Microbiology Bacterial Growth Quiz
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Questions and Answers

In which bacterial growth phase are cells primarily dividing and dying at an equal rate?

  • Stationary phase (correct)
  • Lag phase
  • Decline phase
  • Log phase

    • Which bacterial structure is primarily involved in adherence to surfaces but does not provide motility?

  • Spirochete
  • Flagella
  • Pili (correct)
  • Endospores

    • Which of the following is NOT a characteristic of bacterial endospores?

  • Dehydrated cells with thick walls
  • Susceptible to heat (correct)
  • Dormant form
  • Highly durable

    • What is the primary purpose of flagella in bacteria?

    <p>Motility and locomotion (A)</p> Signup and view all the answers

    Which term describes bacteria that exhibit a variety of shapes?

    <p>Pleomorphic (C)</p> Signup and view all the answers

    Which of the following environmental factors is NOT a primary consideration when categorizing bacteria based on their growth preferences?

    <p>Carbon Source (D)</p> Signup and view all the answers

    What is the expected outcome of placing a bacterial cell into a hypertonic environment?

    <p>The cell will shrink due to water outflow. (D)</p> Signup and view all the answers

    A bacterium described as a 'facultative anaerobe' demonstrates which growth characteristic?

    <p>It grows with or without the presence of oxygen. (A)</p> Signup and view all the answers

    Which term describes a bacterium that thrives in a moderate temperature range, such as 30-35°C?

    <p>Mesophile (A)</p> Signup and view all the answers

    What is the primary method of replication for bacteria?

    <p>Binary fission (D)</p> Signup and view all the answers

    What is the MOST accurate description of the generation time of bacteria?

    <p>The time it takes for one bacterial cell to divide into two cells. (D)</p> Signup and view all the answers

    Regarding pH preferences, what is the typical range favored by medically important bacteria?

    <p>pH 6.0-8.0 (slightly acidic to slight basic) (D)</p> Signup and view all the answers

    Which of the following is NOT an essential chemical element for bacterial growth?

    <p>Sodium (C)</p> Signup and view all the answers

    Which of the following is classified as a 'cidal' agent?

    <p>An agent that kills microorganisms (A)</p> Signup and view all the answers

    In the context of infection control, what is the primary purpose of using an antiseptic?

    <p>To reduce the number of normal flora and kill pathogens on skin (B)</p> Signup and view all the answers

    Which of the following is a strategy to prevent the spread of norovirus?

    <p>Preventing transmission through proper hygiene and environmental controls (A)</p> Signup and view all the answers

    Which of the following is a crucial element in the chain of infection?

    <p>The presence of a susceptible host (B)</p> Signup and view all the answers

    What is the first action to take following a needle stick injury?

    <p>Back bleed the wound and wash the area (B)</p> Signup and view all the answers

    Which of the following is primarily targeted by 'universal/standard precautions' in a healthcare setting?

    <p>All patients and all lab specimens (A)</p> Signup and view all the answers

    What is the main purpose of using a 'static' agent in microbiology?

    <p>To prevent the multiplication of microorganisms (B)</p> Signup and view all the answers

    Which of the following represents a method to achieve sterility effectively?

    <p>Using heat through an autoclave (A)</p> Signup and view all the answers

    Which of the following illnesses, listed in the text, can be spread through airborne transmission?

    <p>Tuberculosis (C)</p> Signup and view all the answers

    What is a primary focus of public health measures with regards to disease outbreaks?

    <p>Researching the disease and implementing prevention measures to control outbreaks (D)</p> Signup and view all the answers

    Which of the following is NOT a method of sterilization or disinfection?

    <p>Non-germicidal detergent (A)</p> Signup and view all the answers

    What is the correct order for removing Personal Protective Equipment (PPE), following the provided sequence?

    <p>Gloves, goggles/face shield, gown, mask/respirator, cleanse hands (A)</p> Signup and view all the answers

    Which type of filter is primarily used to remove airborne particles and is often found in lab settings?

