Christopher C. Whalen

Effect of antibiotic therapy on the density of vancomycin-resistant enterococci in the stool of colonized patients.

BACKGROUND Colonization and infection with vancomycin-resistant enterococci have been associated with exposure to antibiotics that are active against anaerobes. In mice that have intestinal colonization with vancomycin-resistant enterococci, these agents promote high-density colonization, whereas antibiotics with minimal antianaerobic activity do not. METHODS We conducted a seven-month prospective study of 51 patients who were colonized with vancomycin-resistant enterococci, as evidenced by the presence of the bacteria in stool. We examined the density of vancomycin-resistant enterococci in stool during and after therapy with antibiotic regimens and compared the effect on this density of antianaerobic agents and agents with minimal antianaerobic activity. In a subgroup of 10 patients, cultures of environmental specimens (e.g., from bedding and clothing) were obtained. RESULTS During treatment with 40 of 42 antianaerobic-antibiotic regimens (95 percent), high-density colonization with vancomycin-resistant enterococci was maintained (mean [+/-SD] number of organisms, 7.8+/-1.5 log per gram of stool). The density of colonization decreased after these regimens were discontinued. Among patients who had not received antianaerobic antibiotics for at least one week, 10 of 13 patients who began such regimens had an increase in the number of organisms of more than 1.0 log per gram (mean increase, 2.2 log per gram), whereas among 10 patients who began regimens of antibiotics with minimal antianaerobic activity, there was a mean decrease in the number of enterococci of 0.6 log per gram (P=0.006 for the difference between groups). When the density of vancomycin-resistant enterococci in stool was at least 4 log per gram, 10 of 12 sets of cultures of environmental specimens had at least one positive sample, as compared with 1 of 9 sets from patients with a mean number of organisms in stool of less than 4 log per gram (P=0.002). CONCLUSIONS For patients with vancomycin-resistant enterococci in stool, treatment with antianaerobic antibiotics promotes high-density colonization. Limiting the use of such agents in these patients may help decrease the spread of vancomycin-resistant enterococci.

A Trial of Three Regimens to Prevent Tuberculosis in Ugandan Adults Infected with the Human Immunodeficiency Virus

BACKGROUND Infection with the human immunodeficiency virus (HIV) greatly increases the risk of reactivation tuberculosis. We evaluated the safety and efficacy of three preventive-therapy regimens in a setting where exposure to tuberculosis is common. METHODS We performed a randomized, placebo-controlled trial in 2736 HIV-infected adults recruited in Kampala, Uganda. Subjects with positive tuberculin skin tests (induration, > or =5 mm) with purified protein derivative (PPD) were randomly assigned to one of four regimens: placebo (464 subjects), isoniazid daily for six months (536), isoniazid and rifampin daily for three months (556), or isoniazid, rifampin, and pyrazinamide daily for three months (462). Subjects with anergy (0 mm induration in reaction to PPD and candida antigens) were randomly assigned to receive either placebo (323 subjects) or six months of isoniazid (395). The medications were dispensed monthly and were self-administered. RESULTS Among the PPD-positive subjects, the incidence of tuberculosis in the three groups that received preventive therapy was lower than the rate in the placebo group (P=0.002 by the log-rank test). The relative risk of tuberculosis with isoniazid alone, as compared with placebo, was 0.33 (95 percent confidence interval, 0.14 to 0.77); with isoniazid and rifampin, 0.40 (0.18 to 0.86); and with isoniazid, rifampin, and pyrazinamide, 0.51 (0.24 to 1.08). Among the subjects with anergy, the relative risk of tuberculosis was 0.83 (95 percent confidence interval, 0.34 to 2.04) with isoniazid as compared with placebo. Side effects were more common with the multidrug regimens, and particularly with the regimen containing pyrazinamide. Survival did not differ among the groups, but the subjects with anergy had a higher mortality rate than the PPD-positive subjects. CONCLUSIONS A six-month course of isoniazid confers short-term protection against tuberculosis among PPD-positive, HIV-infected adults. Multidrug regimens with isoniazid and rifampin taken for three months also reduce the risk of tuberculosis.

