[Tuberculin test in HIV infection]

Intravenous infected-HIV drug abusers (IDAP/HIV+) are known to have a higher risk of tuberculosis (TB) than others. The effectiveness of tuberculin testing (Mantoux) in the detection of the TB infection in HIV(+) patients is probably lower than HIV(-) individuals. The aim of this paper is to assess tuberculin testing in the active search of cases of TB infection in IDAP individuals and their differences between HIV(+) and HIV(-) ones.

We studied 332 patients with intravenous drug use belonging to a therapeutic community and to in-patients. Tuberculin testing was performed on all of them. They were examinated if had been previously vaccinated with BCG and we carried out the counting of linfocites CD4 in HIV(+) ones. In the cases of negative tuberculin skin test a second test was administered after 7 days. The patients were grouped in HIV(+) and HIV(-) and the variables were statistically assessed by the chi 2 and a logistic regression model.

Tuberculin testing resulted positive in 16.9% IDAP/HIV(+) in comparison with 39.9% of IDAP/HIV(-). The induration size was significantly smaller in HIV(+) than HIV(-) individuals. In both cases, we found that in BCG vaccinated patients positive tuberculin testing was significantly lower than negative tuberculin. The booster effect was detected in 8.9% of HIV(+), whereas in HIV(-) not BCG vaccinated it was of 21.4% and in HIV(-) BCG vaccinated it increased to 30.9%. When the level of the linfocites CD4 exceeds 500/mm3 in HIV(+) the percentage of Mantoux test (+) equals HIV(-) individuals.

A decrease in sensitivity of tuberculin testing in the diagnosis of TB infection in IDAP/HIV(+) was detected. A high percentage of booster effect in IDAP was also demonstrated. We recommend the performance of tuberculin testing at the beginning of HIV infection.