    <p>High-efficiency particulate air filter (HEPA) (B)</p> Signup and view all the answers

    When using a non-germicidal detergent (soap), what is its main function in hand hygiene?

    <p>To remove organic material and loose skin cells (D)</p> Signup and view all the answers

    If a patient room door has a sign indicating protective isolation procedures, this indicates that:

    <p>The patient has a highly contagious disease (C)</p> Signup and view all the answers

    Which of these is the most accurate description of the hand-washing process steps?

    <p>Wet hands, lather, rinse, dry, turn off faucet using paper towels (A)</p> Signup and view all the answers

    Which of the following methods uses electromagnetic waves to disinfect surfaces?

    <p>UV light (D)</p> Signup and view all the answers

    Which of the following is a type of PPE that is most important when dealing with highly infectious airborne pathogens?

    <p>N95 respirator (B)</p> Signup and view all the answers

    Which of the following is a common disease caused by Enterococcus faecium?

    <p>Endocarditis (B)</p> Signup and view all the answers

    What is the appearance of a beta-hemolytic bacteria on a blood agar plate?

    <p>Clear/colorless (C)</p> Signup and view all the answers

    Which of the following is a potential sequelae of Streptococcus pyogenes infection due to an autoimmune reaction?

    <p>Acute glomerulonephritis (C)</p> Signup and view all the answers

    Which of the following is the primary reservoir for Group A Streptococcus?

    <p>Humans (B)</p> Signup and view all the answers

    What is the typical morphology of Streptococcus pneumoniae?

    <p>Gram-positive cocci in pairs with a lancet shape (C)</p> Signup and view all the answers

    Which of the following is the leading cause of subacute bacterial endocarditis?

    <p>Viridans <em>Streptococcus</em> (D)</p> Signup and view all the answers

    Which antibiotic is typically the first choice for treating Streptococcus infections?

    <p>Penicillin (D)</p> Signup and view all the answers

    Why are Enterococcus infections often more difficult to treat with typical antibiotics?

    <p>They are intrinsically resistant to beta-lactams. (B)</p> Signup and view all the answers

    What is the primary function of coagulase in Staphylococcus aureus?

    <p>To form a fibrin clot, protecting the bacteria from phagocytosis. (C)</p> Signup and view all the answers

    Which of these correctly lists the Gram stain, morphology and catalase result for Staphylococcus species?

    <p>Gram-positive cocci, catalase positive (D)</p> Signup and view all the answers

    What is the appearance of Staphylococcus aureus colonies on media?

    <p>Creamy colonies that turn golden/yellow with age (C)</p> Signup and view all the answers

    Which of the following virulence factors of Staphylococcus aureus is responsible for causing vomiting and diarrhea?

    <p>Enterotoxins (D)</p> Signup and view all the answers

    Which of the following clinical conditions is NOT directly caused by Staphylococcus aureus?

    <p>Malaria (B)</p> Signup and view all the answers

    What distinguishes Staphylococcus aureus from other Staphylococcus species in terms of coagulase activity?

    <p><em>S. aureus</em> is coagulase positive, while other species are negative (A)</p> Signup and view all the answers

    What is the mechanism of action for the Staphylococcus aureus virulence factor hemolysin?

    <p>Destructive to various blood cells (D)</p> Signup and view all the answers

    Based on the information given, which of the following is most closely associated with toxic shock syndrome?

    <p>Tampon use by menstruating females (C)</p> Signup and view all the answers

    Study Notes

    Gram Stain List

    • Gram-Positive Cocci (GPC) are bacteria ending in "-coccus"
      • Examples: Streptococcus, Staphylococcus, Enterococcus
    • Gram-Negative Cocci (GNC)
      • Examples: Neisseria, Moraxella (only 2 species)
    • Gram-Positive Bacilli (GPR) are everything else
    • No gram-negative bacilli on Exam 1

