Discovery of Nosiheptide, Griseoviridin, and Etamycin as Potent Anti-Mycobacterial Agents against Mycobacterium avium Complex

Mycobacterium avium complex (MAC) is a serious disease mainly caused by M. avium and M. intracellulare. Although the incidence of MAC infection is increasing worldwide, only a few agents are clinically used, and their therapeutic effects are limited. Therefore, new anti-MAC agents are needed. Approximately 6600 microbial samples were screened for new anti-mycobacterial agents that inhibit the growth of both M. avium and M. intracellulare, and two culture broths derived from marine actinomycete strains OPMA1245 and OPMA1730 had strong activity. Nosiheptide (1) was isolated from the culture broth of OPMA1245, and griseoviridin (2) and etamycin (viridogrisein) (3) were isolated from the culture broth of OPMA1730. They had potent anti-mycobacterial activity against M. avium and M. intracellulare with minimum inhibitory concentrations (MICs) between 0.024 and 1.56 μg/mL. In addition, a combination of 2 and 3 markedly enhanced the anti-mycobacterial activity against both M. avium and M. intracellulare. Furthermore, a combination 2 and 3 had a therapeutic effect comparable to that of ethambutol in a silkworm infection assay with M. smegmatis.

Retrospective study of the predictors of mortality and radiographic deterioration in 782 patients with nodular/bronchiectatic Mycobacterium avium complex lung disease

OBJECTIVES

Some patients with nodular/bronchiectatic Mycobacterium avium complex lung disease (NB MAC-LD) deteriorate and die. The main aim of the study is to evaluate the prognostic factors and radiographic outcomes in patients with NB MAC-LD.

SETTING

Retrospective single-centre review.

PARTICIPANTS

782 HIV-negative patients with NB MAC-LD treated at our institution in Japan.

PRIMARY AND SECONDARY OUTCOME MEASURES

All-cause and MAC-LD progression mortality rates and the prognostic factors, and radiographic deterioration rates and the prognostic factors.

RESULTS

Mean age was 68.1 years, and median follow-up period was 4.3 years. Death from any cause and progression of MAC lung disease (MAC-LD) occurred in 130 (16.6%), and 19 (2.4%) patients, respectively. All-cause and MAC-LD progression 10-year mortality rates were 27.4% and 4.8%, respectively. In 536 patients with MAC-LD who were followed-up for more than 1 year, radiographic deterioration occurred in 221 (41.2%) patients and median time-to-radiographic deterioration was 9 years. A multivariate Cox proportional hazard model showed male sex, older age, body mass index <18.5 kg/m(2), absence of bloody sputum, hypoalbuminaemia and erythrocyte sedimentation rate >40 mm/h to be negative prognostic factors for all-cause mortality, and the presence of idiopathic pulmonary fibrosis, haemoglobin <11.3 mg/dL, C reactive protein >1.0 mg/dL and the presence of cavity to be negative prognostic factors for radiographic deterioration.

CONCLUSIONS

Only 2.4% of patients with NB MAC-LD died from MAC-LD progression. As clinical trials testing the effectiveness of drug therapy in patients with NB MAC-LD are being designed and implemented, the primary end point could be time-to-radiographic deterioration, and trial patients need to be stratified according to these prognostic factors before randomisation.

Non-tuberculous mycobacteria pulmonary infection: Management and follow-up of 31 infected patients

BACKGROUND

The global number of non-tuberculous mycobacteria (NTM) pulmonary infections is increasing. Treatment decisions and management are difficult and the prognosis of these infections has been rarely evaluated.

METHODS

The aim of this study was to evaluate management and prognosis of patients with NTM pulmonary infection in a French teaching hospital. In this study, we evaluated management of patients satisfying the ATS (American Thoracic Society) criteria for NTM pulmonary infection in Amiens hospital from 1992 to 2002 and retrospectively compared this management to ATS guidelines. Short-term and long-term survival was also described.

