What is an exanthem?
rash on the outside of the body
What is an enanthem?
rash on the inside of the body
What are bacterial exanthems?
scarlet fever, SSSS, TSS
What causes Scarlet Fever?
Group A Streptococcus (S. pyogenes)
What are the clinical features of Scarlet Fever?
diffuse erythematous “sandpaper” rash that blanches
starts in groin/axilla → trunk, spares palms/soles
circumoral pallor
strawberry tongue
pastia lines
What is the tx for Scarlet Fever?
1st line
Penicillin V
Amoxicllin: kids
2nd line
Cephalosporins
Clindamycin
Macrolides -Azithromycin
What are complications of Scarlet Fever?
RF, glomerulonephritis, STSS, post strep reactive arthritis, necrotizing fasciitis
What causes Staphylococcal Scalded Skin Syndrome (SSSS)?
exotoxins from S. aureus undergo hematogenous dissemination to the skin; primarily affects children and adolescents
What are the clinical features of SSSS?
rash following URI
diffuse skin pain, blanchable erythema
flaccid bulla/blisters
absence of mucous membrane involvement
sheet-like superficial desquamation
What is the pathophysiology of SSSS?
pathogenic toxins- exfoliative toxin A and B; hematogenous spread of toxins stimulates the separation of epidermal keratinocytes and detachment of the superficial epidermis
What are the risk factors for SSSS?
age < 6 yo, impetigo, immunosuppression, impaired renal fxn, DM, staph pneumo, septic arthritis, bacterial conjuntivitis
Would key clinical sign would help dx SSSS?
+Nikolsky sign
What is the tx for SSSS?
tx like burn pts, hospital admission -isolations, IV fluids
IV Abx: oxacillin or nafcillin alt. Vanc
Supportive care
watch CBC, CMP, UA for sepsis
What causes TSS?
S. Aureus, Group A Strep (S pyogenes)
What are clinical features of TSS?
initial: diffuse red macular rash (palms/soles), fever, hypotension
late: pruritic maculopapular rash w/ desquamation of palms/soles
fatigue, myalgia, GI, Neuro, tachycardia, conjunctival hemorrhage
What is the pathophysiology of TSS?
Toxins (TSS toxin Type 1) and Staph enterotoxin B activate large numbers of T cells → massive cytokine production;
IL-1 causes muscle proteolysis → high fever and myalgias
What are the risk factors for TSS?
tampon usage, surgery, mastitis, burns, sinusitis, osteomyelitis
How is TSS dx according to the CDC guidelines?
Temp >102, hypotension, diffuse macular erythroderma, desquamation, involvement of 3+ organ systems -in absence of any other cause for these sx
How can you dx TSS using labs?
blood cultures, bacterial cultures, inc BUN/Cr, inc CPK, inc LFTs, leukocytosis, thrombocytopenia, anemia
When should you draw the blood culture when testing for infection?
prior to starting the Abx
What is the tx for TSS?
hospital admission
treat shock: fluids, vasopressors, surgical debridement
Empiric Abx: broad -Vancy + Clinda + Zosyn or Cefepime or Carabapenem
What causes folliculitis?
S. Aureus - most common; P. aeruginosa -hot tub
What clinical features are associated with folliculitis?
superficial: perifollicular papules/pustules w/ erythema ± pruritus
deep: nodules, furuncles
hot tub: papules/pustules on trunk and buttocks in bathing suit distribution
What is the tx for folliculitis?
mild: topical mupirocin, topical Clinda
moderate/severe: Dicloxacillin, Cephalexin
MRSA: Bactrim, Clinda
Hot tub: cipro
What is a furuncle?
infection of the hair follicle in which purulent material extends through the dermis into the subcutaneous tissue
What is a carbuncle?
coalescence of several inflamed follicles into a single inflammatory mass w/ purulent drainage from multiple follicles in the epidermis
What is an abscess?
collection of pus within the dermis and deeper skin tissues
What causes furuncles, carbuncles, and abscesses?
S. aureus -most common
What are the clinical features of a furuncle/carbuncle/abscess?
painful, fluctuant, erythematous nodule ± surrounding cellulitis
What is the tx for a furuncle/carbuncle/abscess?
I&D + Abx (pack if > 5cm); Abx cover for MRSA - Bactrim or Tetracycline
When are Abx not indicated after an I&D?
abscess < 2 cm and individual is healthy
What causes Impetigo and Ecthyma?
