Dr. Al-Muhsaini -- Infectious Skin Diseases and Rashes Flashcards
(144 cards)
1
Q
2 ways bacterial infection can happen in the skin
A
- Direct infection of skin and adjacent tissues
- Cutaneous disease due to effect of bacterial toxin
2
Q
2 examples of cutaneous diseases due to effect of bacterial toxin
A
- Staphylococcal scalded skin sydrome
- Toxic shock syndrome
3
Q
3 kinds of *S. aureus *toxins
A
- Toxic shock syndomre toxin-1 (TSST-1)
- Exfoliative toxin (ET-A, ET-B)
- Panton-Valentine leukocidin (PVL)
4
Q
Define TSST-1
A
Superantigen involved in toxic shock syndrome (TSS)
5
Q
2 effects of ET-A and ET-B
A
- Protease activity
- Splits epidermal desmoglein 1
6
Q
2 conditions that exfoliative toxins of S. aureus are involved in
A
- Styphylococcal scalded skin syndrome (SSSS)
- Bullous impetigo
7
Q
Specific S. aureus type that can secrete PVL toxin
A
Community-acquired MRSA strains
8
Q
Effects of S. aureus PVL
A
- Associated with increased virulence (leukocyte destructon, necrosis)
9
Q
Define impetigo and its two types
A
Highly contagious infection seen primarily in children (bullous vs. nonbullous)
10
Q
2 most common causes of nonbullous impetigo
A
- S. aureus
- GAS
11
Q
Clinical presentation of nonbullous impetigo
A
Erythematous macule –> erosion with golden (honey color) crust
12
Q
Diagnosis of nonbullous impetigo
A
Positive culture from exudate under crust
13
Q
Treatment for nonbullous impetigo
A
- Topical mupirocin
- If extensive, can use oral ABX (i.e. cephalexin, dicloxacillin)
14
Q
ONLY cause of bullous impetigo
A
S. aureus
15
Q
Clinical presentation of bullous impetigo
A
Flaccid, transparent bullae –> rupture leaving shiny, dry erosion with no surrounding erythema
16
Q
Pathogenesis of bullous impetigo
A
Cleavage at granular layer due to Exfoliative toxin (ET-A, ET-B) binding to desmoglein 1
17
Q
Treatment for bullous impetigo
A
- Topical mupirocin AND
- Oral antibiotic (i.e. cephalexin, dicloxacillin)
18
Q
Define bacterial folliculitis
A
Superficial infection of hair follicle usually due to S. aureus
19
Q
Clinical presentation of bacterial folliculitis
A
Pustules in follicular distribution associated with hairs
20
Q
3 treatments for bacterial folliculitis
A
- Antibacterial wash (chlorhexidine or triclosan)
- Antibacterial ointments (mupirocin)
- If widespread, can use oral antibiotic
21
Q
Typical cause of frunucle, carbuncle and abscess
A
S. aureus
22
Q
Define furuncle
A
Deep-seated tender nodule of hair follicle
23
Q
Define carbuncle
A
Coalescing of adjacent furuncles with multiple draining sinuses (typically involves nape of neck or back of thighs)
24
Q
Define abscess
A
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
