Bacterial Pathogenesis

Question 1

Oppurtunistic pathogen (1)

Answer 1

Staphylococcus epidermidis

Question 2

Primary pathogen (2)

Answer 2

Streptococcus pneumoniae

Streptococcus pyogenes

Question 3

What are the consequences of adhesion of Enteropathogenic E.coli? (3)

Answer 3

Adhesion = Induces structural and functional changes in MUCOSAL cells

1- Rearrangement of cell cytoskeleton

2- Loss of microvilli

3- Accumulation of Actin

Question 4

Fimbrial Adhesins- Examples (2)

Answer 4

1- E.coli —> Type 1 Fimbriae —> UTI

2- Enterotoxigenic E.coli (ETEC) —> Colonization Factor Antigen —> CFA I, CFA II

Question 5

Outer Membrane Protein- Examples (2)

Answer 5

1- Enteropathogenic E.coli

2- Neisseria gonnorhea

Question 6

Haemagglutinin- Examples (2)

Answer 6

Bordetella pertussis

Helicobacter pylori

Question 7

Exopolysacharides- Example

Answer 7

Streptococcus mutans

Question 8

Binding to Fibronectin- Example

Answer 8

What is Fibronectin?
Glycoprotein in plasma and associated with mucosal cell surfaces of host

Example:
Streptococcus pyogenes- Lipoteichoic acid bind to amino terminus of Fibronectin

Question 9

Extracellular Invasion (2)

Answer 9

S.aureus

S.pyogenes

Question 10

Extracellular pathogen

Answer 10

V.cholera

Question 11

Pathogen inside cell causing local infection

Answer 11

Shigella

Question 12

Systemic spread

Answer 12

Salmonella typhi

Question 13

How can Intracellular bacteria avoid being killed? (3)

Answer 13

1- Inhibition of phagolysome fusion

2- Resistance to lysosomal enzymes

3- Adaptation to cytoplasmic replication

Question 14

Which organism causes Intracellular infections that persists for years and requires extensive antibiotic therapy?

Answer 14

Mycobacterium tuberculosis

Question 15

Which pathogens have an obligate Intracellular lifecycle which requires mammalian cell for growth? (3)

Answer 15

Chlamydia

Rickettsia

Mycobacterium leprae

Question 16

Resistance of Killing by Phagocytes- M. tuberculosis

Answer 16

PREVENT PHAGOSOME LYSOSOME FUSION

Question 17

Resistance of Killing by Phagocytes- Salmonella typhi

Answer 17

FAILS TO STIMULATE O2- DEPENDENT KILLING

Question 18

Resistance of Killing by Phagocytes- Neisseria gonnorhea

Answer 18

PRODUCE CATALASE TO PREVENT EFFECT OF TOXIC O2 RADICALS

Question 19

Resistance of Killing by Phagocytes- Legionella pneumophila

Answer 19

INHIBITS PHAGOLYSOSOME ACIDIFICATION

Question 20

Antigenic variation (1)

Answer 20

N. gonnorhea (Antigenic variation in OMP and FIMBRIA)

Question 21

Immunoglobulin A Proteases (2)

Answer 21

N.meningitidis

H.influenzae

Question 22

Serum Resistance (3)

Answer 22

1- Enterobacteriacae——-> LPS

2- N.meningitidis Group B ——-> Capsule

3- N.gonorrhea ——-> Complement bind forming abnormal configuration in outer membrane, No effective lysis

Question 23

Exotoxins- Lethal Action

Answer 23

On Neuromuscular junction- Clostridium botulinum Toxin A

Question 24

Exotoxins- Pyogenic Effect

Answer 24

Streptococcus pyogenes and Staphylococcus aureus

Question 25

Exotoxins- Act on GIT

Answer 25

1- Clostridium difficile- toxin A/B

2- Enterotoxin of V.cholera, E.coli

3- Shiga toxin on bacillary dysentery

Question 26

Exotoxins- Cytolysis of Cells

Answer 26

Streptococcus pyogenes- Streptolysin O and S

Question 27

Exotoxins- Inhibit metabolic activity

Answer 27

Inhibition of Protein synthesis- Diphatheria toxin

Question 28

Exotoxins- Action on Skin

Answer 28

1-Necrosis: Clostridial toxins, staphylococcal alpha-toxins

2- Erythema: Streptococcal Erythrogenic toxin