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Bacterial Infections of the Skin I Flashcards

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1
Q

what is the most common bacterial infection in children?

A

staph aureus

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2
Q
  • s. aurues
    • characteristics (gram stain, shape, ect)
    • susceptible populations
    • best defense against
    • means of spread
    • other
A
  • gram +, catalase +, cocci in clusters
  • susceptible populations - HIV infected
  • best defense - intact skin
  • spread amongst healthcare workers in hospitals major cause of spread
  • m/c childhood infection
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3
Q

MRSA infection

  • mechanism
  • susceptible populations
  • ttreatment
A
  • s. aureus becomes methicillin resistant via mecA gene, which encodes an alternative penicillin binding protein: PBP-2a
  • susceptible populations:
    • ​previous Abx use*
    • recent hospitalization / chornic illness*
    • older
  • treatment: MRSA-covering Abx + mucopiricin ointment (bactroban)
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4
Q

which patients should always be treated with mupirocin ointment 2% (bactroban)

A

patients who are

  • colonized with MRSA
  • have localized impetigo
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5
Q

impetigo contagiosa:

  • pathogenesis
  • demographics
  • presentation
  • diagnosis
  • treatment
  • prognosis / complications
A
  • pathogenesis: s. aureus > s. pyogenes -> superfiical skin infection
  • demographics: m/c in children
  • presentation: on face - perioral & perinasal- occurs in phases:
    1. 2 mm erythematous papule
    2. vesicles + bullae
    3. yellow, friable (honey-colored) crust from vesicle discharge
  • dx: n/a
  • treatment:
    • localized: class IV steroid - topical mupirocin (bactroban)
      • ​if recurrent: topical mupirocin BID to nares
    • widespread: beta-lactamase resistant PCN
    • complicated: IV ceftiaxone
  • prognosis / complications: :
    • prognosis: self resolves in 2 weeks
    • complication: post-streptococcal glomerulonephritis (no risk reduction with tx)
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6
Q

how to tx recurrent impetigo contagiosa?

A
  • topical mupirocin BID to nares for 7-10 days
  • +/- chlorohexidine washes
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7
Q

bullous impetigo

  • pathogenesis
  • demographics
  • presentation
  • diagnosis
  • treatment
  • prognosis / complications
A
  • pathogenesis: s. aureus (group phage 2 type 71)
  • demographics:
    • newborns m/c
    • adults - may be indicative of HIV
  • presentation:
    • bullae (vesicle > 1cm) that is either on the
      • ​on face, hands: in kids
      • in axilla, groin: adults
      • if large & fragile - suggests pemphigous
  • diagnosis: + culture from lesions
  • treatment: n/a
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8
Q

bullous impetio in adults

  • in common in what situations?
  • may be indicative of what etiology?
A
  • warm climates
  • HIV
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9
Q

what characteristics of a bullae indicative of pemphigous vulgaris

A
  • large
  • fragile
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10
Q

staphyloccocal scalded skin syndrome (SSSS)

  • pathogenesis
  • demographics
  • presentation
  • diagnosis
  • treatment
  • complications
A
  • pathogenesis: s. aureus (group 2 phage 71) releases exofoliative toxin which is located at a mucosal surface (i.e. not isolated in lesions) & disrupts granular layer
  • demographics:
    • neonates & children m/c
    • adults - with renal failure
  • presentation:
    • FEVER + rapid desquamation of skin
    • also:
      • skin tenderness: of neck + groin + axilla in early phases
      • + nikolsky’s sign: sloughing of upper layers of skin up contact
      • blistering beneath granular layer
      • rhinorrhea / conjunctivits
  • diagnosis: take culture from mucosal surface (intact bullae will be -)
  • treatment: oxacillin/nafcillin + HYDRATION
  • prognosis / complications:
    • prognosis: poor in adults with renal disease, good in children
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11
Q

how is the diagnosis for SSSS (staphylococcal scalded skin syndrome) made & why is this important?

A
  • must be taken from mucosal surface, b/c this is where the exofoliative toxin from s. aureus is found. cultures from intact bullae will be negative
    • ​conjunctivae
    • nasopharynx
    • feces
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12
Q

compare & contrast the diagnosis of bullous impetigo vs SSSS

A
  • both: involve obtaining a culture
    • bullous impetigo: culture from lesion
    • SSSS: culture from mucosal surface - nasopharynx, conjunctiva, feces
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13
Q

what is the treatment of SSSS?

