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96 Cards in this Set
- Front
- Back
What are the host defences that the skin has?
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Epidermis- acidic, cold, salt, fat (sebum), Normal flora to compete for sites with pathogens, Langerhans cells
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What are the 3 routes of infection for skin infections
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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
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What are the 4 categories of skin infection
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1. Abcess- acne, folliculitis, furnucles, carbuncles 2. Spreading- impetigo, ecthyma, erysipelas, cellulitis. 3. Necrotizing- fasciitis, myonecrosis. 4. Cutaneous response- toxic shock, scalded skin
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Ok so we know the skin is cold, salty, acidic and fatty to prevent pathogens. What are the skin environments that favor pathogens
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moist, damage, immunocomprimise, blood supply diminished
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What are some complications of discrete skin disease
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ex folliculitis, cellulitis. Can progress and get new sx or have cumulative effects. Ie damage can accumulate and its not so “discrete” anymore
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What causes acne
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propionibacterium acnes- gram +, pleomorphic bacilli. Anerobe (but can tolerate some O2). Can cause opportunistic infections in pts with prosthetic devices or IV lines
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What is the gram and shape and )O2 of propionibacterium acnes?
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Gram +, pleomorphic, aerotolerant anerobe. Normal flora. Causes opportunistic infections in pts with prosthetic devices or IV lines
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Whats the gram and other identifiers for S aureus
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Gram +, catalase +, b hemolytic. Causes abcess
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What is the gram +, catalase +, b hemolytic coci that causes abcess
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S aureus
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aureus is ID how? What are the toxins?
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Gram +, catalase +, b hemolytic. Can cause exfoliative or Pyrogenic (TSST1)
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S What is the pyrogenic skin infection caused by s aureus infections
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TSS-T1
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Ok so we knoe S aureus is gram +, catalase + and b hemolytic. What enzymes does it have?
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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!
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What is the gram + cocci that looks like a bead of strings ? what category of infection does it cause?
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strep pyogenes. GABHS. Causes spreading infections
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What is the toxin associated with strep pyogenes (the gram + bead on string)
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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
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What is the toxin assicated with strep pyogenes that can cause HS reactions?
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M protein, it creates antigenicity that can cause Type II- acute rheumatic fever or Type III- poststrep glomerulonephritis
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How does a rapid strep test test for strep pyogenes?
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Detects A carb in cell wall of the bug (NAG- rhamnose)
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What are the exzymes associated with strep pyogenes?
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1. DNAse- waters down lysed cell contents. 2. Hyalurinidase- spreads infection (also seen in s aureus) 3. Streptokinase- spreading, dissolves clots
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What is a... 1. Macule 2. Papules 3. Vesicle 4. Pustule
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1. Macule- flat, non palpable. 2. Papules- palpable 3. Vesicles- palpable, fluid filled 4. Pustules- palpable, pus filled
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What things contribute to acne vulgaris (an abcess)
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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
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What causes acne in newborns
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maternal hormones
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Whats the progression of acne vulgaris
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1. Hair follicle, microcomedo
2. closed comedo, whitehead 3. Open comedo, blackhead INFLAMMATORY 4. Palpule 5. Pustule |
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Ok so acne begins non inflammatory, what is going on?
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Micromcomedo- follicle opening is partially obstructed by sebum, keratinocytes or hair
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What are the types of Microcomedos (recall that is just a blocked follicle)
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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.
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Whats the junk in a white head? What about a blackhead
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1. White- closed comedo, its sebum 2. Blackhead, open comedo. Melanin, keratinocytes, oxidized lipids. Both of these are the NON INFLAMMATORY stages of acne
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What is the inflammatory stage of acne?
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Its when the comedo ruptures into the epidermis and releases FFA and proinflammatory. There are both palpules and pustules
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What happens when an open or closed comedo ruptures into the dermis
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non inflammatory to inflammatory acne. FFA are released which causes inflammation. There can be both pustules and papules present
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What is the most severe form of acne
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nodules. Painful, pus filled. Deep in skin, inflamed.
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How is acne treated?
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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.
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What are the AB used to treat acne?
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Topical- erythromycin, clindamycin. Systemic- doxycycline, minocycline. Targeted to kill p acnes, can also use with benzyl peroxide to increase cell turnover
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What are the retinoids used to treat acne, how do they work?
