Mycobacterium lentiflavum, a recently identified slow-growing mycobacterial species: clinical significance in immunosuppressed cancer patients and summary of reported cases of infection

Abstract

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.

Mycobacterium lentiflavumin Drinking Water Supplies, Australia

“…The proportion was higher for M. intracellulare (39.4%), M. avium (33.3%), and M. kansasii (52.6%) and much lower for species traditionally thought to be more likely contaminants, e.g., M. gordonae (11.1%). In our study, isolates for 4 (11%) of 36 were clinically significant, similar to published estimates of 10%–21% ( 16 , 22 ). This proportion may be an underestimate given that we could not determine clinical significance in 4 patients.…”

“…2 y later, started CLR monotherapy, improved by 3 mo, but sputum still ZN+ [EMB, RFB, CIP] added for 2 wk3-y follow-up. Poor compliance with drugs, intermittent hemoptysis, weakness, dyspnoea, sputum remained ZN+, CXR unchanged( 22 )49 y/MUnited StatesFever, right upper lobe pulmonary noncavitary nodules, 2×/ sputum C+ at 27 d, bronchoalveolar lavage C–YesMyelofibrosis on pegylated interferon-α2[CIP 500 mg 2×/day, azithromycin 500 od, EMB 1 g od] unknown durationStable disease, lost to follow up; duration of follow-up NS( 22 )¶66 y/MUnited StatesFever, neutropenia, necrotizing pneumonia, single sputum C+ at 28 dYesHematopoetic stem cell transplant for chronic lymphocytic leukemia, graft vs. host disease[CLR 500 mg 2×/day, EMB 1 g od]Died after 12 wk, septic shock from Pseudomonas aeruginosa . Uncertain significance of M. lentiflavum ( 23 )¶28 y/MBrazilCough, fever, reticulonodular infiltrate, PCP+, 1× sputum C–.…”

Nontuberculous Mycobacterial Lung Disease Caused byMycobacterium lentiflavumin a Patient with Bronchiectasis

“…It has been isolated primarily from lymph nodes of young children3, while isolations from other sites, including respiratory specimens, have been frequently described in immunocompromised patients4. M. lentiflavum lung disease in immunocompetent patients has rarely been described in the literature2,6-8, and the isolation of NTM always raises doubts about clinical significance.…”

Disseminated Mycobacterium lentiflavum Responsible for Hemophagocytic Lymphohistocytosis in a Man with a History of Heart Transplantation

“…M. lentiflavum is phylogenetically related to other slow-growing NTM species, such as M. genavense and M. simiae (2), and traditional biochemical tests poorly differentiated M. lentiflavum from these closely related NTM species, which led to misclassification before the advent of molecular diagnosis (13). It is also important to accurately assess the clinical significance of the isolate because, similarly to other NTM species, M. lentiflavum has often been reported as a harmless contaminant.…”

“…Therefore, when possible, antimicrobial susceptibility testing should be performed prior to treatment (23,24). Finally, we performed a brief review of the literature and identified three main clinical presentations of M. lentiflavum infection (Table 1) (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). First, in young children (n ϭ 24) and, rarely, in adults (n ϭ 2), M. lentiflavum can be responsible for lymphadenitis, most often, cervical lymphadenitis, and these cases demonstrate a good outcome after surgical removal alone.…”