Validation of Microbial Recovery of Pharmaceutically Important Gram-negative Bacteria from Peroxygen/Silver based Disinfectants and Evaluation of their Degree of Corrosiveness

Abstract

Evaluation of a neutralization method and the degree of corrosiveness of disinfectants is a crucial initial step that precedes biocidal agents efficacy study. One of the major factors affecting the choice of the disinfectants is their aggressiveness towards materials of construction in the pharmaceutical facility. Two dilutions of each of four commercially used peroxygen/Ag+ -based disinfectants were examined against four Gram-negative microorganisms using Fluid Thioglycolate Medium (FTM) broth for both chemical and physical neutralization. The acceptance criteria of a test group was > 70 % of the control group for each replicate group namely neutralizer efficacy and neutralizer toxicity. Statistical analysis using One-way analysis of variance (ANOVA) was carried out to confirm success/failure of a suspect result. By this analysis; five suspect treatments passed the neutralizer efficacy test. Modified FTM-thiosulfate (FTMT); FTM neutralizer, was tested under the same conditions against the same index of microorganisms and compared to a previously used and tested FTM neutralizer. Neutralization of the modified FTM neutralizing broth was more effective than the previously reported FTM with peroxygens/Ag+ disinfectants especially 1:100 dilution. Using higher dilutions has minimized the reaction time in the present study. In addition, a gravimetric corrosion test was performed to determine the degree of corrosiveness of disinfectants. Bixco showed greatest corrosion rate when compared with other commercially used peroxygens which were not significantly different from the control. Corrosion test is a useful tool to determine the preference among a range of disinfectants especially if they belong to the same class.