Mycobacterium genavense in AIDS patients, report of 24 cases in Italy and review of the literature.

Mycobacterium genavense is a frequently missed agent of disseminated disease in AIDS patients. The increasing frequency with which such organism is being isolated in Italy suggested a comparison of local survey with data reported in literature. Isolates presumed to belong to the species M. genavense were centralized and identified by means of genomic sequencing and/or HPLC analysis of cell wall mycolic acids; clinical data were obtained from relevant patients' record and collected using a proper questionnaire. In 24 cases in which this organism has been isolated in Italy M. genavense was grown, prevalently from blood, in liquid medium after an average of six weeks of incubation. In overwhelming majority, patients were males, presented other opportunistic diseases and were characterized by very low CD4+ counts (average 23/microl); most frequent symptoms were fever, anemia and weight loss. All but two patients, who died before the mycobacterial infection was diagnosed, were treated with at least three drugs; the mean survival was close to one year. A review of literature reports revealed a wide overlapping of clinical and microbiological features.

Activity of seven antimicrobial agents, alone and in combination, against AIDS-associated isolates of Mycobacterium avium complex.

The activity of seven antimicrobial agents (and five two-drug combinations and five three-drug combinations) was investigated against 37 clinical isolates of Mycobacterium avium recovered from blood cultures of AIDS patients. The susceptibility tests were performed in Middlebrook 7H12 broth using a radiometric method. MICs of amikacin, ciprofloxacin, clarithromycin, clofazimine, ethambutol, rifabutin and sparfloxacin were determined. Five antimicrobial agents were tested in combination with clarithromycin and also with clarithromycin plus amikacin to look for possible synergic activity. Synergic activity in combination with clarithromycin and with clarithromycin plus amikacin, was detected for rifabutin (54% and 51% of isolates, respectively), clofazimine (38% and 35%), ethambutol (16% and 32%), ciprofloxacin (8% and 14%) and sparfloxacin (3% and 8%). No antagonism was observed. We conclude that clarithromycin is an essential component in the chemotherapy of M. avium complex disease.

Multicentre evaluation of a biphasic culture system for recovery of mycobacteria from clinical specimens.

A new biphasic system (MB Check, Roche) for isolation of mycobacteria from clinical specimens was evaluated by eight different microbiological laboratories in comparison with methods routinely used in the respective laboratories. Altogether 1125 clinical specimens were processed; pretreatment, if performed, was by a variety of methods. Mycobacteria were recovered from 167 specimens with the biphasic system and 165 specimens with the other methods. The average time required for isolation of Mycobacterium tuberculosis was 22.6 days with the biphasic system and 24.7 days with egg-based media; for other mycobacterial species it was 23.5 versus 20.8 days. The inclusion of a chocolate agar section in the biphasic system facilitated the early detection of contaminants, while the NAP-containing section appeared unable to differentiate Mycobacterium tuberculosis from other mycobacterial species. The biphasic system, which enables recovery of mycobacteria in small laboratories without specialized equipment, is more practical than conventional methods and at least as sensitive.