ABSTRACT
Tuberculosis is one of the most common diseases among HIV-infected patients. A person with a positive tuberculin skin test [TST] acquiring HIV infection has a 3-13% annual risk of developing active tuberculosis. The diagnosis of TB in HIV infected patients may be difficult. QuantiFERON-TB Gold [QFT-G] test is a novel method as an aid for diagnosis of Mycobacterium tuberculosis infection. We evaluated the association between TST and QFT-G test in latent TB infection [LTBI] and TB in HIV-infected patients. One hundred and seventy six HIV-infected subjects from Shiraz Consultation and Behavioral Modification Center [SCBMC] entered our study. The individuals were screened for TST, using 5TU purified protein derivative [PPD]. Also, blood sample was provided for QFT, measuring INF-gamma response to M. tuberculosis antigen. Of 176 participants, 98.3% returned for evaluation of TST results. Among them, 63% and 37% were negative and positive for TST, respectively. All the participants returned for QFT-G sampling. Of them, 64.8% and 27.8% were respectively negative and positive for the test and 7.4% showed undetermined results. The agreement between PPD and QFT-G in their negative results was 39.9% and 8.1% in their positive results and the overall agreement was 50%. Disagreement of TST-/QFT[+] was noticed in 19.7% of the subjects and TST[+]/QFT- disagreement in 24.9%. CD4[+] count <100 mm[3] was seen in 5.9%, >/= 100 and < 200 mm[3] in 17.1% and CD4[+] T cell count >/= 200 mm[3] in 76.9% of subjects. As the agreement rate between QFT-G and TST in HIV-infected patients was fair, a strategy of simultaneous TST and QFT-G testing would maximize the potential for LTBI diagnosis in HIV-infected subjects