A comparative study of tuberculin skin test reactivity between asymptomatic HIV-1 seropositive subjects and healthy volunteers

Abstract

During November 1993-October 1994 tuberculin skin test reactivity (PPD-Thai Red Cross: 0.1 ml of 10 IU) was determined among 399 asymptomatic HIV-1 positive subjects and 405 healthy volunteers, 10% (40/399) had PPD-TRC induration 0-2 mm compared with 4.2% (17/405) (p = 0.001) and 43.4% (173/399) had induration ≥ 10 mm compared with 53.8% (218/405) (p = 0.003) of healthy volunteers. However, the percentage of the PPD-TRC induration 5-9 mm was similar among HIV-1 seropositive subjects and healthy volunteers as 37.6% (150/399) vs 34.8% (141/405) (p = 0.4). The mean PPD-TRC reaction of HIV-seropositive subjects were 6.4 ± 0.9 mm vs. 11.0 ± 0.5 mm among those with CD4lymphocyte counts 200-299 cells/mm3compared with those ≥ 300 cells/mm3(p < 0.001). We provide support for use of induration of ≥ 5 mm of PPD-TRC skin reaction for evidence of latent infection with Mycobacterium tuberculosis as the CDC recommendation in asymptomatic HIV-seropositive subjects. Consideration of tuberculosis chemoprophylaxis should have benefit, particulary in areas where M. tuberculosis is highly prevalent such as Thailand. However, among HIV-1 seropositive carriers with negative tuberculin (PPD-TRC) skin tests, there needs to be a careful evaluation and follow-up for evidence of tuberculous infection.