Micro Winter 11 Skin Infections

Front 1

What are the host defences that the skin has?

Back 1

Epidermis- acidic, cold, salt, fat (sebum), Normal flora to compete for sites with pathogens, Langerhans cells

Front 2

What are the 3 routes of infection for skin infections

Back 2

1. Exogenous- penetrated skin. 2. Endogenous- blood or lymph seeds the skin, can be normal flora. 3. Toxin induced- made at a distant site then causes skin infection

Front 3

What are the 4 categories of skin infection

Back 3

1. Abcess- acne, folliculitis, furnucles, carbuncles 2. Spreading- impetigo, ecthyma, erysipelas, cellulitis. 3. Necrotizing- fasciitis, myonecrosis. 4. Cutaneous response- toxic shock, scalded skin

Front 4

Ok so we know the skin is cold, salty, acidic and fatty to prevent pathogens. What are the skin environments that favor pathogens

Back 4

moist, damage, immunocomprimise, blood supply diminished

Front 5

What are some complications of discrete skin disease

Back 5

ex folliculitis, cellulitis. Can progress and get new sx or have cumulative effects. Ie damage can accumulate and its not so “discrete” anymore

Front 6

What causes acne

Back 6

propionibacterium acnes- gram +, pleomorphic bacilli. Anerobe (but can tolerate some O2). Can cause opportunistic infections in pts with prosthetic devices or IV lines

Front 7

What is the gram and shape and )O2 of propionibacterium acnes?

Back 7

Gram +, pleomorphic, aerotolerant anerobe. Normal flora. Causes opportunistic infections in pts with prosthetic devices or IV lines

Front 8

Whats the gram and other identifiers for S aureus

Back 8

Gram +, catalase +, b hemolytic. Causes abcess

Front 9

What is the gram +, catalase +, b hemolytic coci that causes abcess

Back 9

S aureus

Front 10

aureus is ID how? What are the toxins?

Back 10

Gram +, catalase +, b hemolytic. Can cause exfoliative or Pyrogenic (TSST1)

Front 11

S What is the pyrogenic skin infection caused by s aureus infections

Back 11

TSS-T1

Front 12

Ok so we knoe S aureus is gram +, catalase + and b hemolytic. What enzymes does it have?

Back 12

Coagulase- clots plasma to make local infection. Hemolysins- lyse RBC. Leukocidin (PVL)- necrotic pulm disease due to damages membranes. Hyaluronidase- spreads infection. Staphylokinase (fibrolysin)- dissolves clots to help invade host!

Front 13

What is the gram + cocci that looks like a bead of strings ? what category of infection does it cause?

Back 13

strep pyogenes. GABHS. Causes spreading infections

Front 14

What is the toxin associated with strep pyogenes (the gram + bead on string)

Back 14

1. SPE (strep pyogenes exotoxin). Erythrogenic SUPER AG, causes a rash like scarlet fever. 2. M protein- fimbriae that inhibit phago, helps invade, and creates AG that can cause HS II- acute rheumatic fever. HS III- glomerulonephritis

Front 15

What is the toxin assicated with strep pyogenes that can cause HS reactions?

Back 15

M protein, it creates antigenicity that can cause Type II- acute rheumatic fever or Type III- poststrep glomerulonephritis

Front 16

How does a rapid strep test test for strep pyogenes?

Back 16

Detects A carb in cell wall of the bug (NAG- rhamnose)

Front 17

What are the exzymes associated with strep pyogenes?

Back 17

1. DNAse- waters down lysed cell contents. 2. Hyalurinidase- spreads infection (also seen in s aureus) 3. Streptokinase- spreading, dissolves clots

Front 18

What is a... 1. Macule 2. Papules 3. Vesicle 4. Pustule

Back 18

1. Macule- flat, non palpable. 2. Papules- palpable 3. Vesicles- palpable, fluid filled 4. Pustules- palpable, pus filled

Front 19

What things contribute to acne vulgaris (an abcess)

Back 19

1. Genetics 2. Follicular epidermal hyperproliforation, can be triggered by androgen hormones 3. Excess sebum, lots of factors! 4. Propionbacterium acnes- proinflammatory. 5. Inflammation- 2nd to p acnes

Front 20

What causes acne in newborns

Back 20

maternal hormones

Front 21

Whats the progression of acne vulgaris

Back 21

1. Hair follicle, microcomedo
2. closed comedo, whitehead 3. Open comedo, blackhead  INFLAMMATORY 4. Palpule 5. Pustule

Front 22

Ok so acne begins non inflammatory, what is going on?

