Comparison of sandwich cup collecting bacteria and smear method and improved Lowenstein Jensen culture in detecting acidfast bacilli

Abstract:

ObjectiveTo investigate the clinical diagnostic value of sandwich cup collecting bacteria and smear method (sandwich cup method) in the detection of acidfast bacilli.MethodsFrom July to December 2008 ， 1 782 sputum samples (including 642 morning sputum and 1 140 random sputum) were collected from people who were suspected to have pulmonary tuberculosis at tuberculosis prevention and treatment departments in 4 counties （cities） of Hunan Province. Each sample was dealt with sandwich cup method and improved Lowenstein Jensen(LJ) culture, respectively, the results were analyzed.ResultsThe positive rate of LJ culture and sandwich cup method was 26.64%(171/642) and 23.52% (151/642) in morning sputum, respectively, there was significant difference between the two(χ2=4.56,P=0.04); The positive rate of LJ culture and sandwich cup method was 23.33%(266/1 140) and 18.07% (206/1 140) in random sputum respectively , there was significant difference between the two(χ2=34.60,P=0.00). The positive rate of sandwich cup method in morning sputum was significantly higher than that in random sputum(χ2=7.62, P=0.01), while the positive rate of LJ culture in morning and random sputum showed no statistical difference (χ2=2.42, P=0.12).ConclusionThe positive rate of sandwich cup method is lower than LJ culture in detecting acidfast bacilli, but the former is simple, timesaving and easy to carry out quality control, and is worth popularizing in clinic. The positive rate of sandwich cup method in morning sputum is high, so morning sputum should be kept to detect acidfast bacilli clinically.