RESULTS

Thirty-one patients satisfying the ATS criteria for NTM pulmonary infection were included: 15 patients were infected with Mycobacterium xenopi, nine with Mycobacterium avium intracellulare, four with Mycobacterium kansasii and three patients were infected with rapidly growing mycobacteria. Twenty-seven patients had past or concomitant diseases responsible for local or systemic immunosuppression. Eleven patients were not treated. In the 20 treated patients, 13 different antibiotic combinations were used, often comprising three or more drugs. The median survival was 15 months. Twenty-one patients (67%) died before 5 years of follow-up. Thirty per cent of deaths were attributed to NTM pulmonary infection. Adjusting treatment to the results of susceptibility tests or ATS guidelines was not associated with any significant difference in survival.

CONCLUSION

As the high mortality rate may be related to concomitant diseases, management of NTM pulmonary infection also depends on comorbidities, and should be defined according to the severity of underlying diseases.

[Clinical studies on the pathogenetic factors of cavitary and nodular bronchiectatic types in pulmonary Mycobacterium avium complex disease]

We investigated the clinical, laboratory and radiological findings of 273 newly diagnosed cases of pulmonary Mycobacterium avium complex (MAC) disease, who were diagnosed in our hospital during 7 years from January 1996 to December 2002. Radiological findings of all cases were classified at the time of diagnosis into 2 patterns, the cavitary (Cav) type and the nodular bronchiectasis (NB) type. Clinical and laboratory findings at the time of diagnosis of 44 death cases were compared with those of 273 newly diagnoses cases, to analyze the prognostic factors of this disease. MAC disease cases showed a marked increase in number in recent years, but only in women. Mean age at the first visit was 65.7 years in men and 63.2 years in women, and when limited to fatal cases, it was 72.3 years in men and 69.4 years in women. Low body weight in terms of body mass index (BMI) and moderately low serum albumin level were found at the time of the first hospital visit in all the newly diagnosed and death cases. In the fatal cases, the peripheral blood lymphocyte counts revealed a relatively smaller number than the normal range, and the PPD skin test showed a negative reaction in 57.7% of all cases, suggesting the presence of lowered cell-mediated immunity at the time of diagnosis. Whether malnutrition occurs as a result of MAC disease or the individuals with lower nutrition level are easy to develop to MAC disease remains to be clarified. In regard to radiological findings, many cavitary (Cav) type cases were found in men and nodular bronchiectasis (NB) type in women among newly diagnosed cases, while the cavitary type was observed in many in both men and women fatal cases. The mean duration period from diagnosis to death was 28.3 months in men and 60.2 months in women, showing a longer survival after diagnosis, perhaps due to earlier hospital visits by women. The average age at death was 74.4 years old in men and 73.8 years old in women, and the two radiological patterns did not change throughout the entire disease course.

Clinical and prognostic importance of serotyping Mycobacterium avium-Mycobacterium intracellulare complex isolates in human immunodeficiency virus-negative patients

We studied whether the serotypes of Mycobacterium avium-Mycobacterium intracellulare complex (MAC) isolates determine the prognosis for pulmonary MAC disease. We prospectively monitored a cohort of 68 patients with pulmonary MAC disease for whom the serotype-specific glycopeptidolipids in isolates were identified using thin-layer chromatography and fast atom bombardment mass-spectrometry in 1990 and 1995. Serovar 4 Mycobacterium avium was detected in 40/68 patients (58.8%). Other serotypes were serotypes 1 (five cases), 6 (three cases), 8 (seven cases), 9 (three cases), 14 (four cases), and 16 (six cases). Patients with serovar 4 were significantly (P < 0.01) younger (63.0 +/- 9.8 years) than patients with other serotypes (71.8 +/- 10.3). Patients who failed treatment had a significantly poorer prognosis than other patients. There were no cases of MAC-related death in the cured group. Chest radiographic findings progressively worsened in 36 (90%) of patients with serotype 4, and 14/36 died from respiratory failure caused by pulmonary Mycobacterium avium disease. The patients with serotype 4 had a significantly poorer prognosis than patients with other serotypes. These results show that both the outcome of chemotherapy and the serotypes of MAC isolates are important for assessing the prognosis of pulmonary MAC disease.

Changing mortality rates and causes of death for HIV-infected individuals living in Southern Alberta, Canada from 1984 to 2003

OBJECTIVES

To examine changes over a 2-year period in both the mortality rate and the causes of death in a geographically defined HIV-infected population.