    Characteristics of Bacteria

    • Prokaryotes
      • No true nucleus (bacteria)
      • Nucleoid: single chromosome of double-stranded DNA in a circular loop without a surrounding nuclear membrane.
      • No nuclear membrane
      • Rigid cell wall: protein and peptidoglycan
      • Asexual division
    • Eukaryotes
      • True nucleus - Animal cells, plant cells, fungi
      • Contains double-stranded DNA
      • Nuclear membrane is bound
      • Most do not have a cell wall
      • Sexual and asexual reproduction

    Characteristics of Bacteria (Taxonomy)

    • Domain: Bacteria
    • Phylum: Firmicutes (example: cocci and bacilli)
    • Class: Bacilli
    • Order: Bacillales
    • Family: Staphylococcaceae
    • Genus: Staphylococcus
    • Species: aureus
    • Strain: a genetic variant or subtype (example: Methicillin-resistant S. aureus)
    • Genus name is capitalized, species name not capitalized (example: Staphylococcus aureus) and written in italics or underlined
    • Species name comes second

    Characteristics of Bacteria (Gram Stain)

    • Gram stain is a grouping method used in clinical microbiology to differentiate medically important bacteria based on their wall structures.
    • Gram-positive bacteria have a thick peptidoglycan layer and stain purple.
    • Gram-negative bacteria have a thin peptidoglycan layer and stain pink/red.
    • This difference is due to varying wall structure composed of differents layers in each bacteria type.

    Characteristics of Bacteria (Reagents)

    • Crystal Violet (CV): Attracted to negatively charged bacterial cells, penetrates the cell wall and stains both GP and GN cells.
    • Iodine: Mordant interacts with CV to fix the dye to the cells.
    • Alcohol: Decolorizes thin peptidoglycan layer in Gram-negative cells. Gram-positive cells retain the purple stain ( thick layer).
    • Safranin: Counter stain. Gives color to Gram-negative cells that appear colorless after alcohol decolorization

    Characteristics of Bacteria (Factors Affecting Microbial Growth)

    • Temperature:
      • Psychrophiles: cold-loving (4-15°C)
      • Mesophiles: moderate temperature-loving (30-35°C)
      • Thermophiles: heat-loving (50-60°C+)
    • Osmotic Pressure:
      • Isotonic: Similar internal and external solute concentration.
      • Hypotonic: lower solute concentration outside the cell; cells swell and may rupture.
      • Hypertonic: higher solute concentration outside the cell; cells shrink
    • Chemical Requirements: Carbon, water, nitrogen, sulfur, phosphorus, trace elements (iron, copper, zinc). Hydrogen ion concentration (pH): medically important bacteria prefer pH 6.0-8.0 (body pH ~7).
    • Atmosphere:
      • Obligate aerobes: require oxygen (facultative aerobes can survive with or without it)
      • Obligate anaerobes: do not use oxygen; prefer oxygen-free environments)
      • Facultative anaerobes: can grow with or without oxygen.
      • Capnophiles: require increased CO2.

    Characteristics of Bacteria (Growth Patterns)

    • Replication is by binary fission (cell division).
    • Generation time/doubling time is the time required for one cell to divide into two cells.
    • Growth patterns can be depicted in a cell growth curve with phases such as Lag, Log, Stationary, and Death.

    Characteristics of Bacteria (Defining Terms)

    • Cocci: Spherical bacteria (example: diplococci, streptococci)
    • Bacilli: Rod-shaped bacteria
    • Pleomorphic: vary in shape
    • Spirochete: Helical bacteria
    • Flagella: exterior protein filaments for motility and movement.
    • Pili: hair-like appendages for adherence.

    Characteristics of Bacteria (Other Terms)

    • Endospores: highly durable dehydrated cells, resistant to heat, drying, chemicals, not all gram-positive bacteria forms them (example: C. botulinum).
    • Lipopolysaccharide (LPS): outer membrane component in Gram-negative bacteria; may function as virulence factors (fever, shock, attachment).
    • Capsules: Organized polysaccharide layers that shield bacteria from immune and phagocytic responses. This is also a virulence factor.

