Infectious Derm I - Exam 1 Flashcards
What is the MC pathogen that causes impetigo? More specifically?
Staph aureus
MSSA and MRSA
What is the very specific pathogen that causes bullous impetigo? What can happen as a result?
Epidermolytic toxin A
producing S. aureus causes scalded skin syndrome
What age group is most likely to have impetigo? Where?
kids but can happen at any age
minor breaks in the skin and NOSE
What is the underlying cause of the appearance this? What age group?
Bullous impetigo stains of S. aureus = exfoliative toxin A leads to loss of cell adhesion in the superficial epidermis
MC in newborn and older infants
What am I? What age group is MC?
non-bullous impetigo
all ages
How will non-bullous impetigo manifest clinically? How will they be arranged?
Can be painful and tender
Erosions with crusts
1 – 3 cm lesions
Central healing often after several weeks
Regional lymphadenopathy
arrangement: Scattered, discrete lesions with satellite lesions that occur from autoinoculation
impetigo bullous what is the flow of the lesion? Will there be erythema noted? What are they filled with?
Vesicles progress quickly to bullae after 1-2 days they will collapse and leave erosions with crusts
No erythema noted
Vesicles/bullae are filled with serous fluid
What is the Nikolsky sign? Will it be positive or negative in bullous impetigo?
when you press on the fluid in a bullous it will move laterally
bullous impetigo NEGATIVE Nikolsky sign
How do you diagnose bullous impetigo?
clinical diagnosis but will gram stain and culture the bullous
What is the treatment for impetigo? Bullous impetigo?
What is the pt education associated for impetigo? What is the prevention?
Patient Education:
Good Hygiene
Nails, proper soap, frequent washing
Underlying condition treatment
Mupirocin in other areas where skin barrier has been broken
Wounds covered
Avoid contact with others (>24hrs post ABX initiation)
Prevention:
BPO wash
Check family members for signs
Ethanol or isopropyl gel for hands
What is the follow up for impetigo?
1 week
What is the first line pharm management for impetigo?
topical mupirocin and oral Cephelaxin
**What is the medication management for impetigo if the pt has a PCN allergy?
Azithromycin
Clindamycin
Erythromycin
and topical mupirocin
**What is the outpt tx of impetigo if you suspect MRSA?
topical mupirocin and oral Bactrim or Doxy
What am I? What can cause it? Does it tend to hurt or itch?
folliculitis
S. aureus, fungi, mites, viral
tend to be non-tender/slightly tender and itchy
What are predisposing factors for folliculitis?
Shaving hair bearing areas
Occlusion of hair bearing areas
Hot tub usage
Topical CS
Systemic ABX (gram negative can proliferate)
Diabetes
Immunosuppression
Hot tub use is associated with what pathogen? Where is it typically found?
pseudomonas
on the trunk
**What is the typical presentation of gram negative folliculits?
acne patient who worsens on systemic ABX w/ small follicular pustules = gram neg folliculitis
How do you dx folliculitis?
clinical dx but can gram stain or culture if you really want to
What is the tx for mild folliculitis? What is considered mild? When should you see a resolution?
only a few spots
Warm compresses
Wash with BPO or antibacterial soap (dial)
ABX if spontaneous resolution does not occur within 2-3 weeks or if symptoms worsen
What is the treatment for moderate folliculits?
TOPICAL abx either:
Clindamycin BID x 10 days
Mupirocin TID x 10 days
What is the tx for severe folliculitis that has MSSA? MRSA?
oral cephalexin
oral doxy or bactrim
______ is key in folliculitis. Name 2 ways
prevention is key!
BPO or chlorhexidine body wash
Tender
Red
Hot
Indurated nodule
may have fever
may have constitutional symptoms
abscess
How long does it take for an abscess to form? How do you dx? What pathogen?
days to weeks
gram stain and culture of exudate
MSSA or MRSA
What is the tx for an abscess? When are abx needed?
I&D
Single abscess ≥2 cm
Multiple lesions
Extensive surrounding cellulitis
Immunosuppression or other comorbidities
S/S toxicity ( fever >100.5°F, hypotension, or sustained tachycardia)
Inadequate clinical response to I&D alone
Indwelling medical device (prosthetic joint, vascular graft, or pacemaker)
High risk for transmission of S. aureus to others (athletes, group home)
How do you decide IV vs oral treatment for an abscess?
is the pt toxic? fever, hypotension, tachycardia
is it close to any indwelling devices?