METHODS

A database search of primary care information for the dates and causes of death for all patients documented with HIV infection and living in Southern Alberta between 1984 and 2003 was undertaken. Sociodemographic and clinical characteristics were obtained. Causes of death were then individually confirmed by reviewing the patients' hospital charts, autopsy reports, or death certificates and coded using the International Classification of Diseases, 9th Revisions. AIDS deaths were reconciled with Public Health Reports. The time span was divided into pre-highly active antiretroviral therapy (HAART) (1984-1996) and current HAART (1997-2003) periods.

RESULTS

Between 1984 and 2003, there were 560 deaths in the 1987 individuals living with HIV infection in Southern Alberta. Of these, 436 deaths (78%) occurred pre-HAART and 124 (22%) in the current HAART period. The crude mortality rate declined from 117 deaths per 1000 patient-years pre-HAART to 24 in the current HAART period. In the pre-HAART era, 90% of all deaths were AIDS related whereas only 67% were AIDS related in the current HAART era. The leading causes of AIDS deaths were AIDS multiple causes (31%), Mycobacterium avium complex (18%), Pneumocystis pneumonia (10%) and non-Hodgkin's lymphoma (7%). The proportion of non-AIDS related deaths increased from 7% pre-HAART to 32% in the current HAART era. Accidental deaths, including drug overdose (29%), suicide (7%) and violence (3%), hepatic disease (19%), non-AIDS related malignancies (19%), and cardiovascular disease (16%) accounted for the majority of non-AIDS related deaths. No deaths directly caused by drug toxicity were found. Overall, 21% of patients who died were antiretroviral (ARV)-naive. A total of 14% of patients dying from AIDS were ARV-naive in contrast to 35% dying from non-HIV related conditions. Of all those dying from AIDS, 23% died<3 months after their initial diagnosis, reflecting late presentation. In the current HAART era, 87% of patients who died from AIDS were extensively treated, reflecting HAART treatment failures due mostly to multiclass drug resistance (42%), inexorable disease progression despite ARV (32%), lack of ability or interest to be maintained on a lifelong HAART programme (21%) and, rarely, drug intolerance (<1%).

CONCLUSIONS

Deaths from AIDS-related causes have decreased significantly, but deaths from non-AIDS related conditions have increased, both as an absolute number of deaths and as a proportion of all deaths in HIV-infected patients. The increasing age of the HIV population, and the increased mean CD4 count, increased proportion of intravenous drug users, increased hepatitis B virus and hepatitis C virus coinfection rate, and increased history of smoking seen in our population also influenced the mortality rate and causes of death. These factors must also be considered in projecting future trends in mortality of an HIV-infected population.

[A clinical study of deceased cases of pulmonary M. Avium complex (MAC) disease--: in contrast with survived cases followed-up for 5 years or longer]

We performed a clinical study of pulmonary M. avium complex (MAC) disease comparing decreased cases and survived cases followed-up for 5 years or longer. The results were as follows: 1. At the time of starting the initial medical treatment for pulmonary MAC disease, the deceased cases were older than the survived cases, and the deceased cases were severe than the survived cases in clinical conditions. The spread of the lesions was more extensive and cavities were more frequently observed in the deceased cases than in the survived cases. 2. We classified the clinical pattern of pulmonary MAC disease into a primary infection type and a secondary infection type. Then, we subclassified the primary infection type into a localized type, which contained a tuberculosis-like type and middle, lingular or other lobar pneumonia type, and a diffuse type. The secondary infection type was more frequent in the deceased cases than in the survived cases, and any middle, lingular or other lobar pneumonia type was not observed in the deceased cases. 3. We classified the mode of progression of pulmonary MAC disease in the deceased cases into a tuberculosis-like progression and a diffuse progression. The tuberculosis-like type and the secondary infection type frequently showed the tuberculosis-like progression and the diffuse type frequently showed the diffuse progression. The patients who showed the tuberculosis-like progression were frequently sputum culture positive for MAC, while all patients showing the diffuse progression were culture negative at the time of death. An interval from the estimated onset of the disease to death was shorter in the tuberculosis-like progression type than in the diffuse progression type.

