ISOLATION OF TUBERCLE-BACILLI FROM SPUTUM SAMPLES OF PATIENTS IN THE FIELD STUDIES BY THE CETYLPYRIDINIUM CHLORIDE SODIUM-CHLORIDE AND SODIUM-HYDROXIDE METHODS

A total of 125 sputum specimens, collected in the field, were homogeni sed, aliquoted in sterile universal containers and randomly allocated to the cetylpyridinium chloride - sodium chloride (CPC-NaCl) method an d sodium hydroxide (NaOH) method for culture of tubercle bacilli. Afte r storage for 8 days at ambient temperature in the field laboratory at Thiruvallur, the aliquots were transported to the main laboratory at Madras where they were processed for culture by the respective methods . The yield of positive cultures in the CPC-NaCl (31/125) method was o nly marginally better than that in the NaOH method (27/125) (95% CI be ing-3.4 to 9.8%), while the contamination of cultures was significantl y less in the CPC-NaCl method( 3/125) than in the NaOH method (12/125) (95% CI being 2.2 to 12.2%). As the CPC-NaCl method has advantages ov er the NaOH method in reducing contamination, in augmenting the yield of positive cultures and also in its simplicity, it can be applied in field studies.