If yes, then need to admit for IV abx
When would you consider referring to a general/plastic surgeon for an abscess?
Palms
Soles
Nasolabial areas
Genitalia
What is the pt education for abscesses? What is the prevention?
DO NOT SQUEEZE
prevention:
Antibacterial soap or BPO wash
Avoid heat and friction
Acute
deep seated
red
hot
tender nodule or abscess
What am I?
What size? Where are they usually found?
furuncle
1-2cm
Any hair bearing region (beard, posterior neck, occipital scalp, axillae, buttocks
_____ is a nodule with cavitation after drainage
fluctuant
What is the management? Erythema present should indicate ______
Warm compresses
10 minutes daily
Abx probably necessary
bactrim or clinda or doxy
What am I?
What will the pt present like? Do they hurt?
carbuncle
Patient is typically ill appearing
Fever + along with constitutional symptoms
these are PAINFUL
______ deeper infection composed of interconnecting abscesses usually arising in several contiguous hair follicles. Where are the MC locations?
carbuncle
nape of neck, back, and thighs
How do you dx carbuncle? What is the tx for uncomplicated vs complicated?
Clinical gram stain is helpful with C&S
uncomplicated: bactrim or clinda or doxy
complicated: ADMIT for IV abx
What is the criteria for carbuncle admission? What is the tx?
toxic appearing
Rapid progression
No improvement after 24-48 hours of PO ABX
*** Vancomycin 1-2 g IV daily DOC
_____ infection of hair follicle +/- purulence at the ostium
_____ localized inflammation with a collection of pus enclosed within the tissue
Folliculitis
Abscess
_____ infected nodule evolving from folliculitis
_______ deeper infections of interconnecting furuncles
Furuncle
Carbuncle
_______ rapid progression of infection with extensive necrosis of soft tissues and overlying skin. What is the etiology?
Necrotizing Fasciitis
polymicrobial:
Beta-hemolytic GAS
Pseudomonas aeruginosa
Clostridium
What is the underlying cause of necrotizing fasciitis?
Bacteria release enzymes/gases that degrade fascia resulting in rapid proliferation, local thrombosis, ischemia and necrosis
Where does necrotizing fasciitis usually begin? What age range is MC?
May begin deep at site of nonpenetrating minor trauma (bruise, minor trauma, laceration, needle puncture, surgical incision)
MC Middle age (mid 30 - mid 40’s)
What am I?
What are the risk factors?
Necrotizing Fasciitis
DM, ETOH abuse, liver dz, CKD, malnutrition
How do you dx necrotizing fasciitis? What s/s start to appear after 36-72 hours of onset?
clinical!
Involves soft tissue becomes blue in color and vesicles and bullae appear and spread along the fascial plane
What are s/s of necrotizing fasciitis progression?
Extensive cutaneous soft tissue necrosis develops
Black eschar with surrounding irregular border of erythema
Fever and other constitutional symptoms
**Necrotizing fasciitis is an infection of the ______ and _____ that is rapidly progressive and destructive.
subcutaneous tissue
fascia
What are the key clinical red flags for necrotizing fasciitis?
Severe, constant pain out of proportion to physical exam, or anesthesia
Erythema evolving into a dusky gray color
Malodorous, watery “dirty dishwater” discharge
Gas (crepitus, or crackling sounds) in the soft tissues
Edema extending beyond areas of erythema
Rapid progression despite antibiotic therapy
What is the tx for necrotizing fasciitis? Give abx options
surgical debridment and start broad spectrum abx
Carbepenem
Ampicillin/sulbactam
Clindamycin
MRSA Vancomycin
all depend on the culture
What am I? What is the MC pathogen? What age ranges?
Erysipelas
group A 𝛃-hemolytic strep
young children and older adults
What is the underlying cause of erysipelas?
Acute superficial infection (dermis and dermal lymphatic vessels)
Describe the erysipelas lesion in words
painful/tender/hot
bright red, raised, edematous, indurated plaque
sharp borders
What is the prodrome of erysipelas and cellulitis?
fever, chills, anorexia, malaise
+/- signs of sepsis
What is cellulitis? What is the MC pathogen? What age group?
