Evaluating Disinfection Efficacy against Nosocomial Pathogens

The standard reference strains used in this study were Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 27853), Enterococcus faecalis (ATCC 29212), Citrobacter freundii (ATCC 43864), Proteus mirabilis (ATCC 29906), Candida albicans (ATCC 18804) and Candida parapsilosis (ATCC 22019), which were obtained from Microbiologics (St. Cloud, Minnesota) or from the Culture Collection of the Institute of Health Sciences, Federal University of Bahia (Universidade Federal da Bahia–UFBA), located in Salvador, Brazil. The selection of test strains was based on studies of microorganisms commonly causing nosocomial infections, as well as on the recommendations of regulatory agencies for evaluating the efficacy of chemical disinfectants [57 (link), 59 (link)–65 (link)]. The suspensions of the test microorganisms were prepared by transferring cells from the pure culture to plates containing 15–20 mL of plate count agar: agar (9 g/L); dextrose (1 g/L); tryptone (5.0 g/L) and yeast extract (2.5 g/L). To evaluate the disinfection profile in the chamber against the test microorganisms, the inocula were prepared by suspending 1–5 colonies in 5 mL of 0.85% saline solution and the turbidity was adjusted to McFarland No. 0.5 tube [66 ].