A randomized evaluation of ethambutol for prevention of relapse and drug resistance during treatment of Mycobacterium avium complex bacteremia with clarithromycin-based combination therapy. California Collaborative Treatment Group

Patients with AIDS and Mycobacterium avium complex (MAC) bacteremia are at high risk for relapse and emergence of resistant isolates during monotherapy with clarithromycin. Ninety-five AIDS patients with MAC bacteremia received clarithromycin plus clofazimine, with or without ethambutol, in a prospective, multicenter, randomized open-label trial. Of 80 patients with positive baseline cultures, sterilization or a 2 log10 reduction in colony-forming units of MAC in two consecutive blood cultures occurred in 69% of both groups. There were nine relapses in the two-drug arm and three in the three-drug arm. Kaplan-Meier estimates of risk of relapse at 36 weeks were 68% and 12%, respectively (P = .004). All relapse isolates were resistant to clarithromycin. Median time to clarithromycin resistance was 16 weeks with two drugs and 40 weeks with three drugs (P = .004). Ethambutol reduced relapses and emergence of clarithromycin resistance and should be considered an essential component of clarithromycin-based therapies for MAC bacteremia.

Transient bacteremia due to Mycobacterium avium complex in patients with AIDS

It is generally assumed that Mycobacterium avium complex (MAC) bacteremia, once it develops, is unremitting. On the basis of this presumption, changes in the level of mycobacteremia are used to gauge therapeutic response. In 7 (12%) of 60 patients enrolled in a prospective trial of MAC bacteremia and AIDS, bacteremia became undetectable before the initiation of antimycobacterial therapy. Patients with transient bacteremia reported fewer and shorter symptoms and survived longer than those with sustained bacteremia (59 vs. 31 weeks; P = .022). There was no difference in the duration of AIDS, CD4+ cell count, hematocrit, or body weight between groups. Two additional patients with transient bacteremia were identified outside this study setting. Despite disappearance of detectable mycobacteremia and subsequent administration of antimycobacterial agent(s), bacteremia once again became detectable in 6 patients 4-45 weeks after their negative pretreatment cultures. Patients with disseminated MAC may have fluctuating levels of mycobacteremia that become undetectable in the absence of antimycobacterial therapy.

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.

Examiner dependence on physical diagnostic tests for the detection of splenomegaly: a prospective study with multiple observers

OBJECTIVE

To determine the reliability and validity of various physical diagnostic techniques (including three methods of palpation and three methods of percussion) in detecting ultrasonographically identified splenomegaly.

DESIGN

Prospective, double-blind study.

SETTING

University hospital.

PATIENTS

Twenty-seven hospitalized male patients with suspected human immunodeficiency virus (HIV) infection.

INTERVENTIONS

Three methods of palpation (bimanual, ballottement, and palpation from above) and three methods of percussion (as described by Nixon, Castell, and Barkun et al.) were performed on each patient by eight examiners. Splenic ultrasonography was performed within 96 hours of admission.

MEASUREMENTS AND MAIN RESULTS

The prevalence of splenomegaly by ultrasonography (defined as a spleen > or = 13 cm on the longitudinal scan) in this population was 33.3%. The sensitivity and specificity of each method of palpation and percussion varied by examiner. The ranges of sensitivity across examiners for the three methods of palpation and the three methods of percussion were 0%-64.3% and 7.7%-75%, respectively. The ranges of specificity across examiners for the three methods of palpation and the three methods of percussion were 50%-100% and 60%-100%, respectively. Likelihood ratios pooled across observers revealed that for palpation, palpation from above, and percussion, Castell's method had the highest likelihood ratios [LR = 2.66 and 1.97, respectively; 95% CI = 1.52-4.64 and 1.22-3.19, respectively]. A combination of tests (either palpation or percussion) increased the diagnostic accuracy.

CONCLUSION

Physical diagnostic techniques for the detection of splenomegaly are relatively insensitive but specific. In this study there was high interobserver variability, which did not appear to be associated to the level of experience. Combining tests increases diagnostic accuracy.

