MICROBIO 5.3

Staphylococcus

Commensal bacteria

Bacteria that neither harms or helps the host UNLESS 1) there is break in mucus membrane or 2) immunocompromised

Staph is found on ___% of humans

30

Staph gram status

positive

Staph motility

nonmotile

Staph shape

Cocci in clusters

Staph catalase activity

positive; bubble! (NOT Strep)

Staph oxidase activity

negative

Staph oxygen requirements

Facultative anaerobe (like Strep)

Staph coagulase activity

positive (can clot blod)

Staph culturing reqs

selective via bile salts

Staph hemolytic pattern

beta hemolysis

Staph virulence factors

1. Coagulase —> clots blood to help avoid bacteria from phagocytosis

2. Catalase —> break down reactive oxygen species (hydrogen peroxide, which phagocytes use)

3. Enzymes to break down blood clots (release bacteria from wound

4. Pyogenic toxin: Stimulates fever, rash, shock

5. Exfoliative toxin: separates upper epidermis from rest of skin (e.g. scalded skin syndrome)

6. Hyaluronidase: breaks down connective tissues (unlike Strep, which HAS hyaluronic capsule)

7. Hemolysin —> lyse RBC

8. Lipase —> digest lipids in tissues

Folliculitis

Infected hair follicles; red, swollen, pus-filled

**If on eyelid, stye

Boil

When folliculitis infection spreads to surrounding tissue

Carbuncle

When boils join together

Can trigger fever & chills as carbuncle spreads to deep tissue

What is responsible for folliculitis?

Staph aureus

Scalded skin syndrome

Staph infection that causes skin to redden, form blisters, then peel; skin lacks protective barrier and secondary infection becomes a risk

Usually on infants

What is responsible for scalded skin syndrome?

S. aureus; exfoliative toxins from Staph

Impentigo

Red, itchy skin with pus filled vesicles on face or extremities (limbs)

If ruptured/scratched, fluid can spread infection to other parts of the body or other people

Usually 2-5 yr olds

What is responsible for impentigo?

S. aureus

Treatment for impentigo

Penicillin

Conjunctivitis

Infection in conjunctiva —> transparent layer of tissue covering white of eye (sclera) and inner surface of eyelid

AKA Pink eye

Symptom of conjunctivitis

Eye is pink/red color (inflammation of blood vessels; dilation)

Sticky, pus like discharge

pain, burning itching of eye

Ophthalmia Neonatorum

Conjunctivitis in newborns caused by chlamydia/gonorrhea in birth canal

Can cause permanent eye damage

What is a common practice to prevent Ophthalmia Neonatorum

Prophylactic antibiotic or neomycin is put into newborn eyes.