Cryptosporidium Infection and CD4 Counts

Excerpt Cryptosporidiumis a coccidian parasite that infects the gastrointestinal tract in humans and can cause severe enteritis and malabsorption. Cryptosporidiosis is selflimited in immunocompeten...

A study of the safety, immunology, virology, and microbiology of adjunctive etanercept in HIV-1-associated tuberculosis

Objective: Tumor necrosis factor (TNF), an important inflammatory mediator in tuberculosis, has been implicated in causing accelerated HIV disease progression in HIV-associated tuberculosis. However, TNF blockade, particularly by monoclonal antibody, has been associated with the reactivation of latent Mycobacterium tuberculosis infection by the impairment of mycobacterial immunity. This phase 1 study examined the safety, microbiology, immunology, and virology of TNF blockade using etanercept (soluble TNF receptor, Enbrel) during the initial treatment of HIV-associated tuberculosis. Design: A single-arm trial, with key endpoints compared with historical controls, conducted in Mulago Hospital, Kampala, Uganda. Subjects: Sixteen HIV-1-infected patients and 42 CD4-frequency-matched controls with sputum smear-positive tuberculosis and CD4 cell counts > 200 cells/μl. Intervention: Etanercept 25 mg, eight doses administered subcutaneously twice weekly beginning on day 4 of tuberculosis therapy. Main outcome measures: Serial examination, radiography, sputum culture, CD4 T-cell counts, plasma log10 HIV-RNA copy numbers. Results: Trends towards superior responses to tuberculosis treatment were evident in etanercept-treated subjects in body mass, performance score, number of involved lung zones, cavitary closure, and time to sputum culture conversion. Etanercept treatment resulted in a 25% increase in CD4 cells by week 4 (P = 0.1 compared with controls). The change in CD4 cell count was inversely related to the change in serum neopterin, a marker of macrophage activation. There was no effect on plasma HIV RNA. Conclusion: Etanercept can be safely administered during the initial treatment of pulmonary tuberculosis. Further studies are warranted to examine the effects of etanercept on T-cell numbers, activation and apoptosis in AIDS and tuberculosis.

Impact of pulmonary tuberculosis on survival of HIV-infected adults: a prospective epidemiologic study in Uganda.

BackgroundRetrospective cohort studies of tuberculosis suggest that active tuberculosis accelerates the progression of HIV infection. The validity of these findings has been questioned because of their retrospective design, diverse study populations, variable compliance with anti-tuberculous therapy and use of anti-retroviral medication. To assess the impact of tuberculosis on survival in HIV infection we performed a prospective study among HIV-infected Ugandan adults with and without tuberculosis. MethodsIn a prospective cohort study, 230 patients with HIV-associated tuberculosis and 442 HIV-infected subjects without tuberculosis were followed for a mean duration of 19 months for survival. To assess changes in viral load over 1 year, 20 pairs of tuberculosis cases and controls were selected and matched according to baseline CD4 lymphocyte count, age, sex and tuberculin skin test status. ResultsDuring the follow-up period, 63 out of of 230 tuberculosis cases (28%) died compared with 85 out of 442 controls (19%), with a crude risk ratio of 1.4 [95% confidence interval (CI), 1.07–1.87]. Most deaths occurred in patients with CD4 lymphocyte counts < 200 × 106 cells/l at baseline (n = 99) and occurred with similar frequency in the tuberculosis cases (46%) and the controls (44%). When the CD4 lymphocyte count was > 200 × 106 /l, however, the relative risk of death in HIV-associated tuberculosis was 2.1 (95% CI, 1.27–3.62) compared with subjects without tuberculosis. For subjects with a CD4 lymphocyte count > 200 × 106/l, the 1-year survival proportion was slightly lower in the cases than in the controls (0.91 versus 0.96), but by 2 years the survival proportion was significantly lower in the cases than in the controls (0.84 versus 0.91;P  < 0.02; log-rank test). For subjects with a CD4 lymphocyte count of 200 × 106 cells/l or fewer, the survival proportion at 1 year for the controls was lower than cases (0.59 versus 0.64), but this difference was not statistically significant (P  = 0.53; logrank test). After adjusting for age, sex, tuberculin skin test status, CD4 lymphocyte count, and history of HIV-related infections, the overall relative hazard for death associated with tuberculosis was 1.81 (95% CI, 1.24–2.65). In a nested Cox regression model, the relative hazard for death was 3.0 (95% CI, 1.62–5.63) for subjects with CD4 lymphocyte counts > 200 × 106/l and 1.5 (95% CI, 0.99–2.40) for subjects with a CD4 lymphocyte count of 200 × 106/l or fewer. ConclusionThe findings from this prospective study indicate that active tuberculosis exerts its greatest effect on survival in the early stages of HIV infection, when there is a reserve capacity of the host immune response. These observations provide a theoretical basis for the treatment of latent tuberculous infection in HIV-infected persons.

