ABSTRACT
Objective/background: Collection of one spot and one morning sputum specimen is recom-mended 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 under-stand 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
ABSTRACT
Documentation of structured quality indicators for mycobacteriology laboratories supporting exclusively controlled clinical trials in pulmonary tuberculosis [PTB] is lacking. To document laboratory indicators for a solid [Lowenstein-Jensen medium] culture system in a mycobacteriology laboratory for a period of 4 years [2007-2010]. The sputum samples, collected from PTB suspects/patients enrolled in clinical trials, were subjected to fluorescence microscopy, culture and drug sensitivity testing [DST]. Data was retrospectively collected from TB laboratory registers and computed using pre-formulated Microsoft Office Excel. Laboratory indicators were calculated and analyzed. The number of samples processed in a calendar year varied from 6261 to 10,710. Of the samples processed in a calendar year, specimen contamination [4.8-6.9%], culture positives [78.4-85.1%] among smear positives, smear positives [71.8-79.0%] among culture positive samples, smear negatives among culture negative samples [95.2-96.7%], and average time to report DST results [76-97 days] varied as shown in parentheses. Values of quality indicators in mycobacteriology laboratories supporting exclusively clinical trials of PTB have to be defined and used for meaningful monitoring of laboratories.
ABSTRACT
BACKGROUND & OBJECTIVES: Sensitivity of Ziehl-Neelsen (ZN) method is known to be low for liquefied sputum smears. Information on the ZN sensitivity for centrifuged deposit smears is not known. This study was carried out to determine the sensitivity of ZN method for acid fast bacilli (AFB) in centrifuged deposit smears and liquefied sputum smears made from sputum samples transported in cetyl-pyridinium chloride (CPC) solution. METHODS: Liquefied sputum smears and the corresponding centrifuged deposit smears from each of the 607 consecutive sputum samples collected from tuberculosis patients admitted to receive treatment transported in CPC were read by the same readers and their results compared with culture results. RESULTS: A significantly (P<0.001) higher proportion of samples were positive in centrifuged deposit smears (40%) compared to liquefied sputum smears (30%). The results of 341 culture-positive specimens revealed that the sensitivity of ZN method was 47 per cent using liquefied sputum smears and 63 per cent using centrifuged deposit smears (P<0.001). INTERPRETATION & CONCLUSION: Our study demonstrated that the sensitivity of ZN method for AFB in centrifuged deposit smears and liquefied sputum smears was reduced if sputum samples are transported in CPC solution.