L8: Bacterial Pathogenicity Flashcards by Katlyn Heneghan

_____: Sum of the characteristics that allow bacterium to produce disease (biochemical, structural, genetic)

Virulence

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What are the two primary bacterial defense strategies?

1.Colonize and invade host surfaces
2. Evade complement, phagocytes, and antibody response

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True or False: For a pathogen to penetrate intact skin, there has to either be disruption of skin (catheter, surgery) or transmission by arthropods (B. burdorfi, Lyme)

True

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What do most bacteria have that makes it easier for mucin to trap them?

Mucin binding surface

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What three features do bacteria that are able to EVADE trapping by mucin have?

Lack mucin receptors
Make mucin-degrading enzymes (hydrolases)
Move between mucin strands

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True or False: Colonic bacteria (clostridia, enterobacteria, B. fragilis) tend to be good at evading trapping by mucin layer

True

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_____: small cysteine-rich cationic proteins, a natural bactericidal, that create PORES in bacterial membranes + diffuse through porins and peptidoglycan to reach CYTOPLASMIC MEMBRANE

Defensins

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____, which has a negative charge, binds defensins and prevents them from reaching the cytoplasmic membrane
A. TLR
B. LPS
C. Olg gene
D. Bacterial membranes

B. LPS

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What are two ways that the bacterial cell gets rid of defensins?

(hint: enzymes and pumps)

Peptidase degrades it
Cytoplasmic proteins pump them out

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Which immunoglobulin molecule makes mucin sticky + binds bacterial antigens (via ABC and interact w/mucin via their Fc portions)?
A. sIgG Protease
B. sIGB Protease
C. sIGD Protease
D. sIGA Protease

D. sIGA Protease

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Bacteria produce extracellular enzyme that
cleave ___ at hinge region, breaking links
between bacteria and mucin

IgA

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What are the two type of microbial adhesion factors that exist?

Protein and Polysaccharide

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Are Flagella, Fimbrae, Pili, S Layer, and Afimbrial polysaccharide or protein adhesions?
A. Polysaccharide Adhesions
B. Protein Adhesions

B. Protein Adhesions

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True or False: The capsule and cell wall are protein adhesions

False - polysaccharide

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True or False: Afimbriae, Flagella, Fibriae, and Pili are all appendages

True

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Where in bacteria is the S Layer Found?
A. Cell envelope
B. Cell wall
C. Cytoplasm
D. Outer Membrane

A. Cell envelope

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True or False: In medical situations, adhesions would be considered a major determinant of virulence for many pathogens

True

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Which two rod-shape, hair-like protein structures on surface of
bacteria mediate attachment?

Pili and fimbriae

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Tip structure of fimbriae and pili attaches specifically to receptor on host
cell, often carbohydrate residues of ____ or ___

glycoproteins or glycolipids

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True or False: Fimbrae play vital role in conjugation ; comprise subunits
called pillin that forms a canal that allowed exchange of DNA between two bacterial cells; serves as receptors for certain viruses (bacteriophage)

False - Pili !

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Which is found in greater abundance in the bacteria cell and is specialized for attachment of bacteria to its host?
A. Pili
B. Fimbriae
C. Flagella

B. Fimbriae

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Pili are constantly lost and reformed (due to fragility). How does this help bacteria avoid host defenses?

Change pilus type by altering antigenicity

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True or False: Pili and Fimbriae allow bacteria and host cell to form initial loose
contact, triggering mechanisms of tighter adherence

True

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True or False: Mostly gram-positive pathogen (E.coli - urinary tract
infections and gastroenteritis), V. cholera,
P. aeruginosa, and Neisseria spp have fimbrae and pilli

False - gram negative!

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After adhesion in a bacterial cell, there is ____ ____. What are the two outcomes?

signal transduction 1. Host alters gene expression in response to adhesion binding 2. +/- virulence genes of bacterial cell

_____: Cells surface proteins that do not form pili A. Apillus B. Afimbrial C. Aflagellar

B. Afimbrial

True or False: Afimbrial cells likely mediate WEAKER binding of bacterial and host cells and may bind proteins on carbohydrates rather than host cells

False - Afimbrial cells likely mediate TIGHTER binding of bacterial and host cells and may bind proteins on HOST CELLS rather than carbohydrates

Yersinia, Neisseria, E. coli, and Strep/Staph all share which feature? A. Apillus B. Afimbrial C. Aflagellar

B. Afimbrial

___: filamentous protein structures that provide swimming movement for most motile bacterial cells A. Fibrae B. Flagella C. Pili

B. Flagella

Which pathogen has motility and is its determinant of virulence? (swims into intestinal mucosa to avoid being flushed out by peristaltic action of the gut) A. Strepto B. Staphylo C. Vibrio D. Enterbacteria

C. Vibrio

The distally located flagellar cap protein has been reported to function as adhesins in which three pathogens?

