Granzyme B as a diagnostic marker of tuberculosis in patients with and without HIV coinfection.

Immunodiagnostic tests for tuberculosis (TB) are based on the estimation of interferon γ (IFN-γ) or IFN-γ-secreting CD4(+) T cells following ex vivo stimulation with ESAT6 and CFP-10. Sensitivity of these tests is likely to be compromised in CD4(+) T-cell-depleted situations, like HIV-TB coinfection. CD4(+) and CD8(+) T cells, isolated from 3 groups, viz., HIV-negative patients with active TB, HIV-TB coinfected patients, and healthy household contacts (HHCs) were cocultivated with autologous dendritic cells, and the cytokine response to rESAT6 stimulation was compared between groups in supernatants. While CD4(+) T-cell stimulation yielded significantly elevated levels of IFN-γ and interleukin 4 in HIV-negative TB patients, compared to HHCs, the levels of both these cytokines were nondiscriminatory between HIV-positive TB patients and HHCs. However, CD8(+) T-cell stimulation yielded significantly elevated granzyme B titers in both groups of patients, irrespective of HIV coinfection status. Hence, contrary to IFN-γ, granzyme B might be a useful diagnostic marker for Mycobacterium tuberculosis infection particularly in HIV coinfected patients.

Diagnostic defaulters: an overlooked aspect in the Indian Revised National Tuberculosis Control Program.

INTRODUCTION: The Revised National Tuberculosis Control Program (RNTCP) aims to achieve detection of 70% of new smear-positive patients in a community and to cure 85% of such patients. Though an elaborate recording and reporting system is in place to monitor the success of the program, no record of patients who do not complete the diagnostic process is currently maintained. The present study, performed in a tertiary care hospital, attempted to estimate the proportion of this group of patients, who were labeled "diagnostic defaulters. METHODOLOGY: This prospective observational study was conducted over one year on consecutive patients presenting with cough of more than two weeks' duration. A total of two sputum samples were obtained from each patient, including a spot sample and a morning sample collected on the following day. Zeihl-Neelsen staining, reporting and external quality assessment of smear-microscopy was done per RNTCP guidelines. RESULTS: Of the 2,349 patients recruited, 175 defaulted on the second day. The positivity rates for the spot and morning samples were 18.3% and 18.9%, respectively (p > 0.001).  Of the 175 defaulters, 31 were found to be smear-positive, thereby implying that the proportion of diagnostic defaulters was 17.7%. All 21 diagnostic defaulters contacted by telephone were found to be unaware of their smear-positive status. CONCLUSION: The high proportion of diagnostic defaulters, the majority of whom were unaware of their sputum-positive status, emphasizes the need to recognize the importance of this group of patients to better control tuberculosis.

An alternative 1-day smear microscopy protocol for the diagnosis of pulmonary tuberculosis.

BACKGROUND AND OBJECTIVE: This study was undertaken to assess the feasibility of diagnosing pulmonary tuberculosis (PTB) by collecting two sputum samples on a single day (1-day protocol), and to compare this protocol with the national policy of collecting two samples on consecutive days (2-day protocol). METHODS: A total of 513 individuals with cough that had persisted for more than 2 weeks were screened for PTB by collection of three sputum samples: a spot sample on the first day, a sample collected 1 h after the first sample and a sample collected the following morning. For the 2-day protocol, the diagnostic performance of the first and third samples was considered, while the 1-day protocol was evaluated using the two samples collected on the first day. Staining and microscopy were performed in a blinded manner by two different technicians. RESULTS: Of the 513 patients, 40 defaulted on the second day. Of the total number of patients recruited, 124 (24.2%) were smear-positive. Using the 2-day protocol, 121 patients (97.6%) were identified as smear-positive, whereas with the 1-day protocol 118 patients (95.2%) were identified as smear-positive (P = 0.3). Of the patients who defaulted, seven (17.5%) were smear-positive. Comparison of the variation in results indicated that collection of a morning sample on the second day provided no significant benefit over collection of a second spot sample on the first day. CONCLUSIONS: As the 2-day protocol did not show a statistically significant difference in diagnostic performance compared with the 1-day protocol, the latter may be adopted as an alternative protocol, particularly for patients who are more likely to default.