Predictors of survival in patients with AIDS and disseminated Mycobacterium avium complex disease

Tuberculosis of the Liver, Biliary Tract, and Pancreas

Tuberculosis of the liver, biliary tract, and pancreas is discussed. In addition, tuberculosis in the setting of HIV-AIDS and liver transplantation is explored. Drug-induced liver injury secondary to antituberculosis medication and monitoring and prophylactic treatment for such injury is also considered.

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.

Thioridazine as Chemotherapy for Mycobacterium avium Complex Diseases

Mycobacterium avium-intracellulare complex (MAC) causes an intractable intracellular infection that presents as chronic pulmonary disease. Currently, therapy consists of ethambutol and macrolides and takes several years to complete. The neuroleptic phenothiazine thioridazine kills mycobacteria by inhibiting the electron transport chain. In several experiments with bacterial populations of up to 10¹² CFU/ml, we failed to isolate any bacteria resistant to 3 times the MIC of thioridazine, suggesting the absence of resistant mutants at bacterial burdens severalfold higher than those encountered in patients. In the hollow-fiber model of intracellular MAC (HFS-MAC), thioridazine achieved an extracellular half-life of 16.8 h and an intracellular half-life of 19.7 h. Thioridazine concentrations were >28,000-fold higher inside infected macrophages than in the HFS-MAC central compartment (equivalent to plasma). Thioridazine maximal kill was 5.20 ± 0.75 log₁₀ CFU/ml on day 7 (r² = 0.96) and 7.19 ± 0.31 log₁₀ CFU/ml on day 14 (r² = 0.99), the highest seen with any drug in the system. Dose fractionation studies revealed that thioridazine efficacy and acquired drug resistance were driven by the peak concentation-to-MIC ratio, with a 50% effective concentration (EC₅₀) of 2.78 ± 0.44 for microbial killing. Acquired drug resistance was encountered by day 21 with suboptimal doses, demonstrating that fluctuating drug concentrations drive evolution faster than static concentrations in mutation frequency studies. However, the thioridazine EC₅₀ changed 16.14-fold when the concentration of fetal bovine serum was changed from 0% to 50%, suggesting that intracellular potency could be heavily curtailed by protein binding. Efficacy in patients will depend on the balance between trapping of the drug in the pulmonary system and the massive intracellular concentrations versus very high protein binding of thioridazine.

High Mortality of Disseminated Non-Tuberculous Mycobacterial Infection in HIV-Infected Patients in the Antiretroviral Therapy Era

Background

Little information is available on the mortality and risk factors associated with death in disseminated non-tuberculous mycobacterial infection (dNTM) in HIV-infected patients in the ART-era.

Methods

In a single-center study, HIV-infected dNTM with positive NTM culture from sterile sites between 2000 and 2013 were analysed. The clinical characteristics at commencement of anti-mycobacterial treatment (baseline) were compared between those who survived and died.

Results

Twenty-four patients were analyzed. [The median CD4 27/μL (range 2–185)]. Mycobacterium avium and M. intracellulare accounted for 20 (83%) and 3 (13%) of isolated NTM. NTM bacteremia was diagnosed in 15 (63%) patients. Seven (29%) patients died, and NTM bacteremia was significantly associated with mortality (p = 0.022). The baseline CD4 count was significantly lower in the non-survivors than the survivors (median 7/μL versus 49, p = 0.034). Concomitant AIDS-defining diseases or malignancies were not associated with mortality. Immune-reconstitution syndrome (IRS) occurred to 19 (79%) patients (8 paradoxical and 11 unmasking), and prognosis tended to be better in unmasking-IRS than the other patients (n = 13) (p = 0.078). Patients with paradoxical-IRS had marginally lower CD4 count and higher frequency of bacteremia than those with unmasking-IRS (p = 0.051, and 0.059). Treatment with systemic corticosteroids was applied in 63% and 55% of patients with paradoxical and unmasking-IRS, respectively.

Conclusion

dNTM in HIV-infected patients resulted in high mortality even in the ART-era. NTM bacteremia and low CD4 count were risk factors for death, whereas patients presented with unmasking-IRS had marginally better prognosis. IRS occurred in 79% of the patients, suggesting difficulty in the management of dNTM.

