[7], where S is the average OD value of the duplicate test samples and B corresponds to the average

OD value of the duplicate negative controls plus three times the standard division (SD). The study protocol was approved by the Ethical Clearance Committee of the ALIPB, Addis Ababa University and the Regional Committee for Medical Research Ethics of Southern Norway. Upon recruitment, the aim of the study was explained to the study participants and written informed consent was obtained from each of the study participants. Blood sample selleckchem collection was carried out under aseptic conditions by well-experienced technicians. Individuals tested positive for latent TB by QFTGIT were advised to consult the nearest health facility lest they develop signs/symptoms suggestive of active TB. The results of culture were reported to the health facility. Data were computerized using EpiData software v.3.1 (EpiData Association, Odense M, Denmark) and analysed using Stata version 11. (Statacorp LP, College Station, TX, USA) Frequencies and percentages were used to summarize baseline characteristics of the participants. Means of OD value were compared between categories of the characteristics of participants using the Student’s t-test for 2 independent samples. Correlation between the OD values of IgG or IgA and the level of IFN-γ was assessed using Spearman’s rank correlation coefficient. Linear regression

analysis was performed to assess the association between the OD values Doxorubicin of IgG or IgA and background characteristics of the participants, including age, sex and history of BCG or close contact with TB patients. A P-value of <0.05 was considered statistically significant. A total of 166 individuals (38 patients with culture-confirmed PTB, 73 healthy individuals who were positive for Mtb infection by QFTGIT and

55 non-infected) were included in the study. There were no significant differences in the mean age of patients with culture-confirmed PTB (mean age = 37.4; SD = 14.3) and healthy Mtb-infected subjects (mean age = 35.0; SD = 14.1) (P > 0.05). Among the study participants, 27(16.3%) and 29 (17.5%) had BCG scars and Amoxicillin history of contact with TB patients, respectively. The mean OD values of IgA against ESAT-6/CFP-10 (Fig. 1) and Rv2031 (Fig. 2) antigens were significantly higher in sera of patients with culture-confirmed PTB compared with healthy Mtb-infected and non-infected cases (P < 0.001 in all cases). Similarly, the mean OD values of IgG against ESAT-6/CFP-10 (Fig. 3) and Rv2031 (Fig. 4) were significantly higher in sera of patients with culture-confirmed PTB compared with healthy Mtb-infected cases and non-infected cases (P < 0.05). The mean OD values of serum IgG to both antigens were significantly higher than that of IgA against both antigens in sera of the various study groups (data was not shown).