Impetigo Caused by...
Caused by Group A Streptococcus (S. pyogenes), Staphylococcus aureus
Impetigo Clinical
Vesicles that rupture and result in honey colored crusting
Impetigo Treatment
Penicillin, topical mupirocin
Erysipelas Caused by...
Group A streptococcus
Intradermal infection with lymphatic involvement
Erysipelas Clinical
Well demarcated erythematous patch, with edema, pain, fever
Face and legs most common sites
Rapidly spreading
Erythrasma Caused by...
Corynebacterium minutissimum
Erythrasma Clinical
-well-demarcated, brown-red macular patches of inner thighs, crural region,
scrotum
-toe web lesions appear as maceration
Erythrasma Diagnosis
Skin culture
Wood's lamp: Coral-red fluorescence
Cellulitis Caused by:
-S. aureus and S. pyogenes most commonly
-Haemophilus influenza in young children with facial cellulitis
-S. aureus, Enterobactericeae and anaerobes in diabetics and debilitated patients
Cellulitis Clinical
-subcutaneous tissue with redness, warmth, induration, pain, fever
-red streaking is characteristic of ascending lymphangitis
Folliculitis Caused by...
-physical or chemical irritation or infection
-Staphylococcus aureus
-Pseudomonas aeruginosa: associated with hot tubs
Eosinophilic pustular folliculitis: associated with HIV, sterile pustules
Pityrosporum ovale: caused by a yeast
Gram-negative folliculit
Folliculitis Clinical
-Inflammation of hair follicles
-Seen in areas of friction
Folliculitis Diagnosis
-cultures, Gram stain, potassium hydroxide (KOH) prep (for yeast and fungus), and biopsy
Folliculitis Treatment
-Topical or oral antibiotics
-Topical or oral antifungals
-Topical steroids
Furuncle Caused by...
-Staphylococcus aureus most commonly
-Infection involving an entire hair follicle and the adjacent subcutaneous tissue
Furuncle Clinical
-tender, red, subcutaneous nodule
-becomes fluctuant (like a water-filled balloon)
-may drain spontaneously with pus
Furuncle Treatment
-Drainage
-Dicloxacillin or nafcillin
Carbuncle Caused by...
-Staphylococcus aureus most commonly
-Furuncles that develop close together, expand and join
Carbuncle Clinical
-multiloculated (multiple cavities) subcutaneous nodules
-appear in areas of friction or minor trauma
-may ooze pus
Carbuncle Treatment
-drainage
-dicloxacillin or nafcillin
Complicated Skin and Soft Tissue Infections
-Bullous Impetigo
-Staphylococcal Scalded Skin Syndrome
-Rectal Abscess
-Lymphangitis
-Necrotizing fasciitis
-Meningococcal Disease
-Toxic Shock Syndrome (TSS)
Bullous Impetigo Caused by...
S. aureus, Group A streptococcus
Bullous Impetigo Clinical
-Large flaccid blisters (bullae) at site of infection
-Most commonly seen in newborns and children
-Bullae form in response to epidermolytic toxin A produced by S. aureus
Bullous Impetigo Treatment
penicillin
Staphylococcal Scalded Skin Syndrome (SSSS) Caused by...
-Epidermolytic toxin A and B (ET-A and ET-B) by Staphylococcus aureus
-Desmoglein 1 (associated with keratinocytes adhesion) target in the skin for the toxins
-Infection from skin, throat, nose, mouth, umbilicus, or GI tract- bacteria not found in
the bul
Staphylococcal Scalded Skin Syndrome (SSSS) Clinical
-Bullae: flaccid, ill-defined
-Nikolsky sign (gentle stroking of the skin causes the skin to separate at the
epidermis)
-Sandpaper-like rash
-Perioral crusting
-Widespread desquamation
Perirectal and Perianal Abscesses Caused by...
-aerobic and anaerobic polymicrobial infection of the mucus-secreting anal
glands
-Bacteroides fragilis (most common)
-Escherichia coli, Proteus, Bacteroides, and Streptococcus
Perirectal and Perianal Abscesses Clinical
-Localized collection of pus walled off by deposition of fibrin thrombi
-Indurated fluctuant nodule
Perirectal and Perianal Abscesses Treatment
-Drainage
-Gram (+) and/or gram (-) antibiotics
Lymphangitis Caused by...
-Group A beta-hemolytic streptococcus (GABHS) most common
-Staphylococcus aureus and Pseudomonas, or fungal, viral organisms
-Inflammation and infection of lymphatic channels after abrasion, wound, or complication of infection
-Acute or chronic
Lymphangitis - Streptococcal Clinical
-Red linear streaks, extend towards the local lymph nodes
Lymphangitis - Streptococcal Diagnosis
CBC, blood culture
Lymphangitis - Streptococcal Treatment
appropriate oral or IV antimicrobial depending on the organism
Necrotizing Fasciitis Caused by...
-type I, or polymicrobial
-type II, or Group A streptococcal
-type III gas gangrene, or clostridial myonecrosis
-Deep infection that spreads rapidly through muscle plains
-Destruction of muscles, vasculature, nerves
Necrotizing Fasciitis Diagnosis...
-WBC count
-blood culture
-contrast-enhanced CT
-skin biopsy for culture
Necrotizing Fasciitis Treatment
-antibiotic coverage
-immediate surgical debridement
Meningococcal Disease Caused by...
