Inactivation of Cryptosporidium parvum oocyst infectivity by disinfection and sterilization processes.
BACKGROUND
Cryptosporidium parvum is a common cause of self-limited gastroenteritis in the normal host but may cause severe disease in immunocompromised persons. Person-to-person transmission has been well documented in households, child care centers, and hospitals. Because contaminated environmental surfaces and medical devices such as endoscopes may play a role in disease transmission, we studied the susceptibility of C parvum to chemical agents commonly used for disinfection and evaluated the efficacy of sterilization processes.


METHODS
Seven disinfectants were studied at their use dilution using a suspension test. Antimicrobial activity was assessed with the use of a cell infectivity assay.


RESULTS
All sterilization processes tested (steam, ethylene oxide, Sterrad 100) inactivated 3 logs or greater of C parvum. The only liquid disinfectant/sterilant able to inactivate greater than 3 logs of C parvum was 6% and 7.5% hydrogen peroxide. Agents that did not completely inactivate C parvum included hydrogen peroxide at lower concentrations or exposure times, peracetic acid, sodium hypochlorite, a phenolic, a quaternary ammonium compound, 2% glutaraldehyde, and ortho-phthalaldehyde.


CONCLUSIONS
Most high-level disinfectants used on endoscopes have limited efficacy against C parvum. However, the infectivity of C parvum on dry surfaces decreases rapidly. Therefore, current cleaning and high-level disinfection guidelines are adequate to prevent nosocomial transmission of C parvum by means of endoscopes.
Barbee
S L
SL
Division of Infectious Diseases, UNC School of Medicine, Chapel Hill, NC 27599-7030, USA.
Weber
D J
DJ
Sobsey
M D
MD
Rutala
W A
WA
D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002478:Cells, Cultured; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity*; D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000379:methods* / Q000706:statistics & numerical data; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000469:parasitology; D007668:Kidney / Q000166:cytology / Q000469:parasitology; D016014:Linear Models; D013227:Steam; D013242:Sterilization / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D013997:Time Factors
D004202:Disinfectants; D013227:Steam