Preservation of sputum samples with cetylpyridinium chloride (CPC) for tuberculosis cultures and Xpert MTB/RIF in a low-income country

摘要

Background Culture contamination with environmental bacteria is a major challenge in tuberculosis (TB) laboratories in hot and humid climate zones. We studied the effect of cetylpyridinium chloride (CPC) preservation on culture results and performance of Xpert MTB/RIF. Methods Consecutive sputum samples from microscopy smear-positive TB patients were collected. Two-hundred samples were equally split in two aliquots, one aliquot was treated with CPC and stored at ambient temperature for 7?days. The second aliquot was immediately processed. Samples were decontaminated for 20, 15 or 10?min, and subsequently cultured on L?wenstein-Jensen medium. Furthermore, 50 samples were stored for 7, 14 and 21?days, and 100 CPC-pretreated samples tested by Xpert MTB/RIF. Results CPC pretreated samples showed a higher culture yield compared to non-treated sputum samples across all decontamination times: 94% vs. 73% at 10?min ( p =?0.01), 94% vs. 64% at 15?min ( p =?0.004), and 90% vs. 52% at 20?min ( p Conclusions CPC increases culture yield, decreases the proportion of contamination, and does not alter the performance of Xpert MTB/RIF.