A
  • penicillinase resistant Abx + FLUID/ELECTROLYTIC REPLACEMENT
    • Abx = nafcillin, oxacillin
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14
Q

compare & contrast TEN & SSSS based on

  • cause
  • demographics
  • histology
  • involvement of mucous membranes
  • presence of nikolsky’s sign
  • treatment
A
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15
Q

toxic shock syndrome (TSS)

  • pathogenesis
  • demographics
  • presentation
  • diagnosis
  • treatment
  • complications
A
  • pathogenesis: s. aureus exotoxin (> s. pyogenes) releases TSST-1 exotoxin, a pyrogenic toxin, leading to high fever + multisystemic disease (renal m/c)
  • demographics: young, healthy adults (menstraul or not)
  • presentation (see dx)
  • diagnosis: 3 of the following criteria must be met
    • fever: of at least 102 F
    • hypoTN: SBP < 90 or < 5th percentil in children
    • rash: diffuse macular erythroderma (staph) or scarlitinform (strep)
    • desqamation of soles & palms
    • involvement of 3 + organ systems (renal m/c)
  • treatment: clindamycin + / IV FLUIDS (hypoTN +/- removal of any foreign object
  • prognosis / complications:
    • rapidly progressive / necrotizing fascitis if s. pyogenes (group B strep) cause
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16
Q

what is the treatment of TSS

A

clindamycin +/- IV fluids (hypoTN) +/- removal of any foreign object

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17
Q

compare & contrast the presentation of TSS in menstrual vs non-menstrual patients

A
  • both:
    • febrile ( > 102 F)
    • hypotensive ( SBP < 90 / < 5th percentile)
    • rash + systemic sx
  • menstrual TSS:
    • less common
    • m/c d/t superabsorbent tampons
    • prognosis better:
  • non-menstrual TSS:
    • more common
    • m/c d/t nasal packing, surgery, infections
    • prognosis worse
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18
Q

pyogenic paronychia

  • pathogenesis
  • presentation
  • treatment
A
  • pathogenesis: host of etiological agents -> inflammation of skin folds around fingernail
  • presentation: separation of epioncyium from the nail plate
  • treatment:
    • acute infection:: 1. PCN / 1st gen ceph then 2. TMP-SMX if inneffective
    • chronic infection: requires antifungal + topical steroid
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19
Q

eryrthrasma

  • pathogenesis
  • demographics
  • presentation
  • diagnosis
  • treatment
  • complications
A
  • cornyebacterium minutissimum infects interrigionous areas
  • demographics:
    • in warm, humid climate
    • IC - obesity, DM, advanced age
  • presentation: well defined pink-red patches that -> fade to brown on the that affect the interrigionous areas: axilla + groin +toe webs (esp 4th)
  • diagnosis: wood lamp will produce coral-red color
  • treatment: 20% AlCl + topical clindamycin / erythromycin
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20
Q

pitted keratolysis

  • pathogenesis
  • demographics
  • presentation
  • diagnosis
  • treatment
A
  • pathogenesis: kryptococcus sedentarius digests keratin in stratum corneum of plantar/palmar skin
  • demographics: men with sweaty feet
  • presentation: small crateriform pits (keratin plugs) on weight-bearing plantar skin + FOUL ODOR***
  • diagnosis: woods lamp will show - no flourescence
  • treatment: AlCl / botulinum toxin (tx hyperhydrosis) + Abx
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21
Q

trichomycosis axillaris

  • pathogenesis
  • presentation
  • treatment
A
  • pathogenesis : cornyeobacteria causes a superficial infection of hair follicles
  • presentation: adherent nodules (yellow, red black) on hair shaft in armpits, &:
    • characteristic odor
    • +/- colored sweat
  • treatment: antibacterial soap
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22
Q

which skin infection (s) can cornyebacteria cause and what do they look like?

