skin infections Flashcards
epidemiology of skin disease
15% of GP consultations are skin related
6% of hospital out patient attendances are skin related
In Europe
- 1% of population is referred to a dermatologist per year
- 20% of population have a skin disease requiring medical intervention
epidemiology of skin infections *
High rates in hot humid conditions and poor populations
Low rates in dry temperate conditions and rich populations
in uk:
- 25% of GP skin consultations
- 5% of dermatologist consultations
describe staphylococcus aures *
bacteria
gram +ve - purple on gram stain
makes toxins
has a capsule (AB destroy this capsule)
what are medical considerations for staph aures *
it is commensal on body in nose armpit and groin
most common cause of skin infections
MRSA - no more severe form, just harder to treat because it is resistant to flucloxacillin
causes bone joint and jung infections - especially after flu - causes pneumonia
can cause sepsis
makes toxins
- Panton Valentine Leuocidin (PVL)
- virulence factor
- means more agressive form - necrotising soft tissue infection, inflammatory, form absess
- Exfoliative toxin
- cleavage and blister formation in skin
- TSST-1 (Toxic Shock Syndrome Toxin 1)
- more toxic - septicaemia features
- Enterotoxin
- cause diarrhoea if contaminates food
describe the manifestations of s aures skin infection *
impetigo - infection of the subcorenal layer of the epidermis
folliculitis - infection of the mouth of hair follicle
ecthyma - infection and necrosis of full thickness of the epidermis
boil - abscess of hair follicle (ie a folliculitis with pus)
carbuncle - abcess of several adjacent hair follicles
describe impetigo *
staph aures
honey coloured crusting erosion
crusty
common in children around the nose and mouth, easily transmitted
can get impigotised eczema - ie s. aures on top of eczema
describe bullous impetigo *
staph aures
expholiated toxin cause split of skin at higher levels of the epidermis = bulli formation
in the bulli are bacteria that are producing pus
(same enterotoxin will cause blisters all over in Staphylococcal scalded skin syndrome)
describe ecthyma *
s aures
full thickness infection of the epidermis
crusted thick lesion
surface of skin is necrotic = thick and adherent scar
get from an infected insect bite/in people who are immunosuppressed
describe an abcess *
same as boil
collection of pus underneath
describe staphyloccocal scaleded skin syndrome
staph aures in body
toxin = cleavage of skin in children <5yrs
there is an immune reaction against the toxin
get AB in hospital - flucluxocillin (if resistant = MRSA)
diagnose with swap
describe trephonema pallidum *
gram -ve spirochaete
cause of syphillis - STD
12 million new cases per year worldwide
Increases transmission of HIV
what are the clinical signs of syphilis *
Primary (at 3-8 weeks after initial innoculation)
- Painless ulcer at inoculation site (Genital or oral)
- then this disappears, maybe with a scar
Secondary (at 6-12 weeks)
- Disseminated infection and rapid proliferation
- Generalised rash and lymphadenopathy
Latent syphilis (no clinical signs) - but have syphilis so can be transmitted especially in pregnancy
Tertiary syphilis (usually years later)
- Skin, neurological and vascular manifestations
Congenital
- Acquired perinatally - transfer over placenta
- Early and late manifestations
describe primary syphilis *
ulcer is called a chancre
blood test will be -ve, need to swap at the region q
what do you see in dark field microscopy of chancre sample (
spirochates - ie spiral shaped bacteria
describe secondary syphilis *
maculopapular rash - widespread, red and blotchy
condyloma lata - warts in perianal, armpit and groin
palms and soles typically involved
describe tertiary syphilis *
rare
inflammatory destructive lesions of the bone and the skin
can get thoracic aneurysms - dilated thoracic aorta
what are the effects of neurosyphilis *
- Miscarriage
- Still birth
- Prematurity
- Rashes - like secondary syphilis
- Brain and neurological problems - like tertiary
- Bone disease
- saddle shape nose
- peg like teeth
- blind
- skin lesions
diagnosis and treatment of syphylis
primary - swab
secondary - serology will be positive
plasma cell on rash biopsy suggests syphylis
treatment - penicillin
describe herpes simplex virus *
lay latent in certain tissues eg nerves - can reactivate
type 1 - oral herpes, common at the Vermilion border
type 2 - urogenital herpes
clinical presentation
- Vesicular rash - 2 weeks - painful, tingle, burn - break down and form ulcer
- Eczema herpeticum
- Herpes encephalitis
blisters at early stages are vesicles, at later stages are crusty and pustular like vesicles
can get stomatitis - inflammation of whole mouth
can be anywhere in body - not just mouth/orogenital
describe eczema herpceticum *
eczema means suseptible to staph aures and HSV
can get very ill - need IV acyclovir and supportitive treatment
have punched out ulcers
what happens when HSV reactivates *
have symptoms in the same place
treatment and diagnosis for HSV
swab, PCR - 48hr result
acyclovir
councilling about recurrance
describe varicella zosta *
chickenpox
common in children - mild
more severe in adult - effect brain (encaphalitis), pneumonia in elderly with high mortality
incubation period of about a week
what are the clinical sympotms of varicella zoster *
2 week crust and then get better
malaise, fever, sore throat
rash, vesicles (groups all over body)
lesions in mouth