Disseminated M. avium complex infection in the Swiss HIV Cohort Study: declining incidence, improved prognosis and discontinuation of maintenance therapy

BACKGROUND

Introduction of potent antiretroviral combination therapy (ART) has reduced overall morbidity and mortality amongst HIV-infected adults. Some prophylactic regimes against opportunistic infections can be discontinued in patients under successful ART.

QUESTIONS UNDER STUDY

(1) The influence of the availability of ART on incidence and mortality of disseminated M. avium Complex infection (MAC). (2) The safety of discontinuation of maintenance therapy against MAC in patients on ART.

SETTING

The Swiss HIV-Cohort Study, a prospective multicentre study of HIV-infected adults.

METHODS

Patients with a nadir CD4 count below 50 cells/mm3 were considered at risk for MAC and contributed to total follow-up time for calculating the incidence. Survival analysis was performed by using Kaplan Meier and Cox proportional hazards methods. Safety of discontinuation of maintenance therapy was evaluated by review of the medical notes.

RESULTS

398 patients were diagnosed with MAC from 1990 to 1999. 350 had a previous CD4 count below 50 cells/mm3. A total of 3208 patients had a nadir CD4 count of less than 50 cells/mm3 during the study period and contributed to a total follow-up of 6004 person-years. The incidence over the whole study period was 5.8 events per 100 person-years. In the time period of available ART the incidence of MAC was significantly reduced (1.4 versus 8.8 events per 100 person-years, p < 0.001). Being diagnosed after 1995 was the most powerful predictor of better survival (adjusted hazard ratio for death: 0.27; p < 0.001). None of 24 patients discontinuing maintenance therapy while on ART experienced recurrence of MAC during a total follow-up of 56.6 person-years (upper 95% confidence limit 5.3 per 100 person-years).

CONCLUSION

Introducing ART has markedly reduced the risk of MAC for HIV-infected individuals with a history of very low CD4 counts. Survival after diagnosis of MAC has improved after ART became available. In patients responding to ART, discontinuation of maintenance therapy against M. avium may be safe.

Decision analysis with cumulative prospect theory

BACKGROUND

Individuals sometimes express preferences that do not follow expected utility theory. Cumulative prospect theory adjusts for some phenomena by using decision weights rather than probabilities when analyzing a decision tree.

METHODS

The authors examined how probability transformations from cumulative prospect theory might alter a decision analysis of a prophylactic therapy in AIDS, eliciting utilities from patients with HIV infection (n = 75) and calculating expected outcomes using an established Markov model. They next focused on transformations of three sets of probabilities: 1) the probabilities used in calculating standard-gamble utility scores; 2) the probabilities of being in discrete Markov states; 3) the probabilities of transitioning between Markov states.

RESULTS

The same prophylaxis strategy yielded the highest quality-adjusted survival under all transformations. For the average patient, prophylaxis appeared relatively less advantageous when standard-gamble utilities were transformed. Prophylaxis appeared relatively more advantageous when state probabilities were transformed and relatively less advantageous when transition probabilities were transformed. Transforming standard-gamble and transition probabilities simultaneously decreased the gain from prophylaxis by almost half. Sensitivity analysis indicated that even near-linear probability weighting transformations could substantially alter quality-adjusted survival estimates.

CONCLUSION

The magnitude of benefit estimated in a decision-analytic model can change significantly after using cumulative prospect theory. Incorporating cumulative prospect theory into decision analysis can provide a form of sensitivity analysis and may help describe when people deviate from expected utility theory.

Competing risk adjustment reduces overestimation of opportunistic infection rates in AIDS

To illustrate the importance of adjusting the estimates of cumulative incidence of acquired immunodeficiency syndrome (AIDS) related illnesses for competing risk of other causes of death, we compared unadjusted and adjusted (for competing events) incidence estimates for four AIDS illnesses: pneumocystis cavinii pneumonia (PCP), mycobacterium avium complex (MAC), cytomegalovirus (CMV), and esophageal candidiases. The study population was patients followed by the Johns Hopkins Hospital AIDS Service between 1989 to 1995. Ratios of 4 year unadjusted incidence estimates to 4 year adjusted incidence estimates for the four diseases ranged from 1.38 to 1.86, corresponding to cumulative death rates of 61% to 69%. For CMV, the ratios of 4 year unadjusted to adjusted incidence estimates for five groups of patients ranged from 1.5 to 2.33, corresponding to cumulative death rates of 48% to 78%. We conclude that ignoring the competing risk of death can result in substantial overestimation of disease occurrence, which may give misleading results in estimating and comparing the occurrence of a disease of interest.