Fever of unknown origin in patients with HIV infection in Thailand: an observational study and review of the literature

Fever of unknown origin (FUO) is a common presentation for patients with advanced human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS). We prospectively followed 72 patients, consecutively admitted to a Thai regional hospital with FUO and HIV infection to identify aetiologies and mortality in the era of available antiretroviral therapy (ART). Aetiologies of FUO were identified in 67 patients (93%), of whom 61(85%) had an infectious aetiology. The most common infectious aetiologies were Mycobacterium tuberculosis (n=30; 42%), Cryptococcus neoformans (n=17; 24%), Pneumocystis jiroveci (n=9; 13%), Toxoplasma gondii (n=5; 7%), and salmonella bacteraemia (n=5; 7%). Nineteen patients (26%) had co-infection with two or more pathogens. The median CD4 count was 120 cells/mm(3) (range, 1-581 cells/mm(3)), and the all-cause mortality was 22% (n=16). By multivariate analysis, inadequate antimicrobial treatment was the sole predictor of mortality (aOR=4.9; 95% CI=1.2-21.9; P=0.02). Overall, 58 of 72 patients (81%) had an opportunistic infection suggesting that guideline use of ART and prophylactic strategies remain unmet needs that will benefit individuals and populations with HIV/AIDS in Thailand.

Differential gene expression in mononuclear phagocytes infected with pathogenic and non-pathogenic mycobacteria

The pathogenic mycobacteria are an insidious group of bacterial pathogens that cause the deaths of millions of people every year. One of the reasons these pathogens are so successful is that they are able to invade and replicate within host macrophages, one of the first lines of defence against intruding pathogens. In contrast, non-pathogenic mycobacteria, such as Mycobacterium smegmatis are killed rapidly by macrophages. In order to understand better the series of events that allow pathogenic mycobacteria to survive and replicate within macrophages, while the non-pathogenic mycobacteria are killed rapidly, we inoculated the human monocytic cell line U937 with pathogenic (M. tuberculosis and M. avium) and non-pathogenic (M. smegmatis) mycobacteria and monitored the expression of over 3500 genes at 4, 12 and 24 h post-inoculation using a commercially available gene array system. We observed multiple differences in the gene expression patterns of monocytes infected with pathogenic and non-pathogenic mycobacteria including genes involved in cytokine, lymphokine and chemokine production, adhesion, apoptosis, signal transduction, transcription, protein cleavage, actin polymerization and growth. We also observed differences in gene expression profiles in monocytes infected with M. tuberculosis or M. avium, indicating that there are differences in the host pathogen interactions of mononuclear phagocytes infected with different pathogenic mycobacterial species. These results increase the understanding of the mechanisms used by pathogenic mycobacteria to cause disease, the host response to these organisms, and provide new insights for antimycobacterial intervention strategies.

Prevalence and outcomes of anemia in individuals with human immunodeficiency virus: a systematic review of the literature

In patients with human immunodeficiency virus (HIV), anemia is a commonly encountered hematologic abnormality that has a significant impact on clinical outcomes and quality of life (QOL). This review describes the prevalence of anemia in several populations of patients with HIV and the effects of anemia on survival, morbidity, disease progression, transfusion requirements, and QOL. The prevalence of anemia in HIV disease varies considerably, ranging from 1.3% to 95%: it depends on several factors, including the stage of HIV disease, sex, age, pregnancy status, and injection-drug use as well as the definition of anemia used. In general, as HIV disease progresses, the prevalence and severity of anemia increase. Anemia is also more prevalent in HIV-positive women, children, and injection-drug users than in HIV-negative women, children, and injection-drug users. Anemia has been shown to be a statistically significant predictor of progression to the acquired immunodeficiency syndrome and is independently associated with an increased risk of death in patients with HIV. Treatment of anemia with epoetin-alpha has resulted in significantly fewer patients requiring transfusion as well as decreases in the mean number of units of blood transfused. Resolution of HIV-related anemia has been shown to improve QOL, physical functioning, energy, and fatigue in individuals with HIV. More recently, the use of highly active antiretroviral therapy has also been associated with a significant increase in hemoglobin concentrations and a decrease in the prevalence of anemia.

