Chp 12- Microbial diseases of skin and wounds

3 normal flora

1. diptherioids

2. staphylococci

3. fungi

staphylococcus aureus

1. gram +, cluster cocci

2. facultative anaerobe

3. some have capsules

4. can survive in dried pus

5. VR factors: hemolysins (beta), coagulase, hyaluronidase

6. exotoxin: exfoliatin

7. exotoxin: enterotoxin

folliculitis

• staphylococcus aureus

• infection of hair follices

• pimple

• sty (sebaceous gland of eyelash)

• abscess

• furuncles

furuncle

• staphylococcus aureus

• abscess on skin

• treated with clindamycin or warm compress

carbuncle

• staphylococcus aureus

• excessively large furuncle

• fever

scalded skin syndrome

• staphylococcus aureus

• high fever, danger of septicemia

• red peeling rash

• toxic shcok syndrome

• Exfoliatin: attacks desmosomes b/w epidermal cells. toxin made by lysogenized bacteria

impetigo

• staphylococcus aureus

• and also streptococcus

wound infections

• staphylococcus aureus

acne

• staphylococcus aureus

• growth on sebum

• Propionibacterium acnes

toxic shock syndrome

• staphylococcus aureus

• 5% fatal

• multisystem involvement

• fever

• chills

• diarrhea

Streptococcus pyogenes

• chain of cocci, gram +

• can be transmitted via fomites

• VR factors: streptokinase, hyaluronidase, C5 peptidase, M-protein, exotoxin: erythrogenic toxin, hemolysin

  • Strep pyogene- beta

  • Strep pneumoniae- alpha

scarlet fever

• Streptococcus pyogenes

• rash caused by erythrogenic toxin

• can cause glomerulonephritis, rheumatic fever, Syndeham’s chorea

erysipelas

• Streptococcus pyogenes

• superficial skin w/lymph involvement

• cellulitis= deeper in skin

• can lead to septicemia

pyoderma, impetigo

• Streptococcus pyogenes

necrotizing fasciitis

• Streptococcus pyogenes

• flash eating bacteria

• enters by using streptokinase to break down blood clots

• strong exotoxins to break down proteins

• can spread via fascia and destroy tissue

burn infections

• Pseudomonas aeruginosa

• green pigment made by pyocyanin

cat scratch fever

• Bartonella

• S: swelling, lymph node involvement

• E: cats, can be transmitted through fleas

• Th: macrolide

rocky mountain spotted fever

• Rickettsia infection

  • gram -, pleomorphic, obligate intracellular parasite

• S: rash on trunk, feet, hands, fever, headache, clotting multi-system organ damage

• Inc: 1 week

• E: biological vector

• Th: tetracycline

Lyme disease

• Borrelia burgdorferi

  • gram -, spirochete

• S: based on stages

  • erythema migrans: bulls-eye rash in first weeks

  • secondary stage involves nervous system

  • third stage: many organ system involvement, arthritis, nervous system

• E: Deer tick vector

• Th: antibiotics in first stages

cutaneous anthrax

• Bacillus anthraces

  • sheds endospores in animals

  • S: black crusty ulcer (eschars)

  • E: through wound in skin

  • Th: cephalosporins, penicillin

German measles

• Rubella virus (ssRNA + virus)

• S: rash on trunk, fever, joint pain

• Inc: 7-14 days

• E: respiratory secretions

• can lead to congenital problems (loss of hearing, heart problems), especially during 1st trimester of pregnancy.

• 4x the IgM antibodies

• prevention: MMR (attenuated virus)

Measles

• rubeola

• Inc: 8-12 days

• E: respiratory

• S: koplik spots on cheek (red spots with specks), fever, cough

• complications: pneumonia, invading other organs

  • measles encephalitis: 30% mortality

  • SSPE (subacute sclerosing panencephalitis), occurs 6-8 years later, fatal

• MMR vaccination

chicken pox

• herpes virus: varicellovirus

• Inc: 2-3 weeks

• E: respiratory or lesions

• S: rash to pustules that begin on trunk and spread. can be fatal if it plugs up blood vessels

  • Shingles (herpes zoster): recurrent latent-dormant virus infection

    • resides in ganglia, dermatome, can last up to 2 months (hyperalgia)

• Varivax: chicken pox vaccination

• Reye syndrome: neurological damage in children following chicken pox

Herpes simplex virus

• enveloped

• HHVI: in trigeminal nerve ganglion. causes oral herpes

• HHVII: in sacral verve ganglion: genital herpes

small pox

eradicated

molluscum contagiosum

• scattered white wart-like growths

• from swimming pools

warts

• Papilloma virus (dsDNA)

• remains in surrounding tissue

• genital warts: precancerous

  • Fifth’s disease: erythema infectiosum, “slapped cheeks”

  • Roseola: high fever, rash

ringworm

• dermatomycosis

  • tinea coporis

  • tinea cruris

  • tinea unguium

  • tinea capitis

  • tinia pedis (athlete’s foot)

• treated with clotrimazole or griseofulvin

tinea (pityriasis) versicolor

• leads to patches of skin w/different pigmentation

• Th: antifungal topical drugs (imidazoles)

candidiasis

• yeast

• thrush mouth

• vaginitis

• can develop into systemic disease

gas gangrene

• caused by Clostridium perfringens toxin

• anaerobic

• endospores

• foul odor

• high fever

• ischemia → necrosis

tetanus

• caused by Clostridium tetani

• tetanospasmin: blocks inhibitory neurotransmitters to motor neurons and lead to painful muscle spasms

• Th: antitoxin

Pasteurella

• gram - in many animal bites

Bartonella

• cat- scratch fever

• lymph node enlargement in children

• Th: ampicillin

chiggers (mite larvae)

• form a tube and make a protective wall around it and live in while feeding off hosts blood

• leads to inflammation and itching

scabies

• mites cause itching and scratching that lead to secondary bacterial infections

• lays eggs in skin and burrows

• treated topically

pediculosis

• lice that glue eggs to hair