Title
Decontamination methods for samples preserved in cetylpyridinium chloride and cultured on thin-layer agar Decontamination methods for samples preserved in cetylpyridinium chloride and cultured on thin-layer agar
Author
Faculty/Department
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
Publication type
article
Publication
Paris ,
Subject
Human medicine
Source (journal)
International journal of tuberculosis and lung disease. - Paris
Volume/pages
18(2014) :8 , p. 972-977
ISSN
1027-3719
ISI
000339646400017
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
SETTING: Long transportation times of samples to culture laboratories can lead to higher contamination rates and significant loss of viability, resulting in lower culture positivity rates. Thin-layer agar (TLA) is a sensitive culture method for the isolation of Mycobacterium tuberculosis that has been optimised with N-acetyl-L-cysteine-sodium hydroxide (NALC-NaOH) decontaminated samples. The combination of the TLA culture method and other decontamination procedures has not been extensively validated. DESIGN: Among 390 smear-positive samples, we compared the culture positivity of samples decontaminated using the Petroff method vs. NALC-NaOH neutralised with phosphate buffer (PBS), applied to samples preserved with cetylpyridinium chloride (CPC) or CPC-free, and then of CPC-preserved samples decontaminated with NALC-NaOH neutralised using Difco neutralising buffer. The sediments were inoculated on TLA, and then on MGIT 960 or Lowenstein-Jensen (LJ) as gold standards. RESULTS: Decontamination with NALC-NaOH yielded higher culture positivity in TLA than in the Petroff method, which was further enhanced by neutralising CPC with the Difco buffer. Surprisingly, culture positivity on LJ also increased after using Difco buffer, suggesting that CPC may not be completely neutralised in egg-based medium. CONCLUSIONS: After transportation in CPC, decontamination using NALC-NaOH followed by neutralisation using Difco buffer resulted in the best recovery rates for samples inoculated on TLA and on LJ.
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