Clofazimine as prophylaxis for disseminated Mycobacterium avium complex infection in AIDS

Interventions for the prevention of mycobacterium avium complex in adults and children with HIV

BACKGROUND

Mycobacterium avium complex (MAC) infection is a common complication of advanced acquired immunodeficiency syndrome (AIDS) disease and is an independent predictor of mortality and shortened survival.

OBJECTIVES

To determine the effectiveness and safety of interventions aimed at preventing MAC infection in adults and children with HIV infection.

SEARCH METHODS

We searched MEDLINE, EMBASE, and The Cochrane Library (search date December 2012).

SELECTION CRITERIA

Randomised controlled trials comparing different strategies for preventing MAC infection in HIV-infected individuals.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial eligibility and quality, and extracted data. Where data were incomplete or unclear, a third reviewer resolved conflicts and/or trial authors were contacted for further details. Development of MAC infection and survival were compared using risk ratios (RR) and 95% confidence intervals (CI). The quality of evidence has been assessed using the GRADE methodology.

MAIN RESULTS

Eight studies met the inclusion criteria. Placebo-controlled trials: There was no statistically significant difference between clofazimine and no treatment groups in the number of patients that developed MAC infection (RR 1.01; 95% CI 0.37 to 2.80). Rifabutin (one study; RR 0.48; 95% CI 0.35 to 0.67), azithromycin (three studies; RR 0.37; 95% CI 0.19 to 0.74) and clarithromycin (one study; RR 0.35; 95% CI 0.21 to 0.58) were more effective than placebo in preventing the development of MAC infection. There was no statistically significant difference between those treated with clofazimine (one study; RR 0.98; 95% CI 0.41 to 2.32), rifabutin (one study RR 0.91; 95% CI 0.78 to 1.05), azithromycin (three studies, pooled RR 0.96; 95% CI 0.69 to 1.32) and placebo in number of reported deaths. One study found that the risk of death was reduced by 22% in patients treated with clarithromycin compared to those treated with placebo (RR 0.78; 95% CI 0.64 to 0.96). Monotherapy vs. monotherapy: Patients treated with clarithromycin (RR 0.60; 95% CI 0.41 to 0.89) and azithromycin (RR 0.60; 95% CI 0.40 to 0.89) were 40% less likely to develop MAC infection than those treated with rifabutin. There was no statistically significant difference between those treated with clarithromycin (RR 0.98; 95% CI 0.83 to 1.15), azithromycin (RR 0.98; 95% CI 0.77 to 1.24) and rifabutin in the number of reported deaths. Combination therapy versus monotherapy: There was no statistically significant difference between patients treated with a combination of rifabutin and clarithromycin and those treated with clarithromycin alone (RR 0.74; 95% CI 0.46 to 1.20); and those treated with combination of rifabutin and azithromycin and those treated with azithromycin alone (RR 0.59; 95% CI 1.03). Patients treated with a combination of rifabutin plus clarithromycin were 56% less likely to develop MAC infection than those treated with rifabutin alone (RR 0.44; 95% CI 0.29 to 0.69). Patients treated with a combination of rifabutin plus azithromycin were 65% less likely to develop MAC infection than those treated with rifabutin alone (RR 0.35; 95% CI 0.21 to 0.59). There was no statistically significant difference in the number of reported deaths in all the four different comparisons of prophylactic agents.

AUTHORS' CONCLUSIONS

Based on limited data, azithromycin or clarithromycin appeared to be a prophylactic agent of choice for MAC infection. Further studies are needed, especially direct comparison of clarithromycin and azithromycin. In additions, studies that will compare different doses and regimens are needed.

A phase II/III trial of antimicrobial therapy with or without amikacin in the treatment of disseminated Mycobacterium avium infection in HIV-infected individuals. AIDS Clinical Trials Group Protocol 135 Study Team

OBJECTIVE

To determine the clinical and microbiologic benefit of adding amikacin to a four-drug oral regimen for treatment of disseminated Mycobacterium avium infection in HIV-infected patients.

DESIGN

A randomized, open-labeled, comparative trial.

SETTING

Outpatient clinics.

PATIENTS

Seventy-four patients with HIV and symptomatic bacteremic M. avium infection.

INTERVENTIONS

Rifampin 10 mg/kg daily, ciprofloxacin 500 mg twice daily, clofazimine 100 mg every day, and ethambutol 15 mg/kg orally daily for 24 weeks, with or without amikacin 10 mg/kg intravenously or intramuscularly 5 days weekly for the first 4 weeks.

