Mycobacterium lentiflavum, a recently identified slow-growing mycobacterial species: clinical significance in immunosuppressed cancer patients and summary of reported cases of infection.
The clinical significance of Mycobacterium lentiflavum, a recently identified nontuberculous mycobacterium, remains uncertain, especially in immunosuppressed cancer patients. The records of all patients in whom M. lentiflavum was identified using a gene sequencing technique between January 2001 and December 2003 were reviewed. The mean age among 12 patients was 51+/-20 years, and 11 (92%) patients had a hematologic malignancy. Six of seven (86%) hematopoietic stem cell transplant recipients had received allogeneic donor grafts. Nine (75%) patients had predisposing risk factors for infection, seven (58%) had severe lymphocytopenia (<400 cells/microl), five (42%) were receiving systemic corticosteroid therapy, and three (25%) had acute graft-versus-host disease. Only 1 of the 12 (8%) patients had evidence of probable pulmonary M. lentiflavum infection. Six M. lentiflavum strains were initially misidentified as Mycobacterium simiae and Mycobacterium avium-intracellulare complex using traditional biochemical tests. Four M. lentiflavum isolates were tested for antimicrobial susceptibility; they were susceptible to isoniazid, ethambutol, clarithromycin, and amikacin, and resistant to rifampin. M. lentiflavum was not clinically significant, even in these severely immunosuppressed cancer patients.
Safdar
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Department of Infectious Diseases, Infection Control and Employee Health, Division of Internal Medicine, Unit 402, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4095, USA. asafdar@mdanderson.org
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D006801:Humans; D007165:Immunosuppression Therapy / Q000009:adverse effects*; D009165:Mycobacterium Infections, Nontuberculous / Q000188:drug therapy / Q000209:etiology*; D009369:Neoplasms / Q000145:classification / Q000150:complications* / Q000628:therapy; D009894:Opportunistic Infections / Q000188:drug therapy / Q000209:etiology*; D012189:Retrospective Studies