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MICROBIOLOGY: CMOD-Week 1 > (02) Bacterial Growth and Development > Flashcards

(02) Bacterial Growth and Development Flashcards

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1
Q

How does the growth rate of bacteria complicate identification of pathogens?
- what methods are used to circumvent this problem?

A
  • Fast growing bacteria mask slower growing pathogens like fungus
  • Different media is used to inhibit the growth of bacteria to isolate a single type
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2
Q

What 4 factors does the growth rate of an organism depend on?

A
  1. Nutrient Availability
  2. pH
  3. Salinity
  4. Temperature
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3
Q

Differentiate phototrophs and auxotrophs.

A

Phototrophs
- can make all of their own essential metabolites

Auxotrophs
- must acquire essential metabolites from the environment

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4
Q

What is the effect of acidic pH on most bacteria?

  • notable exception?
  • disease?
A
  • Toxic to most bacteria

Helicobacter pylori
- Stomach Ulcers by secreting urease to convert urea into ammonia and bicarbonate

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5
Q

What is the effect of salt on bacterial growth?

A
  • High Salt environments typically prevent bacterial growth
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6
Q

What is the optimal growth temperature of most human pathogens?
- name for these?

A
  • 30ºC - 37ºC

- Mesophiles

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7
Q

Iron is important to growth and virulence. How do pathogens ensure they have sufficient iron?

A
  1. Secrete Siderophores that bind Fe

2. Siderophore-Fe is ACTIVELY transported back into the bacteria

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8
Q

Average time needed for pathogenic replication?

  • Mycobacterium Tuberculosis?
  • E. Coli?
A
  • 30-60 minutes for most bacteria to replicate
  • Mycobacterium Tuberculosis = 20 hours
  • E. Coli = 20 minutes
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9
Q

What are the 4 phases of bacterial growth?

- explain each of these phases

A
  1. Lag Phase
    - must adapt to new nutrient environment
  2. Exponential Phase
    - Constant optimal doubling times are established
    - Maximal DNA and Protein Synthesis
  3. Stationary Phase
    - Nutrients depleted during exp. phase = waste accumulates
    - cell death = cell growth
  4. Decline
    - more waste, less nutrients
    - Cell death > Cell Growth
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10
Q

What does it mean to measure the turbidity of a liquid culture?

A
  • Measure bacterial concentration using a spectrophotometer
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11
Q

When during which phase is sporulation initiated?

- cell type that does this?

A
  • Stationary Phase

- Gram (+) bacteria initiates sporulation during this time

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12
Q

When is the best time to administer antibiotics?

A
  • Exponential Phase
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13
Q

Planktonic Bacteria vs. Biofilm

- en vitro vs. en vivo prevalence

A

Planktonic Bacteria

  • common in laboratory
  • Free-living Bacteria (en vitro)

Biofilm

  • encased bacteria
  • 80% of infections (en vivo)
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14
Q

Biofilm

  • what forms encasement?
  • clinical importance?
A
  • Carbohydrate matrix encasement

Clinical Importance:

  • Source of recurrent infections and treatment failures
  • IMPAIRS ANTIBIOTIC ACCESS
  • ANTI-PHAGOCYTIC
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15
Q

Common places to find biofilms?

A
  • Heart Valve Implants
  • Implanted Prostheses
  • Dental Plaque
  • In-dwelling catheters
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16
Q

Relationship of Cystic Fibrosis to biofilms?

A
  • Pseudomonas Aeruginosa forms ALGINATE biofilm
17
Q

ATPs produced by oxidative respiration.

  • what general cell types can do this?
  • final electron acceptor
A
  • 34 ATPs produced
  • Cell Types = aerobes and facultative anaerobes
  • O2 = final electron acceptor
18
Q

Compare growth rates of anaerobic respiration to aerobic respiration.
- electron acceptors

A

anaerobic

  • slow, inefficient
  • electrons transferred directly to organic acceptors

Aerobic

  • fast, efficient
  • electrons transferred to oxygen (inorganic)
19
Q

What toxic products are produced as a result of aerobic respiration?
- what counteracts their effects?

A
  • Superoxide anions and Hydrogen Peroxide

Superoxide:
Superoxide dismutase turns it into H2O2

H2O2:
Detoxified by 1) Catalase or 2) Peroxidase

20
Q

What detoxification enzyme may be lacking from facultative anaerobes?

A

Catalase

21
Q

T or F: pathogenic anaerobes can survive brief exposure to oxygen

A

True

22
Q

Folic acid, compare how humans get it vs. bacteria.

A

Humans:
- must get it from enviroment

Bacteria:
- Synthesize their own (major target)

23
Q

Why would it be difficult to isolate Rickettsia or Chlamydia?

A
  • They are OBLIGATE INTRACELLULAR PATHOGENS
  • they depend on a host to grow and would need a lab growing animal cells in culture to grow it (NOT PRACTICAL, not pt. of diagnosis)
24
Q

In the context of commensal organisms that are part of the normal human flora, differentiate resident and transient organisms.

A

Resident - present all the time

Transient - contracted by the environment but removed after a finite time

25
Q

Describe how normal flora of the skin, gut, and vagina prevent growth of pathogenic organisms.

A

Skin:
- Produces Fatty acids to prevent growth of new bacteria

Gut:
- Extremely dense giving little room for growth while producing lots of waste and toxins.

Vagina:
- Flora produces acid to deter growth of new bacteria

26
Q

What tissues of the body are typically sterile?

A
  • Internal Tissues and blood
27
Q

What is blood in bacteria referred to as?

A

Bacteremia

28
Q

Pathogenesis

A

Mechanism of Disease Development

29
Q

Virulence

A

a term expressing degrees of Pathogenicity

30
Q

Colonization

A

the presence and multiplication of microorganisms without tissue invasion or damage

31
Q

Infection

A

colonization that generally leads to disease

32
Q

Epidemic

A

disease that rapidly affects many people in a fixed period of time

33
Q

Virulence factor

A

Any number of products produced and often secreted by pathogens that allow the pathogen to invade and cause disease in a host and evade host defenses.

34
Q

Name 5 examples of virulence factors

A
  1. Adhesion Factors
  2. Capsules
  3. Endotoxins
  4. Exotoxins
  5. Siderophores

MICROBIOLOGY: CMOD-Week 1 (10 decks)

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