Association of DRB1*1501 with disseminated Mycobacterium avium complex infection in North American AIDS patients

The HLA class II allele, DR2 (DRB1*1501), has been repeatedly found to be associated with development of tuberculosis and leprosy. We searched for associations of these and other class II alleles with disseminated Mycobacterium avium complex infection (DMAC) in North American Caucasian homosexual AIDS patients. Molecular typing for HLA-DRB1 and -DQB1 alleles in 176 cases of DMAC and 176 matched controls showed an association of accelerated onset of disease with DRB1*1501 (and the closely linked DQB1*0602) that was stronger upon adjustment for the degree and duration of CD4+ cell deficiency (P=0.04) and in multivariate analysis (P=0.02) than in unadjusted analysis. A similar trend was seen with DRB1*0701, and no other allele showed a relationship of similar magnitude. M. avium complex organisms may more effectively evade host defenses in individuals carrying an HLA polymorphism identical to that associated with M. tuberculosis and M. leprae.

Lymphoproliferative responses to mitogens and prepared antigens of M. avium complex in patients with HIV infection

Published reports have demonstrated that antigens of Mycobacterium avium complex (MAC) can suppress the normal response to mitogens in lymphoproliferation assays. We therefore studied the lymphoproliferative (LP) function of PBMC from 55 HIV-infected patients and 16 controls in response to mitogens with and without MAC antigen. As expected, LP responses decline with progressive decline in CD4 count; MAC antigen in combination with PHA further suppresses that response in a dose-dependent manner. More relevant were the LP responses in those with CD4 counts less than 100. All patients with MAC disease had poor responses (stimulation index, SI < 10) to PHA or anti-CD3 with or without MAC antigen. Those who did not have nor subsequently developed MAC were both good (SI > 10) or poor responders (SI < 10). The suppressive effect of MAC on lymphocyte function may serve as a weak virulence factor which is only relevant in severely immunocompromised HIV patients.

A retrospective study of the addition of ciprofloxacin to clarithromycin and ethambutol in the treatment of disseminated Mycobacterium avium complex infection

Disseminated Mycobacterium avium complex (DMAC) infection is associated with increased morbidity and mortality in HIV-infected individuals. The combination antibiotic regimens containing clarithromycin can decrease symptoms and improve survival in patients with DMAC, however, optimal therapy remains to be defined. Quinolones have been widely used in the treatment of DMAC but their utility has not been established. A retrospective cohort study of DMAC infection was established in a metropolitan hospital providing comprehensive care to over 3000 HIV-infected individuals. Medical records of patients with DMAC diagnosed at the Parkland Memorial Hospital from 1991 to 1994 were reviewed for therapeutic regimens for DMAC, concomitant therapy for HIV and Pneumocystis carinii prophylaxis and date of death. Subjects were included if they were treated with clarithromycin and ethambutol. Cases were defined as those patients who received more than 30 days of ciprofloxacin as therapy for DMAC in addition to the other drugs that they received. The primary endpoint was the time to death from the data of DMAC diagnosis. Covariates effecting survival were analysed through the Cox proportional hazards model. Eighty-nine subjects with DMAC who were treated with clarithromycin and ethambutol were identified. Fifty-eight received ciprofloxacin in addition to clarithromycin and ethambutol. The time to death was significantly better in those subjects who were treated with ciprofloxacin than those who were not (489 days vs 281 days, P=0.01). The sole significant predictor of improved survival on Cox proportional hazards model was ciprofloxacin therapy. Subjects treated with combination of clarithromycin, ethambutol and ciprofloxacin had improved survival over those treated with clarithromycin and ethambutol alone.

