EPA SOP No. MB-09-07. Disinfectant Towelette Test: Testing of Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica).
Test not accredited in our laboratory.
The test organisms used as mandatory to determine the bactericidal activity in this Disinfectant Towelette Test are three bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica).
The geometric mean density for carriers inoculated with S. aureus and P. aeruginosa must be between 1.0 × 105 and 3.2 × 106, and the geometric mean density for carriers inoculated with S. enterica must range between 1.0 × 104 and 3.2 × 105.
To perform the test, 80 glass carriers should be inoculated per microorganism of assay: 60 carriers are required for testing, 6 for control carrier counts, 1-2 carriers for the viability controls and 1-2 additional uninoculated carriers for sterility control. The area of the towlette used for wiping is folded and rotated so as to exposure a new surface of the towlette for each carrier. Sets of 10 inoculated carriers (5 carriers per side of the towelette) are wiped with the tested towelette slide back and forth three times lengthwise with the towelette for a total of six passes across the inoculum or as specified by the client. The addition of 5% of organic soil to the inoculum can be requested, depending on the intended use of the product. The method may be altered to accommodate various towlettes/carriers combination (e.g. more than one towlette per set of ten slides). The area of the towelette used for wiping is folded and rotated so as to exposure a new surface of the towelette for each carrier. An appropriate amount of organic burden may be added, if required. After the exposure time is completed, the slides are transferred into subculture tubes containing an appropriated neutralizer and all subculture tubes are incubated 48 ± 2 hours at 36°C ± 1°C. After the incubation period, results are recorder as positive (if there is growth) or 0 (in the absence of growth), as determined by presence or absence of turbidity.
The identity of the microorganisms in at least three positive carrier sets should be confirmed per test. If there are less than three positive carriers, each carrier should be confirmed. The confirmation tests include Gram stain reactions, cell morphology, colony characteristics on solid media and other phenotypic characteristics.