1) E.coli 2) P. aeruginosa 3) C. difficile

True or False: Flagella may also adhere to amoebae or connect two bacterial species

True

____: Proteins in outermost layer of cell envelope (underneath capsule if present) and has tiled appearance; can function as adhesions (!!)

S Layers

Which three pathogens have S Layers?

1. Gram (+) 2. Gram (-) 3. Archea

How do S Layers contribute to bacterial virulence?

Protect bacterium against 1) complement and 2) phagocyte attack

Teichoic acids and gram-positive cell wall (as seen in Strep and Staph) are examples of ____ adhesions A. Protein Adhesions B. Polysaccharide Adhesions

B. Polysaccharide Adhesions

Capsule of Mycobacteria are also recognized by host cell receptors to promote ____ A. virulence B. adherence

B. adherence

True or False: LPS/cell wall are polysaccharide adherins

True

___: Toxic components of the cell wall of Gram- neg. and positive bacteria are central mediators in the development of septic shock

LPS

Why is iron concentration in human body is low?

Mostly bound to: lactoferrin, transferrin, ferritin, and Hb

Bacteria secrete siderophore, which carries ___

iron

Siderophores-iron complexes are taken up by special _____ receptors on the bacterial surface

siderophores

What happens to iron-siderophore complexes that are internalized by bacteria?

Cleaved to release the iron inside the bacteria

True or False: Since free iron is scarce in tissue fluids and blood, bacterial siderophores compete effectively for Fe3+ bound to lactoferrin and transferrin

True

What are two ways that bacteria remove iron?

1. Bind and directly remove iron from host's transferrin, lactoferrin, or Hb 2. Bacteria make toxins, which kill host, leading to iron release

What is an example of a pathogen that does not require iron (iron abstinence) but uses other ions, such as: manganese? A. Cholera B. Vibrio C. Borrelia burgdorgeri D. Streptococcus

C. Borrelia burgdorgeri

What is the function of invasion?

Allows bacteria to gain deeper access into the host to perpetuate the infection cycle

Which type of invasion occurs when a microbe breaks down the barriers of a tissue to disseminate in the host while remaining outside of host cells? A. Intracellular Invasion B. Extracellular Invasion

B. Extracellular Invasion

_____ degrade host’s extracellular molecules by producing elastase/collagenase, which aids tissue invasion and is associated with keratitis, burn tissue necrosis, and cystic fibrosis A. P. aeruginosa B. C. diff C. E. Coli D. Streptococcus

A. P. aeruginosa

Which five enzymes are secreted by beta-hemolytic Streptococcus and S. aureus to degrade host cell molecules?

1. Hyaluronidase* : cleaves proteoglycans in connective tissue 2. Streptokinase and Staphylokinase: breaks down fibrin clots 3. Lipase: degrades accumulated host oils 4. Nuclease: digests RNA and DNA 5. Haemolysins: lyse erythrocytes and other cell types

S. aureus secretes ____, an enzyme that clots plasma, forming a sticky coat of fibrin around themselves; opposite effect of kinase A. Lipase B. Coagulase C. Nuclease D. Hyaluronidase

B. Coagulase

_____: A microbe penetrates the cells of a host tissue and gains access to the intracellular environment A. Intracellular Invasion B. Extracellular Invasion

A. Intracellular Invasion

Intracellular host invasion can be facilitated by which two aspects?

