Disseminated Mycobacterium avium complex disease in the Swiss HIV Cohort Study: increasing incidence, unchanged prognosis

Mycobacterium avium complex infection in patients with human immunodeficiency virus: A systematic review and meta-analysis

BACKGROUND

Mycobacterium avium-intracellulare complex (MAC) is one of the leading causes of death among people living with human immunodeficiency virus (HIV). The current study was aimed to determine the frequency of MAC infection in patients infected with HIV.

METHODS

Embase, PubMed, and Web of Science were searched for relevant studies. All statistical analyses were performed by STATA version 14.

RESULTS

From 6,627 retrieved articles, 23 were included in the final analysis. A total of 18,463 patients with HIV were included in the analysis. The frequency of MAC infection in patients with HIV was found to be 10.6% (95% confidence interval, 6.9-14.2).

CONCLUSION

The relatively large fractions of HIV-infected patients were coinfected with MAC, which may poses significant public health problems. Continued progress in the development of rapid diagnostic methods and preventive therapy for MAC should lead to further improvements in survival and quality of life in patients with HIV.

Nontuberculous mycobacteria in Denmark, incidence and clinical importance during the last quarter-century

Disease caused by nontuberculous mycobacteria (NTM) is reported to increase due to an ageing population and a rise in the proportion of immunosuppressed patients. We did a retrospective cohort study of NTM-disease in the Danish population through a quarter-century to determine the disease burden and trends in annual incidence rates. 524,119 clinical specimens were cultured for mycobacteria from 1991 through 2015 at the International Reference Laboratory of Mycobacteriology in Denmark. Among these, 8,227 NTM strains were identified from 3,462 patients and distributed according to microbiological disease criteria. We observed no increase in NTM disease incidence or proportion of patients with positive NTM cultures during the study period (Quasi-Poisson regression, p = 0.275 and 0.352 respectively). Annual incidence rates were 1.20/10⁵ for definite NTM disease, 0.49/10⁵ for possible NTM disease and 0.88/10⁵ for NTM colonization. The incidence rate of NTM disease was highest in children aged 0-4 years (5.36/10⁵/year), predominantly with cervical Mycobacterium avium complex (MAC) adenitis. Surprisingly, based on more than half a million clinical specimens cultured for mycobacteria in Denmark through 25 years, the NTM disease burden and trend in incidence in the Danish population has not increased opposed to numerous internationals reports.

Mycobacterium avium Complex Disease

Despite the ubiqitous nature of Mycobacterium avium complex (MAC) organisms in the environment, relatively few of those who are infected develop disease. Thus, some degree of susceptibility due to either underlying lung disease or immunosuppression is required. The frequency of pulmonary MAC disease is increasing in many areas, and the exact reasons are unknown. Isolation of MAC from a respiratory specimen does not necessarily mean that treatment is required, as the decision to treatment requires the synthesis of clinical, radiographic, and microbiologic information as well as a weighing of the risks and benefits for the individual patient. Successful treatment requires a multipronged approach that includes antibiotics, aggressive pulmonary hygiene, and sometimes resection of the diseased lung. A combination of azithromycin, rifampin, and ethambutol administered three times weekly is recommend for nodular bronchiectatic disease, whereas the same regimen may be used for cavitary disease but administered daily and often with inclusion of a parenteral aminoglycoside. Disseminated MAC (DMAC) is almost exclusively seen in patients with late-stage AIDS and can be treated with a macrolide in combination with ethambutol, with or without rifabutin: the most important intervention in this setting is to gain HIV control with the use of potent antiretroviral therapy. Treatment outcomes for many patients with MAC disease remain suboptimal, so new drugs and treatment regimens are greatly needed. Given the high rate of reinfection after cure, one of the greatest needs is a better understanding of where infection occurs and how this can be prevented.

