Treatment of Mycobacterium avium complex infection: do the results of in vitro susceptibility tests predict therapeutic outcome in humans?

The ability of various in vitro methods of antibiotic susceptibility testing to predict therapeutic outcome in patients infected with Mycobacterium avium complex (MAC) was evaluated. Pretreatment bloodstream MAC isolates from 38 patients with AIDS, previously treated in a randomized fashion with either ethambutol, rifampin, or clofazimine, were tested by three conventional methods using broth or agar, as well as by cocultivation with macrophages. The results obtained with each method were compared with the quantitatively determined bacteriologic response to the administration of the single agent in humans. None of the conventional in vitro susceptibility methods was predictive of therapeutic outcome, while the results of cocultivation with macrophages were of moderate predictive value. The positive predictive value of a response in humans based on a response in macrophages (defined by > or = to 1.0 log reduction in baseline colony counts after 5 days of treatment) was 74%. The negative predictive value was 82%.

Treatment of Myocardium avium complex infection: does the beige mouse model predict therapeutic outcome in humans?

To determine the predictive value of a standard murine model in the treatment of disseminated Myocardium avium complex (MAC) infection, beige mice were infected with MAC strains isolated from human immunodeficiency virus-infected patients and treated with the same antibiotic (ethambutol, clofazimine, or rifampin) that had been administered to the subject from whom that strain had been recovered. While ethambutol had the greatest bacteriologic efficacy in humans (mean decrease +/-SD, 1.0+/-0.5 log 10 cfu/mL of blood), clofazimine had the greatest bacteriostatic efficacy in mice (mean decrease +/- SD, 2.8 +/- 0.7 log(10) cfu/g of tissue). A linear correlation was not observed between bacteriostatic activity in mouse liver or spleen and the degree of bacteriologic response in humans (P > or = to .1). Odds ratios for a response in humans based on a bacteriologic response in mice were not significant for each agent (P > or = to .1, all cases).

Disseminated acanthamoeba infection in patients with AIDS: case reports and review.

Acanthamoeba infection has been described as an opportunistic infection in persons with AIDS. We report two cases of patients with AIDS and acanthamoeba infection and review the manifestations of this protozoan infection in patients infected with human immunodeficiency virus. The diagnosis of this infection requires a high index of suspicion because the clinical and histologic manifestations may be confused with those of disseminated fungal or algal disease. Clinicians and laboratory personnel should be aware of this potentially fatal condition so that appropriate diagnostic studies can be performed and treatment can be urgently administered. Early initiation of therapy may alter the clinical outcome of the disease.

The individual microbiologic effect of three antimycobacterial agents, clofazimine, ethambutol, and rifampin, on Mycobacterium avium complex bacteremia in patients with AIDS.

The individual antibacterial activities of clofazimine, ethambutol, and rifampin in the treatment of Mycobacterium avium complex bacteremia in patients with AIDS were determined. Sixty human immunodeficiency virus 1-infected patients who had at least one blood culture positive for M. avium complex were randomized to receive either clofazimine (200 mg), ethambutol (15 mg/kg), or rifampin (600 mg) once daily for 4 weeks. Only ethambutol resulted in a statistically significant reduction in the level of mycobacteremia. The median change in individual baseline colony counts was -0.60 log10 cfu/mL after 4 weeks of ethambutol (P = .046). In contrast, median changes in individual baseline colony counts were -0.2 log10 cfu/mL and +0.2 log10 cfu/mL for clofazimine and rifampin, respectively (both, P > .4). Ethambutol had greater antibacterial activity, as determined by changes in the level of mycobacteremia, than either rifampin or clofazimine, supporting its continued use in combination with other agents in the treatment of M. avium infection.