A
  • erythrasma: pink-red well defined patches -> fade to brown on groin + 4th toe web
  • trichomycosis axillaris: nodules on hair follicles im armpit + odor +/- colored sweat
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23
Q

folliculitis

  • pathogenesis
  • demographics
  • presentation
A
  • pathogenesis: bacterial infection (staph m/c, psueodmonas in pools / hot-tubs) causes infection of hair follicle
  • presentation: pustules (vesicle containing white/yellow fluid content)
  • treatment:
    • general: anti-bacterial soap TID
    • chronic folliculitis of buttocks: AlCl (Drysol) qhs
    • chronic d/t s. arueus: mupirocin 2%
    • blepharitis: opthalmic ointments
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24
Q

tx of chronic folliculitis of the buttocks?

A

Drysol (aluminum chrloride) qhs

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25
treatment of chronic folliculitis d/t staph arueus?
mupirocin
26
sycosis vulgaris * pathogenesis * presentation
* pathogenesis: ***s. aureus*** causes infection of bearded region * presentation: **pustules errupt after shaving**, leaving crop of pustules behind - common _seen on upper lip near nose_
27
# define: * abcess * furuncle * carbuncle
* abscess: localized collection of pus at _any site_ * furuncle: abcess of _hair follicles + surrounding tissue_ (only in hair-bearing areas) * carbuncle: collection of _furnicles_ that can extend into subq tissue +/- systemic sx
28
furunculosis * pathogenesis * demographics * presentation * treatment
* pathogenesis: s. arueus infects hair follicle * demographics: * alcoholism * IC - diabetes, malnutrition, immune disorders * presentation: **furcunle** (acute, inflammatory abcess) * treatment: * _general:_ **warm compress + systemic Abx** * _if localized:_ **incision & drainage then pack with idoform** * NO I&D if nasal furuncle: Abx only * _if chronic_: **mucopirocin BID to nairs + lifestyle to break cycle**: chlorhexidine wash, daily laundering of bedding & clothing, frequent hand washing
29
which type of localized furcuncle should NOT be incised & drained? how should it be treated instead?
**nasal furuncles.** can be treated with Abx ONLY
30
ecthyma * pathogenesis * demographics * presentation * diagnosis * treatment
* pathogenesis: ***s. pyogenes*****,**following scratching of bug bites**-\> ulcerative pyoderma** * demographics: **children** * presentation: **punched-out ulcers (from vesicopustules) with a purulent base** * diagnosis: wound culture confirmatory * treatment: **dicloxacillin _or_ cephalexin**
31
scarlett fever * pathogenesis * demographics * presentation * treatment * complications
* pathogenesis: s. aureus / s. pyogenes produces exotoxin * demographics: young children * presentation: * macular erythroderma or sandpaper (punctate, confluent pustule) rash * circumoral pallor * pastias lines: petichias in skin creases * palmoplantar desquamation * white or red strawberry tongue * treatment: **a penicillin (amoxicillin)** * complications: * ​glomerulonephritis * rheumatic fever
32
erysipelas * pathogenesis * demographics * presentation * diagnosis
* pathogenesis: **s. pyogenes (group A strep)** cause a _superficial variant of cellulitis_ * demographics: pts with _lymphadema_ & venous insufficiency have increased risk * presentation: * on legs \> face: * **_painful, hot, burning_ patch of skin** * **sharply defined ridge-like borders _advance_** * + very sick: fever / chills / HA (lymphocytes \> 20,000) * diagnosis: **elevated DNase B and ASO titers**
33
necrotizing fascitis * pathogenesis * demographics * presentation * diagnosis * treatment
* pathogenesis: ***s. pyogenes*** (children) / polymicrobial (adults) -\> **rapid progressive necrosis of subQ fat / fascia** * demographics: IC, following surgery * presentation: occurs in phases: * **severely painful erythematous induration - "pain _out of proportion_ to skin changes"** * RAPID decline over next 1-2 days * induration goes from erythematous to * **​****_dusky purple/gray_** * **+/- hemorraghic** * **FOUL SMELL** * **late: skin _anesthetic_ (no pain d/t destroyed nerves)** * diagnosis: MRI or probe test (lack of bleeding/resistance = ominous sign) * treatment: **extensive surgical debridement = MAINSTAY**, + * emperic IV therapy with broad spectrum coverage
