Microbiology Practice Questions

Explanation: Viruses are parasitic and need a host to multiply. Bacteria are independent single-celled organisms.

Explanation: The slimy matrix of a biofilm protects the bacteria from heat and chemicals. Mechanical friction (scrubbing) is required to break up the matrix so detergents can work.

Explanation: Aerobic = needs oxygen. Anaerobic = can live without oxygen.

Explanation: Staph is common flora on human skin, making hand hygiene critical to prevent transfer to sterile items.

Explanation: CJD is a fatal neurodegenerative disease caused by Prions (misfolded proteins). Instruments from CJD cases require special processing protocols.

Explanation: To infect a new host, the pathogen must exit the reservoir (source). Blocking the portal of exit (e.g., bandaging a wound) stops the chain.

Explanation: Surgical instruments are fomites. If not cleaned, they transmit infection from patient to patient.

Explanation: Standard Precautions (Universal Precautions) dictate treating EVERY item from the OR as if it is infectious, requiring full PPE.

Explanation: Bioburden is the quantity of microbial life on an object before sterilization. Cleaning reduces bioburden to safe levels.

Explanation: Spirochetes are spiral shaped. Treponema pallidum is the classic example.

Explanation: Bacteria reproduce asexually by dividing in half, a process called binary fission.

Explanation: VRE is a Multi-Drug Resistant Organism (MDRO) that is resistant to the antibiotic Vancomycin.

Explanation: Gram staining colors the cell wall purple (positive) or pink (negative) based on the thickness of the peptidoglycan layer.

Explanation: C. diff produces spores that are not killed by alcohol. Mechanical removal via soap and water hand washing is required.

Explanation: Capsules make bacteria 'slippery' to immune cells and protect them from desiccation (drying).

Explanation: Pseudomonas thrives in water and is a common cause of infections related to wet medical devices or ophthalmic instruments.

Explanation: Opportunistic pathogens take advantage of a weakened host. They may be normal flora in one area (gut) but pathogenic in another (blood).

Explanation: Vectors are living carriers. Fomites are inanimate carriers.

Explanation: Most human pathogens are mesophiles (moderate temp) and require moisture and darkness to thrive.

Explanation: The rigid cell wall maintains the bacteria's characteristic shape (cocci, bacilli, etc.).

Explanation: Hepatitis B (and C and HIV) is transmitted via blood. Needlesticks or splashes in decon pose a significant risk.

Explanation: Fungi are a separate kingdom including single-celled yeasts (Candida) and multi-celled molds.

Explanation: Bacteria are measured in microns (1/25,000 of an inch).

Explanation: Geobacillus stearothermophilus is the challenge organism for Ozone, H2O2 Plasma, and Steam.

Explanation: Gram-negative bacteria have thin walls that lose the purple dye and take up the pink counterstain (Safranin).

Explanation: Protozoa are complex single-celled organisms, often found in water (e.g., Giardia).

Explanation: Bacteria need food, acidity balance (pH), time, temp, oxygen, and moisture (FATTOM). Noise does not affect them.