Comparison of Tuberculin Test Positivity in Pulmonary Tuberculosis With Hiv Seropositive and Seronegative Patients

Abstract

BACKGROUND: HIV & Tuberculosis is a common co-infection that we come across in developing countries. Diagnosis is done by demonstration of acid fast bacilli (AFB) &Tuberculin skin test (TST). Skin test depends on cell mediated immune response which is generally compromised in HIV infected. OBJECTIVE: To compare the demonstration of AFB &TST reactivity in tuberculosis patients who are HIV seropositive & seronegative MATERIALS & METHODS: The study was conducted in the tuberculosis hospital which is attached to the Mysore medical college, Mysore. All patients clinically suspected or diagnostically confirmed as pulmonary tuberculosis were subjected for HIV screening test as per NACO guidelines .Total of 200 patients included for the study out of which 100 each were HIV seropositive & seronegative. They were subjected for microscopic examination of sputum& TST. Sputum microscopy was performed as per RNTCP guidelines. PPD antigen was injected intra-dermally on the left forearm & read after 48 hours & results were noted down. RESULTS: Study group divided into two categories. Category A: Pulmonary tuberculosis patients with HIV seropositivity Category B: Pulmonary tuberculosis patients with HIV seronegativity. Male preponderance was observed in both 79% & 70% with the mean age of 32.7 ± 7.3 years, in females seronegativity was more i.e.30% compared to 21% in seropositive with mean age of 29.3 ± 5.6 years. AFB demonstrated by Sputum microscopy in 99% HIV seronegatives & 54% of HIV seropositives. TST results classified into groups with No response, induration of 1-5mm,6-9mm & >10mm. Among category A 9 of them exhibited No response,32 of them 1-5mm,27 of them 6-9mm & 32 of them >10mm.All category B has responded to TST with only one patient with 1-5mm,25 with 6-9mm,74 with >10mm. DISCUSSION: There is statistically significant difference (p>0.05) in TST &AFB demonstration in pulmonary tuberculosis patients with HIV seropositive & seronegative. Sensitivity of TST is reduced as TST is indicator of cell mediated immune response which is generally compromised in HIV seropositive. Demonstration of AFB is also reduced in HIV seropositive cases. CONCLUSION: TST & demonstration of AFB are common tests done to screen for HIV-TB co infection in HIV seropositive. As the sensitivity of these tests are reduced in HIV seropositive it needs to be interpreted with care.