Palatal Actinomycosis and Kaposi Sarcoma in an HIV-Infected Subject with Disseminated Mycobacterium avium-intracellulare Infection

Actinomyces and Mycobacterium avium-intracellulare are facultative intracellular organisms, members of the bacterial order actinomycetales. Although Actinomyces can behave as copathogen when anatomic barriers are compromised, its coinfection with Mycobacterium avium-intracellulare has not previously been reported. We present the first reported case of palatal actinomycosis co-infection with disseminated MAC, in an HIV-infected subject with Kaposi sarcoma and diabetes. We discuss the pathogenesis of the complex condition of this subject.

High incidence of atypical mycobacteriosis in African HIV-infected adults with low CD4 cell counts: a 6-year cohort study in Côte d'Ivoire

The role of non-tuberculous mycobacteriosis (NTM) in HIV-related diseases in sub-Saharan Africa has long been controversial. In a 6-year cohort of 721 HIV-infected adults with systematic BACTEC blood cultures in Abidjan, Côte d'Ivoire, the incidence of NTM was 1.8/100 person-years overall and 12.2/100 person-years in patients with baseline CD4 cell counts < 100 cells/mm3. In sub-Saharan Africa, where most patients start highly active antiretroviral therapy with low CD4 cell counts, improving the diagnosis of NTM may be relevant.

Factors affecting patient adherence to highly active antiretroviral therapy

OBJECTIVE

To determine the clinical and demographic variables related to adherence to highly active antiretroviral therapy (HAART) in patients treated in our hospital and identify the characteristics of nonadherent patients.

METHODS

Outpatients receiving treatment with HAART (n = 283) were asked about variables related to adherence and to complete the APGAR (family support), State-Trait Anxiety questionnaire (STAI) (emotional situation), and IAS (social support) questionnaires. Patients were classified in 2 groups depending on whether adherence was > or =95% or <95%. Adherence was defined as the percentage of dosage forms prescribed that were obtained by the patient at the hospital pharmacy. A multivariate analysis was created to analyze how each significant variable affected adherence.

RESULTS

Our data showed significant nonadherence for patients with the following factors: low level of education, unemployed, emotional situation, and abuse of substances including intravenous drugs. All significant variables were included in a logistic regression model to optimize the results. This model considered 4 variables: age (95% CI 0.89 to 0.99), number of antiretroviral drugs (95% CI 1.05 to 2.11), STAI Anxiety/Trait test (95% CI 2.02 to 6.02), and abuse of drugs (95% CI 1.20 to 3.95).

CONCLUSIONS

We recommended special intervention to reinforce adherence for younger patients, patients taking a high number of antiretroviral drugs, those who have a history of intravenous drug use, and those with high anxiety status.

Characterization of immune responses during infection with Mycobacterium avium strains 100, 101 and the recently sequenced 104

Mycobacterium avium strain 104 was chosen as the M. avium isolate to sequence, as it is virulent to humans, stable and readily transfectable. As this strain has not been widely studied we sought to investigate the pattern of 104 infection in mice. Bacterial growth and the immune response generated were compared with infection with the low virulence M. avium strain 100, and the high virulence common laboratory strain, 101. Mycobacterium avium strains 104 and 101 grew progressively within mice, while strain 100 was gradually cleared. Strains 104 and 101 induced strong T cell activation and spleen cell cultures produced similar levels of IFN-gamma. In mice infected with strain 100 no significant T cell activation or IFN-gamma production was measured. Further, mice infected with strain 104 or 101 also displayed comparable inflammatory responses and similar granuloma formation, while only minimal inflammation was seen in mice infected with strain 100. Strains 101 and 104 also grew in a similar fashion in bone-marrow-derived macrophages and induced significant levels of TNF and nitric oxide. Thus infection with M. avium strain 104 induced an immunological response comparable to M. avium strain 101 and, with the availability of its sequence, should be a useful tool for designing new vaccines or drugs therapies to treat the increasing incidence of M. avium infection in humans.

