6: Skin infections Flashcards
Summarise the epidemology of skin infectios
15% of GP consultations are skin related
6% of hospital out patient attendances are skin related
Out of that:
- 25% of GP skin problems are skin infections
- 5% of dermatologist consultations are skin infections
- High rates in hot humid conditions and poor populations
What kind of Pathogen is Staph A?
Staphylococcus aureus is a
- Gram +ve bacterium
- commensal
- most common cause skin infections
- might also cause lung, joint and bone infection –> sepsis
- is encapulated
- makes Toxins that cause problems
What is a Impetigo?
Infection of the subcornal layer of epidermis
What is folliculitis?
Infection of the mouth of a hair follicle
What is Ecthyma?
Infection of the whole thickness of the epidermis
What is a boil?
Absess of a hair follicle
What is a carbuncle?
Abcess of several adjacent hair follicles
What is the clinical manifestation of a Stapelococcus Aureus infection?
- Impetigo
- honey coloured, golden
- Might present as: Bullous impetigo
- when staph A produces Exfoliate toxin causing blister formation
- Ecthyma
- necrotic and scar formation (expecially in infected insect bites and immunosupression)
- Abscess
- Staphylococcal scalded skin syndrome
- immune reaction to systemic toxin in children <5 –> causing shredding of skin
How would you treat a skin infection caused by Staph A?
ABX
What causes syphilis?
Summarise its epidemilogy
Caused by Treponema pallidum
- gram -ve bacterium (spirochaete)
- 12 Million new cases/ year worldwide
- increases the transmission of HIV
Explain the time development of a Syphilis infection
- Primary (at 3-8 weeks)
- Painless ulcer at inoculation site (Genital or oral)
- Secondary (at 6-12 weeks)
- Disseminated infection
- Generalised rash and lymphadenopathy
- Latent syphilis (no clinical signs)
- Tertiary syphilis (usually years later)
- Skin, neurological and vascular manifestations
Might also be:
- Congenital
- Acquired perinatally with Early and late manifestations
What happens during a primary infection with syphilis?
At 3-8 Weeks after infection: Painless ulcer at inoculation site (Genital or oral) (called: Chancre)
- ulcer swap would be +ve
- serum might be +ve and -ce
What happens during secondary infection with syphillis?
At 6-12 Weeks
- Disseminated infection
- Generalised rash and lymphadenopathy
- expecially at palms and soles
- Condyloma lata (wart-like lesion of genitals)
What are the characteristics and presentation of tertiary syphillis?
Skin, neurological and vascular manifestations
- bone lesions
- neurosyphillis –> dementia
- gummatous skin lesions
- thoracic aneurism
What is congenital syphillis?
What does it cause?
If mother transmits syphillis ont child might result in
- Miscarriage
- Still birth
- Prematurity
- And if baby survives
- Rashes
- Brain and neurological problems
- Bone disease
What are common types of Human Herpes virus?
What are they known as?
Are DNA Viruses:
- HHV 1
- HHV 2
- together: Herpes Simplex (I and II)
- HHV 3
- Varziella Zosta Virus
- More
What is another Name for HHV I?
Herpes Simplex Virus I
- causing oral herpes presenting as
- Vesicular rash - 2 weeks
- often at junction of cutaneous and mucosal lip
- Eczema herpeticum
- Herpes encephalitis
- Vesicular rash - 2 weeks
What is another name for HHV 2?
How does it present?
Herpes Simplex Virus I
- causing genital herpes presenting as
- Vesicular rash - 2 weeks
- Eczema herpeticum
- Herpes encephalitis
What is eczema hepaticum?
A Herpes simplex infection on top of an eczema due to increases supectibility to infection in eczema
What does the Variella Zoster Virus Cause?
What is another Name for it?
Variella Zosta = HHV 3
- causes chickenpocks and
- shingels
Explain Why Herpes infections regularry reoccur or shingels can develop
Because the Herpes virus have a latency in nerves
- e.g. dorsal route ganglion –> shingels of one dermatome
- or rigeminal nerve ganglion –> lip
- leads to reoccurance e.g. in times of stress
What are the symptoms of chickenpox?
- malaise, fever. sore throat,
- rash all over the body (expecially in face, body, lower leg)
- rather proximal
- last about 2 Weeks with an incupation period of 1 Week
In children: normally not as sever but in adults
- might cause encephalitis or pneumonia
What is Herpes Zoster (shingels)?
It is the recurrent infection of a single dermatome due to latent Herpes Zoster Virus in Dorsl route ganglion
How can you diagnose and treat Chickenox
clinical diagnosis
+ PCR diagnosis of Viral DNA
- treat with acyclovir (though it gets bettwe without treatment)
What are the differnt types of superficial skin fungal infections?
- Dermatophytes (type of mould)
- eg Trichophyton rubrum
- Grow in keratin
- Long hyphae, grow from tip
- Yeasts
- eg Candida
- Grow on warm wet surfaces
- single cell and bud
Name an example of a Dermatophytes (type of mould) skin infection and how it can present
Presents as part of keratin –> skin, hair nail and depenging on site
- Tinea…
- unguinum = nail (yellow, crumbly)
- capitis = head (only in prepubertal children)
- Keroin (localised tinea capitis)
- manuum
- pedis
- crutis (between legs)
- facei
often transmitted by pets
What is the clinical presenation of a Candida rash?
Fungal skin infection at warm, wet surfaces, primarily presenting at
- red, infected area with red dots around it
What is the cause of scabies?
Infection with the mite Sarcoptes scabei
What are the signs of scabies
Diagnosis: look for burrow
- 4-5mm long, s-shaped wiggly lines with black dot at the end (head of mice)
- Commonly in
- genital area
- armpits
- around T10 anteriorly
- back of hand
- cubital fossa
What are the symptomsof scabies?
- First: asymptomatic
- after a couple of weeks
- immune response tu mice leading to generalised eczema
- itching, might lead to blister formation etc.
