Microbiology and Infection Control Flashcards

Which category of microorganism is most resistant to chemical disinfectants and requires sterilization for complete elimination?

Answer: Bacterial endospores (e.g., Bacillus, Clostridium species)

Bacterial endospores are the most resistant form of microbial life to chemical disinfection. They require sterilization processes (moist heat, EO, or other validated methods) for complete elimination.

What is Clostridioides difficile (C. diff), and what specific reprocessing consideration does it require?

Answer: C. difficile is a spore-forming bacterium that causes healthcare-associated diarrhea; its spores are resistant to alcohol-based hand rub and standard quaternary ammonium disinfectants — requiring sporicidal agents and soap-and-water hand hygiene

C. difficile forms resistant spores that are NOT killed by alcohol-based hand rub or many standard disinfectants. Soap and water hand hygiene and sporicidal disinfectants (e.g., bleach/sodium hypochlorite) are required for environmental decontamination.

What is the Gram stain, and what is its significance in microbiology as it relates to bacterial classification and disinfectant susceptibility?

Answer: The Gram stain is a differential staining technique that classifies bacteria as Gram-positive (thick peptidoglycan wall, stain purple) or Gram-negative (thin wall + outer membrane, stain pink) — a classification that correlates with some differences in disinfectant susceptibility

The Gram stain differentiates bacteria into Gram-positive (purple — thick peptidoglycan) and Gram-negative (pink — thin peptidoglycan + outer membrane) categories, which correlates with some differences in antibiotic susceptibility but has less direct impact on sterilization method selection.

What is Mycobacterium tuberculosis' significance in the disinfection hierarchy, and what level of reprocessing do instruments contaminated with TB require?

Answer: M. tuberculosis is naturally resistant to many disinfectants due to its waxy mycolic acid-rich cell wall — it serves as the benchmark organism for intermediate-level disinfection

M. tuberculosis has a waxy, lipid-rich (mycolic acid) cell wall that confers natural resistance to many disinfectants. It is the benchmark organism for defining intermediate-level disinfectants, which must demonstrate tuberculocidal activity to be classified as intermediate-level.

In healthcare settings, what is meant by the term 'healthcare-associated infection' (HAI), and how can CSSD practices contribute to HAI prevention?

Answer: An HAI is an infection that occurs in a patient during the process of healthcare, not present or incubating at admission; CSSD contributes to prevention by ensuring only properly cleaned and sterile instruments reach patients

HAIs are infections acquired during healthcare that were not present at admission. CSSD is a primary defence against device-related HAIs by ensuring all reusable instruments are properly decontaminated and sterile before patient use.

Which of the following is the correct classification of hepatitis C virus (HCV) in terms of disinfectant resistance, and what does this mean for reprocessing?

Answer: HCV is an enveloped virus and is relatively susceptible to disinfectants; however, instruments used in invasive procedures must still be sterilized due to their critical device classification

HCV is an enveloped virus — relatively susceptible to disinfectants and inactivated by standard sterilization and HLD. However, surgical instruments that contact blood are critical devices requiring sterilization regardless of which pathogen may be present.