Mycobacterium avium infection and modulation of human macrophage gene expression

Mycobacterium avium is a facultative intracellular pathogen cleared rapidly via intact host defense mechanisms. In the absence of adequate T cell function, as occurs in HIV-1-induced immunodeficiency, M. avium becomes an opportunistic infection with uncontrolled replication and reinfection of macrophage hosts. How M. avium infects, survives, and replicates in macrophages without signaling an effective microbicidal counterattack is unresolved. To address whether M. avium signals the expression of molecules, which influence mycobacterial survival or clearance, human monocyte-derived macrophage cultures were exposed to M. avium. Within minutes, M. avium, or its cell wall lipoarabinomannan, binds to the adherent macrophages and induces a spectrum of gene expression. In this innate response, the most abundant genes detected within 2 h by cDNA expression array involved proinflammatory chemokines, cytokines including TNF-alpha and IL-1, and adhesion molecules. Associated with this rapid initial up-regulation of recruitment and amplification molecules was enhanced expression of transcription factors and signaling molecules. By 24 h, this proinflammatory response subsided, and after 4 days, when some bacteria were being degraded, others escaped destruction to replicate within intracellular vacuoles. Under these conditions, inducible NO synthase was not up-regulated and increased transferrin receptors may facilitate iron-dependent mycobacterial growth. Sustained adhesion molecule and chemokine expression along with the formation of multinucleated giant cells appeared consistent with in vivo events. Thus, in the absence of T lymphocyte mediators, macrophages are insufficiently microbicidal and provide a nonhostile environment in which mycobacteria not only survive and replicate, but continue to promote recruitment of new macrophages to perpetuate the infection.

Mycobacterium avium complex promotes recruitment of monocyte hosts for HIV-1 and bacteria

In lymphoid tissues coinfected with Mycobacterium avium complex (MAC) and HIV-1, increased viral replication has been observed. This study investigates the role of MAC in perpetuating both infections through the recruitment of monocytes as potential new hosts for bacteria and HIV-1. Increased numbers of macrophages were present in the lymph nodes of patients with dual infection as compared with lymph nodes from HIV(+) patients with no known opportunistic pathogens. In a coculture system, monocyte-derived macrophages were treated with HIV-1 or M. avium and its constituents to further define the mechanism whereby MAC infection of macrophages initiates monocyte migration. Monocyte-derived macrophages treated with bacteria or bacterial products, but not HIV-1, induced a rapid 2- to 3-fold increase in recruitment of monocytes. Pretreatment of the monocytes with pertussis toxin inhibited the migration of these cells, indicating a G protein-linked pathway is necessary for induction of chemotaxis and thus suggesting the involvement of chemokines. Analysis of chemokine mRNA and protein levels from M. avium-treated cultures revealed MAC-induced increases in the expression of IL-8, macrophage-inflammatory protein (MIP)-1alpha, and MIP-1beta with donor-dependent changes in monocyte chemotactic protein-1. Pyrrolidine dithiocarbamate, an antioxidant, inhibited the activation of NF-kappaB and significantly diminished the MAC-induced chemotaxis, concurrently lowering the levels of monocyte chemotactic protein-1 and MIP-1beta. These data demonstrate that MAC induces macrophage production of multiple chemotactic factors via NF-kappaB to promote monocyte migration to sites of MAC infection. In vivo, opportunistic infection may act as a recruitment mechanism in which newly arrived monocytes serve as naive hosts for both MAC and HIV-1, thus perpetuating both infections.

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.

PCR-hybridization assay for Mycobacterium avium complex: optimization of detection in peripheral blood from humans

We evaluated the sensitivity of a DNA amplification test for the detection of Mycobacterium avium in blood samples using different blood components and different DNA extraction methods. M. avium-inoculated blood samples were processed to obtain separate blood components: peripheral blood mononuclear cells (PBMCs), polymorphonuclear cells (PMNCs), and whole-blood sodium dodecyl sulfate (SDS)-lysate pellets. The sensitivity for the detection of the lowest mycobacterial load (1 CFU/ml) was significantly greater (P < 0.01) with DNA extracted from SDS-lysate pellets than with DNA extracted from PBMCs or PMNCs. Subsequently, DNA extraction methods based on guanidine NaOH, and proteinase were compared. The sensitivity of the guanidine-based method was significantly greater (P < 0.01) than those of the others.

