Background: Pulmonary TB is still the most common form of the tuberculosis in HIV infected patients with different presentations according to the degree of immunosuppression. The aim of this study was to investigate the impact of HIV infection on the clinical, laboratory and radiological presentation of tuberculosis.

Methods: We compared 80 HIV negative pulmonary TB patients with 40 HIV positive pulmonary TB patients during 1999-2005 in a teaching hospital of Tehran University of Medical Sciences, Iran.

Results: Tuberculosis was more common in men in both groups. The mean age of HIV positive patients was lower than HIV negatives (35.95+/-10.4 versus 46.95+/-20.39, P =0.002). Weight loss and chronic cough were significantly more frequent in HIV negative patients (76.3% vs. 45% p<0.001 and 93.8% vs. 80%, P<0.05 respectively), whereas fatigue were more prominent in HIV positives (45% vs. 21.3%, P< 0.001). Cavitations and infiltrations were reported in the CXR of HIV/TB patients less than HIV negative patients (OR=0.21, 95% CI: 0.05-0.97, P= 0.01 and OR=0.27%, 95% CI: 0.09-0.75%, P =0.02 respectively). Primary involvement pattern was observed more than secondary involvement in HIV/TB group (OR=3.95, 95% CI: 1.73-9.03, P =0.001). The laboratory findings in HIV/TB patients were as follows: more negative PPD skin (75% vs. 50%) tests, higher ESR (86.5% vs. 63.7%), lower mean Hb (10.6 vs. 12.4) and lower mean leukocyte (6545 vs. 9195) and lymphocyte count (1281 vs. 1838). In all of the above mentioned findings the differences between two groups were significant. Fourthy Seven% of patients had Lymphocyte count less than 1200 which means they were in AIDS stage.

Conclusion: Immune system suppression in HIV can alter the clinical, laboratory and radiological features of tuberculosis. It is crucial to consider tuberculosis in differential diagnosis of every HIV patients with respiratory symptoms.