The Effect of Several Different Decontaminant Solutions for Sputum in Inhibiting Contamination of Mycobacterium Tuberculosis Culture

摘要

As with most of the processed clinical specimens for tuberculosis (TB) culture, sputum is contaminated by the flora of oropharyngeal tract. The best method to establish appropriate culture from sputum is establishing a safe decontaminant solution for the laboratory worker which wouldbe able to effectively decontaminate the specimen without killing numerous TB bacilli, and such solution would be preferred to be in reasonably price and readily available. Bleach is a commonly used disinfectant which is commercially available and could be used as an alternative. The objectiveof this study is to assess the capability of bleach in inhibiting the contaminants for TB culture without decreasing its positivity rate. The research was conducted at TB laboratory of Faculty of Medicine, University of Indonesia (FMUI), using 35 samples of sputum in the volume of 4–6ml with positive acid fast stain (AFS). Each sample was divided into 4 groups that were decontaminated by different methods. The methods are 4% NaOH, 2% NALC-NaOH, 5% oxalic acid and 1% bleach. 1% bleach was prepared from commercially available bleach. Each group was assessed for contaminationand culture positive rate. The positive culture was validated using MPT 64. The number of positive AFS was (+1) 46%, (+2) 37% and (+3) 17%. The bleach group had the lowest contamination rate, which was 2.8% compared to the 5.7% of the 4% NaOH group, and a significant difference was found amongthe four groups (p = 0.000). A significant difference in the proportion of positive culture was also found among the four groups (p = 0.006), but there wasn’t a significant difference in the positivity rate between 1% bleach, 4% NaOH and 2% NALC-NaOH. 1% bleach can be usedas an alternative solution for decontamination of TB culture from highly contaminated sputum with acid fast bacilli (AFB) higher than (+2).