Microbial Pathogenesis

Question 1

Ability of a pathogen to produce disease by overcoming the hosts defense

Answer 1

Pathogenicity

Question 2

Degree of Pathogenicity

Answer 2

Virulence

Question 3

Parts of the body with normal flora

Answer 3

skin, upper respiratory tract, oral cavity, intestine (specially large intestine), vaginal tract

Very little: eyes and stomach

Question 4

Parts of the body with absent microflora

Answer 4

Lower respiratory tract
Muscle tissue
Blood & Tissue fluids
Cerebrospinal fluid
Peritoneum
Pericardium
Meninges

Question 5

Benefits of Normal Flora

Answer 5

Nutrient production & processing
Competition with pathogenic microbes
Normal development of the immune system

Question 6

Portals of Entry of Pathogenic Microbes

Answer 6

Respiratory tract
GI tract
Genitourinary tract
Conjunctiva
Skin
Parenteral route (tissues beneath skin)

Question 7

What is ID50 and LD50?

Answer 7

Infectious dose for 50% of the test population

Lethal dose (of a toxin) for 50% of the test population

Question 8

ID50 of Botulinum?
Shiga toxin (E. coli) ?
Staph enterotoxin?

Answer 8

Botulinum - 0.03 mg/kg
Shiga toxin (E. coli) - 250 mg/kg
Staph enterotoxin - 1350 mg/kg

Question 9

One of the most used element of microorganisms

Answer 9

Fe (iron)

Question 10

Bacterial component used to resist host defense by impairing phagocytosis

Answer 10

Capsule

Question 11

Used to disrupt neutrophil membrane, degenerates neutrophils

Answer 11

Leukocidin

Question 12

Disrupt RBC membrane, liberates FE(iron)

Answer 12

Hemolysin

Question 13

Converts fibrinogen to fibrin, causes isolation of microorganism from host defense

Answer 13

Coagulase

Question 14

Converts Plasminogen to plasmin, digestion of fibrin clot

Answer 14

Bacterial Kinase

Question 15

Degrades hyaluronic acid (helps to hold cell together)

Answer 15

Hyalurodinase

Question 16

Degrades collagen frame work

Answer 16

Collagenase

Question 17

Degrades lecithin

Answer 17

Lecithinase and Phospholipase

Question 18

Degrades DNA in WBC, lowers viscosity of exudates makes microorganism spread easily

Answer 18

DNAses

Question 19

Bacterial source of Exotoxin and Endotoxin

Answer 19

Exotoxin - Mostly Gram positive bacteria

Endotoxin - Gram negative bacteria

Question 20

Relationship of Exotoxin and Endotoxin to the bacteira

Answer 20

Exotoxin - metabolic growth product

Endotoxin - Present in LPS of outer membrane of cell wall

Question 21

Chemistry of Exotoxin and Endotoxin

Answer 21

Exotoxin - Protein or short peptide

Endotoxin - Lipid portion (Lipid A) of LPS of outer membrane

Question 22

Heat stability of Exotoxin and Endotoxin

Answer 22

Exotoxin - Unstable (destroyed at 60-80 C)

Endotoxin - Stable (Withstand autoclaving)

Question 23

Immunology of Exotoxin and Endotoxin

Answer 23

Exotoxin - Converted to toxoid

Endotoxin - Cant be used as toxoids

Question 24

Pharmacology of Exotoxin and Endotoxin

Answer 24

Exotoxin - Specific for a particular cell structure or fnx in host

Endotoxin - General, such as fever, weakness, aches, shock

Question 25

Lethal dose of Exotoxin and Endotoxin

Answer 25

Exotoxin - Small Endotoxin - Considerably Large

Question 26

Representative Disease of Exotoxin and Endotoxin

Answer 26

Exotoxin - gas gangrene, tetanus, botulinum Endotoxin - Typhoid fever, UTI, meningitis

Question 27

Types of Exotoxin

Answer 27

Cytotoxin Neurotoxin Enterotoxin

Question 28

Exotoxin: Superantigens or type I toxins

Answer 28

Membrane acting Non specifically stimulate T cells Cause an intense immune response due to release of cytokines from host cells Fever, nausea, vomiting, diarrhea, shock, death (multiorgan failure)

Question 29

Exotoxin: Membrane-disrupting toxins or type II toxins

Answer 29

Destroys cell integrity Lye host's cell by making pore forming protein channels (Channel Forming Toxin CFT) in the plasma membrane and disrupt phospholipid bilayer RTX-repeats in toxin

Question 30

Exotoxin: A-B toxin or type III toxins

Answer 30

Active in cell | Bind to cell and is translocated

Question 31

Endotoxins does not promote production of anibodies: | True or False

Answer 31

True

Question 32

Part of the body, that endotoxin targets, that regulates the body temperature

Answer 32

Hypothalamus of the brain

Question 33

Life threating loss of blood caused by endotoxins

Answer 33

Septic Schock

Question 34

Portals of Exit of Pathogenic Microbes

Answer 34

Respiratory tract: Cough and Sneezing GI tract: Feces and saliva Genitourinary tract: urine and vaginal secretions Skin Blood: Biting arthropods and needles of syringe

Question 35

What are the fates of infecting microorganisms

Answer 35

1. Destroyed by immune system 2. Eliminated in the secretions and excretions 3. Destroyed within the carcass 4. Organism and host reach an impasse

Question 36

Mechanisms of Drug Resistance

Answer 36

1. Production of enzymes against antibiotics 2. Change in permeability or decrease uptake of drug 3. Increase pumping out of antibiotic 4. Alteration of structural target of the drug 5. Bypass by alternative metabolic pathway

Question 37

Major mechanisms by which resistance is acquired

Answer 37

1. Genetic exchange | 2. Mutation

Question 38

Types of Genetic exchange

Answer 38

1. Conjugation 2. Transduction 3. Transformation

Question 39

DNA transfer between bacteria requiring a sex pilus

Answer 39

Conjugation

Question 40

A small, circular, double-stranded, self replicating molecule ring of DNA in some bacteria

Answer 40

Plasmid

Question 41

DNA sequence that can move from one chromosomal site to another, jumping gene

Answer 41

Transposon (Transposable Genetic Element)

Question 42

Gene transfer from one bacterium to another by a bacteriophange

Answer 42

Transduction

Question 43

Occurs when random pieces of host cell DNA are packaged within a phange capsid during the lytic cycle of a phange

Answer 43

generalized transduction

Question 44

Transduced bacterial genes are restricted to specific genes adjacent to the prophange insertion site

Answer 44

Specialized transduction (restricted transduction)

Question 45

Occurs when free chromosomal DNA (from bacterial cell lysis) is inserted directly into another bacterial cell

Answer 45

Transformation

Question 46

Difference in chromosomal and plasmid resistance

Answer 46

Chromosomal resistance - change in cell structure Plasmid resistance - encoded, synthesis proteins