COMMON SKIN INFECTIONS

D R T.T M O K W E N A

D E R M AT O L O G Y D E PA R T M E N T

Skin Infections

Classification of pyodermas 1. Primary

Impetigo

Ecthyma

Folliculitis

– Superficial

– Deep * Folliculitis of leg

* Furuncle

* Carbuncle

* Sycosis Barbae

Skin Infections

• Cellulitis/ Erysipelas

• SSSS

• TSS

2. Secondary

Secondary infection of preexisting dermatoses

eg. Atopic dermatitis, Scabies

Causative Organisms

• Bacterial

• Fungal

• Viral

• Parasitic

Bacterial Skin Infections

• Very common

• Range from annoying to deadly infections

• Mostly caused by Staph aureus and Strep

Bacterial Skin Infections

• Folliculitis – Infection of hair follicle

– Usually heals without scarring

– Caused by Staph aureus

– Tx: Warm saline compresses. If does not resolve spontaneously in 1- 2 weeks, topical mupirocin. Oral cloxacillin ( very rare)

Young male presenting with pruritic erythematous macules that progressed to papules and pustules

folliculitis

Staph Skin Infections

• Furuncle/Boil

– Infection of pilosebaceous unit (hair follicle and

surrounding tissue)

– Usually must drain before they heal – takes less than 2 wks

– Complicated boils – over middle of face/ spine or with fever

Staph Skin Infections

• Carbuncle

– Several furuncles that are densly packed together

– Common in diabetics

– Tx : severe cases, first I&D

– Oral antibiotics (cloxacillin), or cephalexin if fever

Furuncle Carbuncle

Staphylococcal scalded skin sydrome (SSSS)

• Exotoxin of staph (Phage Group II)

• Acantholysis

• Occult staph. upper respiratory tract infection or

purulent conjunctivitis

• Infants and children

• Tender red skin

Acute Paronychia

– Infection of lateral and posterior nail fold

– Most common pathogen Staph aureus

– Results from nail biting, finger sucking, excessive manicuring or penetrating trauma

– Conservative tx: Warm soaks/ oral antibiotics ( clindamycin, augmentin)

– If abscess or fluctuance is present, spontaneous drainage / incision and drainage.

– I & D: blade is directed away from the nail plate

Acute Paronychia

Impetigo

• Non-bullous – principal pathogen is Staph aureus

• Group A beta hemolytic strep minority of cases

• Bullous form is nearly caused by Staph aureus (common in infants and children < 2yrs)

• Honey crusted lesions/large vesicles

Impetigo (cont…)

• Tx: topical mupirocin as effective as oral antibiotics – Oral antibiotics for nonlocalized cases - cloxacillin,

1st gen cephalosporin, augmentin.

– Macrolides not adequate given increasing resistance.

• Complication: Strep glomerulonephritis

• Nasal carriage, source for reccurrence, tx - topical mupirocin

• Very contagious, appropriate hygiene for prevention

Impetigo contagiosa (Non bullous form))

Impetigo (Bullous form)

Cellulitis

• Painful erythematous infection of dermis and subcut tissue

• Beta hemolytic strep , may be combined

with staph (MRSA on the rise) Commonly occurs near skin breaks, such as

trauma, surgical wounds, tinea infections( in diabetics)

• Tx: 1st gen cephalosporins, augmentin – Limited disease(oral treatment), extensive

disease requires parenteral treatment – I&D if fluctuant

• May turn into necrotizing fascitis – medical emergency

Cellulitis

MRSA Infections

• Community acquired – MRSA – in children in daycare – Athletes – Military recruits

• Healthcare associated –MRSA • Resistant to multiple antibiotics, send for C&S • Tx : CA- MRSA :Clindamycin, Doxycycline, Bactrim,

Vancomycin HA-MRSA : Vanc, Linezolid • Recurrence very common • Prevention: personal hygiene is the key

– Wash hands !! – Do not share personal items – Cover all open wounds

Erythrasma

• Results in pink patches to brown scales, may be pruritic. Lichenification and hyperpigmentation common

• Caused by Corynebacterium minutissimum

• Commonly found in intertriginous areas/ toe webs

• Prevalent among diabetics, obese, and in warm climates, worsened by wearing occlusive clothing

• DDx: tinea, acanthosis

• Dx: KOH neg, Wood’s lamp : coral pink fluorescence

• Tx: oral erythromycin 1-2 weeks

• Abx soap to prevent recc

Erythrasma

Common Viral Skin Infections

Viral warts/Condylomas/Squamous cell papillomas/ Verrucae

• Small, rough tumor w/ cauliflower surface or solid blister

• Hands, feet, genital areas

• Caused by HPV – 6 & 11 serotypes

• Tx : topical irritants – Salicylic acid, podophyllin, cantharidin,trichloroacetic

acid

– Destructive methods: cryo, electro, laser excision/curretage

• Prevention: Gardasil vaccine

Common wart Plantar wart

Herpes simplex infections

• Mucocutaneous: prodrome followed by grouped tensed vesicles over an erythematous base

• Herpetic gingivostomatitis in children • H.labialis/cold sores/Whitlow – caused by HSV 1 • Genital herpes : usually caused by HSV2 • Dx: clinical, if atypical lesion: Tzanck , PCR, Culture,

serology • Tx: acyclovir, valacyclovir: reduce viral shedding and

duration of sx during primary infection • Recc infection: tx with beginning of the first symptom • Frequent eruptions( >6/yr) should receive daily supressive

tx • Herpetic whitlow, no I & D ( risk of bact superinfection or

systemic spread.

Herpes labialis Herpetic gingivostomatitis

Herpetic whitlow

Molluscum contagiousm

• Caused by pox virus, MCV

• Flesh colored, dome shaped,pearly w/ typical central umbilication

• Common in children

• Autoinoculation spreads to neighboring areas

• Tx: self resolving sometimes or cryotherapy( using liquid nitrogen)

Molluscum contagiosum

Hand foot and mouth disease

• Caused by Coxsackie A16, member of enterovirus family

• Tender blisters, fever, sore throat, ulcers in throat,

loss of appetite

• Children under 10 yrs of age • Spread by person to person • Outbreaks in summer and early fall • Symptomatic tx: prevent dehydration

Hand Foot And Mouth Disease

CLASSIFICATION OF CUTANEOUS TUBERCULOSIS

TRUE CUTANEOUS TUBERCULOSIS TUBERCULIDES

EXOGENOUS ENDOGENOUS HEMATOGENOUS

• Tuberculosis chancre

• Scrofuloderma • Acute miliary TB • Papulonecrotic tuberculide

• Warty TB (verrucosa cutis)

• Peri-orifial tuberculosis

• Lupus vulgaris • Lichen scrofulosorum

• Lupus vulgaris • Tuberculous gumma • Erythema induratum of Bazin

• Nodular phlebitic tuberculid