MAIN OUTCOME MEASURE

Clinical and microbiologic response at 4 weeks; quantitative level of bacteremia with M. avium.

RESULTS

No difference in clinical response was noted with the addition of amikacin to the four-drug oral regimen, and only 25% in either group had a complete or partial response at 4 weeks. A comparable quantitative decrease in bacteremia was noted in both treatment groups, with 16% of patients being culture-negative at 4 weeks and 38% at 12 weeks. Toxicities were mainly gastrointestinal. Amikacin was well tolerated. Median survival was 30 weeks in both groups.

CONCLUSIONS

The addition of amikacin to a four-drug oral regimen of rifampin, ciprofloxacin, clofazimine, and ethambutol did not provide clinical or microbiologic benefit.

Mycobacteria as pathogens of respiratory infection

As the result of a formidable effort, the recent TB epidemic in the United States has abated; however, major questions remain as the risk of TB diminishes. Will we maintain an adequate public health effort not only to prevent another resurgence of TB but also to renew our pursuit of TB elimination? Do we have the will to extend the fight against TB worldwide as the TB threat in the United States declines? What is the best way to incorporate new diagnostic technology into routine practice? What are the best strategies for preventing and treating TB in AIDS patients? From the standpoint of NTM lung diseases, the major challenges are to educate clinicians about the variety and clinical presentation of NTM lung pathogens in order to recognize NTM lung disease as early as possible and to maximize treatment options. Hopefully, we can also improve upon the recent unprecedented progress in treatment regimens for NTM diseases of all types.

Preventing Mycobacterium avium complex in patients who are using protease inhibitors: a cost-effectiveness analysis

BACKGROUND

Practice guidelines recommending Mycobacterium avium complex (MAC) prophylaxis for patients with HIV disease were based on clinical trials in which individuals did not receive protease inhibitors.

OBJECTIVE

To estimate the cost-effectiveness of strategies for MAC prophylaxis in patients whose treatment regimen includes protease inhibitors.

DESIGN

Decision analysis with Markov modelling of the natural history of advanced HIV disease. Five strategies were evaluated: no prophylaxis, azithromycin, rifabutin, clarithromycin and a combination of azithromycin plus rifabutin.

MAIN OUTCOME MEASURES

Survival, quality of life, quality-adjusted survival, health care costs and marginal cost-effectiveness ratios.

RESULTS

Compared with no prophylaxis, rifabutin increased life expectancy from 78 to 80 months, increased quality-adjusted life expectancy from 50 to 52 quality-adjusted months and increased health care costs from $233000 to $239800. Ignoring time discounting and quality of life, the cost-effectiveness of rifabutin relative to no prophylaxis was $44300 per life year. Adjusting for time discounting and quality of life, the cost-effectiveness of rifabutin relative to no prophylaxis was $41500 per quality-adjusted life year (QALY). In comparison with rifabutin, azithromycin was associated with increased survival, increased costs and an incremental cost-effectiveness ratio of $54300 per QALY. In sensitivity analyses, prophylaxis remained economically attractive unless the lifetime chance of being diagnosed with MAC was less than 20%, the rate of CD4 count decline was less than 10 x 10(6) cells/l per year, or the CD4 count was greater than 50 x 10(6) cells/l.

CONCLUSION

MAC prophylaxis increases quality-adjusted survival at a reasonable cost, even in patients using protease inhibitors. When not contraindicated, starting azithromycin or rifabutin when the patient's CD4 count is between 50 and 75 x 10(6) cells/l is the most cost-effective strategy. The main determinants of cost-effectiveness are CD4 count, viral load, place of residence and patient preference.

Prevention and treatment of disseminated Mycobacterium avium complex infection in human immunodeficiency virus-infected individuals

Disseminated Mycobacterium avium complex (DMAC) infection is a common complication of advanced HIV disease, and is an independent predictor of mortality. The clinical features of DMAC infection are fever, weight loss, abdominal pain, anemia, elevated serum alkaline phosphatase, and elevated serum lactate dehydrogenase. The diagnosis is made by blood cultures; clinical diagnosis is unreliable. Chemoprophylaxis of DMAC infection with azithromycin is recommended when the CD4 lymphocyte count is below 50 cells/mm3. Established DMAC infection is treated with clarithromycin plus ethambutol, unless the isolate is macrolide-resistant, in which case the optimal therapy is uncertain. Highly active antiretroviral therapy is important in both prevention and treatment of DMAC infection.

