Table 2.

Risk assessment for transmission of methicillin-resistant Staphylococcus aureus (MRSA) (A) and hepatitis B (B) by instruments autoclaved inside the Steriset Container on a gravity cycle

(A) MRSA
Factors contributing to exposure risk	Calculated risk	Supporting reference or data
MRSA prevalence in hospital inpatient population (15%)	15:100	Infection Control Department data from the involved hospital
Risk of transmission via contaminated instruments	1:1	Assume highest risk
Likelihood that contaminated instrument was used	1:1	Assume highest risk
Efficacy of washer/disinfector	1:100,000	Table 1. Consistent removal of 99.999% or more of inoculated MRSA
Effect of MRSA desiccation	1:10	[5] and authors’ unpublished data
Effect of autoclaving inside the Steriset Container on gravity cycle (270 F for 15 minutes, pressure 28–30 psig)	1:10,000,000	Table 1. Consistent killing of 108 colony-forming units (CFU) of MRSA in liquid suspension (limit of detection <1 log10CFU/mL)
Individual risk	~1 × 10-14 (1 in 100 trillion)
(B) Hepatitis B virus (HBV)*
Factors contributing to exposure risk	Calculated risk	Supporting reference or data
Prevalence of hepatitis B (HBsAg positive) in U.S. population (0.5%)	5:1,000	[1,5,6]
Risk of transmission via contaminated instruments	1:1	Assume highest risk
Likelihood that contaminated instrument was used	1:1	Assume highest risk
Efficacy of washer/disinfector (removes 99.999% of vegetative bacteria)**	1:100,000	[1] and Table 1
Effect of HBV desiccation	1:1	[1]
Effect of autoclaving inside the Steriset Container on gravity cycle (270 F for 15 minutes, pressure 28–30 psig)	1:10,000,000	Table 1**
Individual risk	~1 × 10-14 (1 in 100 trillion)

*The risk of transmission of hepatitis C or HIV would be lower than the risk of transmission of hepatitis B.

**Enveloped viruses have greater susceptibility to disinfectants and heat than vegetative bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci.