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Infection. Pathogenicity and
virulence of microorganisms.
Types of infection.
Vinnitsa National Pirogov Memorial Medical
University / Department of microbiology
Infection is the active penetration of
pathogenic microorganism into the
host organism. In result of
penetration infectious process is
developed.
The main properties of pathogen
1. Pathogenicity
2. Infectivity
3. Communicability
4. Adhesiveness
5. Invasiveness
6. Toxigenicity
1.
Adherence factors
Adhesins of the microorganisms:
1. Fimbriae and adhesive pili
2. Capsule
3. Peptidoglycane
4. Teichoic and lipoteichoic acids
5. Fatty acids
6. A-protein (S.aureus) and M-protein
(S.pyogenes)
7. Ligands
Pathogenicity factors: Invasion factors
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Hyaluronidase
Lecithinase
Deoxyribonuclease and ribonuclease
Fibrinolysine
Plasmocoagulase
Collagenase
Hemolysins
Elastase
IgA protease
Leukocidins
Pathogenicity factors:Toxins
Toxin is a specific substance, often a metabolic product of
microorganism, that damages the host.
Classification:
1. Endotoxin
2. Exotoxin
Classification of exotoxins
 Cytotoxins
(enterotoxins and
dermatonecrotoxins)
 Neurotoxins
 Membranotoxins
 Miscellaneous group
Infectious process
 Infectious process is a complex of
physiological, adaptive and
pathological changes that arise in
the host organism due to infection
Infectious disease
 Infectious disease is any change from a
state of health in which part or all of the
host body is not able of carrying on its
normal functions due to presence of a
parasite or its products
Phases of infectious disease
1. Incubation period
2. Prodromal period
3. The period of illness
4. Outcome of disease
Outcome of infectious disease
 The outcome of infectious disease may be:
1. The recovery
2. The formation of convalescent carrying
3. The persistence of pathogen in the host
4. The death
Mechanisms and types of infection
transmission
 The main types of infection transmission are by:

Inhalation (air-borne transmission)
Mechanisms and types of infection
transmission
Ingestion (waterborne, food
borne, and hand borne
transmission) and poor
sanitation
Mechanisms and types of infection
transmission

Inoculation
Mechanisms and types of infection
transmission
Contact (contact
transmission)
 Direct contact
 Indirect contact
 Sexual intercourse

Mechanisms and types of infection
transmission

Biting of blood sucking
insects (vector borne
transmission)
Mechanisms and types of infection
transmission
 Person-to-person
through the
placenta
(congenital
transmission)
Classification of the infections
 Manifested
infection
 Atypical infection
 Inapparent infection
Endogenous infection (autoinfection)
 Exogenous infection

Acute infection (till 3 months)
 Chronic infection (after 6 months)
 Persistent infection (years)

Classification of the infections
 Primary infection
 Secondary infection
 Mixed infection
 Reinfection
 Super infection




Pandemic
Epidemic
Endemic
Sporadic