The diagnosis of two cases of cutaneous ulcer caused by infection with Mycobacterium haemophilum: direct identification in a clinical sample by polymerase chain reaction-restriction endonuclease analysis.

BACKGROUND: Mycobacterium haemophilum was first recovered from subcutaneous lesions of a patient with Hodgkin's disease. Because of its special growth requirements (it grows at 30-32 degrees C and requires iron-supplemented medium), the organism cannot be isolated using routine culture techniques for other mycobacteria. Only a few developed countries have reported infection with this mycobacterium. We report the first two cases diagnosed in Venezuela.

METHODS: The diagnosis of the first case was established using polymerase chain reaction (PCR)-restriction endonuclease analysis of the gene encoding the 65-kDa heat shock protein (hsp65) for the direct identification of M. haemophilum in a clinical specimen in which bacilli were observed on acid-fast smear, but growth was not detected by standard culture procedures.

RESULTS: After recognizing this bacterium as a possible cause of infection in our setting, clinical samples of cutaneous lesions were routinely cultured on blood agar at 30 degrees C for at least 6 weeks, which resulted in the diagnosis of the second case.

CONCLUSIONS: Dermatologists should consider this bacterium in immunocompromised patients with cutaneous ulcerating lesions. Material from the lesions can be screened for mycobacteria using an acid-fast stain and, if acid-fast bacilli are seen, PCR analysis of mycobacterial hsp65 can be an effective tool for early diagnosis. Appropriate culture methods are required for bacteriologic confirmation of infection with M. haemophilum.