Skin- Bacteria Flashcards
What gram stain is Staph Aureus
+
Is Staph Aureus thick or thin walled
Thick
Where are the granulocytes for Staph Aureus found
Intracellularly
What hemolytic is Staph Aureus
Beta
What kind of agar does Staph Aureus grow on
Blood agar
Is Staph Aureus aerobic or anerobic
Aerobic
What color colonies does Staph Aureus grow
White, becomes yellow with age
What catalase and coagulase is S. Aureus
Positive
Is Staph Aureus found normally on the body
Yes found in anterior nares for 30% of population
What is the mechanism of escape for Staph Aureus
Staph in general is coated with fibrin, makes it resistant to phagocytosis
What are other biologically active substances in Staph Aureus
Hemolysins Hyaluronidase Nuclease Lipase Protease
What is the toxin found in S. Aureus
Alpha toxin (Cytotoxin)
What is the action of the toxin found in S. Aureus
Causes necrosis/ Death
Membranes leak
Causes RBCs to lyse
What kind of toxin is Panton- Valentine Leukocidin
Cytotoxin
What is the action of Panton Valentine Leukocidin
Lyses neutrophils, damages host cells
What diseases are associated with Panton Valentine Leukocidin
Pneumonia
Skin Infections
MRSA
What is the virulence of S. Aureus
10^5- 10^6 to start infection
10^ 2 if a suture is present
How does Staph cellulitis act?
Alternates btwn walling off and rapid extension of infection
What is a furuncle what infection causes it
Boil in hair follicle
Can give rise to stye
Staph
Where are carbuncles mostly found?
Back of the neck, formed from furuncle
What causes Chronic furunculosis
Delayed hypersensitivity to staphylococcal
Responsible for inflammation and necrosis
What disease is chronic staph associated with
Chronic granulomatous Dx
Diabetes
Impetigo is a bacterial infection composed of what
S. Aureus, 30% of the time found with streptococci
What is bullous impetigo
Caused by S. Aureus, causes skin to exfoliate.
Blisters contain many staphylococci
Where do the majority of wound infections come from
S. Aureus.
Patients own strain
Hospital acquired
When do you find Staphylococcal pneumonia
Secondary to another lung injury: influenza, aspiration
What causes scalded skin syndrome
S. Aureus
How does Scalded skin present
Toxin absorbed into blood causing erythema and intraepidermal desquamation
What causes Exfoliatins?
S. Aureus
How does exfoliatins present?
Intercellular splitting of epidermis
Split between Statum Spinosum and stratum granulosum
Disruption of intercellular junctions
What infection causes toxic shock
S. Aureus
What are some signs of toxic shock
Rash
Strawberry tongue
How is rash from toxic shock differ from scalded skin syndrome
Rash develops then desquamation at deeper levels than scalded skin syndrome
Pyrogenic exotoxin
Toxic shock syndrome toxin 1
Stimulates cytokines
Direct toxic effect on endothelial cells
Pathogenicity of Pyrogenic exotoxin
Similar to exotoxin of Group A strep
Stimulates enhanced T lymphocytes
Treatment for S. Aureus
Methicillin
Many strains resistant: MRSA