Search

Fastidious mycobacteria usually infect immunocompromised hosts (human immunodeficiency virus-infected or otherwise immunosuppressed patients). We here describe severe lymphadenitis, caused by a fastidious mycobacterium closely related to Mycobacterium genavense, in an apparently immunocompetent woman, whose brother had died from an unidentified mycobacterial infection in 1969. A variety of techniques, including inoculation of nude mice, histopathology, electron microscopy, lipid analysis, ATP measurements, and molecular biology, were used to characterize this mycobacterium. All attempts to culture the etiological agent on many different media failed. The organism multiplied only in congenitally athymic nude mice. Although phenotypically similar to M. genavense, the mycobacterium differs from M. genavense by three nucleotides of the 16S rRNA gene sequence. Various antimycobacterial drugs were administered, including gamma interferon, but multiple relapses occurred. Finally, therapy with a combined regimen of clarithromycin, clofazimine, rifabutin, and ethambutol was curative. To our knowledge, this is the first report of lymphadenitis in an apparently immunocompetent patient, caused by a noncultivable Mycobacterium sp. closely related to M. genavense. This study emphasizes the importance of employing a variety of diagnostic approaches such as the inoculation of laboratory animals, histopathology, electron microscopy, lipid analysis, ATP measurements, and molecular biology to characterize novel microorganisms that cannot be cultured in vitro.

Starting in February 1994, 20 patients (pt) with a median age of 50 years (range 41−63) from 7 European centers have been included. Complete data were obtained in 16 patients so far. CPC were mobilized with chemo (Epirubicine 75mg/m2/d, D1+D2) followed by G-CSF 5μg/kg/d for 14 days. HD chemo consisted in 3 sequential courses of ICE regimen (Ifos. 10g/m2, Carbo. 1200mg/m2and Etop. 1200mg/m2) under CPC protection and G-CSF 5μg/kg/d. Out of the 16 pt, 12 completed full program (3 cycles). One pt died of septic shock before receiving any ICE course. One pt died during the first ICE of renal insufficiency. Two pt had only 2 courses because of toxicity. Among the 16 pt, response rate (RR) was: 7 CR, 6 PR, 1 PD; 3 pt are not evaluable due to early withdrawal (overall RR: 13/16=81%). Thirty-nine cycles of HD chemo were given with a median hematological recovery of 9 days (range 7−12) until neutro. counts 1.0×109/I and 9 days (range 7−17) until thrombo. 20×109/I. No cumulative, hematological toxicity was seen. Accrual of patients is still ongoing and updated results will be presented.