Acute infection of the dermis and subcutaneous tissue
S. aureus (MC) and Group A β-hemolytic streptococcus
middle age adults
What is the MC pathogen associated with cellulitis after being bitten by a cat/dog? Freshwater wound?
Pasteurella multocida
Aeromonas
Describe the cellulitis lesion in words? What is the highlighted word?
painful/tender/hot
bright red, edematous, (+/- induration)
**indistinct borders (not raised)
What are the 2 highlighted risk factors for Erysipelas & Cellulitis?
compromised skin integrity
compromised immune system
How are Erysipelas & Cellulitis dx? When would you order labs?
clinical dx
only if systemic symptoms are present
What are the indications for admission and IV abx for Erysipelas & Cellulitis?
Systemic presentation: Fever > 100.5, hypotension, sustained tachycardia
Rapidly spreading lesion
Progression of clinical features after 48 h of oral abx
Unable to tolerate oral therapy
Comorbidities: immunosuppression, neutropenia, asplenia, cirrhosis, heart/renal failure
If you suspect MRSA _____ is first line IV therapy? ______ is PO therapy
vancomycin (1st line)
clindamycin (first line)
What are 3 abx options for IV MSSA coverage? oral?
IV:
cefazolin
nafcillin
clindamycin
Oral:
cephalexin
nafcillin
clindamycin
What is the abx of choice for Erysipelas & Cellulitis due to dog/cat bite? What organism?
amoxicillin/clavulanate (Augmentin)
pasteurella multocida
What is the abx of choice for Erysipelas & Cellulitis due to human bite? What organism?
amoxicillin/clavulanate (Augmentin)
Eikenella, Group A Streptococcus
What is the abx of choice for Erysipelas & Cellulitis due to exposure in fresh water? What organism?
ciprofloxacin (Cipro)
Aeromonas
What is the abx of choice for Erysipelas & Cellulitis due to exposure in salt water? What organism?
doxycycline
Vibrio vulnificus
What am I? What is the pathogen behind for acute? chronic?
Lymphangitis
acute:
Group A strep
S. aureus
Herpes simplex virus
chronic: Mycobacterium marinum
_____ is the acute inflammatory process involving the subcutaneous lymphatic channels
Lymphangitis
What are 4 portal for lymphangitis? What is the major symptom? Is it painful?
Break in skin
Wound
Paronychia
Primary herpes simplex
Red linear streaks and palpable lymphatic cord
Pain +/- erythema proximal to break in skin
What is the tx for lymphangitis? When are they indicate?
Dicloxacillin or 1st generation cephalosporin
MRSA then Clinda or Bactrim
toxic appearing patient or no improvement after 24-48 hours
Should follow up with the pt in _______ if dx is lymphangitis.
24- 48 hours
if not improving then systemic abx
What is cutaneous candidiasis? What is the MC pathogen? What age?
superficial fungal infection of the skin
Candida albicans
neonates and adults >65 years old
What are the common areas involved for Cutaneous Candidiasis? What are the risks factors?
Genitocrural, gluteal, interdigital, inframammary, axilla, under pannus
Obesity, DM, local occlusion/moisture, steroid/abx use, hyperhidrosis, incontinence
What am I? What will the pt complain of? ** What is important to remember?
Cutaneous Candidiasis
it will tender, painful and itchy
**Satellite lesions typically present
How do you dx cutaneous candidiasis?
KOH prep
What am I?
What is the tx? mild/mod and severe
cutaneous candidiasis
mild/mod: topical ketoconazole for 2-3 weeks
severe: oral fluconazole
What is the important pt education for cutaneous candidiaisis?
Continue topical antifungal x 2 weeks after clearance
keep the areas dry with drying powders and hair dryer
What am I?
What triggers it?
Who is commonly affected?
balanitis
Common infections triggers include candida, Trichomonas vaginalis, gonorrhoeae, streptococcus
Affects uncircumcised men with poor hygiene.
What is the tx for balanitis?
