Microbial Pathogenicity And Virulence Flashcards
What is pathogenicity
Ability to microbes to cause disease
What is virulence
Capacity of the organism to cause disease
Quantitative measure of pathogenicity
Types of bacterial pathogen
Oppurtunistic
Primary pathogens
Oppurtunistic pathogens
Can cause disease in certain conditions
Primary pathogens
Capable of establishing infection and causing disease in healthy individuals
Pathogen
Any microorganism that has the capacity to cause disease
Factors that effect the pathogenicity
Number of parasites in the body
Virulence of the parasite
Immunity of the host
Host defense mechanisms weakining factors
Age
Illness
Immunosuppressive drugs
Physical and chemical characteristics contribute to the pathogenicity
Invasiveness
Infectivity
Pathogenicity
Bacterial product or strategy that contributes to virulence
Colonization
Avoid host defenses
Multiplication and spread
Invasion of host tissues
Destruction of host tissues
Bacterial virulence mechanisms
Adherence , Invasion— Adhesiveness
Degredative enzymes— Invasiveness
Exotoxins, Endotoxins— Toxigenicity
Types of bacterial adhesion molecules
1- Fimbrial adhesins
2- Non-Fimbrial adhsesins
Fimbrial adhesins
First initial step of bacteria to start an infection
Causes colonization
Different species of bacteria produces different types of Fimbria
Enteropathogenic E.coli fimbrial antigens
CFA 1
CFA 2 ( colonization factor antigen)
Binds with mucosal receptors of gut
Uropathogen E.coli fimbrial antigen
P.fimbria
Disprotein molecule helps the bacteria to bind the urinary tract mucosal
Type 1 Fimbriae of E.coli
Mannose
P. Fimbriae E.coli
Galactose
Non-Fimbrial adhesins
Cell surface adhesion molecules
Helps bacteria to bind specific receptors of body
Invasion
After colonization some bacteria exert their pathogenic effects without penetrating the tissues of the host
Toxins, Aggresins
Which bacteria invade colonic mucosal cells by invasins but rarely penetrate deep into the host tissues
Shigella
Which bacteria invade deep tissues
Salmonellae
Avoidance of host defense mechanisms
Capsule
Streptococcal M protein
Resistance to killing by phagocytic cells
Antigenic variation
Ig A proteases
Iron acquisition
Importance of Iron
To be pathogenic—> must be able to multiply in host
In order to multiply bacteria needs iron and synthesizes iron chelations called SİDEROPHORES
Endotoxins on which type of bacteria
Only gram -
Which type of toxin called Lipopolysaccharide
Endotoxin
