Dr. Al-Muhsaini -- Infectious Skin Diseases and Rashes Flashcards Preview

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Flashcards in Dr. Al-Muhsaini -- Infectious Skin Diseases and Rashes Deck (144)
1

2 ways bacterial infection can happen in the skin

  • Direct infection of skin and adjacent tissues
  • Cutaneous disease due to effect of bacterial toxin

2

2 examples of cutaneous diseases due to effect of bacterial toxin

  • Staphylococcal scalded skin sydrome
  • Toxic shock syndrome

3

3 kinds of S. aureus toxins

  • Toxic shock syndomre toxin-1 (TSST-1)
  • Exfoliative toxin (ET-A, ET-B)
  • Panton-Valentine leukocidin (PVL)

4

Define TSST-1

Superantigen involved in toxic shock syndrome (TSS)

5

2 effects of ET-A and ET-B

  • Protease activity
  • Splits epidermal desmoglein 1

6

2 conditions that exfoliative toxins of S. aureus are involved in

  • Styphylococcal scalded skin syndrome (SSSS)
  • Bullous impetigo

7

Specific S. aureus type that can secrete PVL toxin

Community-acquired MRSA strains

8

Effects of S. aureus PVL

  • Associated with increased virulence (leukocyte destructon, necrosis)

9

Define impetigo and its two types

Highly contagious infection seen primarily in children (bullous vs. nonbullous)

10

2 most common causes of nonbullous impetigo

  1. S. aureus
  2. GAS 

11

Clinical presentation of nonbullous impetigo

Erythematous macule --> erosion with golden (honey color) crust

12

Diagnosis of nonbullous impetigo

Positive culture from exudate under crust

13

Treatment for nonbullous impetigo

  • Topical mupirocin
  • If extensive, can use oral ABX (i.e. cephalexin, dicloxacillin)

14

ONLY cause of bullous impetigo

S. aureus

15

Clinical presentation of bullous impetigo

Flaccid, transparent bullae --> rupture leaving shiny, dry erosion with no surrounding erythema

16

Pathogenesis of bullous impetigo

Cleavage at granular layer due to Exfoliative toxin (ET-A, ET-B) binding to desmoglein 1

17

Treatment for bullous impetigo

  • Topical mupirocin AND
  • Oral antibiotic (i.e. cephalexin, dicloxacillin)

18

Define bacterial folliculitis

Superficial infection of hair follicle usually due to S. aureus

19

Clinical presentation of bacterial folliculitis

Pustules in follicular distribution associated with hairs

20

3 treatments for bacterial folliculitis

  • Antibacterial wash (chlorhexidine or triclosan)
  • Antibacterial ointments (mupirocin)
  • If widespread, can use oral antibiotic

21

Typical cause of frunucle, carbuncle and abscess

S. aureus

22

Define furuncle

Deep-seated tender nodule of hair follicle

23

Define carbuncle

Coalescing of adjacent furuncles with multiple draining sinuses (typically involves nape of neck or back of thighs)

24

Define abscess

Inflamed walled-off collection of pus

25

Treatment for simple furuncle (no fluctuance)

Warm compresses and topical antibiotics

26

Treatment for fluctuant furuncle or abscess

Incision and drainage

27

When to give oral antibiotic in the event of furuncle, carbuncle or abscess

  • Location near midface (due to concern for cavernous sinus thrombosis) or external auditory canal
  • Recurrent or recalcitrant
  • Very large or with surrounding cellulitis

28

Body parts in which streptococcal bacteria can reside

  • Aerodigestive tract
  • Vagina

29

Type of streptococcus that is most pathogenic

  • Group A beta-hemolytic streptococci
    • S. pyogenes
    • GAS

30

3 positive antibodies found after infection with GAS

  • Antistreptolysin O (ASO)
  • Antihyaluronidase
  • Anti-DNase-B

31

Streptococcal strain that has erythrogenic toxins and list the 3 produced

S. pyogenes exotoxins (SPE-A, SPE-B, SPE-C)

32

Define ecthyma

Deeper form of nonbullous impetigo with ulceration

33

Cause of ecthyma

GAS, but quickly contaminated by S. aureus

34

Clinical presentation of ecthyma

"Punched out" shallow ulcer with thick, yellow-gray crust commonly in lower legs of children