Hierarchical proportional hazards regression models for highly stratified data

In clinical trials conducted over several data collection centers, the most common statistically defensible analytic method, a stratified Cox model analysis, suffers from two important defects. First, identification of units that are outlying with respect to the baseline hazard is awkward since this hazard is implicit (rather than explicit) in the Cox partial likelihood. Second (and more seriously), identification of modest treatment effects is often difficult since the model fails to acknowledge any similarity across the strata. We consider a number of hierarchical modeling approaches that preserve the integrity of the stratified design while offering a middle ground between traditional stratified and unstratified analyses. We investigate both fully parametric (Weibull) and semiparametric models, the latter based not on the Cox model but on an extension of an idea by Gelfand and Mallick (1995, Biometrics 51, 843-852), which models the integrated baseline hazard as a mixture of monotone functions. We illustrate the methods using data from a recent multicenter AIDS clinical trial, comparing their ease of use, interpretation, and degree of robustness with respect to estimates of both the unit-specific baseline hazards and the treatment effect.

High rates of disseminated infection due to non-tuberculous mycobacteria among AIDS patients in Finland

OBJECTIVE

to determine the rate of disseminated infection due to non-tuberculous mycobacteria (NTM) among Finnish AIDS patients, and to analyse the epidemiology of these infections.

METHODS

in a prospective cohort study HIV-infected patients with CD4 counts < 200 x 10(6)/l were interviewed, and had mycobacterial blood cultures performed at baseline and at 6 months, then subsequently for clinical indications; autopsies were performed on patients who died. The cohort was followed at least for 24 months or to death. Water samples were collected from the homes of patients and from the environment and cultured for organisms of the Myobacterium avium complex (MAC). Environmental and clinical isolates were compared using pulsed field gel electrophoresis (PFGE).

RESULTS

NTM infection occurred in 22 (43%) of 51, 19 isolates were Mycobacterium avium, two M. genavense and one M. intracellulare. Multivariate analysis identified urban residence (P=0.04) and eating raw fish (P=0.04) as independent risk factors. Molecular analysis revealed two clusters of related isolates (three M. avium, two M. genavense) among urban residents.

CONCLUSION

AIDS patients in Finland have high rates of disseminated infection due to NTM. Clusters of identical organisms and association with urban residence suggests that these are newly acquired infections in advanced AIDS.

Nontuberculous mycobacteria: defining disease in a prospective cohort of South African miners

A gold mining work force was followed prospectively over 1 yr for sputum nontuberculous mycobacterial (NTM) isolates. NTM were isolated from 118 men, of whom 32 (27%) met the American Thoracic Society (ATS) case-definitions for pulmonary NTM disease (23 M. kansasii, seven M. scrofulaceum, one M. avium, and one M. abscessus). Determining isolate significance was difficult because most men had been started on presumptive TB treatment before isolate identification (70%). Histologic criteria were considered inappropriate for this high M. tuberculosis incidence population, particularly for patients who had stabilized on presumptive TB treatment. Among men not meeting case-definitions, indicators of disease were significantly more prevalent for M. kansasii than for M. fortuitum, the local laboratory contaminant (ORs: 6.5 for cough, 7. 2 for smear-positivity, 36.0 for radiologic changes, and 14.3 for presumptive TB treatment), suggesting underdiagnosis of M. kansasii disease. Of 53 men with definite or possible M. kansasii disease, 18 (34%) were HIV-positive. HIV-associated M. kansasii disease occurred at an early stage of immunosuppression (median CD4 count, 381 x 10(6)/L) with a good outcome (83% cured after 12 mo of treatment). ATS case-definitions for NTM disease are difficult to apply in this population, and treatment decisions should be guided by the pathogenic potential of the isolate.

The impact of HIV infection on Mycobacterium kansasii disease in South African gold miners

