Lecture 3: Infections Flashcards
MCC of bullous impetigo
Staph Aureus & GAS
Both MSSA and MRSA (GAS and as)
Results in scalded skin syndrome
MC demographic for bullous impetigo
Newborn and older infants
bullies and babies
MC demographic for non-bullous impetigo
All ages
Presentation of non-bullous impetigo
- Painful and tender
- Erosions with crusts
- 1-3 cm lesions
- Central healing
- Regional LAN
- Scattered, discrete lesions
What is autoinoculating?
Kid scratches vesicle, spreads to a different area.
Presentation of bullous impetigo
- No erythema
- Vesicles => bullae
- Yellow => dark brown
- negative Nikolsky sign
Collapse of bullae in 1-2d
How is bullous impetigo dx?
Clinically, BUT often use Gram stain & culture
Tx of impetigo
- Warm water soaks followed by topical mupirocin
- 7d abx for widespread (keflex or erythromycin)
- MRSA = doxy
- Critically ill with MRSA = vanco or linezolid
- Bullous or severe = PO
Patient education for impetigo
- Good hygiene
- Mupirocin in any skin breaks
- Avoid contact with others in first 24h of abx use
- BPO wash
- Ethanol or isopropyl gel for hands
BPO = benzoyl peroxide
How soon should you f/u for impetigo?
1 week
First line systemic tx for impetigo
- Systemic: dicloxacillin/augmentin/cephalexin
- If PCN allergic: macrolides
dicey IM
Define folliculitis
Infection of hair follicle +/- pus in the ostium of the follicle
What does folliculitis become if it progresses? Most common organisms?
- Becomes abscesses or furuncles
- Staph, Pseudomonas hot tub, Viral , fungal, syphilis
How is folliculitis dx?
- Clinical, but it can be confirmed with
- Gram stain
- C&S
- KOH if fungal suspected
Tx of folliculitis
- Mild: warm compresses, BPO wash
- Moderate: topical abx = clinda or mupirocin
- Severe MSSA: Keflex
- Severe MRSA: Doxy or bactrim x10d
almost all superficial MRSA seems to be doxy
What are the typical causative organisms for an abscess related to folliculitis?
MSSA or MRSA
When is abx therapy indicated for an abscessed folliculitis?
- Single >= 2cm
- Multiple
- Surrounding cellulitis
- Immunosuppression and other comorbidities
- S/S toxicity
- Inadequate response
- Indwelling medical device
- High risk of transmission
When is surgery considered for I&D?
- Very large
- Located on palms (nerves?)
- Soles (nerves?)
- Nasolabial areas
- Genitalia
What is a furuncle?
Acute, deep seated, red, hot, tender nodule or abscess
Presentation of a furuncle
- Nodule with cavitation after drainage
- Staphylococcal folliculitis
- Any hair bearing region
Management of a furuncle
- Warm compresses
- Erythema = need abx
- Bactrim
- Clinda
- Doxy
7d take the car of uncles to BCD
What is a carbuncle?
Deeper connection of interconnected furuncles
A car of furuncles
MC location for carbuncles
- Nape of neck
- Back
- Thighs
trunk of the car
Management of uncomplicated carbuncle
- Bactrim
- Clinda
- Doxy
7d take the car of uncles to BCD
When to admit for carbuncle and DOC?
- Toxic
- Rapid progression
- No improvement after 24-48h of PO ABX
- DOC: Vanco 1-2g IV daily
Deep = vanco
What is necrotizing fasciitis?
- Flesh eating disease
- Rapid progression of infection with extensive necrosis of soft tissues and overlying skin
MCC of necrotizing fasciitis?
- GABHS
- Pseudomonas
- Clostridium
Polymicrobial
MC demographic and risk factors for necrotizing fasciitis?
- Middle aged 30-40s
- DM, ETOH abuse, Liver dz, CKD, malnutrition
Often begins with non-penetrating minor trauma
Presentation of necrotizing fasciitis
- Severe pain out of proportion
- Skin hyperthesia
- Cyanosis
- Skin pallor
- Muscle weakness
- Foul smelling exudate
As necrotizing fasciitis develops, what does it appear as?
- Cyanotic
- Vesicle and bullae appearance
- Black eschar with surrounding irregular border
- Fever and systemic symptoms
Clinical red flags for necrotizing fasciitis?
