bacterial virulance factors Flashcards
what is the major virulance factor of strep pneumo?
polysaccharide capsure that prevents phagocytosis
other virulance factors:
IgA protease (inactivates secretory IgA)
adhesins (necessary for adhesion to epithelial cells)
pneumolysin (cytotoxin that causes pores in cell membrane and cell lysis)
what is the major virulance factor for bacillus anthacis?
capsule formed from D-glutamic acid inhibits phagocytosis
what is the major virulance factor for group A strep?
M protein - present in cell wall, interferes with opsinization by the alternative pathway compliment (C….?), M-protein also binds to fibrinogen resulting in flammatory mediator release and vascular leakage
Does gonorhea have a capsule?
NO - N. meningiditis does not not N. gono
how does gonorrhea establish an infection
pili attach to host epithelial cells
gono is motile but has no flagella - movement from attachment and contraction of pili
what virulance factor is responsible for the pathogenicity of H. influenza?
type B capsule consisting of polyribitol phosphate
contains pentose monosaccarides rather than hexose sugards as carbohydrate component of capsule
can cause septic arthritis secondary to hematogenous dissemination from otitis media
growth requires X factor (hematin) and V factor (NAD+)
what is the virulance factor for mycoplasma pneumonea?
protein P1 - adheres to respiratory epithelial cells - no cell wall, only membrane packed with sterols (requies cholesterold for growth media).
1)Staph aureus -
2)SHiN organisms -
3)Gp A Strep -
4)N Meningitidis, E coli, V cholerae -
5)C diphtheriae -
6)spores -
7)Cl perfringes -
8)Bacillus anthracis -
9)Listeria -
10)Mycobac TB -
11)Meningococcus -
12)H influenzae - polyribitol phosphate capsule, satellite phenomenon
13)E coli - lipid A - for presentation with shock
K1 capsular Ag - virulence factor
fimbriae - adhesion factor
14)Yersinia pestis - envelope Ag
1- protein A - binds Fc of IgG 2-IgA protease 3-M protein 4-Fimbriae/pili 5-Transduction beta prophage 6-diplicolinic acid in core 7-lecithinase alpha toxin 8-D-glutamate in capsule 9-Actin rockets, listerolysin O 10-sulfatides,cord factor,tuberculin 11-capsule 12-polyribitol phosphate capsule, satellite phenomenon 13-lipid A - for presentation with shock, K1 capsular Ag (virulence factor), fimbriae (adhesion factor) 14- envelope Ag
What are the virulance factors for Staphylococcus aureus
1) Protein A = binds to Fc of IgG; inhibits component fixation and phagocytosis
2) Toxic Shock Syndrome Toxin(TSST) = superantigen that binds MHC II and T-cell receptor and causes polyclonal T-cell activation
What are the virulance factors for Streptococcus pneumoniae
1) IgA protease
2) Capsule
3) Pneumolysin
What are the virulance factors for Streptococcus pyogenes(Group A)
1) M protein = inhibits complement fixation, resists phagocytosis
2) Streptolysin O, S = cytolytics
3) SpeA, Spec, etc = pyrogenic exotoxins
What are the virulance factors for Viridans group Streptococcus
1) Glycocalyx = aids in sticking to damaged valves
What are the virulance factors for Streptococcus agalactiae(Group B)
1) CAMP factor = enlarges area of hemolysis
what should you know about Enterococci(Group D)
1) Vancomycin resistance leads to VRE
What are the virulance factors for Corynebacterium diphtheria
1) Diphtheria toxin = exotoxin inhibits protein synthesis via ADP-ribosylation of EF-2
what are the encapulated bateria?
SHiNE SKiS
S. pneumo, Hib, N. meningitidis, E. Coli, Salmonella, Klebsiella, Group B Strep
what are the SHiN organismss? what is their common virulance factor?
Strep. pneumo
H. influenza
Niserria meningiditis
IgA protease
what is the virulance factor for Clostridium perfringens?
1) Alpha toxin(“lecithinase,” a phospholipase) = causes myonecrosis(gas gangrene) and hemolysis
what are the virulance factors for Bacillus anthracis?
1) Edema Factor(EF) = mimics adenylate cyclase(inc cAMP)
2) Lethal Factor(LF) = protease that cleaves MAP kinases
3) Protective Agent(PA) = binds to host cell and facilitates entry of EF, LF
3) Polypeptide capsule(uses D-glutamate)
Neisseria gonorrhoeae
1) Pili(fimbriae)
2) IgA proteases
* **Note: NO CAPSULE, unlike N. meningitidis
Which Bacteria/toxins Inactivate EF-2
1) Corynebacterium diphtheria = diphtheria toxin = ADP ribosylation of EF-2
2) Pseudomonas aeruginosa = Exotoxin A = ADP ribosylation of EF-2
what is unique about Pneumocystis jirovecii?
