The intent of study was to assess the antimicrobial properties of Client 999's spray product against the bacterial cultures: Staphylococcus aureus (ATCC6738), Staphylococcus aureus (ATCC 33593 (Methycilin Resistant Staphylocococcus aureus)), Pseudomonas aeruginosa (ATCC 9027), Listeria monocytogenes (ATCC 19114), Salmonella enterica (NCTC-6017), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 8739) and one fungal culture Aspergillus brasiliensis (ATCC 16404).
Overnight cultures of the microorganisms were prepared and diluted to obtain countable numbers. Each of the diluted cultures were spiked onto two 6.5 x 6.5 cm squares made of 22 ga T316L Stainless Steel and the spread using a sterile spreader. One of the squares was a control and the other square was a sample. A Tryptic Soy Agar + Lecithin and Polysortable (TSA + LP) contact plate was pressed onto the surface of the controls. The product was mixed thoroughly by inverting the bottle 20 times and then the sample squares were sprayed evenly with the product and left wet for 4 minutes. After 4 minutes, a Tryptic Soy Agar + Lecithin and Polysorbate (TSA + LP) contact plate was pressed onto the surface of the sample squares. The TSA + LP plates were incubated at 32.5+-2.5oC (bacteria) and 22.5+-2.5oC (fungus) until accurate counts could be determined.
The log value of the samples and controls and the log reduction for each sample as compared the the value of the control was calculated as follows.
CFU/mL = (# of CFU) x (Dilution Factor)
Log Reduction = (Log10 Positive Control CFU/mL) - (Log10 Disinfectant CFU/mL)
Log-reduction is a way to express levels of decreased bacteria load by factors of 10. A 1.0-log reduction would be equivalent to a 90 percent reduction. A 2.0-log reduction would be 99 percent reduction and a 3.0-log reduction would be 99.9 percent reduction. The % reduction would as follows: 100-10 (2log reduction).