34
blistering distal dactylitis * pathogenesis * demographics * presentation * treatment
* pathogenesis: ***s. pyogenes*** * demographics: 2-16 OR DM * presentation: **tense blister on volar pat pad of digit phalanx** * treatment: PCN + I&D
35
perineal dermatitis * pathogenesis * demographics * presentation * treatment * complications
* pathogenesis:s. pyro \> staph * demographics: 1- 8 years old * presentation: **sharp red plaques that** * **​surround perianal region** * **are: PAINFUL - esp on defection, often leading to _fecal retention_ by patient** * treatment: oral cefuroxime or penicillin * complications: ppp * **post-strep glomerulonephritis** * **psoriasis gluttate outbreak**
36
erythema marginatum * pathogenesis * demographics * presentation
* pathogenesis: ***streptoccocal infection*** in the **setting of ARF** * demographics: 5-15 years * presentation: **lesions that are ANNULAR + MIGRATORY + _EXPANDING_** * ​can migrate "**12mm in 12 hrs"**
37
erysipeloid of rosenbach * pathogenesis * demographics * presentation * complications
* pathogenesis: erysipelothrix rhusiopathiae (rod shaped, gram +) contracted _via an abrasin to the hand_ * demographics: **fisherman / fish handlers / poulty handlers** * presentation: **purplish swelling of hands that is _migratory_** * complications: endocarditis (rare)
38
what are the 4 signs of inflammation?
* rubor (erythema) * calor (warmth) * dolor (pain) * tumor (swelling)
39
cutaneous anthrax * pathogenesis * demographics * presentation * diagnosis * treatment
* pathogenesis: ***bacilllus anthracis*** (**gram +, spore forming rod**) * demographics: * occupational - contact with _animals_ * bioterrorism * presentation**: bullae erupt to form _eschar_ (central necrosis) that is** * NON-TENDER * tender regional lypmh nodes -\> suppurative adenitis * diagnosis: gamma bacteriophage * treatment: **PCN G 2 million units IV q 6 hrs for 4-6 days**
40
oslers node (s. aureus) nodule with white center, PAINFUL (osler = ouch)
41
janeway lesions (s. aureus) small, hemorrhagic lesions on palms/soles - PAINLESS
42
impetigo contagiosa ruptured vesicles -\> **yellow, friable (honey colored) crust** (s. aureus \> s. pyogenes)
43
impetigo contagiosa ruptured vesicles -\> **yellow, friable (honey colored) crust** (s. aureus \> s. pyogenes)
44
impetigo contagiosa ruptured vesicles -\> **yellow, friable (honey colored) crust** (s. aureus \> s. pyogenes)
45
bullous impetigo
46
SSSS - desquamation, seen in newborns
47
SSSS rhinorrhea
48
SSSS-histology subcorneal blister (in stratum granulum) with inflammatory infiltrate
49
staphyloccocal toxic shock syndrome (TSS) desquamation of the palms & soles
50
pyorgenic paronychia separation of eponychium from the nail plate
51
erythrasma (coryneobacterium) pink-red -\> brown lesions in the axilla, groin, 4th toe web
52
erythrasma (corynebacterium) wood lamp: produces _coral red_ color
53
pitted kartolysis (kytococcus sedentarius) small, crateriform pits (keratin plugs) + foul odor
54
trichomycosis axillaris (corynebacterium) adhered yellow + red + black nodules on hair shafts in axilla
55
folliculitis: cysts containing wet/yellow fluid
56
sycosis vulgaris (s. aureus) ruptured pustules following shaving that in beared region including upper lip near nose
57
chronic furunculosis acute, inflammatory abscess of hair follicles
58
ecthyma (s. pyogenes \> s. aureus) ulcerative pyoderma on the _shins_ & _dorsal feet_ following scratching of bug bites
59
erysipelas (s. pyogenes) cellulitis patch that is **painful + hot to touch + may burn**; has a _distinctive advancing edge_
60
necortizing fascitis (s. pyogenes or polymicrobial) lesions that is: erthyematous w/ disproportional pain then -\> rapidly progresses -\> dusky purple/gray + foul smelling then -\> anesthetic (numb)
61
blistering distal dactylitis (s. pyogenes) tense, superficial blister on volar pad phalanx of digit
62
perineal dermatitis superficial, perineal plaques up to 3 cm from anus -\> PAINFUL: esp on defication
63
erysipeloid of rosenbach purplish swelling of hands - common in _fisherman / fish handlers_

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