Mycobactericidal activity of various concentrations of bleach.

Treatment of sputum samples using bleach has been proposed to sterilize the sample and increase the sensitivity of smear microscopy, for the diagnosis of tuberculosis (TB). However the concentration and exposure times needed for sterilizing sputum samples are poorly defined. In this study, thirty sputum samples that tested positive for acid fast bacilli by direct smear microscopy at microbiology laboratory were divided into three groups and treated with equal amounts of 5%, 3%, 1% bleach. It was found that 5% and 3% bleach were effective in sterilizing sputum, at a contact time of five minutes, 1% bleach requires a greater contact time for adequate mycobactericidal activity.