common skin infections Flashcards
4 common viral skin infections
- herpes simplex;
- herpes zoester/shingles;
- viral warts;
- molluscum contagiosum
who might get multi-dermal shingles
immunocompromised; diabetes; elderly
herpes simplex usual presentation
cold sore (around mucosa e.g. mouth, genitals); grouped vesicles on erythmatous base; severe pain; often recurrent in same dermatoses (location)
treatments for herpes simplex
topical acyclovir (delicate areas e.g. eyelinds); systemic acyclovir (200mg,5x a day, 5 days)
herpes simplex prophylaxis
acyclovir 200mg TDS for 6-12mo
when is prophylaxis given for herpes simplex
recurrent episodes (>2 per year)
where does HSV lie dormant
sensory ganglia
what can occur in those who have eczema herpeticum (infected eczema) post treatment
flare up
what can be given alongside to reduce eczema flare up
steroids
erythema multiforma classic presentation
red, raised circles - secondary to infection/drugs
shingles presentation
usually dermatomal/ band like pattern - pain; grouped vesicles on erythematous base -> crusting; malaise; fever; Hx of past shingles of chicken pox
why are herpes simplex/zoesta confined to dermatomes usually
they lie dormant in the ganglia of sensory neruons and so affect which ever dermatome is innervated by the nerve
herpes zoester treatment
analgesics; acylovir
3 complications of herpes zoster
post-herpetic neuralgia; cranial nerve syndromes - ramsey hunt syndrome (CN VII), optic involvement (CN II)
what HPV subtypes can cause cancers
16, 18
what HPV subtypes can cause genital warts
6, 11
warts presentation
very variable - may be crusted, hyperkeratotic or can be flat, flesh coloured papule, plaque studded with small black dots (thrombosed capillaries); single or multiple present
treatment for warts
no treatment - self limiting (some quickly, some take longer); topical salicylic acid post filing down; cryotherapy
why is filing down a wart beneficial
microtrauma (esp if bleeds) caused allows for stimulaiton of inflammatory response and for penetration of salicylic acid to root of wart
when should a wart be biopsied
rapidly growing, painful, bleeding
what is molluscum contagiosum
a benign pox virus commonly seen in children or on genital skin
molluscum contagiosum presentation
“pearly papule” with umbilication; often multiple; contain keratotic plug
how is molluscum contagiosum transmited
skin to skin contact - advise to reduce contact with others
5 bacterial skin infections
- impetigo;
- follicultitis/furanculosis;
- ecthyma;
- erysipelas/cellulitis;
- necrotising facitis
necrotising fascitis treatment
emergency - call surgeon for debridement, IV Abx
what organisms cause impetigo
S.aureus; S.pyogenes
impetigo presentation
classicaly a yellow/golden crust to the area; NO visible vesicles;
what is bullous impetigo
impetigo with large pus filled blisters that can rapidly spread -> can grow cultures to confirm
when is Abx given for bullous impetigo
systemically unwell, usually a B-lactam
what can be given as treatment for bullous impetigo
topical abx - mupirocin
what is folliculitis
inflammation of hair follicles
what organisms cause folliculitis
S.aureus; P.aeruginosa
where might p.aeruginosa causing folliculitis be acquired from
hot tub/ pool - wet environment
folliculitis vs furunculosis vs carbunculosis
folliculitis - pustules
furinculosis - nodules, purulent discharge, tender
carbunculosis - larger and deeper inflammaotry nodules with purulent drainage -> plastic surgeon may be needed
treatment for furunculosis
topical Abx - 1% clindamycin OR 2% erythromycin; or incision and drainage
what is ecthyma
deep infection of the skin - down to dermis (usually deeper than cellulitis)
what organisms cause ectyma (2)
S.aureus; S.pyogenes
ecthyma presentation
vesicles/bullae that progress to punched-out ulcerations with adherent crust -> heals w scaring
echyma treatment
oral antistaphylococcal abx (flucoxacillin)
cellulitis presentation
UNILATERAL, red ,hot, swollen (leg), ill-defined
what is erysipelas
a superficial form of cellulitis - tender and well defined
how is cellulitis treated
abx - B-lactams
what can cause nectrotizing fascitis
S.pyogens; group B/C streptococci; clostridium perfringens
symptoms of necrotising fascitits (6)
- severe pain unresponsive to analgesia;
- erythema; skin becomes dusky;
- formation of bullae followed by necrosis;
- gangrene;
- fever;
- systemic toxicity
3 parasitic skin infections
- scabies;
- leishmaniasis
- cutaneous larva migrans
what is scabies
an infection of the skin caused by S.scabiei burrowing into the epidermis; transmitted by skin-skin contact
scabies symptoms (4)
- intense itching especially at night;
- involvement of the finger webs, wrists, elbows, armpits, lower buttocks, thighs etc.
- vesicles, papules, pustules
- burrows
how to diagnoses scabies
look for mites/eggs in a skin scraping sample
treatment for scabies
treat ALL family member/close contacts - permethrin; repeat after 7 days
what is the vector for leishaniasis and where is it normally seen
sand fly; often seen in south america
leishmaniasis presentation
skin lesions with erythema, inflammation, ulceration;
depends on type - if mucocutaneos then lesions of nasal/oral mucosa; if Diffuse Cutaneous - multiple deep skin lesions
treatment of leishmaniasis
amphotericin B
what is cutaneous larva migrans
larva of cat or dog hookworm
presentation of cutaneous larva migrans
cutaneous erythmatous erruption confined to skin of feet, arms or buttocks; rash may be seen moving slowly (movement of the parasite); Hx of walking barefoot abroad (brazil)
treatment of cutaneous larva migrans
antifungals - thiabendazole, albendazole, mebendazole etc.
6 fungal infections of the skin
- tinea corporis
- tinea capitis
- tinea pedis
- tinea cruris
- candidal intertrigo
- pitytiasis versicolor
what is tinea
infectious disease of the skin caused by fungi
tinea general presentation
peripheral scaling discoid lesions; itch
tinea treatment
topical anti-fungals e.g. miconazole, clotrimazole; sytemic antifungals for nails or scalp involvement e.g. terbinafine
what is seen in tinea under a microscope and with wood’s light
micro - branching hyphae
wood’s light - green fluorescence
what is candidal intertrigo
a superficial mycotic infection of the skin that affects moist occluded skin folds (e.g. under breasts, obese folds); yeast
candidal intertrigo presentation
erythematous macerated patch with satellite macules of pustules extending beyond the flexure; may be itchy or painful
what is a macule
a flat, distinct, discolored area of skin
candidal intertrigo treatment
- topical antifungals e.g. clotrimazole, terbinafine;
- antifungal + weak steroid e.g. daktacort;
- keep area dry;
- weight loss
what is pityriasis versicolor
a fungal (yeast) skin infection
pityriasis versicolor presentation
fine scaly, well-demarcated, hypopigmented or hyperpigmented plaques (area of skin slightly raised)
pityriasis versicolor treatment
- selenium sulfide shampoo or kertoconazole shampoo (lather hair then allow it to wash down the body), may be lifelong treatment;
- antifungal with weak steroid (daktacort)
- if resistant then oral antifungals (usually immunocomprismised e.g. HIV)