The value of in vitro drug activity and pharmacokinetics in predicting the effectiveness of antimycobacterial therapy: a critical review

Marked increases in case rates of drug-resistant tuberculosis and nontuberculous mycobacterial infections have brought renewed urgency to the development of new treatment regimens for mycobacterial infections. Preclinical data, such as in vitro measures of drug activity and pharmacokinetics, are used in the design of new treatment regimens. This review surveys the extensive published clinical experience concerning the treatment of drug-susceptible tuberculosis to evaluate the use of these preclinical measures in predicting clinical outcomes of antimycobacterial therapy. In vitro measures of drug activity predict the potency of a drug to prevent the emergence of resistance to other antimycobacterial drugs but do not predict the sterilizing activity of a drug or the activity of drug combinations. In vitro measures of drug activity do not allow reliable predictions of the level at which an organism should be considered resistant. Assays of drug penetration in tissues and activity against intracellular bacilli add modestly to the predictive value of in vitro measures of drug activity but still do not predict sterilizing activity. In contrast, animal models of tuberculosis have predicted relative drug potency (including sterilizing activity), the efficacy of multidrug regimens, and the duration of therapy needed. Despite pharmacokinetic parameters that would suggest the need for multiple doses per day, all of the first-line antituberculous drugs are active when given as infrequently as twice weekly. It is difficult to predict the efficacy of therapy for an intracellular pathogen that has the capacity for dormancy. Better in vitro models are needed, particularly ones that predict sterilizing activity.

Therapeutic efficacy of liposomal clofazimine against Mycobacterium avium complex in mice depends on size of initial inoculum and duration of infection

The therapeutic efficacy of liposomal clofazimine (L-CLF) against Mycobacterium avium complex (MAC) was evaluated in the acute and chronic infection models of the beige mouse (C57BL/6J bgj bgj). The maximum tolerated dose of L-CLF was inversely proportional to the infection level. L-CLF showed higher antibacterial activity than free clofazimine. Treatment with 25 mg of L-CLF per kg of body weight (intravenously) was started at days 1, 8, 15, and 22 postinfection and was studied at three levels of MAC infection (10(4), 10(5), and 10(6) bacilli/mouse). L-CLF treatment caused a significant (P < 0.05 to 0.001) reduction in the numbers of viable bacteria in lung, liver, and spleen at all infection levels, irrespective of time of treatment. However, the best results were obtained when an already established infection was treated (day 22). The organ-related differences in response to the treatment were also affected by the level of infection. A marked reduction in the numbers of CFU was observed in the lungs of mice with lower infection levels, whereas liver and spleen were treated more efficiently at higher infection levels. These studies might help in evaluations of host responses to therapy.

Pattern of utilization of rifabutin for prophylaxis of Mycobacterium avium complex among patients with advanced human immunodeficiency virus disease in a community setting

OBJECTIVE

To characterize the pattern of utilization, effectiveness, and safety profile of rifabutin for Mycobacterium avium complex (MAC) prophylaxis among individuals with advanced human immunodeficiency virus disease in a community setting.

METHODS

Individuals who, while registered in the provincial drug distribution program, had at least one CD4 count below 100 cells/mm3 for the period 1 May 1993 to 31 March 1994 were included. MAC diagnoses were identified through a record linkage with the mycobacterial reference laboratory of the Provincial Centre for Disease Control. In order to determine the occurrence of adverse events, a survey was sent in March 1994 to the 98 primary care physicians prescribing rifabutin prophylaxis in the province. We achieved 100% response rate to the survey.

RESULTS

During the study period 515 patients in our drug treatment program were eligible to receive MAC prophylaxis. Of these, 340 (66%) were being prescribed rifabutin as recommended by current guidelines. Rifabutin prophylaxis use was significantly associated with use of antiretroviral therapy. The product limit estimate of the cumulative incidence of MAC at 10 months was 13.0% among those receiving rifabutin prophylaxis. Diagnosis of MAC was significantly associated with a lower baseline CD4 count (cumulative incidence 7.1% and 18.1% for CD4 > or = 50 and < 50 cells/mm3, respectively, P = 0.01). A total of four cases of uveitis, eight cases of pseudo-jaundice, and five cases of arthralgia in 16 patients were identified by our survey.