35

Ecthyma treatment

Dicloxacillin or first generation cephalosporin

36

Define erysipelas

Superficial type of cellulitis with significant dermal lymphatic involvement

37

Typical cause of erysipelas

GAS

38

Clinical presentation of erysipelas

Well-defined, bright red indurated plaque with sharp, raised borders commonlu on the face or legs, with or without constitutional symptoms

39

Treatment for erysipelas

PCN (if PCN allergic, can use macrolide)

40

Define cellulitis

Infection of the deep dermis and subcutaneous tissue

41

2 causes of cellulitis and the proportion of cases that they are involved in

  • GAS (2/3)
  • S. aureus (1/3)

42

9 rare causes of cellulitis

  • P. aeruginosa
  • H. influenzae
  • Anaerobes
  • Eikenella
  • Streptococcus viridans
  • Pasteurella multocida
  • Vibrio vulnificus
  • Aeromonas
  • Erysipelothrix (erysipeloid)

43

Source of P. aeruginosa leading to cellulitis

Puncture wound involving foot or hand

44

Type of patient affected by H. influenzae causing cellulitis

Children with facial cellulitis

45

Source of anaerobes, Eikenella and Streptococcus viridans causing cellulitis

Human bite

46

source of Pasteurella multocida causing cellulitis

Cat or dog bites

47

Source of Vibrio vulnificus causing cellulitis

Salt water (i.e. following coral injury)

48

Source of Aeromonas  causing cellulitis

Fresh water (i.e. following leech bites)

49

Type of patient who can get cellulitis from Erysipelothrix

Butcher

50

Clinical presentation of cellulitis

Ill-defined area with erythema, swelling and tenderness +/- fever, chills

51

Treatment for cellulitis

Oral/IV antibiotic with good gram positive coverage

52

Define necrotizing fasciitis

Rapidly progressive necrosis of subcutaneous tissue and fascia

53

Cause of necrotizing fasciitis

GAS, but typically mixed infection with 30% mortality

54

4 risk factors for necrotizing fasciitis

  • Advanced age
  • Diabetes
  • Peripheral vascular disease
  • History of alcohol abuse

55

Clinical presentation of necrotizing fasciitis

Tender, erythematous tense plaques recalcitrant to antibiotics

Progresses at an alarming rate --> necrosis of fascia and fat

56

Treatment of necrotizing fasciitis

Extensive surgical debridement

57

6 skin infections by level of depth

  1. Impetigo (epidermis; keratinized layer)
  2. Ecthyma (deeper epidermis)
  3. Erysipelas (Papillary dermis)
  4. Cellulitis (Reticular dermis)
  5. Panniculitis (subcutaneous tissue)
  6. Necrotizing fasciitis (Fascia and fat)

58

Typical age of patients affected by perianal streptococcal disease

Preschool children

59

Strain causing perianal streptococcal disease

GAS

60

Clinical presentation of perianal streptococcal disease

Circular band of erythema around anus +/- painful defecation, blood streaked stool and anal leakage

61

Diagnosis of perianal streptococcal disease

Throat and perianal culture

62

Treatment for perianal streptococcal disease

PCN or erythromycin x 10 - 14 days

63

Type of bacteria: croynebacteria

Gram positive rod-shapped bacteria

64

Cause of erythrasma

Corynebacteria

65

Define erythrasma

Superficial infection in occluded intertriginous areas (i.e. armpit)

66

Clinical presentation of erythrasma

Well-demarcated red-brown macules/patches with fine scale and wrinkling in intertriginous areas

