Yield of culture of Mycobacterium tuberculosis complex in sputum samples transported from tribal areas

BACKGROUND: There is little information on the recovery of Mycobacterium tuberculosis complex from sputum samples collected in the field for bacteriological examination. SETTING: Tribal areas in the State of Madhya Pradesh, in central India. METHODS: Sputum specimens collected from subjects with chest symptoms in a disease prevalence survey were refrigerated until transportation to the laboratory. The specimens were processed for microscopy and culture. The samples were grouped based on the delay in processing for culture from the day of collection into three groups: 0-3, 4-7 and >= 8 days, and the recovery of M. tuberculosis complex in these groups was analysed. The statistical analysis was performed using chi(2) test. RESULTS: Of the 3651 processed specimens, 114 were positive for M. tuberculosis complex by culture and 96 by smear microscopy. The differences in the proportion of 'smear-positive, culture-positive', 'smear-positive, culture-negative' and 'smear-negative, culture-positive' samples between the three groups were not significant. CONCLUSION: In difficult-to-reach areas with limited resources, refrigeration of sputum specimens until they are transported for processing at a reference laboratory for culture seems not to significantly affect the recovery of M. tuberculosis complex isolates.