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. Pathogenicity2. Infectivity3. Communicability4. Adhesiveness5. Invasiveness6. Toxigenicity

1.

Adherence factorsAdhesins of the microorganisms:

1. Fimbriae and adhesive pili2. Capsule3. Peptidoglycane4. Teichoic and lipoteichoic acids5. Fatty acids6. A-protein (S.aureus) and M-protein

(S.pyogenes) 7. Ligands

Pathogenicity factors: Invasion factors

1. Hyaluronidase2. Lecithinase3. Deoxyribonuclease and ribonuclease4. Fibrinolysine5. Plasmocoagulase6. Collagenase7. Hemolysins8. Elastase9. IgA protease10. Leukocidins

Pathogenicity factors:ToxinsToxin is a specific substance, often a metabolic product of

microorganism, that damages the host.Classification: 1. Endotoxin2. Exotoxin

Classification of exotoxinsCytotoxins (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 period2. Prodromal period3. The period of illness4. Outcome of disease

Outcome of infectious disease The outcome of infectious disease may be:1. The recovery2. The formation of convalescent carrying3. The persistence of pathogen in the host4. 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 infectionsManifested infectionAtypical 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