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Preservation of Sputum Samples with Cetylpyridinium Chloride (CPC) for Tuberculosis Cultures and Xpert MTB/RIF in a Low-income Country.

Hiza, H., Doulla, B., Sasamalo, M., Hella, J., Kamwela, L., Mhimbira, F., Reither, K., Gagneux, S., Jugheli, L. and Fenner, L. (2017) Preservation of Sputum Samples with Cetylpyridinium Chloride (CPC) for Tuberculosis Cultures and Xpert MTB/RIF in a Low-income Country. BMC infectious diseases, 17 (1). p. 542. ISSN 1471-2334

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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. 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 Löwenstein-Jensen medium. Furthermore, 50 samples were stored for 7, 14 and 21 days, and 100 CPC-pretreated samples tested by Xpert MTB/RIF. 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 < 0.001). The quantitative culture grading was consistently higher in CPC treated compared to non-CPC treated samples. The proportion of contaminated cultures was lower in CPC pretreated samples across all decontamination times (range 2-6%) compared to non-CPC treated samples (15-16%). For storage times of CPC treated samples of 7, 14, and 21 days, 84, 86, and 84% of the respective cultures were positive. Of 91 CPC treated samples with a positive culture, 90 were also Xpert MTB/RIF positive. CPC increases culture yield, decreases the proportion of contamination, and does not alter the performance of Xpert MTB/RIF.

Item Type: Article
Keywords: CPC, Cetylpyridinium chloride, Contamination, Culture, Low-income country, Mycobacterium tuberculosis, Preservation, Recovery, Sample transport, Sputum, Tuberculosis
Subjects: Tuberculosis > Treatment
Divisions: Ifakara Health Institute > Interventions
Depositing User: Mr Joseph Madata
Date Deposited: 13 Jan 2018 10:38
Last Modified: 13 Jan 2018 10:38

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