Back 22

Micromcomedo- follicle opening is partially obstructed by sebum, keratinocytes or hair

Front 23

What are the types of Microcomedos (recall that is just a blocked follicle)

Back 23

1. Closed- whiteheads. Sebum plug in follicular canal 2. Open comedo- blackhead. Content reaches surface, the follicle opening gets big, its full of melanin, keratinocytes, and oxidized lipids.

Front 24

Whats the junk in a white head? What about a blackhead

Back 24

1. White- closed comedo, its sebum 2. Blackhead, open comedo. Melanin, keratinocytes, oxidized lipids. Both of these are the NON INFLAMMATORY stages of acne

Front 25

What is the inflammatory stage of acne?

Back 25

Its when the comedo ruptures into the epidermis and releases FFA and proinflammatory. There are both palpules and pustules

Front 26

What happens when an open or closed comedo ruptures into the dermis

Back 26

non inflammatory to inflammatory acne. FFA are released which causes inflammation. There can be both pustules and papules present

Front 27

What is the most severe form of acne

Back 27

nodules. Painful, pus filled. Deep in skin, inflamed.

Front 28

How is acne treated?

Back 28

1. Retinoids- kill comedos and inflammation. Can be given topical or oral. 2. AB- kill p acnes. Used with benzyl peroxide to increase skin turnover. Topical or oral.

Front 29

What are the AB used to treat acne?

Back 29

Topical- erythromycin, clindamycin. Systemic- doxycycline, minocycline. Targeted to kill p acnes, can also use with benzyl peroxide to increase cell turnover

Front 30

What are the retinoids used to treat acne, how do they work?

Back 30

Topical- adapalene, tretinoin. Systemic- isotretinoin (teratogen). It is comedolytic and anti-inflammatory. Decreases stickiness of keratinocytes

Front 31

Whats it called when you have a palpule or pustule with a hair in the middle

Back 31

folliculitis. Inflammatory cells w/i wall & ostia or hair follicle. Can be found naywhere hair is and can be superficial or deep

Front 32

What are the bugs that cause folliculitis

Back 32

1. S aureus- gram +, catalase +, b hemolytic. 2. Pseudomonas: gram -, blue pus and green fluorescent siderophage. Pyocyanin and pyoverdin. Hot tub follucilitis

Front 33

Tell me about folliculitis caused by S aureus

Back 33

Sty (hordeolum) or barbers itch- impetigo of bockhart: upper lip or nose

Front 34

Whats a sty

Back 34

folliculitis caused by s aureus. S aureus folliculitis also causes rash on upper lip- barbers itch- impetigo ir bockhart

Front 35

What is hot tub folliculitis caused by?

Back 35

Pseudomonas in tubs that don’t have enough chlorine. Seen in areas near swimwear. Can have systemic: fever. HA, sore throat, GI, etc

Front 36

What is it called when there is purulent discharge from a single opening in an abscess

Back 36

boil (furuncle) common in areas with hair follicles. Caused by S aureus.

Front 37

What is a furuncle?

Back 37

Boil, local abcess that drains from a single opening. Caused by s aureus

Front 38

Whats a carbuncle

Back 38

aggregate of connected furuncles (boils). Caused by s aureus. Several pustular openings. Found in the neck back and thighs

Front 39

What might it be? 1. Large red tender mass in the axilla that drains from a single opening. 2. Cluster of #1 found in back, neck or thigh.

Back 39

1. Furuncle 2. Carbuncle. Both caused by s aureus

Front 40

How is folliculitis treated?

Back 40

AB soap, hand washing. Can use topical or oral AB (must cover MRSA)

Front 41

How are furuncles and carbuncles treated?

Back 41

Warm compress, I&D, AB

Front 42

How are recurrent furnuculosis treated?

Back 42

Mupirocin to nares, peritoneum, axilla for 5 days

Front 43

Why do we treat folliculitis, furuncles and carbuncles?

Back 43

Bc s aureus can have hematogenous spread to other areas. (recall folliculits can be s aureus or pseudomonas- hot tub)

Front 44

What is pyoderma, where is it located?

Back 44

Bacterial skin infection with pus filled leisions in epidermis and dermis. Ex non bollus impetigo and bullous impetigo

Front 45

What does this describe. A single red macule that develops quickly into a vesice/pustule, when rupture it leaves a yellow crust. Does this infection spread fast?

