Comparison of two decontamination/liquefaction methods for microscopy detection and recovery of mycobacteria in clinical practice

N S MORCILLO; C N FERNANDEZ; B R IMPERIALE; A N BODON; J C PALOMINO

PARIS

Congreso; 36th World Conference on Lung Health of the International Union Against Tuberculosis and Lung Disease ( The Union); 2005

IUATLD

The clinical performance of the hypertonic decontamination method (HT), which uses a combination of hypertonic sodium chloride and sodium hydroxide, was compared to that of 4% NaOH plus N-acetyl-L-cysteine (NALC) method in a two phase study: Phase I: 683 respiratory clinical specimens were divided in two parts of equal volume each and decontaminated by NALC or HT. Smears were prepared from each one of the decontaminated volumes and stained by Ziehl-Neelsen for microscopy detection (AFB). After that 0.2 ml were inoculated onto Löwenstein-Jensen slants and 0.5 ml on MGIT960 (BD Argentina) and incubated at 37ºC during 60 and 42 days respectively. Phase II: 3388 respiratory specimens were included under a double blind and randomized design to be treated by either NALC (1357) or HT (2031). Samples were processed as specified in Phase I. AFB and cultures results from Phases I and II showed that no significant differences were found between both HT and NALC when analyzing sensitivity, specificity, the area under the ROC curve, and predictive values. These findings suggest that HT could be used as an inexpensive method in the clinical diagnosis of TB cases especially in low-income countries.