Incidence of primary opportunistic infections in two human immunodeficiency virus-infected French clinical cohorts

BACKGROUND

Clinical guidelines for the prevention of opportunistic infections in human immunodeficiency virus (HIV)-infected individuals have been developed on the basis of natural history data collected in the USA. The objective of this study was to estimate the incidence of primary opportunistic infections in HIV-infected individuals in geographically distinct cohorts in France.

METHODS

We conducted our study on 2664 HIV-infected patients from the Tourcoing AIDS Reference Centre and the hospital-based information system of the Groupe d'Epidémiologie Clinique du SIDA en Aquitaine enrolled from January 1987 to September 1995 and followed through December 1995. We estimated: (1) CD4-adjusted incidence rates of seven primary opportunistic infections in the absence of prophylaxis for that specific infection or any antiretroviral drugs other than zidovudine; and (2) CD4 lymphocyte count decline.

RESULTS

The highest incidence rates for all opportunistic infections studied occurred in patients with CD4 counts < 200/microl. With CD4 counts < 50/microl, the most common opportunistic infections were toxoplasmic encephalitis (12.6 per 100 person-years) and Pneumocystis carinii pneumonia (11.4 per 100 person-years). Mycobacterium tuberculosis was the least common opportunistic infection (< 5.0/100 person-years). Even with CD4 counts > 300/microl, cases of Pneumocystis carinii pneumonia and toxoplasmic encephalitis were reported. The mean CD4 lymphocyte decline per month was 4.6 cells/microl. There was a significant association between HIV risk behaviour and the incidence of cytomegalovirus infection, between calendar year and the incidence of Pneumocystis carinii pneumonia, toxoplasmic encephalitis and Candida esophagitis, and between geographical area and the incidence of Pneumocystis carinii pneumonia and cytomegalovirus infection.

CONCLUSIONS

Geographical differences exist in the incidence of HIV-related opportunistic infections. These results can be used to define local priorities for prophylaxis of opportunistic infections.

Infection of Mice with Mycobacterium avium Primes CD8+ Lymphocytes for Apoptosis upon Exposure to Macrophages

Mycobacterial infection is associated with granuloma formation in which the presence of apoptosis has been recognized. The role of CD4+ T and CD8+ T cells in host protection against mycobacterial infections has been demonstrated. Previous studies, however, have shown that CD8+ T cells have a limited role in host defense against Mycobacterium avium infection, and we hypothesize that M. avium infection could lead to T cell apoptosis. To investigate this hypothesis, C57BL/6 mice were infected with M. avium strain 101, and the rate of apoptosis of splenic lymphocytes cultured ex vivo with peritoneal macrophages was determined and compared with that of controls. When exposed to infected macrophages ex vivo, splenic lymphocytes from M. avium-infected mice underwent apoptosis, as determined by the TUNEL assay. This increased T cell apoptosis above the control level was observed after 3 weeks but not after only 1 week of infection in mice. No splenic T cell apoptosis was observed when lymphocytes from Mycobacterium smegmatis-infected mice were cultured in the presence of M. smegmatis-infected peritoneal macrophages. Likewise, macrophages infected in vitro with heat-killed M. avium did not trigger T cell apoptosis. Culture of macrophages in different chamber from lymphocytes, separated by a transwell membrane, was not associated with increase of apoptosis compared with uninfected control, suggesting a requirement for direct cell-cell interactions to trigger lymphocyte apoptosis. Using a double staining TUNEL followed by anti-mouse CD4 or anti-mouse CD8 monoclonal antibodies, it was observed that only CD8+ T cells but not CD4+ T cells underwent apoptosis at 3 weeks of infection. In conclusion, M. avium infection in C57/BL6 mice for 3 weeks renders CD8+ T cells prone to apoptosis when exposed ex vivo to macrophages infected with M. avium.

