis of clinical isolates of Mycobacterium haemophilum

Mycobacterium haemophilum is an emerging opportunistic pathogen, and since 1989, infections caused by this organism have been identified more frequently in the New York City area than in any other region of the United States. A DNA fingerprinting method, based on restriction fragment length polymorphisms (RFLPs) was developed. A genomic library of M. haemophilum isolate 1A was constructed; screening the library yielded a recombinant strain that incorporated a genetic element present in multiple copies in the M. haemophilum genome. This clone was used to produce a probe for RFLP analyses of PvuII digests of genomic DNA. We used this probe to determine the RFLP patterns of 43 clinical isolates of M. haemophilum from 28 patients. A total of six distinct patterns were observed. Two patterns, designated types 1 and 2, accounted for 91% of the infections in patients from the New York City area. Two isolates from Arizona had identical patterns but were distinct from those of New York isolates, and an isolate from Israel, the type strain, had another distinct pattern (type 6). The type 6 pattern was also seen in a recent isolate from Norway. All of the type 1 isolates and 60% of the type 2 isolates were recovered from patients with AIDS in the New York City area. This molecular subtyping method should provide a useful tool for epidemiological studies and may help identify the associated risk factors, vehicles, and possible reservoirs of this newly emerging pathogen.