Treatment- Improved personal hygiene, use of low to medium potency topical steroid until improved
What are dermatophytes? Give some examples
Unique group of fungi capable of infecting nonviable keratinized cutaneous structures
stratum corneum
nails
hair
How long can arthrospores (dermatophytes) survive in human scales?
up to 12 months
What are 3 genera of dermatopytes? **Which one is MC?
Trichophyton (MC) Hair and nail**
Microsporum
Epidermophyton
**Where is the MC place for a dermatophyte to be in a kid? Where on an adult?
**MC on the scalp
Intertriginous areas in young and older adults
How are dermatophytes transmitted? Which one is MC and least common?
Person to person (MC)
Animals
Soil (least common)
What is the pathophys behind dermatophytes?
dermatophytes produce enzymes (keratinases) that break down keratin allowing fungi to invade epidermis, nail and hair shaft
What are the correct terminology for dermatophytes based on body area for the following:
feet
groin
trunk/extremities
hands
face
hair
facial hair
nails
feet (tinea pedis)
groin (tinea cruris)
trunk/extremities (tinea corporis)
hands (tinea manuum)
face (tinea facialis)
hair (tinea capitis)
facial hair (tinea barbae)
nails (onychomycosis)
What is the term for person-person dermatophyte spread? animal-human? environmental?
Person to person = anthropophilic
Animal to human = zoophilic
Environmental = geophilic
What are predisposing factors for dermatophytes?
atopy, ichthyosis
collagen vascular disease
-RA, SLE, temporal arteritis, scleroderma
steroid use (oral/topical)
sweating, local occlusion
occupational exposure
How do you dx dermatophytes dz?
skin and nail for KOH
Skin - use a blade to scrape skin cells from area
Nail - use a dull scalpel to remove excess keratin from nail
Hair - remove hair at root
2 drops of 10% KOH to glass slide - sit for 15 min
Inspect under low and high power
hyphae and spores will be present
potassium hydroxide is KOH
What device is used in dx dermatophytes? What will microsporum show up as?
Woods lamp
blue green flourescence = microsporum
What is one advantage of a fungal culture over KOH prep? What is the limitations?
differentiates between fungal spp
requires days-wks to return definitive diagnosis
**What is the most sensitive form of dermatophytes diagnostic testing options? What are the 2 limitations?
Dermatopathology via skin biopsy
skin biopsy sample required
more invasive testing
What are the 2 options for dermatophyte treatment?
topical or oral antifungals: -azoles
allylamines:
Naftfine (Naftin)
Terbinafine (Lamisil)
**What do you need to monitor if you prescribed allyamines? **Which one is preferred?
CBC, Cr, LFTs
Terbinafine
What 2 populations are tinea capitis MC in?
kids and alopecia pts
What occurs on the outside of the hair shaft in tinea capitis? What is the name?
has a circular “grey patch” and the hairs will break off inside the circle, very brittle
ectothrix
What occurs within the hair shaft of tinea capitits? What is the name for it?
inflammation with the hair follicle: kerion
will appear with a “black dot”
endothrix
Describe the black dots found in ______
tinea capitis
Broken off hairs near the scalp, swollen hair shafts
Dots occur because broken hairs at the scalp
will be diffuse and poorly circumscribed
What pathogens are the black dots caused by?
T. tonsurans
T. violaceum
What am I? Describe it. What about the hairs?
Kerion
Inflammatory mass in which remaining hairs are loose, boggy, purulent, inflamed nodules, and plaques
PAINFUL and will drain pus from multiple openings
hairs do NOT break off but can be easily pulled out and will have crusting and matting surrounding the hairs
What 2 organisms cause kerion? What happens after it heals?
T. verrucosum
T. mentagrophytes
Heals with scaring alopecia
What am I? How will it heal?
tinea capitis favus
latin for “honeycomb”
doesnt clear spontaneously and will result in scarring alopecia and will have an ODOR
______ kind of tinea capitis pathogen does NOT fluoresce under Wood’s lamp
T. tonsurans
When will you start to see a fungal culture grow for tinea capitis?
for 10-14 days
What is the treatment for tinea capitis?
PO antifungals: terbinafine or griseofulvin
antifungal shampoos: Ketoconazole 2% shampoo QD
What is tinea cruris? Where is it MC found?