Effects of recombinant granulocyte-colony stimulating factor administration during Mycobacterium avium infection in mice

Granulocyte colony-stimulating factor (G-CSF) administration in vivo has been shown to improve the defence mechanisms against infection by different microbes. Here we evaluated a possible protective role of this molecule in a mouse model of mycobacterial infection. The administration of recombinant G-CSF promoted an extensive blood neutrophilia but failed to improve the course of Mycobacterium avium infection in C57Bl/6 or beige mice. G-CSF administration also failed to improve the efficacy of a triple chemotherapeutic regimen (clarithromycin + ethambutol + rifabutin). G-CSF treatment did not protect interleukin-10 gene disrupted mice infected with M. avium. Spleen cells from infected mice treated with G-CSF had a decreased priming for antigen-specific production of interferon gamma compared to control infected mice. Our data do not substantiate previous reports on the protective activity of G-CSF in antimycobacterial immunity using mouse models.

Infections with Mycobacterium tuberculosis and Mycobacterium avium among HIV-infected patients after the introduction of highly active antiretroviral therapy. EuroSIDA Study Group JD

The impact of highly active antiretroviral therapy (HAART) among human immunodeficiency virus (HIV)-infected patients on the incidences of mycobacterial infections has not been studied in detail. We assessed incidences of mycobacterial diseases among HIV- infected patients following the introduction of HAART, using data from the EuroSIDA study, a European, multicenter observational cohort of more than 7,000 patients. Overall incidences of Mycobacterium tuberculosis (TB) and Mycobacterium avium complex (MAC) were 0.8 and 1.4 cases/100 person-years of follow-up (PYF), decreasing from 1.8 (TB) and 3.5 cases/100 PYF (MAC) before September 1995 to 0.3 and 0.2 cases/100 PYF after March 1997. After adjustment for changes in CD4 cell count and use of antiretroviral treatment in Cox proportional hazards models, the risk of MAC decreased with increasing calendar time (hazard ratio per calendar year; HR = 0.58 [95% confidence intervals: 0.45-0.74], whereas this was not the case for TB; 0.95 [0.74-1.22]). In conclusion, we documented marked decreases in the incidence of TB and to an even larger extent of MAC among HIV-infected patients from 1994 to 1999. The decrease in TB was associated with the introduction of HAART and changes in CD4 cell count. These factors could also explain some of the decrease in MAC over time, though there remained a significantly lower risk of MAC than expected.

Discontinuing or withholding primary prophylaxis against Mycobacterium avium in patients on successful antiretroviral combination therapy. The Swiss HIV Cohort Study

OBJECTIVE

To assess the safety of discontinuing or withholding primary prophylaxis against disseminated Mycobacterium avium infection (MAC) in HIV infected patients on successful antiretroviral combination therapy.

SETTING

National prospective multicentre cohort study.

DESIGN

HIV-infected patients were eligible for the analysis if: (i) they had a history of at least two CD4 cell counts < 50 x 10(6)/l; (ii) they had never had MAC; (iii) they had discontinued or never begun primary prophylaxis against MAC; (iv) they received antiretroviral therapy and demonstrated an increase in CD4 cell counts to > or = 100 x 10(6)/l that was sustained for at least 12 weeks. From this time point until last follow-up, incidence of disseminated MAC disease was measured, and 99% confidence intervals were calculated assuming a Poisson distribution of events.

RESULTS

Two-hundred and fifty-three patients (22.5% female; median age, 37 years, 30% injecting drug users) were eligible for analysis. Sixty-six per cent were in Centers for Disease Control and Prevention (CDC) stage C, and 28% were in CDC stage B. Their median nadir CD4 cell count was 10 x 10(6)/l, the median duration of CD4 cell count < 50 x 10(6)/l was 12 months. During a total follow-up of 364.3 patient-years there was no case of disseminated MAC. The one-sided 99% confidence limit for incidence density of MAC was 1.3 per 100 person-years.

