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Microbiology Final Review Flashcards

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  • Goal of aseptic technique
    To prevent contamination of cultures, media, and the environment by unwanted microorganisms.
  • Define ubiquity in microbiology
    The concept that microorganisms are found everywhere in the environment.
  • Pure culture versus mixed culture
    Pure culture contains only one type of microorganism; mixed culture contains two or more different microorganisms.
  • Quadrant streak plate method
    A technique to isolate individual bacterial colonies by sequentially streaking four quadrants on an agar plate.
  • Purpose of heat fixation in smear preparation
    To kill the bacteria, adhere them to the slide, and preserve cellular structures for staining.
  • Gram stain cell wall differences
    Gram-positive bacteria have thick peptidoglycan layers; Gram-negative bacteria have thin peptidoglycan and an outer membrane.
  • Function of a bacterial capsule
    Protects bacteria from desiccation, phagocytosis, and helps in adherence to surfaces.
  • Characteristics of bacterial endospores
    Highly resistant, dormant structures formed to survive harsh conditions; contain dipicolinic acid.
  • Effect of pH on microbial growth
    Microbes have optimal pH ranges; deviations can inhibit metabolism and growth.
  • Terminology for temperature classifications of microbes
    Psychrophiles: cold-loving; mesophiles: moderate temperature; thermophiles: heat-loving.
  • Anaerobic jar purpose
    Creates an oxygen-free environment to culture anaerobic bacteria.
  • Difference between disinfection and sterilization
    Disinfection reduces harmful microbes; sterilization completely removes or kills all microorganisms.
  • Ionizing vs non-ionizing radiation in microbial control
    Ionizing radiation penetrates and damages DNA; non-ionizing (UV) causes thymine dimers, affecting surface microbes.
  • Disk diffusion method
    A test to evaluate antimicrobial effectiveness by measuring inhibition zones around antibiotic disks on agar.
  • Difference between antimicrobials and antibiotics
    Antimicrobials include all agents that kill or inhibit microbes; antibiotics are antimicrobials produced by microorganisms.
  • Broad spectrum vs narrow spectrum antibiotics
    Broad spectrum target many types of bacteria; narrow spectrum target specific groups.
  • Herd immunity
    When a high percentage of a population is immune, reducing disease spread and protecting unvaccinated individuals.
  • R0 (basic reproductive number)
    The average number of secondary infections produced by one infected individual in a susceptible population.
  • Difference between incidence and prevalence
    Incidence is the number of new cases; prevalence is the total number of cases at a given time.
  • Selective vs differential media
    Selective media inhibit unwanted microbes; differential media distinguish microbes based on biochemical reactions.
  • Catalase test purpose
    Detects the enzyme catalase by breaking down hydrogen peroxide into water and oxygen.
  • MacConkey agar use
    Selective for Gram-negative bacteria and differential for lactose fermentation.
  • Purpose of ELISA in serology
    Detects and quantifies antigens or antibodies using enzyme-linked antibodies.
  • General steps for unknown microbe identification
    Observe morphology, perform staining, biochemical tests, and compare results to identification charts.
  • How to label microbial cultures
    Labels go on the base of the plate or tube, including organism name, date, and initials.
  • Signs of contamination in cultures
    Unexpected colony morphology, mixed growth, or growth in negative controls.
  • Purpose of oil immersion lens
    Increases resolution by reducing light refraction between the slide and lens.
  • Mycolic acids in acid-fast bacteria
    Waxy, long-chain fatty acids that make the cell wall resistant to decolorization.
  • Kirby-Bauer method
    Standardized disk diffusion test to determine bacterial susceptibility to antibiotics.