Mycobacteriosis in the compromised host

The studies of rare genetic defects, the preliminary results of population-based studies, being validated by the experimental immunocompromised animal models and the current observations accumulated in immunocompromised patients with mycobacterial diseases provide us with insights into the importance of the macrophage activation pathway in controlling human infection with pathogenic and non pathogenic intracellular multiplying mycobacteria. Initial cytokine production by infected macrophages and/or dendritic cells could be crucial in the overall regulation of self cure, acquired protection or immunopathological sequelae expressing the disease. Knowledge of molecular and genetic cross-talks between phagocytic and specialized antigen presenting cells and different mycobacterial products associated with persistence or replication of the intracellular bacteria, could provide further informations on the global immune regulation of the early host responses to infection and the following events. It seems likely that the development of mycobacterial infections in humans will turn out to be as much dependent on the genetic make up of the host as or the virulence of the bacteria.

Effects of antiretroviral therapy and opportunistic illness primary chemoprophylaxis on survival after AIDS diagnosis. Adult/Adolescent Spectrum of Disease Group

OBJECTIVE

To examine the effects of antiretroviral therapy (ART) and opportunistic illness chemoprophylaxis on the survival of persons with AIDS and survival time based on year of AIDS diagnosis.

DESIGN

Longitudinal medical record review.

SETTING

Ninety-three hospitals and clinics in nine cities in the USA.

PATIENTS

We observed 19,565 persons with AIDS from 1990 through January 1998.

INTERVENTIONS

Prescribed use of antiretroviral monotherapy, dual- and triple-combination therapies, primary prophylaxis against Pneumocystis carinii pneumonia and Mycobacterium avium complex, and pneumococcal vaccine.

MAIN OUTCOME MEASURES

Time from AIDS diagnosis to death in the presence and absence of ART. Survival curves were compared of AIDS cases diagnosed during 1990-1992 and 1993-1995.

RESULTS

Triple ART had the greatest effect on the risk of death [relative risk (RR), 0.15; 95% confidence limit (CL), 0.12, 0.17], followed by dual ART (RR, 0.24; 95% CL, 0.22, 0.26), and monotherapy (RR, 0.38; 95% CL, 0.36, 0.40). Risk of death was decreased among persons receiving Pneumocystis carinii pneumonia prophylaxis (RR, 0.79; 95% CL, 0.70, 0.89) and Mycobacterium avium complex prophylaxis (RR, 0.76; 95% CL, 0.68, 0.86). Median survival increased from 31 months [95% confidence interval (CI), 30-32 months] for AIDS cases diagnosed during 1990-1992 to 35 months (95% CI, 35-38 months) for cases diagnosed during 1993-1995.

CONCLUSIONS

The risk of death was decreased for persons receiving triple ART compared with persons receiving dual therapy and persons receiving monotherapy. Increased use of ART and improved ART regimens probably contributed to prolonged survival of persons whose diagnosis was made during 1993-1995 compared with persons whose diagnosis was made during 1990-1992.

Clinical and laboratory findings of disseminated Mycobacterium avium complex infection (DMAC) in a pair matched case-control study

A pair matched case/control study was conducted from January 1991 to 30 June 1992 in order to define clinical and laboratory findings associated with DMAC infection in AIDS patients. Since DMAC infection is usually associated with advanced immunodeficiency, and therefore also with other opportunistic illnesses, in addition to the number of CD4+ lymphocytes, cases and controls were matched using the following criteria: date of AIDS diagnosis and antiretroviral therapy, number and severity of associated opportunistic infections and, whenever possible, type of Pneumocystis carinii prophylaxis, age and gender, in this order of relevance. Cases (defined as patients presenting at least one positive culture for MAC at a normally sterile site) and controls presented CD4+ lymphocyte counts below 50 cel/mm3. A significantly higher prevalence of general, digestive and respiratory signs, increased LDH levels, low hemoglobin levels and CD4+ cell counts were recorded for cases when compared to controls. Increases in gammaGT and alkaline phosphatase levels seen in cases were also recorded for controls. In conclusion, the strategy we used for selecting controls allowed us to detect laboratory findings associated to DMAC infection not found in other advanced immunosupressed AIDS patients without DMAC.