CONCLUSION

Discontinuing or withholding primary prophylaxis against MAC is safe in patients who have a sustained increase in their CD4 cell count to > or = 100 x 10(6)/l.

Prognostic factors of survival of HIV-infected patients with cytomegalovirus disease: Aquitaine Cohort, 1986-1997. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine (GECSA)

OBJECTIVE

To analyse survival of HIV-infected patients who developed cytomegalovirus (CMV) disease and to identify prognostic factors of their survival.

METHODS

Cases of CMV disease diagnosed in the Aquitaine Cohort of HIV-infected patients (n = 4297) during the 1986-1996 period, were reviewed using standardised definitions. Follow-up was extended to December 1997. Cox model was used to determine factors associated with survival after the initial manifestations of CMV disease, considering protease inhibitor (PI) prescription and anti-CMV treatment as time dependent covariates.

RESULTS

253 patients presented a CMV disease of which 221 (87.3%) died (median survival: 7 months). A better prognosis for survival was associated with: PI prescription [relative hazard (RH): 0.26; 95% confidence interval (CI): 0.11-0.59], anti-CMV treatment (RH: 0.37; CI: 0.25-0.54), CD4+ lymphocyte cell count > 50/mm3 (RH: 0.66; CI: 0.47-0.94) and absence of neoplasia (RH: 0.70; CI: 0.52-0.94) whereas the disseminated CMV disease worsened prognosis (RH: 1.83; CI: 1.20-2.80).

CONCLUSION

Antiretroviral treatment including PI, improved short-term prognosis of CMV disease regardless of its clinical manifestations.

Cost-effectiveness of azithromycin for preventing Mycobacterium avium complex infection in HIV-positive patients in the era of highly active antiretroviral therapy. The Swiss HIV Cohort Study

We conducted a cost-effectiveness analysis to determine the clinical and economic consequences of Mycobacterium avium complex (MAC) prophylaxis in HIV-infected patients in the era of highly active antiretroviral therapy (HAART) in a health care system with access unrestricted by financial barriers. The analysis was performed from a health care perspective and compared azithromycin (1200 mg/week) with no prophylaxis over a period of 10 years based on data from the Swiss HIV Cohort Study (SHCS) and randomized controlled trials. The main outcome measures were: expected survival; average health care costs; and cost-effectiveness in 1997 Swiss francs ( pound1 corresponds to about 2.3 CHF) per life-year saved. In patients with an initial CD4 count <50 cells/mm(3) and no AIDS, azithromycin increased expected survival by 4 months. In patients with AIDS, HAART durability had a major impact on expected survival and costs. Incremental survival increased from 2 to 4 months if we assumed a 10 year, instead of a 3 year, HAART effect. The cost-effectiveness of azithromycin relative to no prophylaxis in patients without AIDS was between 47,000 CHF (3-year HAART effect) and 60,000 CHF (10-year HAART effect) per life-year saved. The cost-effectiveness ratio increased to 118,000 CHF per life-year saved in patients with symptomatic AIDS. In conclusion, in the era of HAART, MAC prophylaxis with azithromycin increases expected survival and reduces health care costs substantially. Starting MAC prophylaxis in patients without AIDS is more effective and cost-effective than in patients with AIDS.

Heterodimer-loaded erythrocytes as bioreactors for slow delivery of the antiviral drug azidothymidine and the antimycobacterial drug ethambutol

