BUGS, FUNGUS AND CRITTERS
Transcript of BUGS, FUNGUS AND CRITTERS
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BUGS, FUNGUS AND CRITTERS
Sierra Wolter MD, FAAD
Phoenix Children’s Hospital Medical Group
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OBJECTIVES
• Recognize physical exam clues that aid in the diagnosis of common cutaneous
infections.
• Become familiar with bedside diagnostic tests used in pediatric dermatology.
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OUTLINE
• Bugs
• Staphylococcus
• Streptococcus
• Fungus
• Yeast
• Dermatophytes
• Critters
• Scabies
• Insects
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PLEASE NOTE
• Photos are NOT included in the printed material. This is because I do not own
publication rights to most of the photos used in the lecture.
• Some good resources to find corresponding photos (because google is usually
wrong with derm things)
• Visual DX (web and app based paid program)
• DermNetNZ.org (free)
• Dermis.net (free)
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BUGS
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STAPHYLOCOCCUS STREPTOCOCCUS
BACTERIA
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IMPETIGO
• Most commonly occurs on sites of
disrupted skin barrier (eczema, bite,
scratch)
• Head and neck (especially perinasal)
• Morphology
• ‘Honey crusting’
• Scab or crust
• Bullae, erosions, vesicles
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IMPETIGO
• Staph aureus >> strep pyogenes (80%> 30%)
• May be multiple organisms
• Treatment
• Culture
• Topical antibiotics
• Oral antibiotics (widespread, resistant organisms, strep pyogenes, bullous forms)
• Less often MRSA (unless you see pustules)
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IMPETIGO
• Sequelae (rarely)
• Post-strep glomerulonephritis
• Guttate psoriasis
• NOT rheumatic fever
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HOW TO GET A GOOD SKIN CULTURE
• For dry or crusted lesions, moisten the
tip of the swab (H2O or culture media)
first
• Rub hard
• Rupture any vesicle or pustules – culture
swab, an 11 blade or a sterile needle –
and gather extruded material
• More is always better
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CELLULITIS
• Edema + erythema + warmth
• Usually tender or painful
• May observe purulence, drainage, peau
d’orange
• Look for predisposing factors
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NOT CELLULITIS
• Insect bites
• Grouped and itchy
• Contact dermatitis
• Itchy and demarcated
• Stasis dermatitis
• Bilateral lower legs in high risk individual
(related to chronic edema or poor venous
return)
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BLISTERING DISTAL DACTYLITIS
• Blistering of distal fat pad and periungual
skin
• Strep > staph
• Treatment
• Drain and culture
• Warm compresses
• Oral antibiotics
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NOT BLISTERING DISTAL DACTYLITIS
• Herpetic whitlow
• Intact vesiculopustules, edema and pain
• Look for HSV lesions in/near mouth
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STAPHYLOCOCCUS AUREUS
• Skin
• Impetigo
• Cellulitis
• Blistering distal dactylitis
• Folliculitis
• Abscesses and Furuncles
• Systemic
• Staph scalded skin syndrome
• Toxic shock syndrome
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STAPHYLOCOCCUS AUREUS
• Skin
• Impetigo
• Cellulitis
• Blistering distal dactylitis
• Folliculitis
• Abscesses and Furuncles
• Systemic
• Staph scalded skin syndrome
• Toxic shock syndrome
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FOLLICULITIS
• Inflammation of hair follicles
• Hair bearing sites
• Causes: staph, pityrosporum, sterile
• Treatment
• Culture (sometimes)
• Antiseptic wash (benzoyl peroxide, chlorhexidine)
• Topical antibiotics
• Oral antibiotics (short-term)
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ABSCESSES, FURUNCLES, CARBUNCLES
• Tender, fluctuant, red nodule(s) with
central pustule
• Often community acquired MRSA
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ABSCESSES, FURUNCLES, CARBUNCLES
• Treatment
• Incision and drainage with culture
• Addition of oral antibiotics for some
patients
• Conflicting evidence
• Most authors suggest if > 5cm, facial,
surrounding cellulitis or high risk
comorbidities
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ABSCESSES, FURUNCLES, CARBUNCLES
• Post-treatment or prevention