Co-infection with opportunistic pathogens promotes human immunodeficiency virus type 1 infection in macrophages

Human immunodeficiency virus type 1 (HIV-1) infection is dependent on susceptible host cells that express both CD4 and chemokine co-receptors. The co-receptor CCR5 is associated with primary infection by macrophage-tropic virus isolates, whereas CXCR4 is commonly associated with T cell- and dual-tropic viruses. Once infected, lymphocytes and macrophages may replicate HIV-1 or harbor latent virus, depending on environmental factors and cellular activation. Immune activation is often associated with viremia, which is consistent with enhanced infection and viral replication in activated cells harboring virus. In this regard, opportunistic infections activate the immune system with the detrimental sequelae of enhanced viral replication and viremia. Under these conditions, viral expansion extends beyond T cells to tissue macrophages, many of which are co-infected with opportunistic pathogens. The opportunistic infections promote macrophage susceptibility to HIV-1 through cytokine modulation and altered chemokine co-receptors, potential targets for intervention.

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.

Use of PCR in detection of Mycobacterium avium complex (MAC) bacteremia: sensitivity of the assay and effect of treatment for MAC infection on concentrations of human immunodeficiency virus in plasma

We evaluated the sensitivity and specificity of a PCR-based qualitative test for the rapid diagnosis of Mycobacterium avium-M. intracellulare complex (MAC) bacteremia in patients with AIDS disease. Eleven subjects with newly culture-proven MAC bacteremia had the following tests performed at biweekly intervals during the first 8 weeks of therapy: blood culture, Mycobacterium-specific PCR, and quantitative human immunodeficiency virus (HIV) viral-load testing. Mycobacterium genus-specific biotinylated primers were used to amplify a sequence of approximately 582 nucleotides within the 16S rRNA genes of M. avium and M. intracellulare. Detection of the amplified product was performed with an oligonucleotide probe-coated microwell plate combined with an avidin-horseradish peroxidase-tetramethylbenzidine conjugate-substrate system. While not as sensitive as BACTEC culture, PCR detected 17 of 18 specimens which grew >/=40 organisms/ml (94.4% sensitivity) and 9 of 16 specimens which grew </=40 organisms/ml (56.3% sensitivity). No clear change in HIV viremia occurred in response to successful treatment of patients' MAC bacteremia. Use of the PCR test allowed detection of MAC bacteremia in 1 day, with a sensitivity similar to those of quantitative blood culture techniques, and it may prove useful for rapid screening of suspected cases. HIV viremia was unaffected by 8 weeks of MAC therapy.

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.

Mycobacterium avium complex augments macrophage HIV-1 production and increases CCR5 expression

Infection with HIV-1 results in pronounced immune suppression and susceptibility to opportunistic infections (OI). Reciprocally, OI augment HIV-1 replication. As we have shown for Mycobacterium avium complex (MAC) and Pneumocystis carinii, macrophages infected with opportunistic pathogens and within lymphoid tissues containing OI, exhibit striking levels of viral replication. To explore potential underlying mechanisms for increased HIV-1 replication associated with coinfection, blood monocytes were exposed to MAC antigens (MAg) or viable MAC and their levels of tumor necrosis factor alpha (TNFalpha) and HIV-1 coreceptors monitored. MAC enhanced TNFalpha production in vitro, consistent with its expression in coinfected lymph nodes. Using a polyclonal antibody to the CCR5 coreceptor that mediates viral entry of macrophage tropic HIV-1, a subset of unstimulated monocytes was shown to be CCR5-positive by fluorescence-activated cell sorter analysis. After stimulation with MAg or infection with MAC, CCR5 expression was increased at both the mRNA level and on the cell surface. Up-regulation of CCR5 by MAC was not paralleled by an increase in the T cell tropic coreceptor, CXCR4. Increases in NF-kappaB, TNFalpha, and CCR5 were consistent with the enhanced production of HIV-1 in MAg-treated adherent macrophage cultures as measured by HIV-1 p24 levels. Increased CCR5 was also detected in coinfected lymph nodes as compared with tissues with only HIV-1. The increased production of TNFalpha, together with elevated expression of CCR5, provide potential mechanisms for enhanced infection and replication of HIV-1 by macrophages in OI-infected cells and tissues. Consequently, treating OI may inhibit not only the OI-induced pathology, but also limit the viral burden.