-Neisseria meningitidis
-Carried in nasopharynx
-Transmitted via respiratory secretions
-3 clinical syndromes can occur:
� acute meningococcemia
� meningitis
� chronic meningococcemia
Acute Meningococcemia Clinical
-Cutaneous lesions
� petechiae
� stellate purpura
-small, irregular, smudged appearance; raised with pale grayish vesicular
centers
� hemorrhagic bullae
-Other findings:
� fever
� meningitis: neck stiffness, headache
� septic or sterile (immune complex) a
Meningococcal Disease Diagnosis
-increased CSF protein
-leukocytosis
-positive CSF and blood cultures
Meningococcal Disease Treatment
-penicillin G
-third-generation cephalosporins
-vaccine for high-risk groups
Toxic Shock Syndrome (TSS) Caused by toxins of...
-Caused by toxins of:
� 1) S. aureus
� 2) Group A beta-hemolytic streptococci (S. pyogenes)
Toxic Shock Syndrome (TSS) Clinical
-Fever
-Rash
-Hypotension
-Constitutional symptoms
-Multi-organ involvement
Streptococcal TSS vs Staphylococcal TSS
Staphylococcal TSS Diagnosis
-Involvement of 3 or more organ systems:
� Gastrointestinal - vomiting or diarrhea
� Muscular - myalgias
� Hepatic - decreased liver function
� Renal - raised urea or creatinine levels
� Hematologic - thrombocytopenia with bruising
� Central nervous syste
Streptococcal TSS Diagnosis
-Isolation of Group A streptococcus from:
� Normally sterile sites: blood, cerebrospinal fluid [CSF], surgical wounds
� Non-sterile sites: throat, vagina, sputum
-Hypotension
� systolic blood pressure <90 mm Hg
-Involvement of 2 or more organ systems:
� R
Toxic Shock Syndrome - Treatment
-Nafcillin
-Clindamycin
-Erythromycin
Tinea Versicolor
-Benign, superficial cutaneous fungal infection
-Hypopigmented or hyperpigmented macules and patches on the chest and back
-Caused by Pityrosporum orbiculare or P. ovale (Malassezia furfur)
Tinea Versicolor: Diagnosis
-Ultraviolet (Wood's) light - coppery-orange fluorescence
-Potassium hydroxide (KOH) - "cigar-butt" hyphae, spores with short mycelium; "spaghetti and meatballs" or "bacon and eggs
Tinea Versicolor: Treatment
-Topical agents:
-Selenium sulfide - daily for 2 weeks; at least 10 minutes prior to being washed off
-Azole, ciclopiroxolamine, and allylamine antifungals - every night for 2 weeks
Tinea Capitis
-Superficial fungal infection of the scalp
-Propensity for attacking hair shafts and follicles
-Scaly erythematous lesions and hair loss
-In the US:
-Trichophyton tonsurans has replaced Microsporum audouinii and M. canis as the most common cause
Tinea Capitis: Treatment
-Griseofulvin
-20 - 25 mg/kg/d for 6 - 8 weeks
-Accumulates in keratin of hair and nails, rendering them resistant to invasion by the fungus
-Fatty meals increase absorption
Tinea Corporis
-Superficial dermatophyte infection
-Pruritic annular erythematous scaly patch with central clearing
-Majocchi's granuloma: granulomatous reaction; fungal hyphae invade hairs and hair
follicles
-Potassium hydroxide (KOH): septate branching hyphae
Tinea Corporis: Treatment
-Topical agents
-Azole, ciclopiroxolamine, and allylamine antifungals
-Every night for 2 weeks
-Systemic therapy
-For Majocchi's
Tinea Pedis
-Most common presentation: "moccasin" distribution
-Erythema with scale extending to sides of feet
-Trichophyton rubrum most common cause
Tinea Unguium: Onychomycosia
-Most common presentation: distal subungual
-Thickening of nails
-Subungual debris
-Yellow discoloration
-Most commonly due to Trichophyton rubrum
Molluscum Contagiosum
-Cutaneous infection caused by a large DNA poxvirus that affects both children and adults
Molluscum Contagiosum Transmission:
-Direct skin contact
-Autoinoculation
-Flesh-colored, white, translucent, or even yellow in color
-Number of lesions: from 1 - 20 up to hundreds
-Diagnosis made on clinical grounds
Molluscum Contagiosum - Treatment
-Cantharidin
-Tretinoin - cream 0.1% or gel 0.025% daily
-Podophyllin
-Trichloracetic acid
-Silver nitrate or phenol
-Cryotherapy with liquid nitrogen
-Aldara 5% cream
-Salicylic acid
Human Papillomavirus: Verruca
-Many serotypes
-Can lead to various presentations of warts
-Verruca vulgaris (common warts):
-Due to HPV types 2 and 4
-Verrucous papules
-Can koebnerize (spread after trauma)
Herpes Simplex
-Type I: 90% orofacial, 10% genital, Vesicular lesions on oral mucosa, tongue, and lips; Later rupture, resulting in ulcer; Can recur, usually in the same location, due to reactivation along sensory root
ganglion
Type II: Primary genital herpes, Cervical
Varicella Zoster Virus: Chickenpox
-VZV remains dormant in the sensory roots after primary infection
-Transmitted from the skin and respiratory tract
-Incubation for 2 weeks
-Lesions: "dewdrops on a rose petal"; begin on the face, scalp, and trunk with sparing of the extremities
Herpes Zoster
-Due to reactivation of latent varicella zoster virus in sensory ganglion -Vesicles present in a dermatomal distribution: follow sensory nerves
-Can result in post-herpetic neuralgia