BUGS, FUNGUS AND CRITTERS

BUGS, FUNGUS AND CRITTERS

Sierra Wolter MD, FAAD

Phoenix Children’s Hospital Medical Group

OBJECTIVES

• Recognize physical exam clues that aid in the diagnosis of common cutaneous

infections.

• Become familiar with bedside diagnostic tests used in pediatric dermatology.

OUTLINE

• Bugs

• Staphylococcus

• Streptococcus

• Fungus

• Yeast

• Dermatophytes

• Critters

• Scabies

• Insects

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)

BUGS

STAPHYLOCOCCUS STREPTOCOCCUS

BACTERIA

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

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)

IMPETIGO

• Sequelae (rarely)

• Post-strep glomerulonephritis

• Guttate psoriasis

• NOT rheumatic fever

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

CELLULITIS

• Edema + erythema + warmth

• Usually tender or painful

• May observe purulence, drainage, peau

d’orange

• Look for predisposing factors

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)

BLISTERING DISTAL DACTYLITIS

• Blistering of distal fat pad and periungual

skin

• Strep > staph

• Treatment

• Drain and culture

• Warm compresses

• Oral antibiotics

NOT BLISTERING DISTAL DACTYLITIS

• Herpetic whitlow

• Intact vesiculopustules, edema and pain

• Look for HSV lesions in/near mouth

STAPHYLOCOCCUS AUREUS

• Skin

• Impetigo

• Cellulitis

• Blistering distal dactylitis

• Folliculitis

• Abscesses and Furuncles

• Systemic

• Staph scalded skin syndrome

• Toxic shock syndrome

STAPHYLOCOCCUS AUREUS

• Skin

• Impetigo

• Cellulitis


• Folliculitis

• Abscesses and Furuncles

• Systemic

• Staph scalded skin syndrome


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)

ABSCESSES, FURUNCLES, CARBUNCLES

• Tender, fluctuant, red nodule(s) with

central pustule

• Often community acquired MRSA


• 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


• 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

NOT AN ABSCESS

• Hidradenitis suppurativa

• Clinical clues

• Intertriginous

• Comedones

• Sinus tracts, sclerotic scarring (not the

mere postinflammatory change seen in

most abscesses)

STREPTOCOCCUS PYOGENES

• Skin

• Impetigo

• Cellulitis


• Intertrigo

• Erysipelas

• Ecthyma

• Perianal strep

• Necrotizing fasciitis

• Systemic



• Skin

• Impetigo

• Cellulitis


• Intertrigo

• Erysipelas

• Ecthyma

• Perianal strep


• Systemic



• Skin

• Impetigo

• Cellulitis


• Intertrigo

• Erysipelas

• Ecthyma

• Perianal strep


• Systemic


Strep => oral antibiotics (to reduce chance for

sequelae)

ERYSIPELAS

• Involves ONLY superficial layers of the

skin, unlike cellulitis

• Well demarcated

• Face and lower extremities

• Acute onset, often with systemic

symptoms

ERYSIPELAS

• Almost always beta hemolytic strep

• Treatment

• IV cefazolin (systemic features)

• PCN or amoxicillin (milder cases)

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)

ECTHYMA

• Treatment

• Culture

• Gently debride crust (domeboro, H2O2, or

warm water soaks)

• Penicillin

PERIANAL STREP

• Bright red and well demarcated

• Often with thin desquamative scale at

periphery

• Itchy or painful

• +/- blood streaked stool

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

STREP NECROTIZING FASCIITIS

• Occurs in otherwise healthy individuals

(unlike clostridial infection)

• May be preceded by minor injury, VZV

infection or pharyngitis


• Usually acute with systemic symptoms

• Early

• Edematous, taut, shiny, red +/- crepitus

• Pain out of proportion to exam


• Usually acute with systemic symptoms

• Early

• Edematous, taut, shiny, red +/- crepitus

• Pain out of proportion to exam

• Late

• Bullae, purpura, necrosis


• 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

FUNGUS

CANDIDA

• Intertrigo

• Beefy red confluent erythema with satellite

papules

• Treatment

• Nystatin or ketoconazole cream

BID/TID for one week past clinical

improvement

• Reinfection common

CANDIDA

• Paronychia

• Most common cause of chronic paronychia

• Moisture (saliva) a factor

• May see nail dystrophy

PITYROSPORUM

• Colonizing yeast

• Overgrowth in adolescence (due to

increased sebum production)

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

NOT PITYROSPORUM

• Pityriasis alba

• Follicular eczema

DERMATOPHYTES

• Many species

• Trichophyton > microsporum >

epidermophyton

• Live only on keratinized skin

• Named for site of infection

• Tinea + capitis, facei, corporis, pedis,

manuum, cruris

TINEA

• Clues on scalp

• Pustules + alopecia + lymphadenopathy

• ‘Black dots’

• Any acute scalp scaling with obvious

alopecia

TINEA

• Clues on body

• Annular scaled plaques that improve but

then flare when steroids applied

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

TINEA

• Clues on feet

• ‘Moccasin distribution’

• Scaling or maceration between 4th and 5th

toes

• ‘One hand, two foot’

TINEA

• Clues on groin

• Involves the folds and spares the scrotum

(unlike candida)

TINEA

• Clues on face

• May be annular, often scalier at periphery

• Look for scalp involvement

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)

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)

TINEA

• Treatment

• Terbinafine cream

• BID for 4-6 weeks

• Available OTC (~$9)

• Azoles less effective for dermatophyte

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

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

WHICH ONE IS FUNGUS?

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

CRITTERS

SCABIES

• Adults and older kids

• Classic presentation

• Wrists + hands – excoriated papules and

burrows

• Groin – papules and nodules

• ITCHY

BABY SCABIES

• Infants

• Inflammatory and widespread

• Polymorphic lesions (nodules + vesicles +

pustules + urticarial + papules)

• Palms/soles, diaper area, armpits +

anywhere else

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

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

PAPULAR URTICARIA

• Treatment

• Find the source and eliminate it

• Daily suppressive antihistamine

• Topical steroid as spot treatment

OBJECTIVES

• Recognize physical exam clues that aid in the diagnosis of common cutaneous

infections.

• Become familiar with bedside diagnostic tests used in pediatric dermatology.

BUGS, FUNGUS AND CRITTERS

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