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Topical- adapalene, tretinoin. Systemic- isotretinoin (teratogen). It is comedolytic and anti-inflammatory. Decreases stickiness of keratinocytes
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Whats it called when you have a palpule or pustule with a hair in the middle
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folliculitis. Inflammatory cells w/i wall & ostia or hair follicle. Can be found naywhere hair is and can be superficial or deep
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What are the bugs that cause folliculitis
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1. S aureus- gram +, catalase +, b hemolytic. 2. Pseudomonas: gram -, blue pus and green fluorescent siderophage. Pyocyanin and pyoverdin. Hot tub follucilitis
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Tell me about folliculitis caused by S aureus
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Sty (hordeolum) or barbers itch- impetigo of bockhart: upper lip or nose
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Whats a sty
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folliculitis caused by s aureus. S aureus folliculitis also causes rash on upper lip- barbers itch- impetigo ir bockhart
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What is hot tub folliculitis caused by?
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Pseudomonas in tubs that don’t have enough chlorine. Seen in areas near swimwear. Can have systemic: fever. HA, sore throat, GI, etc
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What is it called when there is purulent discharge from a single opening in an abscess
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boil (furuncle) common in areas with hair follicles. Caused by S aureus.
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What is a furuncle?
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Boil, local abcess that drains from a single opening. Caused by s aureus
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Whats a carbuncle
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aggregate of connected furuncles (boils). Caused by s aureus. Several pustular openings. Found in the neck back and thighs
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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.
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1. Furuncle 2. Carbuncle. Both caused by s aureus
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How is folliculitis treated?
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AB soap, hand washing. Can use topical or oral AB (must cover MRSA)
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How are furuncles and carbuncles treated?
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Warm compress, I&D, AB
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How are recurrent furnuculosis treated?
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Mupirocin to nares, peritoneum, axilla for 5 days
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Why do we treat folliculitis, furuncles and carbuncles?
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Bc s aureus can have hematogenous spread to other areas. (recall folliculits can be s aureus or pseudomonas- hot tub)
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What is pyoderma, where is it located?
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Bacterial skin infection with pus filled leisions in epidermis and dermis. Ex non bollus impetigo and bullous impetigo
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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?
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Non bullous impetigo. Infectious and spreads fast. Caused by S aureus in 1 infection and GAS in 2 infection
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Describe Non bollus impetigo, what causes it?
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Single red maculae that turns into pustule nad leaves crust when it ruptures. Caused by s aureus or GAS. Spreads fast, so treat it!
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Who might get this infection. Single red maculae that turns into a pustule and leaves yellow crust.
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Non bollus impetigo. Kids under 6. Seen with: hot/humid, contact sports, poor hygiene
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Whats the difference in the causative agent in non bullous and bullous impetigo.
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Non bollus is S aureus in a primary infection but GAS in secondary. Bollus is ALWAYS s aureus
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What is more common non bullous or bullous impetigo
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non bollus.
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Describe bullous impetigo
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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
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Does non bullous or bullous impetigo cause exfoliation
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bullous, local exfoliation bc of exfoliation toxins A and B from s aureus
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Who gets bullous nad non bullous impetigo. Where?
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bullous, kids under 2. Non bullous, kids under 6. Both have face and legs, non bullous is also arms
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What is an ulcerative pyoderma that extends into dermis. It has a green yellow crust and violaceous margins (raised with induration)
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Ecthyma, caused by GAS
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Ecthyma is caused by what? What does it look like?
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GAS. Ulcer that goes into dermis, green yellow crust, raised with induration. NOT contagious
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Can ecythma be passed by contact
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RARELY contagious. Caused by DM (immune compromise), poor hygiene etc. leaves a pigmented scar
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How can you get that deep nasty ulcer that is seen in ecthyma?
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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
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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.
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Ecthyma, the deep ulcer
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Is the treatment for impetigo and ecythma (the pyodermas) the same?
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You bet! Increase hygiene, debridement, topical AB- mupirocin, Oral AB- cephalosporin, etc
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Is the fascia involved with cellulitis?
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NO! uncomplicated nonnecrotizing imflammation, only dermis and hypodermis are affected
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Is cellulitis inflammatory?
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You bet: pain, swelling, tenderness, red, warm. HEET- hot, erythema, edema, tender
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What causes cellulitis
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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
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What causes crepitant cellulitis
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clostridium perfringens. Can develop into myonecrosis
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When might you see a hot swollen orange skin arm
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cellulitis. There will be HEET (hot, erythema, edema, tender) the borders of the infection blend into the surrounding skin
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Is cellulitis usually local or extensive?
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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
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What can extensive cellulitis turn into?