    Characteristics of Bacteria (Host-Parasite Interactions)

    • Host: organism being infected by a pathogen
    • Parasite: any invader or agent causing disease
    • Pathogen: microorganism capable of causing disease
    • Primary pathogen: regularly causes infection and disease in a healthy host
    • Opportunistic pathogen: usually does not cause disease in a healthy host but may cause disease in an immunocompromised host
    • Host barriers:
      • Microbiome (normal flora)
      • Anatomic barriers (skin)
      • Stomach acid
      • White blood cells (neutrophils)
      • Antibodies
    • Organism factors leading to disease:
      • Evasion of the immune response (capsule)
      • Ability to attach to host cells (pili)
      • Exotoxins or enterotoxins

    Characteristics of Bacteria (Hospital Epidemiology)

    • HAI (healthcare associated infection): infection acquired during a hospital stay/treatment
    • Colonization: presence of organisms on a body surface without disease
    • Infection: when organisms invade tissues causing clinical signs and symptoms
    • Nosocomial infection: infection acquired by a patient after admission to the hospital
    • Steps in Outbreak Investigation:
    1. Identify etiologic agent, reservoir, and mode of transmission
    2. Eliminate the reservoir
    3. Prevent transmission
    4. Prevent future outbreaks
    • Chain of infection: source, mode of transmission, susceptible host

    Characteristics of Bacteria (Sterilization & Disinfection)

    • Approaches to control microorganism growth:
    • Body's own defense mechanisms
    • Chemotherapeutic agents
    • Public health measures
    • Sterilization & Disinfection
    • Antiseptic: inhibits microorganism growth (isopropyl alcohol, hydrogen peroxide)
    • Aseptic: used to sterilize (kill) (povidone iodine) - example: surgery, phlebotomy
    • Cide/Cidal: to kill
    • Stasis/Static: to prevent multiplication without necessarily killing
    • Disinfectant: kills equipment and surfaces (e.g., 10% bleach solution)

    Characteristics of Bacteria (Staphylococcus)

    • Gram-positive cocci in grape-like clusters .- Found in skin, mucous membranes, and feces.
    • Catalase-positive (enzyme breaks down 3% H₂O₂).
    • Staphylococcus aureus is coagulase-positive. -Other Staph species are coagulase-negative.
    • S. aureus is commonly found in noses, armpits, skin, and groins; and survives in the environment
    • Common virulence factors: . Coagulase . Protein A (prevents phagocytosis) . Enterotoxins . Lipase . Hyaluronidase . Hemolysins (damage red blood cells)
    • Notable disease associations: . Skin infections . Food poisoning (e.g., staphylococcal food poisoning; scalded skin syndrome) . Toxic shock syndrome

    Characteristics of Bacteria (Methicillin-Resistant Staphylococcus aureus - MRSA)

    • MRSA emerges when S. aureus develops resistance to methicillin.
    • Related to the acquisition of the mecA or mecC gene
    • Antibiotic treatment: vancomycin or alternatives like daptomycin, tigecycline, or others like linezolid.
    • #1 cause of community acquired skin and soft tissue infections
    • Can cause pneumonia, bacteremia, endocarditis, joint, and surgical site infections

    Characteristics of Bacteria (Coagulase-negative Staphylococcus species)

    • Staphylococcus epidermidis: Colonizes the skin of most people, low virulence. Liking to form biofilms . Can cause infections of prosthetic devices, surgical wounds, etc, with its preferred method of attachment to devices, prosthetic heart valves.
    • Staphylococcus saprophyticus: Has affinity for binding to the epithelial cells of the urethra or bladder.
    • Can cause urinary tract infections (UTIs), especially in sexually active young women.

