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

Balaji, S.; Kumar, V.; Prabu, S.; Radhakrishnan, R.; Gomathi, S.; Kannan, T.; Chandrasekaran, V.; Swaminathan, S.; Selvakumar, N.

International Journal of Mycobacteriology; 2016; 5; 265-268.

Abstract: 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 2 h. 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 .

Keywords: Drug resistance survey; Lo¨wenstein–Jensen media; Mycobacterium tuberculosis; Sputum

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