S. Aureus or Group A Streptococcus
Who is most likely to get Impetigo or Ecthyma?
children ages 2-5
What is Impetigo?
contagious epidermal infection; honey crusted lesions, “pyoderma”
What is Ecthyma?
ulcerative form of impetigo; extends into the dermis
What are the clinical features of Ecthyma?
“punched-out ulcers” covered w/ yellow crust surrounded by raised violaceous margins
What are the clinical features of non-bullous impetigo?
most common; begins as pustules overlying erythema, lesions break → golden/honey crusts; involve face and extremities; well localized
What are the clinical features of bullous impetigo?
due to S. Aureus toxin A; vesicles enlarge to form flaccid bullae w/ clear yellow fluid → become darker and more turbid → rupture → thin brown crust; only on the trunk
What is the tx for Impetigo?
localized 1st line: Mupirocin (bactroban) ointment
extensive: Cephalexin or Doxycycline
What is unique about Erysipelas?
involves upper dermis and superficial lymphatics; clear demarcation of involved tissues
What is unique about cellulitis?
involves the deeper dermis and subcutaneous tissue, spreads more; purulence
What causes Erysipelas and Cellulitis?
S. pyogenes -MCC or S. Aureus
What are the shared clinical features of Erysipelas and Cellulitis?
skin erythema, edema, and warmth; fever
What is the biggest risk factor for developing Erysipelas or Cellulitis?
pre-existing skin infection
What disease is Milian’s ear sign evident in?
Erysipelas
What is the tx for Erysipelas and Cellulitis?
Outpt: Cephalexin;
PCN allergy → Bactrim
Inpt (septic or immunocompromised):
IV Vanc + Cefepime
PCN allergy → IV Vanc + levofloxacin
What causes Lymphangitis?
Immunocompetent: MCC- S. pyogenes and S. aureus
Immunocompromised: G- organisms
Animal bite: Pasteurella multocida
Cat bite: Bartonella henselae
Fish exposure: Erysipelothrix
What are the clinical features of Lymphangitis?
seen w/ cellulitis, typically due to puncture, erythematous streaking, fever
What is the tx for Lymphangitis?
IV or oral broad spectrum Abx; surgical debridement
How does cutaneous TB present?
variety of presentations: inflammatory papules, verrucous plaques, suppurative nodules, chronic ulcers, other lesions
What causes cutaneous TB?
M. tuberculosis
What are the risk factors for cutaneous TB?
immunocompromised, hx of TB, F > M
How is cutaneous TB transmitted?
direct inoculation of TB into skin, extension into the skin from underlying infective focus, spread to the skin via the bloodstream
What are the clinical features of cutaneous TB?
painless, shallow ulcers w/ granulomatous base
Verruocas cutis- painless, violet/red indurated wart like plaques
scrofuloderma -firm painless, subcutaneous nodules → enlarge and ulcerate → scar
cutis orificialis
How is cutaneous TB diagnosed?
PPD
Acid fact bacilli smear (rapid results)
Mycobacterial culture -GOLD standard
skin biopsy: tuberculoid granuloma ± caseating necrosis
What is the tx for cutaneous TB?
2 months of intensive therapy
Ethambutol + Rifampin + Isoniazid + Pyrazinamide
Followed by 4 moths of maintenance
Isoniazid + Rifampin
What is another name for Leprosy?
Hansen’s disease
What causes Leprosy?
Mycobacterium leprae; spread via droplets
How long is the incubation period for Leprosy?
months to years
What are the risk factors associated with Leprosy?
armadillo exposure, close contact w/ infected, older age, immunosuppression
What are the clinical features of Leprosy?
hypopigmented or reddish patches
diminished sensation w/in skin patches
paresthesisas in hands or feet
painless wounds or burns on hands/feet
lumps or swelling on the earlobes or face
tender, enlarged peripheral nerves
hair loss
How can you dx Leprosy?
PCR or Acid fast stain
What is the tx for Leprosy?
Tuberculoid: Dapsone + Rifampin x 1 yr
Lepromatous: Dapsone + Rifampin + Clofazimine x 2 yrs
What are complications of untreated Leprosy?
nerve damage → paralysis, deformation of hands/feet; corneal ulcers, blindness, saddle nose deformity
What are the predisposing conditions that increase risk of Erythrasma?
warm climates, hyperhidrosis, poor hygiene, obesity, DM
What are the clinical features of Erythrasma?
limited to body folds, Asx or pruritic, duration varies, well demarcated, brown-red or tan patches ± scaling
What color would Erythrasma illuminate as under a Woods lamp?
coral-red florescence
What is the tx for Erythrasma?
