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Bacteriology > Infectious Disease, Microbiology, Bacterial Genetics > Flashcards

Infectious Disease, Microbiology, Bacterial Genetics Flashcards

1
Q

Transmission: spread by contact with the agent on the infected host or from saliva, discharges on the skin, feces, urine, respiratory or genital secretions

A

direct transmission

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2
Q

organism shed by host into water, milk, food, air, bedding, dust, equipment; contact with contaminated inanimate objects

A

indirect transmission

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3
Q

Sources of infectious agents

A

normal microbiota
infected and diseased host
soil. water, fomites

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4
Q

Parts of infectious disease triangle

A

Host, Environment, Organism

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5
Q

3 main parts of the bacterial cell envelope

A

Cell wall, periplasm, inner membrane

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6
Q

Characteristics of bacterial inner membrane

A 
lipid bilayer
uptake systems
export systems
electron transport
permeability barrier
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7
Q

Characteristics of bacterial periplasm

A

viscous, oxidizing environment
contains enzymes catalyzing formation of disulfide bonds
contains proteins participating in small molecule break down of polymers to bite size compounds

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8
Q

Characteristics of bacterial cell wall

A

peptidoglycan

counters osmotic pressure

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9
Q

What bond links NAG and NAM in the bacterial cell wall

A

B (1,4) glycosidic bonds (pentapeptide linked to NAM)

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10
Q

Main difference between cell wall of gram positive and negative bacteria

A

Negative - thin (and has extra outer membrane)

Positive - thick

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11
Q

What colors do gram positive and negative bacteria stain?

A

Negative - pink

Positive - purple

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12
Q

Describe the outer and inner leaflets of the outer membrane of gram negative bacteria

A

Outer leaflet of outer membrane = Lipopolysaccharides

Inner leaflet = phospholipids

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13
Q

What are the 3 components of LPS?

A

O-antigen
Core
Lipid A

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14
Q

most abundant molecule on the surface of gram neg bacteria

A

LPS

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15
Q

what is the toxic region of LPS

A

Lipid A

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16
Q

What is the purpose of a bacterial capsule

A

protection, immune evasion

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17
Q

what is the shape of the bacterial genome

A

double stranded DNA, helical, supercoiled, forms a circle

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18
Q

the bacterial genome is (haploid/diploid)

A

haploid

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19
Q

circular DNA molecules capable of autonomous replication

A

plasmids

20
Q

In bacteria, DNA replication in (unidirectional/bidirectional) from a single origin of replicaiton

A

bidirectional

21
Q

Operon

A

have the same promoter, all genes transcribed as one block (ex. one promotor, one transcriptional start site, 3 open reading frames, 3 proteins produced from one mRNA)

22
Q

regulon

A

promoter binds the same regulatory factors which allow genes to be expressed at the same time and/or under the same conditions even though they are not physically close to one another on the genome

23
Q

Translation is initiated by the binding of the (30S/50S) subunit to the ribosome binding site on the mRNA

A

30S

24
Q

3 sites of the 50S subunit

A

A (acceptor)
P (peptide)
E (exit)

25
Q

4 ways bacteria acquire new DNA material

A

Natural transformation (uptake of naked DNA)
Conjugation (transfer of plasmid DNA from one bacterium to another)
Transduction (infection by bacteriophage)
Acquire genes that specify antibiotic resistance genes, genes encoding virulence factors (e.g. toxins)

26
Q

To cause disease a bacteria must

A

Interact with host surfaces
Avoid clearance by the host
Acquire nutrients to grow

27
Q

What are 3 ways bacteria interact with host surfaces

A

adherence
biofilms
invasion

28
Q

2 requirements for adhesion

A 
adhesin (binding entity on bacterium)
cognate receptor (binding molecule on host surface)
29
Q

obstacle to adhesion

A

both surfaces negatively charged

30
Q

3 major types of adhesin-receptor interactions

A

Lectin-carbohydrate (bacterial adhesin is the lectin in most cases)
Protein-protein (fibronectin, integrins)
Hydrophobin-lipid (hydrophobic region of protein adhesin interacts with lipids)

31
Q

major types of bacterial adhesin (initial)

A

pilus

fibrillar surface proteins

32
Q

major type of bacterial adhesin (intimate)

A

integral membrane adhesin

33
Q

communities of microorganisms encased within an extracellular polymeric matrix and living on a surface

A

biofilm

34
Q

rational for biofilms ability to protect against toxic environment

A

bacteria on periphery are killed, cells in the middle are protected

35
Q

ability to gain entry inside host cells, allows bacteria to cross physical barriers, hide from the immune system, disseminated from the site of infection

A

invasion

36
Q

general strategy for invasion and the two main mechanisms

A

General strategy: rearrangement of actin cytoskeleton

Mechanisms: zipper, trigger

37
Q

Invasion - zipper mechanism

A

activation of membrane-located host cell receptors by invasion factor(s) on surface of bacteria - receptors are ALREADY present on surface of host cells

38
Q

__________ and accumulation of more receptors lead to engulfment of bacteria by zipper-like mechanism

A

invagination

39
Q

invasion - trigger machanism

A

requires injection of bacterial proteins into the cytoplasm of host cell

40
Q

Type Three Secretion System (TTSS)

A

common and well-characterized injectisome system

41
Q

in TTSS trigger mechanism, bacterial effectors subvert eukaryotic signaling pathways, rearranging actin to form _________ that will engulf bacteria

A

pseudopods

42
Q

Main ways bacteria avoid clearance by the host

A

Antigenic variation (changing antigens and epitopes)
Phase variation (turn-off production of a protein)
slgA protease (prevents trapping of bacteria in mucus bathing mucosal surfaces)
Capsule
Interference with complement cascade (C5a peptidase)

43
Q

2 ways bacteria can survive in host cell

A

Cytosolic and Intravacuolar (in both, protected from antimicrobial content of lysosome)

44
Q

Characteristics of a bacterial capsule (4)

A

Antiphagocytic
Host mimicry
Sheild (stealth mode)
Prevents activation of complement cascade

45
Q

Why is acquiring iron an issue for bacteria?

A

It is one of the most abundant elements in nature BUT… it is insoluble under physiologic conditions and sequestered in animal hosts

46
Q

Bacterial solutions for acquiring iron

A

Receptors for host iron binding proteins

Siderophores (high affinity for iron)

Bacteriology (1 decks)

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