The impact of human immunodeficiency virus (HIV) infection on Mycobacterium kansasii disease in miners was investigated with a retrospective study covering a single workforce. M. kansasii, isolated from 43 HIV-positive and 202 HIV-negative miners, was the most common nontuberculous mycobacterial (NTM) species in both HIV groups. CD4 counts were unusually high for M. kansasii disease (mean 490 x 10(6)/L, from 14 HIV-positive men). Treatment outcomes were similar: mortality during treatment was higher in HIV-positive than in HIV-negative men (9% and 2%, respectively), but not significantly so. The majority of a sample of 31 HIV-positive and 92 HIV-negative men had radiological silicosis and/or old tuberculosis scarring prior to M. kansasii disease. A normal premorbid radiograph was more common in HIV-positive men (45% versus 24%; odds ratio [OR], 2.62; 95% confidence interval [95% CI], 1.01 to 6.67). New cavitation was less common (55% versus 78%; OR, 0.34; 95% CI, 0.13 to 0.88) and new hilar adenopathy more common (OR, 5.07; 95% CI, 1.24 to 21.9) in HIV-positive than in HIV-negative men. Miners, who have additional NTM risk factors, develop M. kansasii disease that occurs at an earlier stage of HIV infection and more closely resembles disease in HIV-negative men than has been found for HIV-associated M. kansasii disease in other settings.

A prospective randomized trial of four three-drug regimens in the treatment of disseminated Mycobacterium avium complex disease in AIDS patients: excess mortality associated with high-dose clarithromycin. Terry Beirn Community Programs for Clinical Research on AIDS

The optimal regimen for treatment of Mycobacterium avium complex (MAC) disease has not been established. Eighty-five AIDS patients with disseminated MAC disease were randomized to receive a three-drug regimen of clarithromycin, rifabutin or clofazimine, and ethambutol. Two dosages of clarithromycin, 500 or 1,000 mg twice daily (b.i.d.), were compared. The Data and Safety Monitoring Board recommended discontinuation of the clarithromycin dosage comparison and continuation of the rifabutin vs. clofazimine comparison. After a mean follow-up of 4.5 months, 10 (22%) of 45 patients receiving clarithromycin at 500 mg b.i.d. had died (70 deaths per 100 person-years) compared with 17 (43%) of 40 patients receiving clarithromycin at 1,000 mg b.i.d. (158 deaths per 100 person-years) (relative risk, 2.43; 95% confidence interval, 1.11-5.34; P = .02). After 10.4 months, 20 (49%) of 41 patients receiving rifabutin had died (81 deaths per 100 person-years) compared with 23 (52%) of 44 patients receiving clofazimine (94 deaths per 100 person-years) (relative risk, 1.20; 95% confidence interval, 0.65-2.19; P = .56). Bacteriologic outcomes were similar among treatment groups. In treating MAC disease in AIDS patients, the maximum dose of clarithromycin should be 500 mg b.i.d.

Predictors of survival and eradication of Mycobacterium avium complex bacteremia (MAC) in AIDS patients in the Canadian randomized MAC treatment trial. Canadian HIV Trials Network Protocol 010 Study Group

OBJECTIVE

To assess the importance of baseline characteristics including medical history, indicators of current disease status, therapeutic drug use, in vitro drug susceptibility, immune status and mycobacterial load on bacteriologic response and survival in HIV-positive patients with Mycobacterium avium complex (MAC) bacteremia.

DESIGN

An observational substudy of an open-label randomized controlled trial of two alternative therapeutic regimens for MAC.

SETTING

Twenty-four hospital-based HIV clinics in 16 Canadian cities.

MAIN OUTCOME MEASURES

The main outcome measures were survival and bacteriologic response, defined by consecutive negative blood cultures for MAC at least 2 weeks apart within 16 weeks of study entry.

RESULTS

Prior AIDS diagnosis, low Karnofsky score, active unstable AIDS-related conditions, absence of antiretroviral therapy and absence of Pneumocystis carinii pneumonia prophylaxis were associated with shorter survival by univariate regression using the proportional hazards model. On multivariate analysis, antiretroviral therapy was not an independent predictor of mortality, and previous rifabutin prophylaxis was independently associated with poor survival outcomes, a result consistent across study treatment. Using a logistic regression model, baseline quantitative mycobacterial load [relative odds of clearing, 1.97 for a decrease of 1 log10 colony forming count; 95% confidence interval (CI), 1.36-2.87; P < 0.001] and Karnofsky score were the only statistically significant univariate predictors of clearance, although previous prophylaxis with rifabutin was also a significant predictor in a multivariate model (relative odds of clearing, 0.39; 95% CI, 0.17-0.88; P < 0.05).

CONCLUSIONS

This study indicates that although the level of MAC bacteremia is an important predictor of clearance, it is not associated with survival.