Interdigital maceration and scaling between toes

67

One diagnostic test for erythrasma

Wood's lamp = bright coral-red fluorescence due to perphyrn production

68

Treatment for erythrasma

Topical antibiotic clindamycin, erythromycin

69

2 general characteristics about pseudomonas and its cutaneous manifestations

  • Grows well in aqueous environment
  • Has ability to produce variety of pigments

70

2 pseudomonal infections

Green nail syndrome

Pseudomonal folliculitis (hot tub folliculitis)

71

Define green nail syndrome

Subungual pseudomonal infection causing green discoloration of nail and onycholysis

72

Treatment for green nail syndrome (3)

  • Trim nail
  • Acetic acid soaks
  • Topical ciprofloxacin

73

Presentation of pseudomonal foliculitis

Erythematous follicular papules and pustules at sites of exposure to water (i.e. via whirlpool, hot tub, rarely swimming pool) with sparing of face and neck

NOTE: Self-limited in immunocompromised person

74

Define acute meningococcemia

Acute and potentially life-threatening infection of the blood vessels

75

Cause of acute meningococcemia

Neisseria menigitidis

76

Neisseria meningitidis: type of bacteria

Encapsulated gram negative diplococcus

77

Presentation of acute meningococcemia

Erythematous macules/papules --> evolve to stellate purpuric pathces/plaques with ischemic necrosis and/or hemorrhage, accompanied by high fever and toxic appearance

78

Treatment of acute meningococcemia

High dose IV PCN

NOTE: If resistant, use third generation cephalosporin

79

Type of patients affected by SSSS (3)

  • Neonates
  • Young children
  • Adults with renal insufficiency or if immunocompromised

80

Location of pathogen (name it) and how this affects culture in SSSS

S. aureus at a distant site (extralesional) = negative bullae culture

81

SSSS presentation

  • Fever
  • Initial tenderness of skin and erythema over body folds --> generalized wrinkled appearance with subsequent exfoliation, perioral crusting/fissuring
  • + Nikolsky sign

82

Nikolsky sign

Slight rubbing of the skin results in exfoliation of the skin's outermost layer

83

Treatment for SSSS (3)

  • Penicillinase resistant penicillin (i.e. diclocacillin)
  • First generation cephalosporin
  • IV fluid support

84

Define toxic shock syndrome (tSS)

Rapidly progressie multiorgan illness (high mortality; 30 - 60%)

85

2 pathogens of TSS

  • Staphylococcus aureus
  • GAS (strep. TSS)

86

5 causes of TSS

  • Women who use superabsorbent tampons (rare nowadays)
  • Infections with wounds
  • Catheters
  • Deep abscesses
  • Nasal packing

87

2 toxins involved in TSS

  • S. aureus = TSST-1
  • GAS = S. pyogenes exotoxins (SPE-A)

88

4 presenting manifestatinos of TSS

  • Fever
  • Hypotension
  • Macular exanthem
  • Involvement of 3 or more organ systems

89

Describe exanthem in TSS (4)

  • Diffuse scarlatiniform exanthem on trunk spreading outwards
  • Palmoplantar edema
  • Erythema (with desquamation 1 - 3 weeks later)
  • Hyperemia of conjunctiva

90

Describe the difference between STSS vs. TSS

  • Generalized exanthem less common in STSS
  • STSS more likely in an otherwise healthy adult

91

3 treatments for TSS

  • Remove any nidus of infection
  • Intensive supportive therapy, fluid support
  • IV antibiotics

92

Describe exanthem in scarlet fever and its cause

Diffuse exanthem from GAS pharyngitis with erythrogenic toxin (SPE-A, B, C)

93

Main age group affected by scarlet fever

Children

94

8 manifestations of scarlet fever

  • Sore throat
  • Headache
  • Fever
  • Tiny pink papules on erythematous background (sandpaper like)
  • Strawberry tongue,
  • Palatal petechiae
  • Circumoral pallor
  • Linear petechiael streaks along bod folds (Pastia's lines)

