Figure 5From: Lysis of tubercle bacilli in fresh and stored sputum specimens: implications for diagnosing tuberculosis in stored and paucibacillary specimens by PCREffect of storage on USP smear grade status of sputum samples. The reduction in smear grade status of 3+, 2+ and 1+ samples have been shown separately. 1 M and 2 M refer to 1 month and 2 months of sputum storage at -20°C.Back to article page