    Characteristics of Bacteria (Streptococcus)

    • Gram-positive cocci in chains
    • Normal flora of the upper respiratory and intestinal tracts
    • Catalase-negative
    • Compare to Staphylococcus (positive)

    Characteristics of Bacteria (Enterococcus)

    • Gram-positive cocci
    • Commonly found in normal intestinal flora
    • Relatively low virulence
    • Can cause UTIs, endocarditis, wound infections

    Characteristics of Bacteria (Classification by Hemolysis)

    • Alpha (α): partially lysed RBCs
    • Beta (β): completely lysed RBCs
    • Gamma (γ): no hemolysis

    Characteristics of Bacteria (Streptococcal Diseases)

    • S. pyogenes (Group A): Pharyngitis, scarlet fever, rheumatic fever, acute glomerulonephritis, impetigo, cellulitis.
    • S. agalactiae (Group B): Neonatal infections (meningitis, septicemia, pneumonia).
    • S. pneumoniae: Pneumonia, otitis media, meningitis
    • Viridans Strep: normal flora(subacute bacterial endocarditis
    • Group D. Strep: Normal flora
    • There are vaccines available for some of these diseases

    Characteristics of Bacteria (Antibiotic Treatment of Strep and Enterococcus)

    • Streptococcus: Penicillin is often the drug of choice. In cases of penicillin-resistant S. pneumoniae, vancomycin or 3rd gen cephalosporins may be used.
    • Enterococcus: Intrinsically resistant to penicillins or cephalosporins, so a combination of a penicillin and an aminoglycoside is often required. In cases of resistance to drug combo (eg, vancomycin-resistant enterococcus), alternatives include synercid, linezolid, or daptomycin

    Characteristics of Bacteria (Gram-Positive Bacilli)

    • Spore-forming:
      • Bacillus spp.: low virulence, in soil, water, dust, animal products. Common lab contaminants. Spores survive in soil for years; can stain gram variable
      • Clostridium spp.: Anaerobic, in soil, water, vegetation, and the large bowel of humans and other animals. Large box like rods; can stain gram variable.

    Characteristics of Bacteria (Non-Spore Forming GPRs)

    • Corynebacterium spp.: Found in environment & human flora; normal flora(mouth, skin, respiratory/genitourinary tracts)
    • Nocardia spp.: Found in soil and water; NOT part of normal human flora; partially acid-fast.

    Characteristics of Bacteria (Gram-Positive Bacilli - Common Diseases)

    • Listeria monocytogenes: stillbirths, meningitis, neonates, pregnant women. Foodborne illness/infection.
    • Corynebacterium diphtheriae: severe pharyngitis often with a thick, leathery gray membrane. Affects myocardium and peripheral nervous systems (neurotoxin).
    • Corynebacterium jeikeium: opportunistic infection of prosthetic heart valves, septicemia and skin
    • Gardnerella vaginalis: bacterial vaginosis is characterized by the foul smelling discharge

    Characteristics of Bacteria (Gram-Positive Bacilli-Common Diseases-Spore forming)

    • Bacillus anthracis: Anthrax
    • Bacillus cereus: Food poisoning
    • perfringens: Food poisoning, gas gangrene
    • difficile: Pseudomembranous colitis
    • botulinum: Food poisoning from improperly canned food

    Characteristics of Bacteria (Neisseria)

    • Many species part of the normal flora of respiratory and urogenital tracts.
    • N. gonorrhoeae: Obligate human pathogen, causes gonorrhea (PID, etc,), sexually transmitted infection..
    • N. meningitidis: Causes meningitis (inflammation of the meninges, the membranes surrounding the brain and spinal cord -life threatening condition)..

    Characteristics of Bacteria (Moraxella catarrhalis)

    • Gram-negative diplococci. Normal flora of upper respiratory tract
    • NOT fastidious(no special growth requirements/medium).
    • Causes otitis media and sinusitis in children and pneumonia and bronchitis in immunocompromised adults,
    • Common respiratory infection; susceptible to many antibiotics; known resistance to penicillin for most isolates; decongestants important to reduce inflammation.

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    Test your knowledge on bacterial growth phases, structures, and characteristics with this quiz. Explore questions about endospores, flagella functions, and environmental influences on bacteria. Whether you're studying for an exam or just want to learn more about microbiology, this quiz is for you!

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