BACTERIAL VIRULENCE Flashcards
Examples of virulence factors:
- Capsule
- Protein A
- IgA protease
- M protein
Found in the cell wall of S. aureus, inhibits phagocytosis by binding Fc portion of IgG; also inhibits compliment
Protein A
Enzymes that cleave IgA, allows colonization of mucosal surfaces
IgA protease
The following microorganisms produce IgA protease:
- S. pneumoniae
- H. influenzae
- Neisseria gonorrhoeae
- Neisseria meningitidis
Mnemonic: SHiNeNe
Found as a surface molecule of group A streptococcus, prevents phagocytosis:
M protein
How does M protein cause RHD/Rheumatic fever?
When a person is infected with group A strep which has the M protein, the body produces antibodies against the M protein, eventually eliminating the disease. While the antigens are gone, the antibodies against the M protein are still present, and these antibodies can go against TISSUE antigens (Tissue antigens have an M protein-like structure) which will then cause Rheumatic fever.
If the antibodies attack the tissue antigens in the heart valves, it will then cause Rheumatic Heart Disease (RHD).
A toxin found only in gram-negative (-) bacteria; component of outer membrane; Released only when bacteria die (not secreted); HEAT RESISTANT
Endotoxin
Proteins synthesized and secreted by some bacteria; produced by some gram (+) and some gram (-) bacteria.
Exotoxin
Bacteria with exotoxin are HEAT-SENSITIVE except:
Staphylococcal enterotoxin (heat-resistant exotoxin producing bacteria) - produced by S. aureus
Common effect of endotoxin:
Lowers Blood pressure - causes SHOCK (septic shock)
Has an endotoxin activity; Like LPS but with some structural differences (lacks O-antigen)
Lipooligosaccharide
Lipooligosaccharide is found on:
Non-enteric gram negatives; Neisseria meningitidis is most important example
An organism that has the Diptheria toxin
Corynebacterium diphtheriae
Exotoxin A is present in what microorganism?
Pseudomonas aeruginosa
Most common cause of nosocomial infection”
Pseudomonas aeruoginosa
Shiga toxin which cause shigellosis is present in:
Shigella
Shiga-like toxin is present in:
Enterohemorrhagic E. coli. (EHEC)
EHEC typically causes:
- “Bloody diarrhea”
- Can also cause hemolytic uremic syndrome (HUS) when toxin reaches systemic circulation
Classic serotype of EHEC
E. coli O157:H7
The causative agent of “Traveler’s diarrhea” and “Watery diarrhea”
Enterotoxigenic E. coli (ETEC)
Anthrax makes three (3) proteins. What are these proteins?
- protective antigen (PA)
- lethal factor (LF)
- edema factor (EF)
Edema toxin is a combination of _____ and _____ anthrax proteins:
Protective antigen (PA) + Edema factor (EF)
Lethal toxin is a combination of _____ and _____ anthrax proteins:
Protective antigen (PA) + Lethal factor (LF)
Three types of anthrax diseases:
- Skin (most common) - Cutaneous anthrax
- Lungs (inhalation –> necrotizing pneumonia) - Inhalational anthrax
- GI (ulcers) - Gastrointestinal anthrax
Most lethal anthrax disease:
Inhalational anthrax
Organism that causes voluminous “rice-water” diarrhea
Vibrio cholerae
Causes whooping cough disease:
Bordetella pertussis
Exotoxin present in Clostridium tetani:
Tetanospasmin
Organism that causes spastic muscle paralysis
Clostridium tetani
Exotoxin present in Clostridium perfringens
Alpha toxin
Organism that causes Gas gangrene:
Clostridium perfringens
Organism that causes flaccid paralysis:
Clostridium botulinum
Botulism in infants are caused by:
contaminated honey
Botulism in adults are commonly caused by:
contaminated/expired canned goods
Exotoxin present in Streptococcus pyogenes (group A strep):
Streptolysin O (SLO)
Between SLO and SLS, which of them cannot cause the production of antibodies:
SLS (Streptolysin S)
- SLO causes production of ASO (Anti-streptolysin O)
Oxygen lablile streptolysin:
Oxygen stable streptolysin:
Oxygen labile: SLO (Streptolysin O)
Oxygen stable: SLS (Streptolysin S)
Antigenic streptolysin antigen:
SLO (Streptolysin O)
Activate a MASSIVE number of T-cells
Superantigens
Superantigen present in S. aureus:
Toxic shock syndrome toxin (TSST-1)
Superantigen present in S. pyogenes (group A strep)
Pyrogenic exotoxin A or C
