Mycobacterial infection in HIV seropositive and seronegative populations, 1987-93

HIV-1 Coinfection Does Not Reduce Exposure to Rifampin, Isoniazid, and Pyrazinamide in South African Tuberculosis Outpatients

There are contrasting data in the literature about antituberculosis plasma drug concentrations in HIV-1-coinfected patients. We report the pharmacokinetics of rifampin, isoniazid, and pyrazinamide in a cohort of patients being treated for active tuberculosis, the majority of whom were coinfected with HIV-1 and had commenced antiretroviral therapy within 2 months of starting antituberculosis treatment. We also examined the association between antituberculosis drug concentrations and reported drug side effects at the 2-month clinical review. One hundred patients with pulmonary tuberculosis (65% coinfected with HIV-1) were intensively sampled to determine rifampin, isoniazid, and pyrazinamide plasma concentrations after 7 to 8 weeks of a daily quadruple-therapy regimen dosed according to World Health Organization (WHO) weight bands. Pharmacokinetic parameters were determined for each patient by using nonlinear mixed-effects models. HIV-1-coinfected patients had lower clearance rates for rifampin (21% decrease) and isoniazid (23% decrease) than HIV-1-uninfected patients, with resulting higher areas under the concentration-time curve from 0 to 24 h (AUC_0–24) and maximum concentrations of drug in serum (C_max). Antiretroviral therapy (ART) that included double-standard-dose lopinavir/ritonavir further lowered rifampin clearance, by 46%, and increased the AUC_0–24. The current uniform dosing (per kilogram of body weight) across WHO weight bands was associated with a trend of decreased pharmacokinetic exposures for the lowest weight band. Use of fat-free mass as opposed to total body weight for allometric scaling of clearance significantly improved the model. Ambulant HIV-1-coinfected patients, the majority of whom were coprescribed ART, did not have reduced antituberculosis drug concentrations compared to HIV-1-uninfected patients.

HIV and tuberculosis co-infection in an inner London hospital--a prospective anonymized seroprevalence study

OBJECTIVES

Since 1987 there has been an increase in tuberculosis notifications in the U.K., with this increase disproportionately affecting London. A recent national survey suggests that co-infection with HIV occurs in less than 5% of tuberculosis patients. This study asked if local co-infection rates in Inner London differed from the national results.

METHODS

157 consecutive patients starting antituberculous chemotherapy were venesected 2 weeks into treatment. Anonymized blood samples were screened for antibodies for HIV-1 and HIV-2 by enzyme-linked immunosorbent assay (ELISA). Epidemiological data were collected on each patient which was also coded before HIV test results were known.

RESULTS

Of 157 patients commencing antituberculous therapy, 39 patients (24.8%) were found to be co-infected with HIV-1. HIV-negative and positive patients were similar in terms of age and sex. When 98 patients giving their country of origin as other than Europe were considered there were 22 co-infected with HIV (22.4%). Of the 39 HIV-positive identified in this study, 37 were also identified by our voluntary HIV testing programme.

CONCLUSIONS

This study has shown that there may be very different rates of co-infection at a local level in the U.K. The local variation may be missed by national surveys and diverse local testing procedures. Anonymous testing identified only two patients with tuberculosis and HIV infection who were not identified by our voluntary HIV testing programme and this suggests that offering HIV tests to patients with tuberculosis is largely taken up by those at risk of HIV infection. Surveillance studies of this type are important in identifying marked local variation from the national pattern of HIV and Mycobacterium tuberculosis infection.