Microbiology and Infection Control Flashcards

Which of the following microorganisms is used as the biological indicator (BI) for validating ETO (ethylene oxide) sterilization?

Answer: Bacillus atrophaeus (subtilis)

Bacillus atrophaeus (formerly B. subtilis) spores are the standard biological indicator for ETO sterilization validation due to their high resistance to this agent.

What is the primary purpose of using enzymatic detergents in the manual cleaning of endoscopes?

Answer: To break down proteins, fats, and carbohydrates in organic soil

Enzymatic detergents contain enzymes (proteases, lipases, amylases) that chemically break down organic soil — proteins, fats, and carbohydrates — facilitating their physical removal.

In chain-of-infection terminology, 'mode of transmission' for an endoscopy-associated infection most commonly refers to:

Answer: Direct contact via the contaminated endoscope (contact transmission)

Endoscopy-associated infections are primarily transmitted via direct contact when a contaminated scope comes into contact with mucosal surfaces of a new patient.

Which organism has caused the most widely publicized endoscopy-related outbreaks in recent years, largely due to the difficulty of cleaning duodenoscopes?

Answer: Carbapenem-resistant Enterobacteriaceae (CRE)

CRE, particularly carbapenem-resistant Klebsiella pneumoniae, has caused major outbreak clusters linked to duodenoscopes because their elevator mechanism is difficult to adequately clean.

The Spaulding classification system categorizes medical devices based on:

Answer: The risk of infection based on the intended use and body site

The Spaulding classification (critical, semi-critical, non-critical) categorizes devices by the level of infection risk associated with how and where they contact the patient.

Which personal protective equipment (PPE) is considered MINIMUM required when handling a high-level disinfectant such as glutaraldehyde?

Answer: Gloves, gown, eye protection, and face shield

Handling glutaraldehyde requires gloves, liquid-resistant gown, and eye/face protection (goggles and face shield) due to its irritant and sensitizing properties on skin, eyes, and airways.

What does 'MIC' (Minimum Inhibitory Concentration) measure in microbiology?

Answer: The lowest concentration of antimicrobial that prevents visible bacterial growth

MIC is the lowest concentration of an antimicrobial agent (antibiotic or disinfectant) that inhibits visible growth of a microorganism after overnight incubation.