Duration of efficacy of treatment of latent tuberculosis infection in HIV-infected adults

BackgroundTreatment of latent infection is needed to protect HIV-infected individuals against tuberculosis. A previous report addressed short-term efficacy of three regimens in HIV-infected adults. We now report on long-term efficacy of the study regimens. MethodsThree daily self-administered regimens were compared in a randomized placebo-controlled trial in 2736 purified protein derivative (PPD)-positive and anergic HIV-infected adults. PPD-positive subjects were treated with isoniazid (INH) for 6 months (6H), INH plus rifampicin for 3 months (3HR), INH plus rifampicin and pyrazinamide for 3 months (3HRZ), or placebo for 6 months. Anergic subjects were randomized to 6H or placebo. Results6H initially protected against tuberculosis in PPD-positive individuals; however, benefit was lost within the first year of treatment. Sustained benefit was observed in persons receiving 3HR and 3HRZ. In a Cox regression analysis, the adjusted relative risk for tuberculosis compared with placebo was 0.67 [95% confidence interval (CI), 0.42–1.07] for 6H, 0.49 (95% CI, 0.29–0.82) for 3HR, and 0.41 (95% CI, 0.22-0.76) for 3HRZ. When the rifampicin-containing regimens were combined, the adjusted relative risk for tuberculosis compared with placebo was 0.46 (95% CI, 0.29–0.71). Among anergic subjects, a modest degree of protection with 6H was present (adjusted relative risk, 0.61; 95% CI, 0.32–1.16). Treatment of latent tuberculosis infection had no effect on mortality. ConclusionSix months of INH provided short-term protection against tuberculosis in PPD-positive HIV-infected adults. Three month regimens including INH plus rifampicin or INH, rifampicin and pyrazinamide provided sustained protection for up to 3 years.

Withdrawal of steroids after renal transplantation : clinical predictors of outcome

Withdrawal of steroid therapy in renal transplant recipients is associated with a risk of acute allograft rejection. To define clinical risk factors for rejection associated with steroid withdrawal, we analyzed the clinical characteristics of 107 patients with drawn from steroid therapy at various times after transplantation. Both univariate and multivariate analyses suggested that the timing of steroid withdrawal is an important predictor of steroid withdrawal failure. Withdrawal of steroids was successful in only 13 of 32 patients (41%) in whom prednisone was discontinued shortly after transplantation. In contrast, steroid withdrawal has been successful in 59 of 75 patients (79%) in whom prednisone was discontinued at least 6 months after transplantation. Black race and donor-recipient racial mismatch also were significant predictors of rejection associated with steroid withdrawal. In patients undergoing steroid withdrawal at least 6 months posttransplant, serum creatinine concentration also correlated independently with the risk of rejection. Neither age, sex, HLA match, pretransplant PRA, source of the allograft (cadaver vs. living relative), acute tubular necrosis, nor the presence of diabetes was predictive of the outcome of steroid withdrawal.