1st line
topical erythromycin or clindamycin
2nd
topical miconazole or benzoyl peroxide
Severe: oral Abx
clarithromycin
erythromycin
What is the cause Meningitis/Meningococcemia?
Neisseria meningitidis
What are the clinical manifestations of Meningitis/Meningococcemia?
HA, N/V, myalgias
Triad: sudden onset fever, AMS, nuchal rigidity
Petechial rash: purpura and ecchymosis
What cutaneous features are associated w/ Meningitis/Meningococcemia?
maculopapular rash on trunk, LE, and mucous membranes → petechiae appear, lesions become purpuric/hemorrhagic, bullae
What is a complications of Meningitis?
purpura fulminans: purpura, ecchymoses, confluent green/black necrosis associated w/ DIC
What is the GOLD standard for dx Meningitis/Meningococcemia?
Blood or CSF culture
What is the tx for Meningitis/ Meningococcemia?
IV Ceftriaxone
What is the cause of Syphilis?
Treponema pallidum -a spirochete
How is Syphilis transmitted?
direct contact w/ an infectious lesion, fetal infection via placenta
What are the clinical features of Primary Syphilis?
painless ulcer or chancre -heal spontaneously, non-tender regional LAD
What are the clinical features of Secondary Syphilis?
diffuse, bilateral, symmetric maculopapular rash +palms/soles, copper brown lesions, Condyloma Lata, regional LAD, cutaneous ulcerations
What are the clinical features of Late stage Syphilis?
gumma, neurosyphilis, AR, AA, aortitis
What is the tx for Syphilis?
PCN G benzathine; Alt: Doxy
-late stage = longer prescription time
What causes Chancroid?
Haemophiles ducreyi
What are the clinical features of a Chancroid?
erythematous → pustule → ulcer
LAD → bubo, swollen inflamed lymph node
painful genital ulcers w/ irregular borders covered by a gray or yellow exudate
What is the tx for a Chancroid?
1st line: Azithromycin or Ceftriazone
Alt: Erythromycin
What is the cause of Cat-Scratch Disease?
Bartonella henselae
What are the clinical features of Cat-Scratch Disease?
erythematous papule/vesicle, regional LAD proximal to lesion, prolonged fever
What are the complications of Cat-Scratch Disease?
visceral organ involvement, ocular manifestations, infection of conjunctiva, neuro sx, encephalopathy, MSK sx
What is the tx for Cat-Scratch Disease?
1st line: Azithromycin
Clarithromycin or Trimethoprim-sulfamethoxazole
What causes Rubella (German Measles)?
Rubella virus
What are the clinical features of Rubella?
low fever, cough LAD, Exanthem: pink or red non-confluent maculopapular rash, face → trunk, spares palms/soles, Forcheimer spots: red macules or petchial spots on the soft palate
What is the tx for Rubella?
supportive care: antipyretics, hydration
What is the cause of Rubeola (measles)?
Rubeola virus
What are the clinical features of Rubeola?
stage 1: incubation
stage 2: prodrome - High fever, cough, coryza, conjunctivitis (3 C’s)
Stage 3: Koplik spots, exanthem: begins at hairline → spreads craniocaudally and centrifugally
Stage 4: recovery, cough may persist
What is the tx for Rubeola?
supportive, Vitamin A, Ribavirin -high risk pts
What is the most common cause of measle related deaths?
Pneumonia
What is the cause of Roseola Infantum (6th disease)?
Human Herpes virus 6 (HHV-6)
What are the clinical features of Roseola?
acute onset high-fever up to 104 → small rose-pink maculopapular rash, begins on the trunk and spreads, nonpruritic
What is the cause of Hand, Foot, and Mouth Disease?
Coxsackie A16, Coxsackie A6, Enterovirus A71
What are the clinical features of Hand, Foot, and Mouth Disease?
mild fever, reduced appetite, oral lesion w/ halo of redness, painful vesicles, refusal to eat, rash of hands/feet + palms/soles
What is the cause of Erythema Infectiosum (Fifth Disease)?
Parvovirus B19
What are the clinical features of 5th Disease?
fever, HA, nausea → malar rash w/ circumoral pallor, “slapped cheek appearance”, lacy eruption on the trunk, palms/soles spared, aplastic crisis