Treatment of Mycobacterium avium complex bacteremia in AIDS with a four-drug oral regimen. Rifampin, ethambutol, clofazimine, and ciprofloxacin. The California Collaborative Treatment Group

OBJECTIVE

To determine the quantitative microbiologic response and the clinical response of patients with Mycobacterium avium complex bacteremia and AIDS to an oral antimycobacterial regimen.

DESIGN

A phase II, multicenter clinical trial.

SETTING

Four university-affiliated medical centers.

PATIENTS

Forty-one patients with HIV infection who had at least two consecutive blood cultures positive for M. avium complex and who had not received previous antimycobacterial therapy were enrolled in the study. Thirty-one patients were evaluable with regard to the efficacy of the oral regimen.

INTERVENTIONS

Patients received a combination of orally administered rifampin (600 mg), ethambutol (15 mg/kg body weight), clofazimine (100 mg once daily), and ciprofloxacin (750 mg twice daily) for 12 weeks. Parenterally administered amikacin, 7.5 mg/kg daily for 4 weeks after the first 4 weeks of oral therapy, was used at the discretion of the individual investigator.

MEASUREMENTS

Clinical symptoms, Karnofsky scores, and adverse events were monitored. Colony counts for M. avium complex were determined.

MAIN RESULTS

The mean logarithmic (log) baseline colony count decreased from 2.1 to 0.7 after 4 weeks of oral therapy (P less than 0.001). Suppression of bacteremia was sustained throughout therapy. Thirteen patients (42%) became culture negative during therapy. The mean duration of treatment was 9.7 weeks. Nineteen evaluable patients (61%) completed 12 weeks of therapy. Adverse reactions to one or more agents were common.

CONCLUSIONS

A rapid reduction in symptoms and bacteremia can be achieved as early as week 2 of therapy using an oral regimen of rifampin, ethambutol, clofazimine, and ciprofloxacin. Colony counts rose dramatically after therapy was discontinued, suggesting that more prolonged periods of therapy are necessary to eradicate systemic infection.

Impact of Pneumocystis carinii and cytomegalovirus on the course and outcome of atypical pneumonia in advanced human immunodeficiency virus disease

Patients undergoing bronchoscopy for possible pneumocystis pneumonia were studied retrospectively to characterize the impact of common viral pathogens on the course of advanced human immunodeficiency virus (HIV) disease and atypical pneumonia. In 327 episodes, Pneumocystis carinii was found in 220 (67%), cytomegalovirus (CMV) in 145 (44%), and herpes simplex virus in 16 (5%). Early deterioration in oxygenation and use of intensive care was less common in CMV-positive patients. Neither CMV nor P. carinii was a predictor of mortality in multivariate analyses. CMV was not associated with an increased prevalence of later CMV disease. Isolation of CMV from the bronchoalveolar lavage fluid of these patients was not an indication for antiviral therapy. Pulmonary shedding of CMV may be associated with a decreased inflammatory response to P. carinii. The outcome of HIV-associated atypical pneumonia where no clear pulmonary pathogen is found on routine evaluation was no better than that of treated P. carinii pneumonia.

The impact of concomitant viral pathogens on the course of Pneumocystis carinii pneumonia

A large retrospective study was conducted to evaluate the impact of culturing cytomegalovirus from the respiratory secretions of AIDS patients with Pneumocystis carinii pneumonia. Pneumocystis carinii was found in 220 (67%) of 327 episodes and cytomegalovirus was found in 106 (48%) of the P. carinii-positive patients. Cytomegalovirus-positive and -negative patients were similar at baseline and had a similar number of hospital days, but had a lower incidence of early deterioration in oxygenation, fewer intensive-care days, were less frequently intubated, and had a higher 30-day survival. The better short-term outcome of cytomegalovirus positive patients observed in this study may relate to the immunosuppressive effects of cytomegalovirus.