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Inactivation of Cryptosporidium parvum oocyst infectivity by disinfection and sterilization processes
S L Barbee1, D J Weber, M D Sobsey
1Division of Infectious Diseases, UNC School of Medicine, Chapel Hill, NC 27599-7030, USA.
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.
Insights
High-level disinfectants show limited efficacy against Cryptosporidium parvum (C. parvum). However, current cleaning and disinfection protocols are adequate for preventing endoscope-associated transmission due to rapid C. parvum inactivation on dry surfaces.
Area of Science:
- Infectious Diseases
- Microbiology
- Environmental Health
Background:
- Cryptosporidium parvum causes gastroenteritis, severe in immunocompromised individuals.
- Transmission occurs via person-to-person contact and contaminated surfaces/medical devices.
- The role of environmental surfaces and endoscopes in C. parvum transmission necessitates disinfection studies.
Purpose of the Study:
- To investigate the susceptibility of C. parvum to common chemical disinfectants.
- To evaluate the efficacy of sterilization processes against C. parvum.
Main Methods:
- Seven disinfectants were tested at use dilution via suspension tests.
- Cell infectivity assays were employed to assess antimicrobial activity.
- Sterilization processes (steam, ethylene oxide, Sterrad 100) were evaluated.
Main Results:
- Steam, ethylene oxide, and Sterrad 100 inactivated >3 logs of C. parvum.
- Only 6% and 7.5% hydrogen peroxide effectively inactivated >3 logs of C. parvum.
- Lower concentrations/times of hydrogen peroxide, peracetic acid, sodium hypochlorite, phenolic, quaternary ammonium, 2% glutaraldehyde, and ortho-phthalaldehyde showed limited efficacy.
Conclusions:
- Most high-level disinfectants demonstrate limited efficacy against C. parvum.
- C. parvum infectivity diminishes rapidly on dry surfaces.
- Current cleaning and high-level disinfection guidelines are sufficient to prevent nosocomial transmission via endoscopes.