Bacterial Pathogenesis 1

Question 1

Transduction vs transformation vs conjugation

Answer 1

Transformation: kill and uptake
Transduction: Phage
Conjugation: sex pili

Question 2

Two naturally competent bacteria

Answer 2

Bacillus subtilis and strep pneumo (Nat. competent usually only take up linear DNA, not circular or from phages)

Question 3

Bacteria that only transform their own genus

Answer 3

H. Influenza and Neissera Gonorrhoeae

Question 4

A transducing phage transfers DNA during the…

Answer 4

lytic phase

Question 5

What two organelles assist in gene transfer in conjugation?

Answer 5

Relaxasomes and Transferasomes

Question 6

F plasmids

Answer 6

contain “tra” genes for transfer. Result in sex pili

Question 7

Col plasmids

Answer 7

contain bacteriocins (proteins to kill bac) or genotoxins (kill host cells)

Question 8

mob plasmids

Answer 8

can only transfer by hitchhiking along with other plasmids that contain tra genes

Question 9

Pathogenicity islands

Answer 9

10-200kb and have different G+C% content than rest of the bac chromosome

Question 10

EPEC and EHEC

Answer 10

Enteropathogenic and enterohaemorrhagic E. Coli. Attach to actin pedestals and inject molecules into the host cells

Question 11

Facultative intracellular bacteria

Answer 11

have genes that control virulence factor expression so they can survive both inside and outside of host cells

Question 12

Enzymes that destroy cell defences, made by extracellular bacteria

Answer 12

chemokines, sIgA

Question 13

How intracellular pathogens are different

Answer 13

• resistant to Reactive OS and NO, (superoxide dismutase, SOD, made by Staphylococci and salmonella) (Listeria suppresses NO synthase expression in host)
• Legionella and Mycobacterium prevent phagolysosome fnx
• Listeria, Francisella, and Rickettsia escapre phagosomes

Question 14

Listeria

Answer 14

Gram+ facultative anaerobe. 3rd leading cause of death due to food poisoning. Uses genes like plcA and hly. These lead to InIA and InIB make non-phagocyte cells to phagocytose bacteria (muahahaha!) by changing actin cytoskeleton

Question 15

What nutrients are in high demand in the body?

Answer 15

1. Metals/cations (Fe, Mn, Zn, Cu, Mo)
2. Amino Acids
3. Carbs
4. O2 and other election acceptors

Question 16

Three ways that bacteria avoid dying from lack of amino acids inside a cell

Answer 16

1. M. Tuberculosis makes its own tryptophan
2. C. Trachomatis turns reticulate bodies into aberrant bodies
3. L. pneumophila uses ankB and polyUb to use host as a food source

Question 17

Enterobactin

Answer 17

a molecule made by bacteria to steal iron from host. Host counters with lipocalin which breaks down enterobactin. Bacteria counters by glucosylating enterobactin.

Question 18

Salmonella

Answer 18

Cause typhoid (enteric fever, humans only) and gastroenteritis (non-typhoid, affect many animals)

Question 19

Salmonella PA1-encoded effectors

Answer 19

trigger host membrane ruffles that envelope and internalize bound bacteria

Question 20

Toxin types

Answer 20

I- bind and act as host cell surface (super antigens)
II- Act on host cell membrane (phospholipase and pore-forming toxins)
III- A-B type toxins, includes single chain (DT and BoNT) and multisubunit toxins (cholera and anthrax toxins)

Question 21

Other ways to categorize toxins

Answer 21

• non-protein vs protein
• Endotoxin vs exotoxins
• effector proteins

Question 22

Non-protein toxins

Answer 22

aka Endotoxins. Stimulate TLR4 or TLR2/6. Lead to septic shock, DIC or Acute respiratory system

Question 23

Mycobacterium ulcers makes a ____ toxin called _____ that does _____

Answer 23

non-protein, polyketide-derived mycolactone, Buruli ulcers (necrotic lesions)

Question 24

Superantigens bind ____ outside the peptide cleft

Answer 24

MHC II. T cells are activated and then exhausted and die, inflammation goes crazy. Spread by diarrhea

Question 25

Staph Aureus

Answer 25

• 1/3 of population is colonized
• thrives in hospital (HA-MRSA)
• Daycare and wrestlers (CA-MRSA)
• Causes food poisoning, sepsis, abscesses, and cellulitis, bacteremia/sepsis
• Surfaces have adhesins, capsule, Protein A, MSCRAMMS

Question 26

Protein A

Answer 26

binds IgG

Question 27

Toxic Shock Syndrom toxin 1

Answer 27

TSST-1, superantigen (superabsorbent tampons that grew staph aureus)

Question 28

AgrC and AgrA

Answer 28

Sensor Kinase and Response Regulator (Hamemelitannin from witch hazel inhibits MRSA quorum sensing)

Question 29

E. Coli can sense

Answer 29

Adrenergens in the body

Question 30

Phospholipases

Answer 30

-a toxin of C. perferingens: hydrolyzes the lipid lecithin, contributes to gangrene

Question 31

Pore-formin toxins

Answer 31

• Alpha (helixes)
• Beta (barrel)
• These represent about 30% of the toxins
• Eg Aerolysins (inserts itself spirally)

Question 32

A/B toxins

Answer 32

A subunit is responsible for the enzymatic activity, B mediates binding

Question 33

How do A/B toxins enter cells?

Answer 33

• Fuse with endosomes (DT, BoNT)

- Retrograde transport (cholera and shiga toxin)

Question 34

Cholera Toxin does what?

Answer 34

produces abnormally high cAMP levels, cause more Cl- to be produced in gut. Diarrhea, dehydration, loss of electrolytes.

Question 35

What is Diptheria?

Answer 35

Colonization of throat by Corynebacterium diphtheriae. G+, non-motile, aerobic. Only in humans. Causes a pseudomembrane in throat and lungs; removal can make you bleed, can make you choke.

Question 36

How does DT enter cells?

Answer 36

Heparin-binding epidermal growth factor (HB-EGF)-like receptors. These are present in the heart and nerve cells in large numbers

Question 37

Toxoids

Answer 37

non-toxic version of a toxin, used in a vaccine. Can affect children and adults