Skin + Soft Tissue Infections Flashcards
what is cellulitis
inflammation of dermis + subcutaneous tissue
most common organisms that cause cellulitis
staph aureus or group A strep through broken skin
signs + symptoms of cellulitis
painful, red, hot, swelling of site
- lower leg / cannula site / wound most common sites
non-dermal features of cellulitis
lymphadenopathy
fever
is bilateral leg cellulitis common?
NO - very rare, think venous eczema if bilateral erythema
risk factors for cellulitis
previous cellulitis diabetes CKD liver disease cancer immunodeficiency venous insufficiency age
management of staph aureus cellulitis
oral flucloxacillin 1-2 weeks
- IV if severe
- clindamycin/clarithromycin if penicillin allergic
management of step A cellulitis
oral phenoxymethylpenicillin
- IV benzylpenicillin if severe
treatment of cellulitis from human/animal bite wound
co-amoxiclav
what is erysipelas
superficial cellulitis
- affects dermis + upper subcutaneous tissue
what organism causes erysipelas
group A strep
presentation of erysipelas
raised, well defined erythema
systemic symptoms
usually affects legs
asymmetrical butterfly distribution on cheeks + nose if affecting face
treatment of erysipelas
phenoxymethylpenicillin or benzylpenicillin
what vein is most commonly affected by superficial thrombophlebitis
long saphenous
- usually non infectious cause + self limiting
treatment of superficial thrombophlebitis
topical anti-inflammatory
skin abscess presentation
what is the underlying pathology?
painful, fluctuant swelling of the skin
- localised collection of pus within dermis or epidermis
what organisms cause a skin abscess
usually staph aureus, including MRSA
management of skin abscess
incision + drainage under local anaesthesia
fluid culture
when are antibiotics used in the management of a skin abscess?
if abscess > 2cm
multiple abscesses
systemically unwell
immunocompromised
what antibiotic would be used to treat skin abscess if one was required
co-trimoxazole
what is folliculitis?
how does it present?
superficial infection of hair follicles causing itchy pustules
- usually staph aureus
what is hot tub folliculitis?
infection by pseudomonas aeruginosa
what are furuncles?
abscesses which result from deep infection of hair follicle
- usually staph aureus
- may rupture
what are carbuncles?
larger than furuncles with multiple openings
- due to infection of several adjacent hair follicles
- usually staph aureus
treatment of mild folliculitis
conservative management
topical antiseptics e.g. triclosan
treatment of moderate-severe folliculitis
topical antibiotics e.g. mupirocin or oral flucloxacillin
treatment of furuncles and carbuncles
incision + drainage, may also need oral flucloxacillin
what is pyomyositis
purulent muscle inflammation
- usually due to staph aureus
what muscles are most commonly affected by pyomyositis
pelvic + thigh muscles
presentation of pyomyositis
pain over muscle + fluctuant swelling
weakness
systemic symptoms
definitive diagnosis of pyomyositis
MRI
- bloods will show increased WBC + CRP
treatment pyomyositis
IV antibiotics until improvement then 2 weeks oral
what is necrotising fasciitis
rare but life threatening infection of soft tissue
- bacteria enters through break in skin e.g. following surgery/trauma
- infection spreads rapidly across fascial layer leading to tissue death
what are the two types of necrotising fasciitis
Type 1 - polymicrobial
Type 2 - monomicrobial
when is type 1 necrotising fasciitis most commonly seen
post surgery
what organism causes type 2 necrotising fasciitis
group A strep e.g. strep pyogenes
presentation of necrotising fasciitis
rapidly expanding inflamed area of skin
may progress to bullae + purple discolouration
severe pain
skin crepitus- crackly on palpation. seen as gas bubbles on plain X ray
blood results in necrotising fasciitis
increased WBC, CK, lactate
management necrotising fasciitis
urgent surgical debridement
IV antibiotics
IV antibiotics given in necrotising fasciitis
IV Carbapenem + clindamycin +/- vancomycin for MRSA coverage
what is Fourniers gangrene
polymicrobial (type 1) necrotiising fasciitis of male perineum
what is gas gangrene
myonecrosis due to alpha toxin from clostridium perfrigens
where are clostridia bacteria usually found?