CONCLUSION

Our data demonstrates that rifabutin prophylaxis of MAC is being used by approximately 66% of eligible individuals. Rifabutin use was associated with antiretroviral use, which may reflect individuals' attitudes towards medications. Our intention-to-treat analysis, with a 10 month cumulative MAC incidence of 13.0% among those receiving rifabutin prophylaxis, is in keeping with break-through rates previously reported in the context of clinical trials. Our results also support previous observations that the risk of MAC infection greatly increases at CD4 counts < 50 cells/mm3. Rifabutin prophylaxis was generally well-tolerated in our program.

Primary care of the HIV patient: standard practice and new developments in the era of managed care

It is easy when taking care of the patient with AIDS to lose sight of the whole person and become focused on the details of micromanagement, distracted by the array of new therapies, and overwhelmed by the financial risks of the disease. It is therefore critical that a healing and respectful relationship is developed with patients and they are engaged in the decisions regarding their care. Physicians must also continue the search for new therapies and struggle to ensure that patients have access to state-of-the-art treatment. In this, the primary care physician plays a critical role, through identifying study centers, becoming an investigator in expanded access programs, and using referrals to clinical trials to provide new therapies to patients and improve understanding of HIV treatment. Finally, quality of life must be at the forefront of physicians' medical conscience. Ultimately, the physician must know when the best treatment he of she can offer is the assurance of a dignified and comfortable death.

In vitro activities of 2,2'-bipyridyl analogues against Mycobacterium avium and M. tuberculosis

SETTING

Because of widespread emergence of resistant Mycobacterium tuberculosis and the high incidence of opportunistic infection caused by M. avium (MAC) in AIDS patients, there is an urgent need for new drugs against these organisms.

OBJECTIVE

To evaluate the activity of newly synthesized 2,2'-bipyridyl analogues against MAC and M. tuberculosis.

DESIGN

Susceptibility of MAC and M. tuberculosis to VUF-8514 and VUF-8842 were determined by both tube dilution method using 7H9 broth and radiometric (BACTEC) method using 14C-palmitic acid.

RESULTS AND CONCLUSIONS

The MICs of 8514 against MAC and M. tuberculosis wee 1 microgram/ml and 0.5 microgram/ml respectively, while for 8842 the respective values were 8 micrograms/ml and 2 micrograms/ml. In general, the MBC values for both drugs were two-fold higher than their corresponding MIC values. However, both drugs exhibited high bactercidal activities against both organisms. The MICs of clinical isolates of both organisms were in the same range as reference strains; furthermore, two isolates of M. tuberculosis that showed resistance to rifampicin were found to be susceptible to 8514. Thus, these two bipyridyl analogues show great promise in chemotherapy of tuberculosis and M. avium infection.

Clofazimine: a review of its medical uses and mechanisms of action

Clofazimine has been in clinical use for almost 40 years, but little is known of its mechanism of action. The primary indication for clofazimine is multibacillary leprosy, but it is useful in several infectious and noninfectious diseases, such as typical myocobacterial infections, rhinoscleroma, pyoderma gangrenosum, necrobiosis lipoidica, severe acne, pustular psoriasis, and discoid lupus erythematosus. Postulated mechanisms of action include intercalation of clofazimine with bacterial DNA and increasing levels of cellular phospholipase A2. Clinical experience, possible mechanisms of action, and side effects of clofazimine are summarized.

Esophageal infections: risk factors, presentation, diagnosis, and treatment

Infections of the esophagus are unusual in the general population and strongly imply immunodeficiency, although immunocompetent individuals are not exempt. HIV infection is predominant among risk factors for infectious esophagitis. For all immunocompromised patients, the most frequently identified esophageal pathogens are Candida, CMV, and HSV. Peculiar to HIV-infected patients are idiopathic esophageal ulcers as well as unusual bacteria and parasites. Patterns of presentation differ with each infecting organism, and clinical features should be used as a guide in achieving a correct diagnosis. For example, a patient with AIDS presenting with esophageal symptoms and thrush, along with abdominal pain, nausea, vomiting, and fever, is unlikely to resolve all symptoms with empiric antifungal therapy alone. Parsimony of diagnosis does not hold among immunodeficient patients in whom concurrent infections are common. Accurate and timely diagnoses are essential as effective treatments are available for particular etiologies. Finally, among immunocompromised patients, all esophageal symptoms are not necessarily due to an infection, and possible diagnoses of pill esophagitis, acid-peptic injury, or structural and functional abnormalities should not be overlooked.