bacterial/viral infections of skin (8)

Question 1

what are the virulence factors of S. aureus?

Answer 1

Protein A, capsule, coagulase

Toxins: DNAse, enterotoxin, exfoliatin (causes skin lesions), leuokocidin, TSS

Question 2

what is the reservoir and transmission of S. aureus?

Answer 2

• Nasal carriers will transmit to susceptible site

- Infected patient can transmit via direct and indirect contact

Question 3

what infection is the following describing:
“contagious childhood infection (spread via direct & indirect). Usually starts infection around the nostrils. Mix of step and staph infection”

Answer 3

impetigo

Question 4

describe the rash in impetigo

Answer 4

• Yellow crusted skin lesions can spread across face and appear on trunk & limbs
• Some cases can show severe bullae (associated with S. aueres due to exfoliatin)

Question 5

whats the main way to diagnose impetigo?

Answer 5

clinical appearance hx

Question 6

if you cultured impetigo, what would you see?

Answer 6

• Yellow crusted skin lesions can spread across face and appear on trunk & limbs
• Some cases can show severe bullae (associated with S. aueres due to exfoliatin)

Question 7

how would you treat a mild case of impetigo?

Answer 7

mupirocin ointment topically

Question 8

how would you treat a severe case of impetigo?

Answer 8

penicillinase resistant penicillins (nafcillin or oxacillin) or amoxicillin with penicillinase inhibitor or cephalosporins

Question 9

how would you treat an extensive or drug resistant case of impetigo?

Answer 9

get sensitivity test and prescribe appropriately

Question 10

describe the prevention for impetigo

Answer 10

cover lesions, discard dressings, isolate infected children, no sharing of towels, clothing, laundry for infected clothing, wash hands, treat carriers topically: mupirocin

Question 11

what two materials can staph grow on in piercings?

Answer 11

plastic and nyelon

Question 12

what is the infection in piercings?

Answer 12

cogaulase negative Staph epidermidis

Question 13

if you cultured the piercing infection, what would you see?

Answer 13

gram + cocci growing in clumps, catalase positive, coagulase negative, non hemolytic

Question 14

how do you treat a piercing infection?

Answer 14

take piercing out. You cannot the infection otherwise. Elimination of biofilms by cleaning and antibiotics is not likely effective

Question 15

describe the lesion in scabes

Answer 15

Produces linear lesions which itch severely due to cell mediated hypersensitivity. Worse at night. Typically wrists or genitals

Question 16

how do you diagnose scabes?

Answer 16

clinical findings, plus observation of mites in skin scrapings

Question 17

how do you treat scabes

Answer 17

topical steroids for itching. Permethrin to kill mites

Question 18

what are furunculitis?

Answer 18

infections of hair follicles

Question 19

what is an infection in the eye lash follicle called?

Answer 19

a sty

Question 20

how do you diagnose a furunculitis?

Answer 20

clinical apperance and hx

Question 21

if you cultured a furunculitis, what would you see?

Answer 21

Smears from pus show mixed bacterial populations including gram + cocci, coagulase positive and beta hemolytic, DNAse positive, salt resistant, along with other organisms

Question 22

how do you treat furunculitis?

Answer 22

drain abscess, remove dead tissue, cover with dressing

mupirocin ointment for mild cases

Question 23

why cant you give mupirocin orally or in IV?

Answer 23

because it is broken down too quickly

Question 24

what is a way to prevent furunculitis and impetigo?

Answer 24

Remove carriers from ICUs, operating rooms and newborn nurseries. Carrier state can usually be eliminated with mupirocin

Question 25

what disease is the following describing
“widespread exfoliation due to a localized infection by S. aureus. The exfoliatin toxin causes separation between epidermal cells. Usually seen in newborns. The skin that is peeling off can be sterile because the infection is else where”

Answer 25

scalded skin syndrome

Question 26

why does scalded skin syndrome have a good prognosis?

Answer 26

because the infection is superficial

Question 27

what disease is the following describing:

“systemic immune reaction to super antigen toxic shock syndrome toxin or streptococcal toxic shock syndrome toxin”

Answer 27

exfoliating rash of TSS

Question 28

describe cellulitis/erysipelas

Answer 28

Infections beneath the surface of the skin that spreads in a diffuse manner. Eryisipelas is superficial. Cellulitis is deeper and associated with lymphadenopathy, fever and bacteremia.

Question 29

what is the organism in necrotizing fascitis

Answer 29

group A streptococcus or C. perfringes if gas gangrene

Question 30

describe the rash in necrotizing fascitis

Answer 30

starts as minor skin infection which becomes rapidly extensive, spreading through the subcutaneous fascia with widespread necrosis and gangrene of extremities

Question 31

what antibiotics are used to treat erysipelas & cellulitis

Answer 31

penicillin or cephalosporin

Question 32

when do post surgical infections usually arise?

Answer 32

5 days to 2 weeks after surgery

Question 33

what disease is the following describing:
“condition analogous to rheumatic fever but tends to follow skin infections rather than pharyngitis. Associated with particular protein M types”

Answer 33

post streptococcal nephritis