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.

Clinical features and outcome in disseminated mycobacterial diseases in AIDS patients in Taiwan

OBJECTIVE

To describe and compare the clinical features and outcome of disseminated tuberculosis (TB) and Mycobacterium avium complex (MAC) disease in AIDS patients.

DESIGN

Prospective cohort study.

SETTING

A 1800-bed university teaching hospital, the largest centre for HIV/AIDS patients in Taiwan.

METHODS

From July 1994 through June 1997, a standardized protocol was used to record the demographic and clinical features in all hospitalized HIV-infected patients, and to perform routine studies and invasive procedures for diagnosis of disseminated mycobacterial diseases. To compare the survival, control patients were selected from the HIV-infected patients hospitalized in the same hospital during the same study period, and had similar age, sex, CD4+ cell counts and antiretroviral therapy regimens.

RESULTS

A total of 22 cases of disseminated TB and 15 cases of disseminated MAC were identified. Disseminated TB and MAC occurred in patients with similarly low CD4+ cell counts (median, 23 versus 5 x 10(6)/l; P = 0.08). The clinical features favouring disseminated TB included night sweats, peripheral lymphadenopathy, acid-fast bacilli in sputum smears, chest radiographic findings of hilar enlargement, and lack of prior AIDS-defining illnesses. Hepatosplenomegaly, elevated serum alkaline phosphatase (more than twice the upper limit of normal), elevated serum gamma-glutamyl transpeptidase (more than three times the upper limit of normal), and leukopenia favoured disseminated MAC. The patients with disseminated TB survived much longer than patients with disseminated MAC (mean survival, 96 versus 22 weeks, P = 0.008) but had a similar outcome to control patients (P = 0.60).

CONCLUSION

Disseminated TB and MAC are distinguishable by clinical features in AIDS patients with similar immunocompromised states. Those features may facilitate diagnosis and selection of specific therapeutic regimens. Disseminated TB was not associated with a shortened survival period in AIDS patients when they completed anti-TB treatment. In contrast, disseminated DMAC was associated with shortened survival despite treatment with potent regimens. These results may emphasize the importance of prophylaxis for MAC in this population.

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.

[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.

Molecular analysis of the gene encoding F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis

The gene fgd, which codes for F420-dependent glucose-6-phosphate dehydrogenase (FGD), was cloned from Mycobacterium smegmatis, and its sequence was determined and analyzed. A homolog of FGD which has a very high similarity to the M. smegmatis FGD-derived amino acid sequence was identified in Mycobacterium tuberculosis. FGD showed significant homology with F420-dependent N5,N10-methylene-tetrahydromethanopterin reductase (MER) from methanogenic archaea and with several hypothetical proteins from M. tuberculosis and Archaeoglobus fulgidus, but FGD showed no significant homology with NADP-dependent glucose-6-phosphate dehydrogenases. Multiple alignment of FGD and MER proteins revealed four conserved consensus sequences. Multiple alignment of FGD with the hypothetical proteins also revealed portions of the same conserved sequences. Moderately high levels of FGD were expressed in Escherichia coli BL21(DE3) carrying fgd in pBluescript.

Diagnosis and treatment of hepatic disease in patients with HIV

Liver involvement with opportunistic infections and neoplasms is a well-recognized component of AIDS, affecting most patients. The cause of hepatic disease in these patients may be divided into hepatitis, granulomatous disease, mass lesions, vascular lesions, hepatotoxic drugs, and nonspecific findings. With a rational approach, most patients with AIDS and liver disease can be diagnosed and treated in a cost-effective manner with low morbidity.

