Bacteriology Part 1 Flashcards

1
Q

Advantages of bacteria replication

A
  • Allows selection and adaptation to environmental changes

- Difficult for host to control bacterial growth rely upon vaccines and antibiotics

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2
Q

Most species of bacteria utilize ______ for growth

A

Carbohydrates (glucose)

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3
Q

Some bacteria use _______ or _________ for growth so they don’t have to compete with other bacteria for glucose

A
Amino acids (clostridia)
Fatty acids (leptospira)
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4
Q

Most bacteria range in size from ___ to ___ µm

Filter sterilization is ≤ ___ µm

A
  1. 4 - 2.0µm

0. 45µm

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5
Q

Cell wall defines shape; What is the nomenclature for different bacteria with spherical structure?

A
Single cells
Pairs - Diplococci
Chains - Streptococci
Tetrads - Micrococci
Grapelike structures - Stapylcocci
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6
Q

What nomenclature is used to describe rod and spiral bacterial structure

A

Rods = bacilli; coccobacilli = long rods

Spirals (comma shaped) = Vibrio; 4-20 coils = Spirochetes

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7
Q

What does penicillin do?

A

Inhibits cell wall synthesis

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8
Q

What does gram-negative bacteria have that gram-positive bacteria does not have (5)

A

1) Thin peptidoglycan layer
2) Outer membrane
3) Pili
4) Porin proteins
5) Periplasmic space

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9
Q

What are the four steps for classification of bacteria (positive vs. negative gram stain)

A

Step 1: Crystal violet
Step 2: Gram’s iodine
Step 3: Decolorizer (alcohol or acetone) - extracts crystal violet from gram negative only
Step 4: Safranin Red - stains gram negative

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10
Q

Cell Envelope

A
  • Cellular material located external to the cell membrane (unique to bacteria and target of many antibiotics)
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11
Q

Difference between Peptidoglycan for Gram positive and Gram negative bacteria

A

Gram Positive: Thick peptidoglycan - permeable barrier

Gram Negative: Thin peptidoglycan - Crosslinked to the outer membrane (Outer membrane = permeable barrier)

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12
Q

Basic subunit of the peptidoglycan includes:

A

Disaccharide linked to a D/L pentapeptide

  • NH2 group for cross linking
  • D-Alanine to D-Alanine bond which is broken and used for cross linking
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13
Q

Cross-linking differences between gram negative and gram positive bacteria

A

Gram Negative: Little crosslinking

Gram positive: Highly crosslinking between polysaccharides - rigid structure

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14
Q

Teichoic Acid (Gram positive - Cell envelope)

A
Polysaccharide that is crosslinked to cytoplasmic membrane and peptidoglycan (membrane stability)
TLR signaling (Innate immunity)
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15
Q

Gram Negative (Cell Envelope)

  • Outer Membrane
  • Periplasmic Space
  • Inner membrane
A

Outer membrane: Permeability barrier
- Lipopolysaccharide
- Porins (Molecular sieve 600 Dalton cutoff)
Periplasmic Space: Peptidoglycan - thin; not an effective barrier
Inner Membrane: Proteins embedded in phospholipid membrane

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16
Q

Function of outer membrane

A

Cell growth stimulates innate immunity

17
Q

Important things to know about lipopolysaccharide (LPS)

A

Unique to Gram-negative bacteria

  • O-antigen is variable
  • Lipid A - fever inducing - also known as endotoxin
  • PAMP recognized by TLRs
18
Q

Which cells of innate immunity recognize PAMPs

A

Macrophages and Neutrophils

19
Q

PAMP for gram negative bacteria vs Gram positive bacteria

A

Gram neg. - LPS

Gram pos. - Lipoteichoic Acid

20
Q

Pili and Fimbriae

A

Pili and Fimbriae: polymers of proteins
Function: Adherence to eukaryotic cells and between bacteria
Fimbriae are components of some vaccines

21
Q

Flagella (And there appearance in Pseudomonads and Enteric bacteria)

A

Flagella: polymers of proteins
Function: Motility (non-motile bacteria are often nonvirulent)
Pseudomonads - have a single polar flagellum
Enteric bacteria - have flagella distributed over the entire cell surface

22
Q

What is the basis of the evolution of virulence factors

A

Evolved by gene duplication of flagellum

Flagellum retains motility function, while the duplicated genes evolve new functions

23
Q

Virulence Factors
Type II:
Type III:
Type IV:

A

Type II: Secrete protein across the inner membrane
Type III: Deliver toxins directly into host cells
Type IV: Deliver DNA into host cells

24
Q

Capsule

A

Capsule: Polymer of polysaccharide or protein
Function: Prevent host cell phagocytosis
- Many capsules are developed to produce vaccines

25
Haemophilus | Reservoir and Characteristics?
Humans are the only known reservoir; effective immunization controls diseases - Unique growth properties - Haemophilus influenzae type B - Capsule and neutralizing antibodies - Conjugate vaccines
26
Hib (Haemophilus influenza type B) pathogenisis
Hib is transmitted among humans via the respiratory tract from clinically active case, convalescent patients, or carriers
27
Explain Hib primary infections
Colonization of nasopharynx Occasional invasion of sinuses, middle ear, bronchi - Life threatening infections due to invasion of blood stream/meninges
28
Hib virulence is associated with the expression of:
Type b polysaccharide capsule
29
The _____ and the _____ can become inflamed during bacterial meningitis
Pia mater; arachnoid
30
6 types of Hib and associated sugars
``` A - Glucose B - Ribose and ribitol** C - Galactose D - Hexose E - Hexosamine F - Galactosamine ```
31
Hib meningitis is most prevalent in what population?
The very young (< 1 yr)
32
Describe immunity to Hib
- Good relationship between age and susceptibility - In children less than 3 mo, maternal Ab is protective - Most invasive disease occurs between 3 mo and 3 yrs - Children < 3 yrs show humoral immunodeficiency to Hib - Children > 3 yrs develop Ig to Hib
33
1st generation Hib vaccine | Effectiveness and problems
``` Purified capsular polysaccharide of Hib 90% effective in children > 24 mo; ineffective < 18 mo Problems: - Poor immunogens - Stimulate T-independent Ab - Poor immunologic memory ```
34
2nd generation Hib vaccine Vaccine: Protein carrier:
PRP (Polysaccharide) protein conjugates Vaccine: PRP-D Protein Carrier: Diptheria toxoid