The efficacy of three common hospital liquid germicides to inactivate Cryptosporidium parvum oocysts.

We evaluated three commonly used hospital disinfectants against three concentrations of Cryptosporidium parvum oocysts (1.5 x 10(6), 1.5 x 10(5), 1.5 x 10(4)). A 10% phenol product, a 10% povidone-iodine product and a 2.5% glutaraldehyde product were tested against Cryptosporidium parvum oocysts without organic load. In-vitro excystation was used to determine viability and a cell culture assay was used to determine infectivity of germicide-treated oocysts. A 2.5% glutaraldehyde product was the most effective in halting excystation of sporozoites and infection in cell monolayers. However, this occurred only at the longest exposure time of 10 h and with the lowest concentration of oocysts (1.5 x 10(4)). The 10% phenol product and the 10% povidone-iodine product also decreased excystation, but were unable to halt infection. Although the ability of C. parvum to with-stand chemical treatment is well known, the ability of oocysts to remain viable and infectious after a 10 h treatment in glutaraldehyde is cause for concern. Endoscopic equipment that may come into contact with these organisms cannot be immersed into glutaraldehyde for this length of time due to its corrosive nature. Thus, the results of this research are cause for concern in hospital disinfection units.