HSPA Microbiology for Sterile Processing 2 — Questions and Answers
Question 1: Why is Geobacillus stearothermophilus used as the BI organism for steam sterilization?
- Most common hospital pathogen
- Its spores are highly resistant to moist heat, making it a reliable challenge organism (Correct answer)
- It grows fastest in culture
- It is visible to the naked eye
Correct answer: Its spores are highly resistant to moist heat, making it a reliable challenge organism
G. stearothermophilus spores are exceptionally resistant to steam, requiring conditions beyond normal sterilization for kill.
Its D-value at 121°C is approximately 1-2 minutes, making it significantly more resistant than any pathogen. If the cycle kills these spores, all pathogens have been eliminated.
Question 2: What is a biofilm and why is it significant in sterile processing?
- Thin film of plastic for packaging
- Complex microbial community in a protective matrix that is extremely resistant to cleaning and sterilization (Correct answer)
- A type of biological indicator
- A filter in water treatment
Correct answer: Complex microbial community in a protective matrix that is extremely resistant to cleaning and sterilization
Biofilms are microbial communities encased in a protective matrix making them extremely difficult to remove.
Organisms in biofilm are 100-1,000 times more resistant to antimicrobials. Biofilms form rapidly when bioburden dries. Prevention through prompt pre-treatment is the best strategy.
Question 3: What is the significance of bacterial endospores in sterilization?
- Easily killed by hand washing
- The most resistant form of microbial life and the benchmark for sterilization efficacy (Correct answer)
- Only found in viruses
- Make bacteria easier to identify
Correct answer: The most resistant form of microbial life and the benchmark for sterilization efficacy
Endospores are the most resistant microbial form, capable of surviving extreme conditions.
Endospores survive boiling, desiccation, radiation, and most chemicals. This is why sterilization, not just disinfection, is required for critical devices. BIs use spore populations to test cycles.
Question 4: What is the chain of infection and how does SPD break it?
- Process of instrument contamination only
- Sequence of six elements required for infection; SPD breaks it by eliminating transmission through sterile instruments (Correct answer)
- How bacteria reproduce
- Order of cleaning steps
Correct answer: Sequence of six elements required for infection; SPD breaks it by eliminating transmission through sterile instruments
SPD breaks the chain by eliminating contaminated instruments as a mode of transmission through proper cleaning and sterilization.
The six links are: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host. SPD eliminates the transmission link through thorough decontamination and sterilization.
Question 5: What is the difference between transient and resident microflora on hands?
- No difference
- Transient flora are recently acquired and easily removed; resident flora are permanent skin inhabitants (Correct answer)
- Transient flora are more dangerous
- Only resident flora matter in SPD
Correct answer: Transient flora are recently acquired and easily removed; resident flora are permanent skin inhabitants
Transient flora are temporary organisms easily removed by hand washing; resident flora are permanent. Both can contaminate sterile items.
Transient flora include potential pathogens acquired from contaminated surfaces. Hand hygiene is critical before handling sterile items, after handling soiled items, and after removing gloves.
Question 6: What are prions and why are they a unique challenge?
- A type of bacteria
- Misfolded proteins that are extremely resistant to standard sterilization methods (Correct answer)
- Large viruses easily killed by autoclaving
- Only affect animals
Correct answer: Misfolded proteins that are extremely resistant to standard sterilization methods
Prions are infectious misfolded proteins extraordinarily resistant to conventional sterilization and disinfection.
Prions survive standard steam, ETO, H2O2 plasma, and most disinfectants. WHO-recommended decontamination involves NaOH immersion plus steam sterilization at specific parameters.
HSPA Microbiology for Sterile Processing 2
Why is Geobacillus stearothermophilus used as the BI organism for steam sterilization?