Diarrheal diseases associated with HIV infection

Diarrhea is a major complication of HIV infection and adversely impacts health care costs, quality of life, and even survival of patients. There is a wide variety of potential causes of diarrhea in HIV-infected patients, and the number of pathogens found continues to increase with time. In addition, there is some controversy concerning the role of some organisms in the pathogenesis of diarrhea and the appropriate diagnostic evaluation of affected patients. This article reviews our current understanding of these pathogens and some of the diagnostic and therapeutic approaches for diarrhea associated with HIV infection.

Comparison of BACTEC 12B vs solid media for the recovery of Mycobacterium avium complex from blood cultures in AIDS patients

We compared liquid (BACTEC 12B) and solid culture media for the diagnosis of Mycobacterium avian complex (MAC) bacteremia among 258 AIDS patients with a positive blood culture. Neither culture media alone had adequate sensitivity; BACTEC 12B detected growth earlier. Use of both liquid and solid media may improve the yield of mycobacterial blood culture.

Hematologic complications of human immunodeficiency virus infection and the acquired immunodeficiency syndrome

The hematologic manifestations of HIV infection and AIDS are common and may cause symptoms that are life-threatening and impair the quality of life of these patients. The most important of these manifestations are cytopenias. Anemia and neutropenia are generally caused by inadequate production because of suppression of the bone marrow by the HIV infection through abnormal cytokine expression and alteration of the bone marrow microenvironment. Thrombocytopenia is caused by immune-mediated destruction of the platelets, in addition to inadequate platelet production. The incidence and severity of cytopenia are generally correlated to the stage of the HIV infection. Other causes of cytopenia in these patients include adverse effects of drug therapy, the secondary effects of opportunistic infections or malignancies, or other preexisting or coexisting medical problems that may be prevalent in the HIV-infected population. Diagnosis of the mechanism and cause of the cytopenia may allow for specific management. Optimal management of the underlying HIV infection is essential, and mild cytopenia in asymptomatic patients may need no specific management. Supportive care for anemia includes the use of erythropoietin in addition to the judicious use of red blood cell transfusions. Therapy for neutropenia includes the use of the myeloid growth factors G-CSF and GM-CSF. Immune-mediated thrombocytopenia may be treated with a combination of zidovudine, corticosteroids, IVGG, and splenectomy. Platelet transfusions are sometimes needed for the treatment of thrombocytopenia caused by decreased production. Other hematologic manifestations such as hypergammaglobulinemia and lupus anticoagulants are commonly asymptomatic and usually require no specific therapy, but they can rarely cause morbidity and require specific interventions.

Clarithromycin and ethambutol with or without clofazimine for the treatment of bacteremic Mycobacterium avium complex disease in patients with HIV infection

OBJECTIVE

To compare the efficacy of two- and three-drug regimens for treating Mycobacterium avium complex (MAC) bacteremia in patients with AIDS.

DESIGN

Randomized open-label clinical trial.

SETTING

Outpatient HIV specialty centers' clinics.

PATIENTS

A total of 106 adults with AIDS and MAC bacteremia.

INTERVENTIONS

Patients were treated with clarithromycin 500 mg twice daily and ethambutol 800-1,000 mg daily and were randomized to receive clofazimine 100 mg daily or no clofazimine.

MAIN OUTCOME MEASURES

Quantitative blood MAC cultures, symptoms, adverse reactions and survival.

RESULTS

Patients randomly assigned to three drugs had significantly higher baseline colony counts of MAC in blood than patients receiving two drugs. The proportion of patients becoming culture-negative was 65% in the two-drug group and 54% in the three-drug group. The median time to negative culture was 58 days for patients in the two-drug and 63 days for the three-drug group. At the last visit during treatment, the mean reduction in colony forming units/ml of MAC in blood was 1.8 log10 for the two-drug group and 2.3 log10 for the three-drug group. Improvement in fever and night sweats was reported by 87 and 89% of the two-drug patients and 84 and 86% of the three-drug patients. During the study, 38% of two-drug patients and 61% of three-drug patients died (P = 0.032), and time to death was shorter in patients treated with three drugs (P = 0.012). In a multivariate analysis, both assignment to clofazimine and high baseline colony counts of MAC bacteremia were significantly associated with death (P < 0.05).