Immunoadjuvant Prednisolone Therapy for HIV-Associated Tuberculosis: A Phase 2 Clinical Trial in Uganda

Background. Human immunodeficiency virus (HIV)-infected patients with tuberculosis (TB) respond to effective antituberculous therapy, but their prognosis remains poor. Mounting evidence from clinical studies supports the concept of copathogenesis in which immune activation that is triggered by TB and mediated by cytokines stimulates viral replication and worsens HIV infection, especially when immune function is preserved.Methods. We performed a phase 2, randomized, double-blind, placebo-controlled clinical trial in Kampala, Uganda, to determine whether immunoadjuvant prednisolone therapy in HIV-infected patients with TB who have CD4(+) T cell counts >/=200 cells/ mu L is safe and effective at increasing CD4(+) T cell counts.Results. Short-term prednisolone therapy reduced levels of immune activation and tended to produce higher CD4(+) T cell counts. Although prednisolone therapy was associated with a more rapid clearance of Mycobacterium tuberculosis from the sputum, it was also associated with a transient increase in HIV RNA levels, which receded when prednisolone therapy was discontinued. The intervention worsened underlying hypertension and caused fluid retention and hyperglycemia.Conclusion. The benefits of prednisolone therapy on immune activation and CD4(+) T cell counts do not outweigh the risks of adverse events in HIV-infected patients with TB and preserved immune function.

Investigation of the Relationships between Immune-Mediated Inhibition of Mycobacterial Growth and Other Potential Surrogate Markers of Protective Mycobacterium tuberculosis Immunity

Tuberculosis (TB) vaccine development is hindered by the lack of clear surrogate markers of protective human immunity to Mycobacterium tuberculosis. This study evaluated the hypothesis that immune-mediated inhibition of mycobacterial growth would more directly correlate with protective TB immunity than other immunologic responses. Bacille Calmette-Guérin (BCG) vaccination, known to induce partial protection against TB, was used as a model system to investigate mechanistic relationships among different parameters of antigen-specific immunity. Effects of primary and booster intradermal BCG vaccinations were assessed in 3 distinct assays of mycobacterial inhibition. Correlations between vaccine-induced growth inhibition and other immune responses were analyzed. BCG significantly enhanced all antigen-specific responses. Peak responses occurred at 2 months after boosting. Statistical analyses suggested that each assay measured unique aspects of mycobacterial immunity. Despite previous evidence that type 1 immune responses are essential for TB immunity, interferon-gamma production did not correlate with mycobacterial inhibition. These results have important implications for TB vaccine development.

Reasons for not HIV testing, testing intentions, and potential use of an over-the-counter rapid HIV test in an internet sample of men who have sex with men who have never tested for HIV.

Background: Correlates of main reasons for not HIV testing, HIV testing intentions, and potential use of an over-the-counter rapid HIV test (OTCRT) among men who have sex with men who have never tested for HIV (NTMSM) are unknown. Methods: We evaluated these correlates among 946 NTMSM from 6 US cities who participated in an internet-based survey in 2007. Findings: Main reasons for not testing were low perceived risk (32.2%), structural barriers (25.1%), and fear of testing positive (18.1%). Low perceived risk was associated with having fewer unprotected anal intercourse (UAI) partners and less frequent use of the internet for HIV information; structural barriers were associated with younger age and more UAI partners; fear of testing positive was associated with black and Hispanic race/ethnicity, more UAI partners, and more frequent use of the internet for HIV information. Strong testing intentions were held by 25.9% of all NTMSM and 14.8% of those who did not test because of low perceived risk. Among NTMSM who were somewhat unlikely, somewhat likely, and very likely to test for HIV, 47.4%, 76.5%, and 85.6% would likely use an OTCRT if it was available, respectively. Conclusions: Among NTMSM who use the internet, main reasons for not testing for HIV vary considerably by age, race/ethnicity, UAI, and use of the internet for HIV information. To facilitate HIV testing of NTMSM, programs should expand interventions and services tailored to address this variation. If approved, OTCRT might be used by many NTMSM who might not otherwise test for HIV.