“Jock Itch”
Inguinal folds and thighs
What pt population is tinea cruris MC? co-exists with _______ typically
males
Tinea Pedis
Describe tinea cruris in words.
Large scaling, well demarcated dull red/tan/brown plaques
CENTRAL CLEARING
with lateral scaly border with papules and pustules at the margins
Once you start to treat tinea cruris, what happens? What 2 parts of the body are rarely involved?
it begins to lack scale
scrotum and penis are rarely involved
What am I?
How do you dx?
What is the tx?
tinea cruris
clinical dx
topical antifungal +/- 3 weeks
if failure of topicals, then PO griseofulvin
What are some prevention strategies for tinea cruris?
Wear shower shoes while bathing
Put on socks before pants
Antifungal/drying powders
Benzoyl peroxide wash
Alcohol based sanitizer gels
Avoid tight fitted clothing/use cotton underwear
What am I?
What are the 2 slang term for it?
tinea corporis
ring worm or wrestlers infection
Describe tinea corporis in words. Does it always have to be itchy?
What is the tx?
Sharply marginated plaques
Vesicles and papules
Central clearing
NO! can be asymptomatic
topical antifungals or oral if a large surface area (Terbinafine)
What labs do you need to draw before prescribing terbinafine?
CBC, Cr, LFTs
What am I? Describe it in words
tinea pedis
Erythema
Scaling
Maceration
+/- bullae formation
What is the MC pt for tinea pedis? What else do you need to check?
20-50 pt
tinea cruris dx then absolutely check feet!!
**Tinea cruris dx, then what should you do?
**also need to check feet for tinea pedis
What are the risk factors for tinea pedis?
hot, humid climate
occlusive footwear
hyperhidrosis
What are the 4 subtypes of tinea pedis?
interdigital
Moccasin
Inflammatory
Ulcerative
What type of tinea pedis? Describe it in words? Where is the MC site?
interdigital type
dry, scaling, maceration with fissuring
MC site = between 4th and 5th toe
What type of tinea pedis? Describe it in words
moccasin type
well demarcated, scaling with erythema, papules at margin with fine WHITE scale with hyperkeratosis
What are the 2 MC patterns consistent with moccasin type tinea pedis?
MC on soles or lateral border of feet
aka looks like the foot was dipped in liquid
MC bilateral
Describe tinea pedis inflammatory type in words. What if pus is seen?
Vesicles or bullae with clear fluid
After rupture erosions with ragged ringlike border
Pus usually indicates secondary bacterial infection
**_____ can occur with inflammatory type tinea pedis. Where are the 3 MC places?
ID reaction (think autoreaction to the inflammatory caused by the tinea pedis fungal infection)
MC on sole, instep, and web spaces
What am I? What is also likely to occur?
tinea pedis ulcerative type
May have secondary bacterial infection S. aureus
Where does ulcerative type tinea pedis usually start? Where does it go?
Extension of interdigital tinea pedis onto the plantar and lateral foot
What is the tx for tinea pedis? When are oral antifungals best?
topical antifungals
Best for hyperkeratotic tinea pedis
Terbinafine
What are some prevention strategies for tinea pedis?
Wash with BPO daily
Use antifungal powder (Zeasorb AF)
Shower shoes in communal showers
Alcohol based sanitizers
What am I? What is it caused by? Who is the MC pt? Is it contagious?
Pityriasis Versicolor or tinea versicolor
Overgrowth of Malassezia furfur (yeast)
adolescents with OILY skin
**NOT CONTAGIOUS!!
What are risk factors for Tinea Versicolor?
Climate
Sweating
Immunodeficiency
Products
Steroid use
Oily skin
What will a pt complain of with tinea versicolor?
Clinically asymptomatic, patient can experience some itching possibly psychological. The appearance is why patients come seek treatment!
How do you dx tinea versicolor? What is the tx?
KOH prep that will show budding yeast with a classic “spaghetti and meatballs” appearance
Selenium sulfide or zinc pyrithion (head and shoulders)
or topical antifungals
Describe tinea versicolor in words
rash consisting of hypopigmented macules and papules with fine scales
can also be hyperpigmented or erythema +/- plaques
Describe erysipelas in words
localized painful, distinctly demarcated, raised erythema and edema often with streaking and prominent lymphatic involvement