CONCLUSION

The addition of clofazimine to a regimen of clarithromycin and ethambutol for MAC bacteremia in AIDS patients does not contribute to clinical response and is associated with higher mortality.

A comparison of two regimens for the treatment of Mycobacterium avium complex bacteremia in AIDS: rifabutin, ethambutol, and clarithromycin versus rifampin, ethambutol, clofazimine, and ciprofloxacin. Canadian HIV Trials Network Protocol 010 Study Group

BACKGROUND

Bacteremia with the Mycobacterium avium complex is common in patients with the acquired immunodeficiency syndrome (AIDS), but the most effective treatment for this infection remains unclear.

METHODS

We randomly assigned 229 patients with AIDS and M. avium complex bacteremia to receive either rifampin (600 mg daily), ethambutol (approximately 15 mg per kilogram of body weight daily), clofazimine (100 mg daily), and ciprofloxacin (750 mg twice daily) (the four-drug group) or rifabutin (600 mg daily), ethambutol (as above), and clarithromycin (1000 mg twice daily) (the three-drug group). In the three-drug group the dose of rifabutin was reduced by half after 125 patients were randomized, because 24 of 63 patients had uveitis.

RESULTS

Among 187 patients who could be evaluated, blood cultures became negative more often in the three-drug group than in the four-drug group (69 percent vs. 29 percent, P<0.001). Among patients treated for at least four weeks, the bacteremia resolved more frequently in the three-drug group (78 percent vs. 40 percent, P<0.001). In the three-drug group, bacteremia resolved more often with the 600-mg dose of rifabutin than with the 300-mg dose (P=0.025), but the latter regimen was more effective than the four-drug regimen (P<0.05). The median survival was 8.6 months in the three-drug group and 5.2 months in the four-drug group (P = 0.001). The median Karnofsky performance score was higher in the three-drug group than in the four-drug group from week 2 to week 16 (P<0.05). Mild uveitis developed in 3 of the 53 patients receiving the 300-mg dose of rifabutin, an incidence about one quarter that observed with the 600-mg dose (P<0.001).

CONCLUSIONS

In patients with AIDS and M. avium complex bacteremia, treatment with the three-drug regimen of rifabutin, ethambutol, and clarithromycin leads to resolution of the bacteremia more frequently and more rapidly than treatment with rifampin, ethambutol, clofazimine, and ciprofloxacin, and survival rates are better.

Altered in vitro handling of Mycobacterium avium complex by monocytes and serum from HIV(+) patients

In patients with acquired immunodeficiency syndrome (AIDS), mycobacterial diseases are leading opportunistic infections. The reasons for the peculiar propensity for disseminated infection with Mycobacterium avium complex (MAC) remain unclear. We have previously examined, in detail, the ability of monocytes from healthy donors to take up and kill MAC under both nonopsonic and opsonic conditions. We have now evaluated the in vitro ability of peripheral blood monocytes from HIV(+) patients to take up and kill MAC organisms, and have discovered a reduced ability under both nonopsonic and opsonic conditions. This reduction is due to: 1) apparent defect(s) in the phagocytes themselves, and 2) substance(s) in the HIV(+) serum which actively suppresses phagocyte activity.

Mycobacterium avium complex infection in AIDS: clinical features, treatment, and prevention

Infection with Mycobacterium avium complex (MAC) may cause a serious disseminated bacterial infection in up to 40% of patients with advanced HIV infection. Disseminated MAC has a negative impact on quality of life and contributes significantly to morbidity and mortality. Prompt diagnosis and aggressive treatment can diminish those effects. Disseminated disease can be prevented in many patients with the use of rifabutin prophylaxis. Nurses play an important role in evaluating symptoms and educating patients about the prevention and treatment of disseminated MAC.