- Severe, constant pain out of proportion to PE
- Erythema turning into dusky gray
- Malodorous, dirty dishwater discharge
- Gas in the soft tissues
- Edema beyond erythema
- Rapid progression
Tx of necrotizing fasciitis
- Debridement
- Broad spectrum ABX: carbapenem, unasyn, clinda, vanco for MRSA, all depends on gram stain and C&S
What is erysipelas?
Acute, superficial infection of the dermis and dermal lymphatic vessels
MC demographic and etiology of erysipelas?
- GABHS
- MC in young children or older adults
How does erysipelas present?
- Prodrome of fever, chills, anorexia, malaise
- General signs of sepsis potentially
- Lesions that are painful/tender/hot, bright, red, edematous plaques with sharp borders
What is cellulitis?
Acute infection of the dermis and subcutaneous tissue
Etiology of cellulitis and MC demographic
- Staph and GABHS
- Cat/dog: Pasteurella multocida
- Freshwater: aeromonas
- MC: middle aged adults
Presentation of cellulitis
- Prodrome
- General signs of sepsis potentially
- Painful/red/hot/tender
- bright red
- Indistinct/irregular borders
Erysipelas has sharp borders and is superficial
RFs for cellulitis
- Minor skin trauma
- Body piercing
- IVDU
- Tinea pedis infection
- Animal bites
- PVD
- Immunosuppressed
- Lymphatic damage
Dx of cellulitis
Clinical
Workup of labs and imaging mainly for systemic or r/o abscess
Indications for admission for cellulitis
- Systemic presentation
- Rapidly spreading
- Progression after 48h of abx
- Unable to tolerate PO
- Comorbidities of immunosuppression/liver/heart/renal failure
IV management for cellulitis/erysipelas
- MRSA: vanco 1st, dapto 2nd
- MSSA: cefazolin, clinda, nafcillin
Extra deep
Oral management for cellulitis/erysipelas
- MRSA: clinda 1st, amox + bactrim or doxy
- MSSA: keflex, nafcillin, clinda
Bite or water exposure requires different management in regards to erysipelas & cellulitis. What are the ABX?
- Dog/cat bite: augmentin (animal are augmented)
- Human bite: Eikenella = broad spectrum (augmentin)
- Freshwater = cipro for aeromonas (fresh cod)
- Saltwater = doxy for vibrio (salty duck)
If Eik bites, you need broad coverage
Etiologies for lymphangitis
- Acute: GAS, staph, HSV
- Chronic: mycobacterium marinum
marinating
Tx of lymphangitis
- Dicloxacillin or 1st gen cephalo (keflex)
- MRSA: clinda or bactrim
Dependent on sensitivity
Followup for lymphangitis
24-48h after, checking for improvement
MCC of cutaneous candidiasis and MC demographic
- MCC: candida albicans
- MC in neonates and seniors
RFs for cutaneous candidiasis
- Obesity
- DM
- Local occlusion/moisture
- Steroid/abx use
- Hyperhidrosis
- Incontinence
Presentation of cutaneous candidiasis
- Pruritic
- Tender/painful
- Macerated
- Erythematous
- Satellite lesions
How is cutaneous candidiasis dx?
KOH prep
fungus need KOH
Tx of mild-mod cutaneous candidiasis?
Topical antifungals: keto, eco, clotri, miconazole
Tx of severe cutaneous candidiasis?
Oral antifungals: fluconazole x 2-3 wk
What is balanitis?
- Inflammation of the Glans penis
- MC in uncircumcised men with poor hygiene
What is a dermatophyte?
Unique group of fungi capable of infecting non-viable keratinized cutaneous structures (stratum corneum, nails, hair)
3 genera of dermatophytes
- Trichophyton (MC) in hair and fails
- Microsporum
- Epidermophyton
Where are dermatophytes MC in? Transmission methods?
- MC in the scalp or children or intertriginous areas of young/older adults
- Transmission:
- Person to person is MC
- Animals
- Soil is least common
What are the tinea locations?
- Tinea pedis: feet
- Tinea cruris: groin
- Tinea corporis: trunk/extremities
- Tinea manuum: hands
- Tinea facialis: face
- Tinea capitis: hair
- Tinea barbae: facial hair
- Onychomycosis: nails
What are the 3 classifications of dermatophyte transmission?
