In-use tests of disinfectants

Abstract

The method described by Kelsey and Maurer (1966) and Maurer (1978) was employed in the "in-use" testing of working disinfectants from four selected sites in a food microbiology laboratory. The sites were: 1.) discard jar, 2.) discard culture spreader jar 3.) discard pipette jar 4.) floor-mop bucket. The phenolic compound represented by name, crusade was used at 10% concentration. The neutralizer was Tween 80 in quarter strength ringer`s solution. In all 80 samples of the disinfectant was collected over one week, from 15th to 19th February, 1993. Results of nine samples collected at the end of the day (9 hours in my study) were within the Kelsey& Maurer satisfactorily count limit. Fifteen more samples which were collected just before the in-use solutions were to be discarded-24 hours- also fell within the limit. The study showed that it is possible to conduct a simple in-use testing of disinfectants in any laboratory where tests sites similar to those in the study are being used. A higher concentration of 10% (v/v) of the disinfectant was used instead of the 4% (v/v) recommended by the manufacturer which proved completely ineffective in preliminary studies. It has been recommended that the continued use of this particular disinfectant should be reviewed. Aerobic sporing and non-sporing Bacillus species, Lactobacillus species, and Staphylococcus albus, all Gram positive organisms were identified. In addition, the fungi, Asppergillus niger and species of Penicillium were isolated isolated on a Potato Dextrose Agar plate on one occasion