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[5] and authors’ unpublished data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)