Disseminated infection with Mycobacterium avium complex (MAC) remains the most common serious bacterial infection in patients with advanced AIDS. The organisms that make up this complex are found ubiquitously in the environment, yet rarely cause disseminated disease in nonimmunocompromised human patients; on the contrary, up to 50% of patients with AIDS may ultimately develop the pathology. Hence, therapeutic strategies able to inhibit HIV and Mycobacterium replication are needed. Because of the rapid plasma elimination and toxicity of the most commonly used drugs, daily multiple-drug therapies must often be continued throughout life, frequently causing major side effects and, as a consequence, poor patient compliance. Therefore, alternative strategies that reduce the toxicity of the drugs and allow prolonged application intervals are sorely needed. Since erythrocytes (RBCs) can behave as bioreactors able to convert impermeant prodrugs to membrane-releasable active drugs, new compounds (AZTpEMB, AZTpEMBpAZT, and AZTp2EMB) consisting of both an antiretroviral and an antimicrobial drug were designed and synthesized. Among these, only AZTp2EMB was hydrolyzed by erythrocyte enzymes and could be encapsulated inside RBCs. AZTp2EMB-loaded RBCs slowly released AZT and EMB in culture medium, reducing its concentration by one-half about every 48 hr of incubation at 37 degrees C. Moreover, when AZTp2EMB-loaded erythrocytes were incubated for 6 days in the presence of human macrophages infected with Mycobacterium avium (M. avium) a marked bactericidal effect (>1 log) was observed. Thus, AZTp2EMB-loaded erythrocytes could be used as endogenous bioreactors for AZT and EMB delivery in the treatment of HIV and M. avium infection.

Isolation of blood-borne Mycobacterium avium by using the nonradioactive BACTEC 9000 MB system and comparison with a solid-culture system

We conducted a 12-month prospective study comparing two approaches to the detection of Mycobacterium avium in the blood of human immunodeficiency virus type 1-infected patients, namely, a lytic centrifugation system combined with Middlebrook solid culture medium (the conventional procedure) and the nonradiometric BACTEC 9000 MB system. Species identification relied on 16S rRNA probe hybridization and cell wall fatty acids chromatography. M. avium was isolated in 17 of 345 (5%) blood specimens by the BACTEC 9000 MB automated system and in 14 of 345 (4%) blood specimens by the conventional procedure (nonsignificant, chi2 test). Detection time was 16 +/- 6 days by the BACTEC 9000 MB automated system and 27 +/- 3 days by the conventional procedure (P < 0.001, Student t test). Non-M. avium mycobacteria were not recovered during the study period. Contamination rate was 8% (30 specimens) by the BACTEC 9000 MB system and 0% by the conventional procedure, indicating the necessity of using an antibiotic mixture (PANTA, consisting of polymyxin B, amphotericin B, nalidixic acid, trimethoprim, and azlocillin). Working time was 1 min 30 s by the BACTEC 9000 MB system and 8 min by the conventional procedure, which was 1.8 times more expensive than the BACTEC system. Use of the BACTEC 9000 MB system increased the sensitivity of M. avium detection and reduced detection time in blood culture.

Cellular reaction to Mycobacterium avium complex (MAC) clinical isolates differing in hemolytic activity and virulence for C57BL/6 mice

In this study we showed that Mycobacterium avium complex (MAC) clinical isolates differed by the expression of hemolytic activity. Two hemolytic MAC strains were less susceptible to the mycobactericidal effect of murine macrophages than two unhemolytic MAC isolates. In vivo, hemolytic MAC bacilli survived in the spleens of infected mice for a longer time than unhemolytic MAC strains. This suggested a role of hemolysins in the virulence of MAC strains. There was no difference in the cytotoxicity of T cells from mice immunized with M. bovis BCG towards macrophages infected in vitro with MAC strains expressing or not expressing hemolytic activity.

Rationale for and efficacy of prolonged-interval treatment using liposome-encapsulated amikacin in experimental Mycobacterium avium infection

The potential of liposome-encapsulated antibiotics for prolonging drug application intervals was investigated by using a murine model of chronic lethal Mycobacterium avium infection. Liposomal encapsulation of amikacin, but not of ciprofloxacin, resulted in high and sustained drug levels in infected tissues, exceeding the minimal inhibitory concentration for M. avium for at least 28 days. As a consequence, once-weekly and even once-monthly treatments with liposomal amikacin significantly reduced bacterial replication in infected tissues and extended the survival time of infected mice.