95

Treatment for scarlet fever

PCN or erythromycin x 10 - 14 days

96

Define HSV

Neurotropic virus which hides in the dorsal root ganglion until reactivation

97

2 primary HSV infections

  • Primary herpetic gingivostomatitis
  • Primary genital infection

98

Typical age group affected by primary herpetic gingivostomatitis

Children

99

9 manifestations of primary herpetic gingivostomatitis

  • Abrupt onset of erythematous, friable gingiva
  • Painful vasicles clusteres on oral mucosa, tongue, lips and/or perioral
  • Skin --> vasicles rupture, leaving small ulcers with characteristic gray base
  • May have:
    • Pharyngitis
    • Tonsillitis
    • Difficulty eating or swallowing
    • Enlarged lymph nodes
    • Fever
    • Anorexia

100

6 Manifestations of primary genital herpes infection

  • Constitutional symptoms
  • Painful grouped vesicles in genitalia --> progress to pustules, crusting and exquisitely tender ulcers
  • May have:
    • Painful lymphadenopathy
    • Cervicitis
    • Urethritis
    • Proctitis

101

4 treatments for primary HSV infection

  • Hydration, pain control, hospitalization
  • Acyclovir 200 mg 5 times/day x 7 - 10 days or 400 mg TID (15/mg/kg five/day)
  • Valacyclovir 1 g BID for 7 - 10 days
  • Famciclovir 250 mg TID for 7 - 10 days

102

2 recurrent herpes infections

  • Herpes labialis
  • Genital herpes

103

Most common HSV-1 manifestation

Herpes labialis

104

4 triggers of herpes labialis

  • Pyrexia
  • Stress
  • Sunburn
  • Trauma

105

2 Manifestations of herpes labialis

  • Prodrome (pain, burning, tingling) may precede eruption
  • Grouped vesicles on erythematous base which typically evolve into pusules and then apinful ulcers

106

Manifestation of genital herpes

+/- prodrome followed by grouped vesicles --> pustules --> ulceration

107

5 other herpes infections aside from gingivostomatitis, labial and genital forms

  • Eczema herpeticum
  • Herpetic whitlow
  • Herpes gladiatorum
  • Chronic ulcerative HSV
  • Keratoconjuncivitis

108

Define eczema herpeticum

Disseminaed form of HSV mainly seen wit atopic dermatitis that can also occur when there are other reasons for breakdown of the skin barrier

109

Presentation of eczema herpeticum

Monomorphic umbilicated vesiculopustules or punched out ulcrations with hemorrhagic crust

110

Common complication of eczema herpeticum

Seconday bacterial infection

NOTE: may progress to life-threatning infection

111

Define herpetic whitlow

Painful primary herpetic infection of hand (typically distal phalanx) more common in healthcare workers or caregivers

112

Presentation of herpetic whitlow

Exquisite pain and swelling of finger with characteristic vesicular lesions

113

Define herpes gladiatorum

HSV primary infection primarily, noted in wrestlers, involving extramucosal sites typically over face, neck, or arms

114

Which kinds of patients are most likely to be affect by chronic ulcerative HSV

Immunocompromised

115

Presentation and complications of keratoconjunctivitis

Branching dendritic corneal ulcerations (seen with fluorescein stain)

Can lead to scarring and blindness

116

5 diagnostic methods for HSV

  • Taznck smear shows multinucleated epithelial giant cells (does not differentiate from VZV)
  • Viral culture
  • Direct fluorescent anibody (DFA)
  • Viral PCR
  • Histology skin Bx

117

Transmission of VZV

Airborne respiratory droplets

118

Presentation of VZV (6)

  • Itchy red papules --> vesicles (blisters) on the trunk and face, and then sprading to other parts of the body
  • High fever
  • Headache
  • Respiratory signs
  • Vomiting
  • Diarrhea

119

Describe the natural history of VZV (4)

  • Usually more severe in adults or immunocompromised patients
  • May be life-threatening in complicated cases
  • Typically clears up within 1 - 3 weeks, but may leave scars
  • After initial infection (chickenpox), virus lies dormant in spinal dorsal root ganglion until reactivation --> herpes zoster

120

Presentation of herpes zoster (4)

