Efficacy of commonly used sterilant 70% (w/v) ethanol in controlling identified surface microbes in biotechnology laboratory

Abstract

The alarming trend of the resistance in microbes drives researchers to re-evaluate the existing materials and methods used to maintain aseptic conditions in laboratories. Therefore, this study was designed to better understand surface microbes in biotechnology laboratory areas that may develop resistance and the action needed to control the transmission by re-evaluating the efficiency of commonly used surface sterilant: 70% ethanol. For this purpose, surface swabs were collected from the four commonly used uncleaned working spots: media preparation area, molecular area, inoculation area, and incubation area. Pure colonies were characterised morphologically and biochemically using gram staining, catalase, oxidase, indole, urase, and gelatin tests. According to morphological and biochemical characteristics, the representative bacteria were concluded as Bacillus spp., from media preparation and molecular area, Staphylococcus spp., and Pseudomonas spp, from inoculation and incubation area, respectively. All the isolates were sensitive to the antibiotic Kanamycin. Then these isolated bacteria were used as surface inoculum to find the efficacy of 70% ethanol as surface steriliser after 2, 5, and 10 mins of sterilisation. After sterilisation, the bacteria concentration was 8-11 times lower than the positive control, and there were no significant differences (α=0.01) among negative and tested bacteria samples in bacterial concentration and times used. This study also tested whether ethanol is effective against surface bacteria for up to 24 hours and concluded that there is a need for immediate cleaning. Overall, this study confirmed the acceptability of the most undertaken sterilisation practice (using 70% ethanol) at biotechnology laboratories using isolated surface bacteria.