Back 45

Non bullous impetigo. Infectious and spreads fast. Caused by S aureus in 1 infection and GAS in 2 infection

Front 46

Describe Non bollus impetigo, what causes it?

Back 46

Single red maculae that turns into pustule nad leaves crust when it ruptures. Caused by s aureus or GAS. Spreads fast, so treat it!

Front 47

Who might get this infection. Single red maculae that turns into a pustule and leaves yellow crust.

Back 47

Non bollus impetigo. Kids under 6. Seen with: hot/humid, contact sports, poor hygiene

Front 48

Whats the difference in the causative agent in non bullous and bullous impetigo.

Back 48

Non bollus is S aureus in a primary infection but GAS in secondary. Bollus is ALWAYS s aureus

Front 49

What is more common non bullous or bullous impetigo

Back 49

non bollus.

Front 50

Describe bullous impetigo

Back 50

intraepidermal leision that starts as a single vesicle, it forms a thin white blister, this is the bullea. The blister has exfoliation toxin that stays local

Front 51

Does non bullous or bullous impetigo cause exfoliation

Back 51

bullous, local exfoliation bc of exfoliation toxins A and B from s aureus

Front 52

Who gets bullous nad non bullous impetigo. Where?

Back 52

bullous, kids under 2. Non bullous, kids under 6. Both have face and legs, non bullous is also arms

Front 53

What is an ulcerative pyoderma that extends into dermis. It has a green yellow crust and violaceous margins (raised with induration)

Back 53

Ecthyma, caused by GAS

Front 54

Ecthyma is caused by what? What does it look like?

Back 54

GAS. Ulcer that goes into dermis, green yellow crust, raised with induration. NOT contagious

Front 55

Can ecythma be passed by contact

Back 55

RARELY contagious. Caused by DM (immune compromise), poor hygiene etc. leaves a pigmented scar

Front 56

How can you get that deep nasty ulcer that is seen in ecthyma?

Back 56

Untreated impetigo, preexisting tissue damage, immunocompromised, poor hygiene (recall this one isn’t really transmissible) ppl who get it are kids, ppl with DM, neglected elderly. Leaves a pigmented scar

Front 57

If an old person with DM who is staying in a shotty life care center has a skin infection on her leg what is it likely.

Back 57

Ecthyma, the deep ulcer

Front 58

Is the treatment for impetigo and ecythma (the pyodermas) the same?

Back 58

You bet! Increase hygiene, debridement, topical AB- mupirocin, Oral AB- cephalosporin, etc

Front 59

Is the fascia involved with cellulitis?

Back 59

NO! uncomplicated nonnecrotizing imflammation, only dermis and hypodermis are affected

Front 60

Is cellulitis inflammatory?

Back 60

You bet: pain, swelling, tenderness, red, warm. HEET- hot, erythema, edema, tender

Front 61

What causes cellulitis

Back 61

1. GAS, some s aureus 2. MRSA- IV drug user, HIV, prision, athlete, military, homosexual 3. Acinetobacter baumannii- multi drug resistant. Pasteurella multocida; Aeromonas hydrophilia and Legionella sp

Front 62

What causes crepitant cellulitis

Back 62

clostridium perfringens. Can develop into myonecrosis

Front 63

When might you see a hot swollen orange skin arm

Back 63

cellulitis. There will be HEET (hot, erythema, edema, tender) the borders of the infection blend into the surrounding skin

Front 64

Is cellulitis usually local or extensive?

Back 64

Can be both! 1. Local- pain is minimal, no systemic infection, if tx works labs not necessary. 2. Extensive- you need to do the labs, but you might not ID the bug. Can turn into necrotizing fasciitis or myonecrosis

Front 65

What can extensive cellulitis turn into?

Back 65

Necrotizing fasciitis or myonecrosis. Do a lab workup for extensive cellulitis

Front 66

What is the work up involved with extensive cellulitis

Back 66

1. Gram stain exudates 2. Culture aspirate 3. CT/MRI to RO fasciitis and osteomylitis

Front 67

Cellulitis is painful, do we treat pain

Back 67

NO! no NSAIDS bc they mask worsening disease and inhibit PMN cytokine release

Front 68

Why don’t we treat pts with cellulitis NSAIDS

Back 68

they mask worsening disease and inhibit PMN cytokine release

Front 69

OK so we don’t use NSAIDS for cellulitis, how DO we treat?

Back 69

Penicillinase resistant synthetic penicillin, 1st generation cephalosporin, surgical debridement, drain pus, elevation, immobilization of limb

Front 70

What pathogen causes cellulitis if a pt had surgery 24 hours ago?

