Staphylococcus ( Genus )
Basics:
- Gram positive
- Non-motile
- Arrangement: grape clusters
- Coagulase test:
- Positive for Staphylococcus aureus ( Will appear golden )
- Negative for Staphylococcus epidermidis
Generalizable Characteristics for Staphylococcus infections:
- Foodborne infections
- Normal flora of the skin and the upper respiratory system
- Opportunistic when given the chance
- Risk factor: Foreign bodies
- Community OR hospital acquired
- Often associated with abscesses or puss - THIS IS KEY
Staphylococcus aureus ( Pathogen ):
- Diseases caused by Staphylococcus aureus:
- Food borne infections
- Think about how the type II toxin can be used
- Surgical Wounds
- Opportunistic infection
- Boils OR pimples
- Gram positive bacteria like Staphylococcus aureus reside on the drier
parts of the skin and will gain access to deeper tissues when given the
opportunity
- Serious conditions: ( THIS IS KEY )
- Osteomyelitis
- Endocarditis
- Pneumonia
- Staphylococcus associated Toxic Shock Syndrome (cytokines)
- MRSA (very resistant S.A)
- CA-MRSA (carriers)
- Bacteremia- blood shows presence of microbes
- Scalded Skin Syndrome
- Peeling of the skin caused by a toxin known as Exfoliatis
,Staphylococcus aureus: Virulence and Virulence Factors
- MSCRAMMS ( Microbial Surface Components Recognizing Adhesive Matrix
Molecules )
- Major virulence factor category
- Collection of proteins that can be categorized into 2 groups:
- Group A: Surface Proteins:
- Will be produced in the exponential phase of growth
- Function to limit host resources and suppress the immune
system
- Members of group A:
- Coagulase = forming clots
- Protein A
- Clumping Factor A
- Collagen binding protein
- Fibrinogen binding protein
- Group B: Secreted Proteins
- Will be produced in the stationary phase of growth
- Function to damage the host
- Members of group B:
- TSST-1 ( Toxic Shock Syndrome Toxin -1 ) (superantigen)
- Alpha Toxin ( Type II toxin associated with foodborne
illness )
- Enterotoxin B
- Protein A:
- Similar to the Protein G in Streptococcus pyogenes
- Function: bind the Fc region of host antibodies to prevent signaling of the
host immune system; will secrete IgA protease to degrade antibody
that has bound incorrectly
- Coagulase: Enzyme
- Forms clots
- Degrades fibrinogen to fibrin
- Hyaluronidase: Enzyme
- Hyaluronic acid is present in the connective tissue of the host
- This enzyme will aid in the destruction of the “glue” that is the
Hyaluronic acid
- Fibrinolysin: Enzyme
- Enzyme that will breakdown fibrin clots
- CAPSULE
● Adhesion and biofilm formation
Staphylococcus aureus: Toxin & Enzymes
1. Toxic Shock Syndrome Toxin:
a. Superantigen
, b. Synergistic with the LPS of gram negative bacteria
2. Enterotoxin:
a. Enterotoxin B is part of the secretable proteins within MSCRAMM
b. Superantigen
c. Present in foodborne illness
d. Heat stable
3. Exfoliative Toxin:
a. Responsible for causing Scalded skin syndrome in infants and children
b. Causes boils in adults
4. Staphylokinase: Enzyme
a. Degrade clots
5. Alpha toxin:
a. Also known as the alpha hemolysin
b. Type II toxin
c. Will cause pores to form in the cytoplasmic membrane of host neutrophils and
erythrocytes
6. Other hemolysis ( beta, delta, and gamma )
a. Similar in function to the alpha hemolysin
b. Will be found in different strains of Staphylococcus aureus
7. Leukocidin:
a. Toxin that will target leukocytes, mainly phagocytes
8. Quorum signaling:
a. Small peptides and regulatory RNA molecules
b. Autoinducer 2
Staphylococcus aureus: Additional mechanisms for virulence:
1. Sequestration of epithelial cells
a. Uses MSCRAMM
2. Evasion of Neutrophil Killing
a. Blockade of neutrophil recruitment
i. CHIP: chemotaxis inhibitory protein -->counteracts pathogens
ii. EaP: Extracellular adhesion protein
b. Inhibition of antimicrobial peptide killing
i. Staphylokinase ( degrade clots )
ii. Aureolysin
iii. Surface changes
c. Neutralization of ROS
i. Catalase
ii. SOD (superoxide dismutase- neutralizes reactive O2 species)
iii. Pigment
d. Neutrophil cytolysis:
i. PSM: Phenol soluble modulin
3. Evasion of opsonophagocytosis: prevent phagocytosis trigger by the opsonization