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Necrotizing fasciitis or myonecrosis. Do a lab workup for extensive cellulitis
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What is the work up involved with extensive cellulitis
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1. Gram stain exudates 2. Culture aspirate 3. CT/MRI to RO fasciitis and osteomylitis
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Cellulitis is painful, do we treat pain
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NO! no NSAIDS bc they mask worsening disease and inhibit PMN cytokine release
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Why don’t we treat pts with cellulitis NSAIDS
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they mask worsening disease and inhibit PMN cytokine release
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OK so we don’t use NSAIDS for cellulitis, how DO we treat?
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Penicillinase resistant synthetic penicillin, 1st generation cephalosporin, surgical debridement, drain pus, elevation, immobilization of limb
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What pathogen causes cellulitis if a pt had surgery 24 hours ago?
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GAS, fast progression bc it has spreading factors
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What pathogen caused cellulitis of there is not an obvious portal of entry and no obvious primary site of infection
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s aureus
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When might cellulitis be caused by: 1. GAS 2. S aureus
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1. GAS- <24 hrs post op 2. S aureus: no obvious site of entry, no obvious primary infection
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What increases risk fo cellulitis
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skin leision (varicella), immunocomprimise, chronic steroid use
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Does s aureus commonly cause cellulitis
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yes. But it spreads less and so is associated more with local abcess
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What might the bug be… Gram +, b hemolytic, cocci, coagulase +, catalase +,
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s aureus, can cause cellulitis (folliculitis cellulitis)
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Acinetobacter baumannii causes what
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uncommon cause of cellulitis. Aerobic, gram -, associated with trauma. Multi drug resistant
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What are the uncommon bugs that cause cellulitis, usually its s aureus
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1. Acinetobacter baumannii- trauma 2. Pastuerella multocida- cat bites 3. Water bugs: aeromonas hydrophilia, legionella, vibrio vulnificus
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What is pasteurella multocida associated with?
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Cat bites (less common dog bites), purulent drainiage
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What bug might cause cellulitis associated with fresh and salt water
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Fresh: aeromonas hydrophilia, legionella Salt: vibrio vulnificus
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Compare and contrast aeromonas hydrophilia and legionella both cause cellulitis and are associated with freshwater.
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Both are motile bacilli. Aeromonas is facultative anerobe, Legionella is aerobic
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What pathogen caused cellulitis of there is not an obvious portal of entry and no obvious primary site of infection
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s aureus
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When might cellulitis be caused by: 1. GAS 2. S aureus
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1. GAS- <24 hrs post op 2. S aureus: no obvious site of entry, no obvious primary infection
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What increases risk fo cellulitis
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skin leision (varicella), immunocomprimise, chronic steroid use
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Does s aureus commonly cause cellulitis
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yes. But it spreads less and so is associated more with local abcess
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What might the bug be… Gram +, b hemolytic, cocci, coagulase +, catalase +,
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s aureus, can cause cellulitis (folliculitis cellulitis)
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Acinetobacter baumannii causes what
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uncommon cause of cellulitis. Aerobic, gram -, associated with trauma. Multi drug resistant
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What are the uncommon bugs that cause cellulitis, usually its s aureus
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1. Acinetobacter baumannii- trauma 2. Pastuerella multocida- cat bites 3. Water bugs: aeromonas hydrophilia, legionella, vibrio vulnificus
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What is pasteurella multocida associated with?
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Cat bites (less common dog bites), purulent drainiage
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What bug might cause cellulitis associated with fresh and salt water
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Fresh: aeromonas hydrophilia, legionella Salt: vibrio vulnificus
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Compare and contrast aeromonas hydrophilia and legionella both cause cellulitis and are associated with freshwater.
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Both are motile bacilli. Aeromonas is facultative anerobe, Legionella is aerobic
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Ok so we can have cellulitis that is crepetant and associated with IV drug use, what pathogens are associated?
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Clostridium, becteroides, prevotella, peptostreptococcus, peptococcus
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What is erysipelas
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special kind of cellulitis caused by GAS and sometimes s aureus (seen in recurrent infection
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What is the prodrum of erysipelas
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its special cellulitis caused often by GAS. Chills, fever, toxicity. Spreads! Bright red painful edematous rash. Induration with sharp demarcated borders. Desquamation with resolution
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How can you tell the dif btwn cellulitis and erysipelas
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erysipelas is bright red with sharp lines of demarcation . erysipelas also affects the legs
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What is the epidemiology of erysipelas
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new virulence factors, gets the young and old. Not fatal. Resolves with desquamation
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What is the treatment for erysipelas
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AB- penicillin G for GAS, elevate affected limb (leg mostly), no immunity- reinfection is possible
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