1. Natural phagocytosis mechanisms (macrophage, neutrophil) 2. Induced uptake: pathogens signals host cell to engulf adhered bacteria (type 3 secretion systems)

True or False: Salmonella and Shigella use type III secretion systems

True

True or False: Host cells can be phagocytes (macrophages and neutrophils) or non-phagocytic cells (epithelial and endothelial)

True

What type of lifestyle do Chlamydia, Rickettsia, and Mycobacterium have? A. Facultative Intracellular B. Obligate Intracellular C. Anaerobic Intracellular

B. Obligate Intracellular

______is a facultative intracellular pathogen that persists for years and require extensive antibiotic therapy A. Mycoplasm B. Neiserria C. Mycobacterium tuberculosis

C. Mycobacterium tuberculosis

What are the three general intracellular niches in which pathogens reside?

1. Within phagolysome 2. Within phagosome 3. Within host cell cytosol

Chlamydia, Salmonella, Legionella, and Mycobacterium all: A. prevent phagosome-lysosome fusion B. escape from phagosome into cytoplasm

A. prevent phagosome-lysosome fusion

Where does Coxiella burnetti reside? A. phagosome B. phagolysome C. host cell cytosol

B. phagolysome

Where do: Shigella, Listeria, and Rickettsia reside? A. phagosome B. phagolysosome C. host cell cytosol

C. host cell cytosol Escaping from phagosome into cytoplasm is mediated by a bacterial protein that disrupts host’s membranes either by degrading membranes or by forming pores in the membrane

True or False: In addition to the host cell lysis, Shigella and Listeria utilize a pathway of cell-to-cell spread

True - Involves extension of the infected cell into an adjacent cell, followed by membrane fusion and formation of a bacteria-containing vacuole in the adjacent cell

Bacteria residing in macrophages and neutrophils may use these cells as _____ spread systemically via blood or lymphatic circulatory systems

vehicle to

Salmonella, Yersinia, and Brucella move between tissue in which manner? A. Lyse host membrane B. Vehicle to spread C. Cell to cell spread

B. Vehicle to spread

Chlamydia and Rickettsia: A. lyse the host cell membrane B. vehicle to spread C. cell to cell spread

A. lyse the host cell membrane - releasing infectious bacteria which attach to and invade adjacent cells

_____: network of polymers covering surface of bacteria, usually polysaccharides (proteins)

Capsules

True or False: Capsules protect against host immune response (complement activation, phagocyte-mediated killing, and abx therapy) and leads to host mediated pathogenesis

True

What three pathogens utilize capsules?

1. S. pneumoniae 2. Neisseria 3. P. aeruginosa

Some bacteria have capsule that resemble host polysaccharide, such as: hyaluronic acid in _____ or sialic acid in ______ A. Neisseria and Salmonella B. Neisseria and S. pyogenes C. S. pyogenes and Neisseria D. S. pyogenes and Salmonella

C. S. pyogenes and Neisseria

True or False: Bacterial capsules that resemble host polysaccharides, as in hyaluronic acid, is immunogenic

False - it is NOT immunogenic and host does NOT produce antibodies that opsonize capsular surface

True or False: Capsules may mediate specific or non-specific attachment

True

Which molecule is a reactive form of nitrogen made by some cells in the human body as an antibacterial defense?

In E. coli, resistance to NO is mediated by ____, which is normally part of the respiratory system

flavohemoglobin

What is the function of flavohemoglobin?

Converts NO into NO3-

What are two LPS modifications that prevent formation of complement components?

1. Sialic acid bound to O antigen (E. coli) or to LOS of Neisseria 2. Changes in length of O antigen side chains prevents MAC killing (serum resistance)

Which two mechanisms prevent migration of phagocytes?

1. Enzymes that degrade C5a, strategy for interfering with signaling function of complement 2. Toxic proteins that kill phagocytes, inhibit migration, or reduce ox burst strength

What are the three major ways that pathogens evade host's antibody response?

1. Alter pilus protein 2. Capsule that resembles host 3. Bacteria coat themselves with host proteins (fibronectin or bind to Igg, e.g protein A or G)

______ helps bacteria evade antimicrobial peptides made by epithelial tissues in lungs (as part of innate immune response) A. capsule shedding B. capsule uncloaking C. capsule evasion

A. capsule shedding

What are 2 host proteins that pathogens can coat themselves with to evade host antibody response?

Fibronectin Immunoglobulin - Note: these proteins bind Fc portion of antibodies but do not lead to bacteria opsonization

When Protein A binds to S. Aureus, the ___ portion of the IgG is not available for the receptor, leading the pathogen free to begin infecting cells

Fc portion

L8: Bacterial Pathogenicity Flashcards

(82 cards)