system
Basics:
- Gram positive
- Non-motile
- Arrangement: grape clusters
- Coagulase test:
- Positive for Staphylococcus aureus ( Will appear golden )
- Negative for Staphylococcus epidermidis
Generalizable Characteristics for Staphylococcus infections:
- Foodborne infections
- Normal flora of the skin and the upper respiratory system
- Opportunistic when given the chance
- Risk factor: Foreign bodies
- Community OR hospital acquired
- Often associated with abscesses or puss - THIS IS KEY
Staphylococcus aureus ( Pathogen ):
- Diseases caused by Staphylococcus aureus:
- Food borne infections
- Think about how the type II toxin can be used
- Surgical Wounds
- Opportunistic infection
- Boils OR pimples
- Gram positive bacteria like Staphylococcus aureus reside on the drier
parts of the skin and will gain access to deeper tissues when given the
opportunity
- Serious conditions: ( THIS IS KEY )
- Osteomyelitis
- Endocarditis
- Pneumonia
- Staphylococcus associated Toxic Shock Syndrome (cytokines)
- MRSA (very resistant S.A)
- CA-MRSA (carriers)
- Bacteremia- blood shows presence of microbes
- Scalded Skin Syndrome
- Peeling of the skin caused by a toxin known as Exfoliatis
,Staphylococcus aureus: Virulence and Virulence Factors
- MSCRAMMS ( Microbial Surface Components Recognizing Adhesive Matrix
Molecules )
- Major virulence factor category
- Collection of proteins that can be categorized into 2 groups:
- Group A: Surface Proteins:
- Will be produced in the exponential phase of growth
- Function to limit host resources and suppress the immune
system
- Members of group A:
- Coagulase = forming clots
- Protein A
- Clumping Factor A
- Collagen binding protein
- Fibrinogen binding protein
- Group B: Secreted Proteins
- Will be produced in the stationary phase of growth
- Function to damage the host
- Members of group B:
- TSST-1 ( Toxic Shock Syndrome Toxin -1 ) (superantigen)
- Alpha Toxin ( Type II toxin associated with foodborne
illness )
- Enterotoxin B
- Protein A:
- Similar to the Protein G in Streptococcus pyogenes
- Function: bind the Fc region of host antibodies to prevent signaling of the
host immune system; will secrete IgA protease to degrade antibody
that has bound incorrectly
- Coagulase: Enzyme
- Forms clots
- Degrades fibrinogen to fibrin
- Hyaluronidase: Enzyme
- Hyaluronic acid is present in the connective tissue of the host
- This enzyme will aid in the destruction of the “glue” that is the
Hyaluronic acid
- Fibrinolysin: Enzyme
- Enzyme that will breakdown fibrin clots
- CAPSULE
● Adhesion and biofilm formation
Staphylococcus aureus: Toxin & Enzymes
1. Toxic Shock Syndrome Toxin:
a. Superantigen
, b. Synergistic with the LPS of gram negative bacteria
2. Enterotoxin:
a. Enterotoxin B is part of the secretable proteins within MSCRAMM
b. Superantigen
c. Present in foodborne illness
d. Heat stable
3. Exfoliative Toxin:
a. Responsible for causing Scalded skin syndrome in infants and children
b. Causes boils in adults
4. Staphylokinase: Enzyme
a. Degrade clots
5. Alpha toxin:
a. Also known as the alpha hemolysin
b. Type II toxin
c. Will cause pores to form in the cytoplasmic membrane of host neutrophils and
erythrocytes
6. Other hemolysis ( beta, delta, and gamma )
a. Similar in function to the alpha hemolysin
b. Will be found in different strains of Staphylococcus aureus
7. Leukocidin:
a. Toxin that will target leukocytes, mainly phagocytes
8. Quorum signaling:
a. Small peptides and regulatory RNA molecules
b. Autoinducer 2
Staphylococcus aureus: Additional mechanisms for virulence:
1. Sequestration of epithelial cells
a. Uses MSCRAMM
2. Evasion of Neutrophil Killing
a. Blockade of neutrophil recruitment
i. CHIP: chemotaxis inhibitory protein -->counteracts pathogens
ii. EaP: Extracellular adhesion protein
b. Inhibition of antimicrobial peptide killing
i. Staphylokinase ( degrade clots )
ii. Aureolysin
iii. Surface changes
c. Neutralization of ROS
i. Catalase
ii. SOD (superoxide dismutase- neutralizes reactive O2 species)
iii. Pigment
d. Neutrophil cytolysis:
i. PSM: Phenol soluble modulin
3. Evasion of opsonophagocytosis: prevent phagocytosis trigger by the opsonization
system
