Adequacy of examining one sputum specimen in tuberculosis drug resistance surveys.

OBJECTIVE/BACKGROUND: Collection of one spot and one morning sputum specimen is recommended for tuberculosis (TB) drug resistance surveys. This was a retrospective analysis of Mycobacterium tuberculosis cultures isolated from two spot sputum specimens collected from smear positive TB patients in a TB drug resistance survey. It was conducted to understand the value of a second specimen. METHODS: A TB drug resistance survey was conducted in the state of Tamil Nadu, India, to estimate the prevalence of drug resistance among new sputum smear-positive (NSP) and previously treated (PT) patients diagnosed in Revised National Tuberculosis Control Program microscopy centers. A total of 2425 patients (1524 NSP and 901 PT cases) were enrolled in the study. From these patients, two spot sputum specimens (C and D) were collected within a period of 2h. No preservative was added to sputum. The samples were transported at ambient conditions without cold storage to the central laboratory for culture of M. tuberculosis. Culture yield from each sample was computed and analyzed. RESULTS: The proportion of cultures retrieved from C and D specimens among NSP cases (89.3% and 89.7%) and PT cases (90.8% and 90.3%) were similar. The culture grades of C and D samples were comparable (chi-square test, 3560.135; p<.001) and the agreement was moderate (kappa test, 0.454). CONCLUSION: The findings of the study reveal the adequacy of single spot sputum specimen from smear positive pulmonary TB patients for bacteriological examination in a quality-assured TB laboratory to determine precisely the level of drug resistance in a province of India.

Incidence of active pulmonary tuberculosis in patients with coincident filarial and/or intestinal helminth infections followed longitudinally in South India.

BACKGROUND: Filarial (and other helminth) infections are known to modulate mycobacteria-specific pro-inflammatory cytokine responses necessary for maintaining latency in tuberculosis (TB). We sought to address whether helminth co-infection alters progression to active pulmonary TB in a co-endemic area of South India. METHODS/PRINCIPAL FINDINGS: Incidence of active pulmonary TB was assessed in 5096 subjects from five villages among helminth-infected (hel⁺) and -uninfected (hel⁻) groups. Baseline stool examinations, circulating filarial antigen, and tuberculin skin testing (PPD) were performed along with chest radiographs, sputum microscopy, and culture. During three follow-up visits each 2.5 years, patients were assessed using PPD tests and questionnaires and--for those with potential symptoms of TB--sputum microscopy and culture. Of the 5096 subjects, 1923 were found to be hel⁺ and 3173 were hel⁻. Follow up interval stool examination could not be performed. In each group, 21 developed active TB over the course of the study. After adjusting for sex, age, BCG vaccination status, and PPD positivity, no difference was seen in active TB incidence between hel⁺ and hel- groups either at baseline (relative risk (RR) 1.60; 95% confidence interval (CI): 0.69, 3.71, P = 0·27), or when followed prospectively (RR 1.24; 95% CI: 0.48, 3.18, P = 0·66). CONCLUSIONS/SIGNIFICANCE: Our findings suggest that, despite the immunomodulatory effects of helminth infection, baseline co-morbid infection with these parasites had little effect on the clinical progression from latent to active pulmonary TB.