1)fungus with No ergosterol in cell membrane
Bacillus cereus
1) Cereulide = cytotoxin that destroys mitochondria
B. cereus infection causes nausea and vomiting
what is the virulance factor for Dermatophytes?
1) Keratinase
association for Actinomyces
1) Sulfur granules(not a virulence factor,)
Mycobacterium tuberculosis
sulfatides (inhibit phagosome-lysosome fusion - allows it to survive and multiply IN MACROPHAGES),
cord factor (causes release of TNF-alpha),tuberculin
1) Mycolic acid in cell wall
catylase positive,
aerobic
LPS but NO LIPID A, so no exotoxin or endotoxin
can be grown with radioactive palmitate as carbon source allowing faster detection (still 1-2 weeks)
false negative PPD in AIDs or immunosuprerssed!
what is the virulance factor for Mycobacterium leprae
1) Mycolactone = cytotoxic and immunosuppressive
what are the virulance factors for Neisseria meningitidis
1) Lipooligosaccharide(LOS) = analogous to LPS in Gm- bacteria and acts as an endotoxin
2) Capsule
3) IgA Proteases
what is the virulance factor for Neisseria gonorrhoeae
1) Pili(fimbriae)
2) IgA proteases
* **Note: NO CAPSULE, unlike N. meningitidis
what is the virulance factor for Haemophilus influenzae
1) Capsule = type B most virulent
2) IgA proteases
what are the virulance factors for Pseudomonas aeruginosa
1) Capsule = slime layer; CF strains are mucoid
2) Exotoxins = exotoxin A(inactivates EF-2), Exoenzyme B, cytotoxin(leukocidin), and phospholipase C are all anti-phagocytic; elastase destroys tissue
3) Pigments = pyocyanin is toxic for leukocytes; also a yellow one
what are the virulance factors for E. Coli(general)
1) Fimbriae = impt. for cystitis and pyelonephritis
2) K Capsule = impt. for pneumonia, neonatal meningitis
3) LPS = septic shock
what is the virulance factor for ETEC E. Coli
1) Heat-labile toxin(LT) = activates adenylate cyclase similar to cholera to stimulate Cl- and H2O efflux(diarrhea)
2) Heat-stable toxin(ST) = activates guanylate cyclase to dec absorption of NaCl, water in gut
what is the virulance factor for EHEC E. Coli
1) Shiga-like toxin = inactivates 60S ribosome by removing adenine from rRNA; seen in HUS
what is the virulance factor for Klebsiella
1) Capsule(mucoid; can be quite large)
what are the virulance factors for Salmonella Typhi
1) Flagella(distinguishes from Shigella)
2) Vi capsular antigen(not in other Salmonella species)
3) Adhesion/invasion antigens(similar to Shigella)
what are the virulance factors for Shigella dysenteriae
1) Adhesion/invasion antigens(similar to Salmonella)
2) Shiga Toxin = inactivates 60S ribosome by removing adenine from rRNA; the bacterium can still cause significant disease without this toxin, making mucosal invasion the true virulence determinant
what is the virulance factor for Campylobacter jejuni
1) Flagella(single, polar)
what is the virulance factor for Vibrio cholerae
1) Cholera toxin = activates Gs and inc. cAMP via adenylate cyclase; inc Cl- and H2O efflux in gut
what is the virulance factor for Yersinia enterocolitica
1) LcrV antigen = secretion system
2) Yops(Yersinia outer proteins) = secretion system
what are the virulance factors for Helicobacter pylori
1) Urease
2) Flagella
3) CagA protein = surface complex that injects proteins into cell; correlates with more virulent strains
4) Vacuolating cytotoxin
what are the methods for visualizing Spirochetes, what are the major virulance factors?
1) Borrelia(visualized with aniline dyes - Wright’s and Giemsa - and light microscopy)
2) Leptospira(darkfield)
3) Treponema(darkfield microscopy)
4) All have periplasmic flagella that are highly active and necessary for virulence
what are some importnat features of Mycoplasma pneumoniae? what is mechanism for the virulance facfor responsible for the very severe form of disease?
1) Lacks cell wall
2) Cholesterol in cell membrane
3) Terminal organelle = cytoskeletal and adhesive components impt. for motility and attachment
4) Community Acquired Respiratory Distress Syndrome(CARDS) Toxin = binds to surfactant proteins and ribosylates several proteins; not present in all strains, but worse when it is