how do they cause gas gangrene?
normal gut flora
major trauma or GI surgery
signs + symptoms of gas gangrene
extreme pain
skin crepitus - crackly on palpation
swollen, dark purple skin + bullae
treatment gas gangrene
surgical debridement
IV antibiotics - penicillin + clindamycin
what causes shingles
herpes zoster
- reactivation of VZV in dorsal root ganglion
presentation of shingles
dermatomal vesicular rash lasting 3-5 days
- pain may precede rash
complication of shingles
post herpetic neuralgia
- persistence of pain once rash has gone
what does multi-dermatomal shingles suggest?
immunosuppression
what is Ramsay hunt syndrome?
reactivation of VSV in geniculate ganglion of CN7
- Herpes zoster oticus
presentation of ramsay hunt syndrome
CN7 palsy
auricular pain
vesicular rash in ear
what is Hutchisons sign?
what does it suggest?
vesicles on tip/side of nose - herpes zoster opthalmicus with ocular involvement
- VSV reactivation in ophthalmic division of CN5
treatment of shingles
oral aciclovir 7-10 days
- if presents within first 72 hours
- > 50 years old
- immunosuppressed
management of post herpetic neuralgia
amitriptyline / gabapentin
what is tinea pedis
athletes foot
- cracked white skin between toes
- moist skin key risk factor
what is tinea cruris
itchy plaque with red raised edge in groin creases
what is tinea corporis
ringworm
- round, scaly plaques with red raised edge + central clearing
- typically on trunk + limbs
what is tinea capitis
itchy scaly scalp, sometimes yellow
investigation of suspected fungal infection
skin scrapings
management of tinea infections
keep affected areas clean + dry
topical clotrimazole/miconazole/ketoconazole/terbinafine
+ mild corticosteroid if very inflamed
first line treament for tinea capitis
topical anti fungal + oral (terbinafine/itraconazole)
what is onychomycosis
fungal nail infection
- dermatophyte infection most common
presentation onychomycosis
yellow or white streaks
scaling/thickening - subungal hyperkeratosis
lifting of nail - onycholysis
investigation of onychomycosis
microscopy + culture of nail clipping
treatment onychomycosis
dermatophyte infection: oral terbinafine ( 3months for finger, 6 months for toe)
candida infection: superficial - topical amorolfine 5% for - 6 months on fingers - 12 months on toes extensive- oral terbinafine or itraconazole
presentation of staphylococcal scalded skin syndrome (SSSS)
widespread fluid filled blisters
thin walled + nikolsky’s sign positive
painful erythroderma
- spares mucous membranes
what is candida intertrigo
candida fungal infection seen in skin folds e.g. under breasts, groin areas
treatment options for candida intertrigo
clotrimazole cream
nystatin
oral fluconazole
diffuse scarlatiniform rash which later desquamates suggests what syndrome?
toxic shock syndrome
- staph aureus
- mostly seen palms + soles and skin folds
how is infection by sarcoptes scabiei treated
benzyl benzoate
malathion lotion
what toxin produced by staph aureus causes SSSS
SSST
what toxin is associated with MRSA
panton valentine leukocidin
what is the most common causative organism of tinea fungal infections
trichophyton rubrum
what causes erythema infectiosum
paravirus B19
- red cheeks: slapped cheek disease
what can paravirus B19 cause in early pregnancy
spontaneous abortion due to low RBC
what virus causes hand foot mouth disease
cocksackie A16
treatment of viral warts
topical salicylic acid - topical keratolytic
cryotherapy
large warty lesion often affecting people in contact with farm animals
orf
bullseye rash - well demarcated, expanding rash with clear inner ring at bite site
suggests what?
lyme disease
rash also known as erythema migrans
organism responsible for Lyme disease
borrelia burgdorferi
- transmitted by ticks (must be attached for >24 hours for infection to occur)
treatment Lyme disease
oral doxycycline 10-21 days
fleshy, firm, umblicated pearlescent lesions
molluscum contagiosum