- Person to person = anthropophilic
- Animal to human = zoophilic
- Environmental = geophilic
How are dermatophytes tested?
- KOH prep showing hyphae and spores
- Woods lamp with black light will show microsporum
- Fungal cultures (more definitive but takes days-weeks)
- Dermatopathology skin biopsy (more sensitive but need an entire skin biopsy)
Tx of tineas
- Topical Imidazoles: clotrim, mico, keto
- Topical Allylamines: naftifine, terbinafine
Systemic tx of dermatophytes
- Imidazoles PO: Itra, keto, flucon
- Allylamines: Terbinafine
Who is tinea capitis MC in?
AA children
What is ectothrix?
- A grey patch with a scaly appearance
- Hair shafts are broken off and brittle
- An infection OUTSIDE of the hair shaft
What is endothrix?
- Black dot appearance
- Infection within the hair shaft
How does non-inflammatory tinea capitis appear?
- Scaling
- Pruiritis
- Alopecia
- Adenopathy
How does inflammatory tinea capitis present?
- Painful
- Tender
- Alopecia
How do the black dots appear in tinea capitis?
- Broken off hairs => swollen shafts
- Diffuse and poorly circumscribed
- MCC: T tonsurans or violaceum
TVs in the house (endothrix is inside)
What is kerion?
- Inflammatory mass in which remaining hairs are loose
- Boggy, purulent, inflamed nodules, and plaques
- Crusting and matting
- MCC: T. verrucosum and mengatophytes (heals with scars)
very mangy kerion
What is favus?
- Latin for honeycomb
- Perifollicular erythema and matting of hair
- Malodorous and scarring
Which tinea does not fluoresce?
T tonsurans
not light cause it weighs a ton
Tx of tinea capitis
- PO antifungals: terbinafine or griseofulvin (take with greasy meal)
- Antifungal ketoconazole shampoo
What is tinea cruris/jock itch commonly seen with?
Tinea pedis
Athletes and jocks
How does tinea cruris present?
- Large scaling, well-demarcated plaques
- Central clearing
- Papules/pustules at margins
Tx of tinea cruris
- Topical keto or econazole
- Griseofulvin if above fails
What is tinea corporis?
- RING WORM
- Wrestler’s infection
Presentation of tinea corporis
- sharply marginated plaques
- Vesicles and papules
- Central clearing
Tx of tinea corporis
- Topical antifungals
- Oral antifungals (if big): terbinafine x 4 wks
How does tinea pedis/athlete’s foot present?
- Erythema
- Scaling
- Maceration
- +/- bullae formation diagnosed tinea
4 subtypes of tinea pedis
- Interdigital
- Moccasin
- Inflammatory
- Ulcerative
How does interdigital tinea pedis present?
- Dry scaling
- Maceration
- Fissuring, esp with hyperhidrosis
- MC between 4th and 5th toe
How does moccasin tinea pedis present?
- Well demarcated
- Scaling with erythema
- Papules at margins
- Fine white scaling
- Hyperkeratosis, which is MC on soles/lateral borders of feet and occurs bilaterally
How does inflammatory tinea pedis present?
- Vesicles or bullae with clear fluid
- Presence of pus = secondary bacterial infection
- Ruptures will leave erosions with ringlike border ID reaction can occur
- MC on the sole, instep, and webspaces
How does ulcerative tinea pedis present?
Extension of interdigital tinea pedis onto plantar and lateral foot, presenting with a secondary bacterial infection
Tx of tinea pedis
- Topical: ketoconazole & econazole BID x 2-4wk
- Oral best for hyperkeratosis: terbinafine
What is tinea versicolor?
- AKA pityriasis versicolor
- Not a dermatophyte infection
- MC in adolescents, due to an overgrowth of malassezia furfur
NOT CONTAGIOUS
How does tinea versicolor typically present?
- Macules w/ w/o scale
- Patches w/ w/o scale
- Plaques w/ w/o scale
- Hypo/hyperpigmentation
- Erythema
What does KOH prep show for tinea versicolor?
Hyphae and budding yeast spaghetti and meatballs
very colored
Tx for tinea versicolor
- Selenium sulfide or zinc pyrithion
- Topical antifungals: ketoconazole
PO only if topicals fail