• Many regimens described
• One approach
• Mupirocinintranasally/perinally/periumbilically daily for first week of every month x 3-6 months
• Bleach baths 3x per week x 2 months then weekly thereafter
• Consider treating all family members
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NOT AN ABSCESS
• Hidradenitis suppurativa
• Clinical clues
• Intertriginous
• Comedones
• Sinus tracts, sclerotic scarring (not the
mere postinflammatory change seen in
most abscesses)
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STREPTOCOCCUS PYOGENES
• Skin
• Impetigo
• Cellulitis
• Blistering distal dactylitis
• Intertrigo
• Erysipelas
• Ecthyma
• Perianal strep
• Necrotizing fasciitis
• Systemic
• Toxic shock syndrome
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STREPTOCOCCUS PYOGENES
• Skin
• Impetigo
• Cellulitis
• Blistering distal dactylitis
• Intertrigo
• Erysipelas
• Ecthyma
• Perianal strep
• Necrotizing fasciitis
• Systemic
• Toxic shock syndrome
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STREPTOCOCCUS PYOGENES
• Skin
• Impetigo
• Cellulitis
• Blistering distal dactylitis
• Intertrigo
• Erysipelas
• Ecthyma
• Perianal strep
• Necrotizing fasciitis
• Systemic
• Toxic shock syndrome
Strep => oral antibiotics (to reduce chance for
sequelae)
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ERYSIPELAS
• Involves ONLY superficial layers of the
skin, unlike cellulitis
• Well demarcated
• Face and lower extremities
• Acute onset, often with systemic
symptoms
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ERYSIPELAS
• Almost always beta hemolytic strep
• Treatment
• IV cefazolin (systemic features)
• PCN or amoxicillin (milder cases)
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ECTHYMA
• Begin as vesicles or pustules
• Become well demarcated, punched out
ulcers with thick crust
• Often scar
• Not the same thing as ecthyma
gangrenosusm (pseudomonas)
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ECTHYMA
• Treatment
• Culture
• Gently debride crust (domeboro, H2O2, or
warm water soaks)
• Penicillin
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PERIANAL STREP
• Bright red and well demarcated
• Often with thin desquamative scale at
periphery
• Itchy or painful
• +/- blood streaked stool
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PERIANAL STREP
• Treatment
• Rapid strep +/- culture
• Oral penicillin or amoxicillin
• Carriers
• Common (40-50%)
• Can consider mupirocin + bleach bath
eradication method as used in staph
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STREP NECROTIZING FASCIITIS
• Occurs in otherwise healthy individuals
(unlike clostridial infection)
• May be preceded by minor injury, VZV
infection or pharyngitis
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STREP NECROTIZING FASCIITIS
• Usually acute with systemic symptoms
• Early
• Edematous, taut, shiny, red +/- crepitus
• Pain out of proportion to exam
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STREP NECROTIZING FASCIITIS
• Usually acute with systemic symptoms
• Early
• Edematous, taut, shiny, red +/- crepitus
• Pain out of proportion to exam
• Late
• Bullae, purpura, necrosis
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STREP NECROTIZING FASCIITIS
• Diagnosis and Treatment
• Surgical consult and exploration
• Labs and imaging may not be definitive –
may be used to support diagnosis, but
shouldn’t delay care
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FUNGUS
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CANDIDA
• Intertrigo
• Beefy red confluent erythema with satellite
papules
• Treatment
• Nystatin or ketoconazole cream
BID/TID for one week past clinical
improvement
• Reinfection common
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CANDIDA
• Paronychia
• Most common cause of chronic paronychia
• Moisture (saliva) a factor
• May see nail dystrophy
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PITYROSPORUM
• Colonizing yeast
• Overgrowth in adolescence (due to
increased sebum production)
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PITYROSPORUM
• Folliculitis
• Monomorphic tiny pustules and papules
across chest and back
• Tinea versicolor
• Fine scaled papules on chest, back and
upper arms
• White, red, orange or brown
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NOT PITYROSPORUM
• Pityriasis alba
• Follicular eczema
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DERMATOPHYTES