  1. Prodromal pain/paresthesias
  2. Grouped, painful erythematous macules/papules along single sensory dermatome
  3. Vesicles/bullae
  4. Hemorrhagic crust and dry over 7 - 10 days

NOTE: Lesions are infectious until dry

121

6 complications of zoster

  • Post-herpetic neuralgia (PHN)
  • Scarring
  • Secondary bacterial infection
  • Meningoencephalitis
  • Ramsay-Hunt syndrome
  • Ocular blindness

122

Define Ramsay-Hunt syndrome

Ear canal/auricle/tympanic membrane involvement with painful vesicles, facial paralysis/paresis, ipsilateral hearing loss

123

Pathogenesis of ocular blindness due to zoster

  1. Lesions on tip of nose
  2. Possible ocular infection
  3. Nasociliary nerve involvement (branch of the ophthalmic nerve)

124

Transmission of HPV

Mainly via direct skin contact

Less likely via fomites

125

2 divisions of HPV

  • Genital vs. nongenital
  • Benign or low risk (HPV 6/11) vs. high risk (HPV 16/18) (risk malignant transformation)

126

3 clinical manifestations of HPV infection

  • Common, plantar, flat warts
  • Filiform warts
  • Condyloma acuminata (lesions without significant scale in genital area)

127

5 treatment options for HPV

  • Watchfl waiting
  • Cryotherapy with liquid nitrogen
  • Salicylic acid
  • Other topical treatments (depending on locaiton of warts)
  • Surgical excision

128

2 vaccines against HPV and the types they cover

  • Gardasil (6, 11, 16, 18)
  • Cervarix (16 and 18)

129

Clinical presentation of molluscum contagiosum (poxvirus)

Umbilicated pink, firm, waxy papules

NOTE: Usually self-limited

130

Describe the types of patients that may be affected by poxvirus and what this means about the infection itself (3)

  • Usual = children
  • If adult, transmission is likely sexual
  • AIDS = larger lesions

131

3 treatments for molluscum contagiosum

  • Cartharidin
  • Cryosurgery
  • Curettage

Among others

132

4 classic childhoos viral exanthems

  • Rubella (German measles)
  • Measles (Rubeola)
  • Erythema infectiosum
  • Roseola infantum (exanthem subitum)

133

Describe the exanthem and enanthem of measles

  • Erythematous macules and papules begin on the face and spread cephalocaudally
  • Koplik sports (grey papules on buccal mucosa)

134

4 complications of measles

  • Encephalitis
  • Otitis media
  • Pneumonia
  • Myocarditis

135

Describe the exanthem and enanthem of rubella

  • Pruritic, pink to red macules and papules which begin on the face and spread to neck, turnk, and extremities over 24 hours
  • Tender lymphadenopathy (occipital, postauricular, cervical)

136

4 complications of rubells

  • Arthralgia/arthritis
  • Hepatitis
  • Myocarditis
  • Pneumonia

137

Describe the exanthem and enanthem of erythema infectiosum

  1. Bright red macular erythema over cheeks
  2. Lacy eruption mainly on the extremitis

NOTE: school-age children affected, self-limited milk prodrome and 10%with arthralgias

138

Etiology of erythema infectiosum

Parvovirus B19 (also causes hydrops fetalis during pregnancy)

139

Describe the exanthem and enanthem of roseola infantum

Pink macules and papules surrounded by white halos beginning on trunk and spreading to neck and proximal extremities

140

Etiology of roseola infantum

Human herpesvirus 6 (HHV6)

141

Cause of tinea versicolor (pityriasis versicolor)

Malassezia furfur (yeast form = pityrosporum ovale or P. orbuiculare)

Yeast part of normal cutaneous flora

142

Presentation of tinea versicolor and where/when it occurs

  • Hyper/hypopigmented (pink, coppery brown or paler) macules and patches with fine scale
  • Lipid-rich areas of skin
  • Common in summer

143

Treatment for tinea versicolor

Topical antifungal

If extensive, use oral antifungal

144