Temporal trends in AIDS-related survival

Although research indicates that AIDS-related survival has improved over calendar time, studies of temporal AIDS-related survival patterns are often confounded by the stage of AIDS diagnosis. The objective of the present study was therefore to assess temporal trends in AIDS-related survival from clinical indicators other than point of AIDS diagnosis. The study sample consisted of 2126 adult HIV-positive patients who were treated between 1987 and 1996 at a large southwestern academic medical center. Proportional hazards analyses indicate that survival from each of the following clinical baselines improved in a linear fashion over calendar period: first CD4 count, first CD4 count of 200 or greater, first CD4 count less than 200, and diagnosis of Pneumocystis carinii pneumonia, cytomegalovirus, and Mycobacterium avium complex. These findings indicate that previously estimated survival trajectories have persisted through the mid-1990s, even when defining survival from clinical indicators other than AIDS diagnosis.

Change in colony morphology influences the virulence as well as the biochemical properties of the Mycobacterium avium complex

Factors that influence colony morphology are of crucial importance for drug development as well as for understanding the virulence of Mycobacterium avium complex (MAC) strains. The MAC 101 strain used in the present study grows as smooth transparent (SmT) colonies that tend to become opaque and pigmented when incubated for long periods of time. However, when MAC was passaged in animals, two types of colonies were recovered. The new rough transparent (RgT) colony morphology appeared more flat and transparent, having a central spot, irregular edges at times, and a dry, granular appearance like that of the rough mutants. In animal studies, the RgT bacilli multiplied at a much faster rate than that of the SmT bacilli, causing 60-80% mortality compared with the 10% mortality observed in mice infected with SmT. In vitro studies indicated that the SmT MAC did not grow and multiply as well in resident peritoneal macrophages as the RgT MAC did. The two morphotypes did not differ in their growth ratesin vitro but the RgT MAC failed to reduce dimethylthiazol-diphenyltetrazolium bromide (MTT), alamar blue and neutral red, suggesting that there might be significant changes in the cell wall or elsewhere causing changes in cellular permeability. These two morphotypes could serve as models for studying the biochemical markers or the identification of factors responsible for the virulence of the MAC.

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.

[Disseminated infection with Mycobacterium avium complex (MAC) in HIV infection]

EPIDEMIOLOGY

Disseminated MAC-infection is one of the most frequent opportunistic infections occurring in HIV-infected patients. Severely immunocompromised patients with CD4-counts < 50/microliter are at greatest risk for the disease. Survival of untreated infection is very poor (5 to 6 months). With therapy survival is prolonged by about 4 months. CLINICAL PRESENTATION AND DIAGNOSTIC PROCEDURES: The leading symptom of MAC-infection is fever eventually accompanied by weight lost, night sweats, enlarged lymph nodes, hepatosplenomegaly, abdominal pain and anemia. Blood cultures are very sensitive and the most appropriate examination. Other diagnostic procedures include bone marrow cultures, biopsies of the gastrointestinal tract, lymph nodes and the liver. Detection of MAC in sputum and stool samples only proves colonisation but not dissemination. However, colonisation of the gastrointestinal tract frequently precedes disseminated disease.

THERAPY

Combination of clarithromycin, rifabutin and ethambutol has proven to be the most efficacious therapy and therefore has to be considered as standard therapy for disseminted MAC-infection. Problems most frequently encountered with this medication include uveitis (rifabutin) gastrointestinal disturbances (clarithromycin) and leucopenia (rifabutin) as well as drug interactions with protease-inhibitors (rifabutin).

PROPHYLAXIS

Clarithromycin, rifabutin and azithromycin given as primary prophylaxis can diminish the risk of disseminated MAC-infection. Although a survival benefit has been seen with clarithromycin, primary prophylaxis of MAC-infection is not standard care in many centers. Reasons to withhold MAC-prophylaxis include lower incidence rates in some countries as well as possible side effects and drug interactions.

CONCLUSION

Disseminated MAC-infection is a frequent opportunistic disease in HIV-infected persons who are severely immunocompromised. Antibiotic combination therapy with clarithromycin, rifabutin and ethambutol improves clinical symptoms and survival. Primary prophylaxis with different regimens is efficacious but the specific epidemiologic situation in each country has to be considered.