• Many species
• Trichophyton > microsporum >
epidermophyton
• Live only on keratinized skin
• Named for site of infection
• Tinea + capitis, facei, corporis, pedis,
manuum, cruris
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TINEA
• Clues on scalp
• Pustules + alopecia + lymphadenopathy
• ‘Black dots’
• Any acute scalp scaling with obvious
alopecia
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TINEA
• Clues on body
• Annular scaled plaques that improve but
then flare when steroids applied
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TINEA
• Clues on body
• Annular scaled plaques that improve but
then flare when steroids applied
• Majocchi’s granuloma
• Deep follicular involvement seen after
application of potent topical steroids
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TINEA
• Clues on feet
• ‘Moccasin distribution’
• Scaling or maceration between 4th and 5th
toes
• ‘One hand, two foot’
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TINEA
• Clues on groin
• Involves the folds and spares the scrotum
(unlike candida)
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TINEA
• Clues on face
• May be annular, often scalier at periphery
• Look for scalp involvement
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HOW TO PROVE IT’S TINEA
• In office procedures
• Wood’s lamp immunofluorescence
• KOH prep (or other fungal stain)
• Send out
• Fungal culture
• Scraping (low yield)
• Hair pull (higher yield)
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TINEA
• Treatment
• Orals if on hair bearing site (scalp, face), Majocchi’s granuloma, or widespread
• Prednisone for 1-3 weeks concurrently if there is kerion
• Topicals if not (corporis, hands, feet)
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TINEA
• Treatment
• Terbinafine cream
• BID for 4-6 weeks
• Available OTC (~$9)
• Azoles less effective for dermatophyte
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TINEA
• Treatment
• Griseofulvin micro
• 20-25 mg/kg/day for 2 months (higher than most pharm references say to use)
• Max 1000mg in a day
• Can cause headache and abdominal pain; rare SJS
• No labs required
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TINEA
• Treatment
• Oral terbinafine
• Recalcitrant tinea capitis (especially trichophyton) and nails
• Weight based dosing
• Rare hepatotoxicity and hypersensitivity
• Idiosyncratic and sudden; routine labs likely won’t catch it
• Counsel on risks and symptoms
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WHICH ONE IS FUNGUS?
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ONYCHOMYCOSIS
• Confirm diagnosis before treating
• Nail clipping for PAS stain and/or culture
• Multiple treatment regimens described
• Topicals for limited disease (nail lacquers)
• Terbinafine x 3 months
• Once weekly fluconazole
• Pulsed itraconazole
• Griseofulvin does NOT work
• Treatment failure and reinfection common
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CRITTERS
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SCABIES
• Adults and older kids
• Classic presentation
• Wrists + hands – excoriated papules and
burrows
• Groin – papules and nodules
• ITCHY
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BABY SCABIES
• Infants
• Inflammatory and widespread
• Polymorphic lesions (nodules + vesicles +
pustules + urticarial + papules)
• Palms/soles, diaper area, armpits +
anywhere else
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BABY SCABIES
• Treatment
• Permethrin
• Head to toe in infants, neck down if over
age 2
• Applied to ALL close contacts at night,
washed off in AM, repeat in a week
• Hot water laundry
• Bag up unwashables for a month
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PAPULAR URTICARIA
• Insect bite hypersensitivity
• Central punctum and/or excoriation
• Grouped urticarial papules
• Exposed sites → flying insects and fleas
• Groups of three and ‘hidden’ sites → bed
bugs
• Lack of findings in other family
members does NOT rule this out
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PAPULAR URTICARIA
• Treatment
• Find the source and eliminate it
• Daily suppressive antihistamine
• Topical steroid as spot treatment
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OBJECTIVES
• Recognize physical exam clues that aid in the diagnosis of common cutaneous
infections.
• Become familiar with bedside diagnostic tests used in pediatric dermatology.