Lesson 9

Question 1

Opportunistic (potential) pathogens :-

Answer 1

are bacteria which cause a disease in a compromised host which typically would not occur in a healthy (noncompromised) host.

Question 2

Pathogenicity :-

Answer 2

The ability of pathogen to cause a disease

Question 3

Virulence :-

Answer 3

is the measure of the pathogenicity

Question 4

virulence factors :-

Answer 4

Factors that are produced by a microorganism and evoke disease

1. Certain structures of the bacterial cell:-
   capsule, cell wall peptidoglycan, outer
   membrane proteins, lipopolysaccharides of
   gram “-“ bacteria, pili, flagella.
2. Physiological and biochemical signs:-
   the formation of enzymes, metabolites, toxins that have an adverse effect on the microorganism

help bacteria
1-invade the host
2-cause disease
3-Weaken host immune system

Question 5

ENZYMES OF AGRESSION :-

Answer 5

proteases - destroy antibodies
coagulase - coagulates blood plasma
fibrinolysin - dissolves fibrin
collagenase - destroys collagen
Lecithinase - destroys lecithin; 
hyaluronidase - destroys hyaluronic acid
nearaminidase - destroys the neuraminic acid

Question 6

Types of toxins

Answer 6

Exotoxins
are released into the environment during the life of the microorganism.
Germ + 
Act at specific sites
Produce characteristic diseases

Endotoxins
are tightly bound to the bacterial cell and released after cell death.
Germ -
Lipopolysaccharides act throughout the body
Fever, weakness, aching (pain)

Question 7

Classification of protein toxins by mechanism of action :-

Answer 7

1. Cytotoxins - block protein synthesis at the subcellular  level (histotoxin of diphtheria causative agent).
2. Membranotoxins - destroy the membranes of  erythrocytes and leukocytes.
3. Functional blockers - disrupt the function of tissue  systems (neurotoxins, enterotoxins).
4. Exfoliatins and erythrogens - disrupt the interaction  of cells between themselves and the intercellular  substance.