Back 70

GAS, fast progression bc it has spreading factors

Front 71

What pathogen caused cellulitis of there is not an obvious portal of entry and no obvious primary site of infection

Back 71

s aureus

Front 72

When might cellulitis be caused by: 1. GAS 2. S aureus

Back 72

1. GAS- <24 hrs post op 2. S aureus: no obvious site of entry, no obvious primary infection

Front 73

What increases risk fo cellulitis

Back 73

skin leision (varicella), immunocomprimise, chronic steroid use

Front 74

Does s aureus commonly cause cellulitis

Back 74

yes. But it spreads less and so is associated more with local abcess

Front 75

What might the bug be… Gram +, b hemolytic, cocci, coagulase +, catalase +,

Back 75

s aureus, can cause cellulitis (folliculitis  cellulitis)

Front 76

Acinetobacter baumannii causes what

Back 76

uncommon cause of cellulitis. Aerobic, gram -, associated with trauma. Multi drug resistant

Front 77

What are the uncommon bugs that cause cellulitis, usually its s aureus

Back 77

1. Acinetobacter baumannii- trauma 2. Pastuerella multocida- cat bites 3. Water bugs: aeromonas hydrophilia, legionella, vibrio vulnificus

Front 78

What is pasteurella multocida associated with?

Back 78

Cat bites (less common dog bites), purulent drainiage

Front 79

What bug might cause cellulitis associated with fresh and salt water

Back 79

Fresh: aeromonas hydrophilia, legionella Salt: vibrio vulnificus

Front 80

Compare and contrast aeromonas hydrophilia and legionella both cause cellulitis and are associated with freshwater.

Back 80

Both are motile bacilli. Aeromonas is facultative anerobe, Legionella is aerobic

Front 81

What pathogen caused cellulitis of there is not an obvious portal of entry and no obvious primary site of infection

Back 81

s aureus

Front 82

When might cellulitis be caused by: 1. GAS 2. S aureus

Back 82

1. GAS- <24 hrs post op 2. S aureus: no obvious site of entry, no obvious primary infection

Front 83

What increases risk fo cellulitis

Back 83

skin leision (varicella), immunocomprimise, chronic steroid use

Front 84

Does s aureus commonly cause cellulitis

Back 84

yes. But it spreads less and so is associated more with local abcess

Front 85

What might the bug be… Gram +, b hemolytic, cocci, coagulase +, catalase +,

Back 85

s aureus, can cause cellulitis (folliculitis  cellulitis)

Front 86

Acinetobacter baumannii causes what

Back 86

uncommon cause of cellulitis. Aerobic, gram -, associated with trauma. Multi drug resistant

Front 87

What are the uncommon bugs that cause cellulitis, usually its s aureus

Back 87

1. Acinetobacter baumannii- trauma 2. Pastuerella multocida- cat bites 3. Water bugs: aeromonas hydrophilia, legionella, vibrio vulnificus

Front 88

What is pasteurella multocida associated with?

Back 88

Cat bites (less common dog bites), purulent drainiage

Front 89

What bug might cause cellulitis associated with fresh and salt water

Back 89

Fresh: aeromonas hydrophilia, legionella Salt: vibrio vulnificus

Front 90

Compare and contrast aeromonas hydrophilia and legionella both cause cellulitis and are associated with freshwater.

Back 90

Both are motile bacilli. Aeromonas is facultative anerobe, Legionella is aerobic

Front 91

Ok so we can have cellulitis that is crepetant and associated with IV drug use, what pathogens are associated?

Back 91

Clostridium, becteroides, prevotella, peptostreptococcus, peptococcus

Front 92

What is erysipelas

Back 92

special kind of cellulitis caused by GAS and sometimes s aureus (seen in recurrent infection

Front 93

What is the prodrum of erysipelas

Back 93

its special cellulitis caused often by GAS. Chills, fever, toxicity. Spreads! Bright red painful edematous rash. Induration with sharp demarcated borders. Desquamation with resolution

Front 94

How can you tell the dif btwn cellulitis and erysipelas

Back 94

erysipelas is bright red with sharp lines of demarcation . erysipelas also affects the legs

Front 95

What is the epidemiology of erysipelas

Back 95

new virulence factors, gets the young and old. Not fatal. Resolves with desquamation

Front 96

What is the treatment for erysipelas

Back 96

AB- penicillin G for GAS, elevate affected limb (leg mostly), no immunity- reinfection is possible