Monitoring of microbiology laboratory working environment

Abstract

A total of 80 samples of in-use disinfectant solutions from floor mop bucket were collected over four working weeks and bacterial contamination measured by the in-use test technique to ascertain the level of sterility of three important rooms in the CSIR-Food Research Institute’s accredited Microbiology Laboratory. Phenolic compound represented by the brand name Crusade® was used at a concentration of 4 % (v/v), with Tween 80 in diluent of Salt Peptone Solution as the neutralizer. High average bacteria survival levels were recorded early, during three and six hours of disinfection of the floors throughout the four weeks study period, with an average bacterial count of log103 cfu/ml. Later disinfection procedures at 9 and 24 hours resulted in the reduction in counts, with an average load of log102 cfu/ml. Comparative mean counts (cfu/ml) per day of disinfection showed that the microbial load during disinfection was high at the beginning of each working week, usually on Mondays and Tuesdays with noticeable reductions through Wednesdays and then lower counts on Thursdays and Fridays of each week. The high levels detected each Monday during the four weeks may be attributed to bacteria build up over the two non working days of Saturdays and Sundays when no cleaning and disinfecting activities were undertaken. None of the samples taken met the satisfactory limit of less than 250 cfu/ml after 24 hours of incubation at 30°C as described by earlier researchers for the in-use testing of working disinfectant