Bacterial Infections of the Skin I Flashcards
what is the most common bacterial infection in children?
staph aureus
- s. aurues
- characteristics (gram stain, shape, ect)
- susceptible populations
- best defense against
- means of spread
- other
- 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
MRSA infection
- mechanism
- susceptible populations
- ttreatment
- 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)
which patients should always be treated with mupirocin ointment 2% (bactroban)
patients who are
- colonized with MRSA
- have localized impetigo
impetigo contagiosa:
- pathogenesis
- demographics
- presentation
- diagnosis
- treatment
- prognosis / complications
- pathogenesis: s. aureus > s. pyogenes -> superfiical skin infection
- demographics: m/c in children
- presentation: on face - perioral & perinasal- occurs in phases:
- 2 mm erythematous papule
- vesicles + bullae
- 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
-
localized: class IV steroid - topical mupirocin (bactroban)
- prognosis / complications: :
- prognosis: self resolves in 2 weeks
- complication: post-streptococcal glomerulonephritis (no risk reduction with tx)
how to tx recurrent impetigo contagiosa?
- topical mupirocin BID to nares for 7-10 days
- +/- chlorohexidine washes
bullous impetigo
- pathogenesis
- demographics
- presentation
- diagnosis
- treatment
- prognosis / complications
- 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
-
bullae (vesicle > 1cm) that is either on the
- diagnosis: + culture from lesions
- treatment: n/a
bullous impetio in adults
- in common in what situations?
- may be indicative of what etiology?
- warm climates
- HIV
what characteristics of a bullae indicative of pemphigous vulgaris
- large
- fragile
staphyloccocal scalded skin syndrome (SSSS)
- pathogenesis
- demographics
- presentation
- diagnosis
- treatment
- complications
- 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
how is the diagnosis for SSSS (staphylococcal scalded skin syndrome) made & why is this important?
- 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
compare & contrast the diagnosis of bullous impetigo vs SSSS
- both: involve obtaining a culture
- bullous impetigo: culture from lesion
- SSSS: culture from mucosal surface - nasopharynx, conjunctiva, feces
what is the treatment of SSSS?
-
penicillinase resistant Abx + FLUID/ELECTROLYTIC REPLACEMENT
- Abx = nafcillin, oxacillin
compare & contrast TEN & SSSS based on
- cause
- demographics
- histology
- involvement of mucous membranes
- presence of nikolsky’s sign
- treatment
toxic shock syndrome (TSS)
- pathogenesis
- demographics
- presentation
- diagnosis
- treatment
- complications
- 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
what is the treatment of TSS
clindamycin +/- IV fluids (hypoTN) +/- removal of any foreign object
compare & contrast the presentation of TSS in menstrual vs non-menstrual patients
- 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
pyogenic paronychia
- pathogenesis
- presentation
- treatment
- 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
eryrthrasma
- pathogenesis
- demographics
- presentation
- diagnosis
- treatment
- complications
- 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
pitted keratolysis
- pathogenesis
- demographics
- presentation
- diagnosis
- treatment
- 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
trichomycosis axillaris
- pathogenesis
- presentation
- treatment
- 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
which skin infection (s) can cornyebacteria cause and what do they look like?
- 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
folliculitis
- pathogenesis
- demographics
- presentation
- 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
tx of chronic folliculitis of the buttocks?
Drysol (aluminum chrloride) qhs
treatment of chronic folliculitis d/t staph arueus?
mupirocin
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
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
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
which type of localized furcuncle should NOT be incised & drained?
how should it be treated instead?
nasal furuncles. can be treated with Abx ONLY
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
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
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)
- on legs > face:
- diagnosis: elevated DNase B and ASO titers
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
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
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
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”
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)
what are the 4 signs of inflammation?
- rubor (erythema)
- calor (warmth)
- dolor (pain)
- tumor (swelling)
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
oslers node (s. aureus)
nodule with white center, PAINFUL (osler = ouch)
janeway lesions (s. aureus)
small, hemorrhagic lesions on palms/soles - PAINLESS
impetigo contagiosa
ruptured vesicles -> yellow, friable (honey colored) crust (s. aureus > s. pyogenes)
impetigo contagiosa
ruptured vesicles -> yellow, friable (honey colored) crust (s. aureus > s. pyogenes)
impetigo contagiosa
ruptured vesicles -> yellow, friable (honey colored) crust (s. aureus > s. pyogenes)
bullous impetigo
SSSS - desquamation, seen in newborns
SSSS
rhinorrhea
SSSS-histology
subcorneal blister (in stratum granulum) with inflammatory infiltrate
staphyloccocal toxic shock syndrome (TSS)
desquamation of the palms & soles
pyorgenic paronychia
separation of eponychium from the nail plate
erythrasma (coryneobacterium)
pink-red -> brown lesions in the axilla, groin, 4th toe web
erythrasma (corynebacterium)
wood lamp: produces coral red color
pitted kartolysis (kytococcus sedentarius)
small, crateriform pits (keratin plugs) + foul odor
trichomycosis axillaris (corynebacterium)
adhered yellow + red + black nodules on hair shafts in axilla
folliculitis: cysts containing wet/yellow fluid
sycosis vulgaris (s. aureus)
ruptured pustules following shaving that in beared region including upper lip near nose
chronic furunculosis
acute, inflammatory abscess of hair follicles
ecthyma (s. pyogenes > s. aureus)
ulcerative pyoderma on the shins & dorsal feet following scratching of bug bites
erysipelas (s. pyogenes)
cellulitis patch that is painful + hot to touch + may burn; has a distinctive advancing edge
necortizing fascitis (s. pyogenes or polymicrobial)
lesions that is: erthyematous w/ disproportional pain then -> rapidly progresses -> dusky purple/gray + foul smelling then -> anesthetic (numb)
blistering distal dactylitis (s. pyogenes)
tense, superficial blister on volar pad phalanx of digit
perineal dermatitis
superficial, perineal plaques up to 3 cm from anus -> PAINFUL: esp on defication
erysipeloid of rosenbach
purplish swelling of hands - common in fisherman / fish handlers
