skin infections Flashcards
what are the features of Staphylococcus aureus?
- gram-positive bacteria
- commensal in 30% of humans
- colonization in the nose axilla and groin
what skin infections does Staphylococcus aureus cause?
- impetigo (golden crusting)
- folliculitis (causes abscesses)
- ecthyma (thick-crusted necrotic lesions)
- boils and (carbuncles = cluster of boils)
what diseases does Staphylococcus aureus cause when it produces toxins?
what are the different types of toxins produced?
- Staphylococcal Scalded Skin syndrome
affects children under the age of 5
(Exfoliative toxin)
- Toxic shock Syndrome
(Toxic Shock Syndrome Toxin 1)
- Food poisoning
- Necrotizing soft tissue infections
(Enterotoxin)
How to treat an infection with Staphylococcus aureus?
- antibiotic treatment
- treated with Flucloxacillin
how is infection with Staphylococcus aureus diagnosed?
- taken with a swab
what are the features of Treponema pallidum?
- a gram negative spirochaete
what does Treponema pallidum cause?
- syphilis
what are the stages of syphilis?
- Primary – painless ulcers at the site of inoculation
- Secondary - disseminated infection with rash
- Latent – asymptomatic period.
- Tertiary – affects the skin, nervous and vascular tissue can also cause thoracic aneurysms
how can syphilis be transmitted?
- sexually transmitted
- transmitted through the placenta causing congenital syphilis
what are features of congenital syphilis?
Miscarriage
Still birth
Prematurity
Rashes
Brain and neurological problems
Bone disease
how to diagnose syphilis?
- swab
- blood test and serology
treatment for syphilis?
antibiotics
normally penicillin
what kind of viruses are herpes viruses?
Members of the human herpes virus
DNA virus
what are the two types of the herpes virus? what are their features?
- Type 1 – causes oral infections
- Type 2 – causes genital infections.
clinical presentation of the herpes virus?
- painful vesicular rash (fades after 2-4 weeks)
- eczema herpeticum
- herpes encephalitis
- remains latent in the nervous system so in times of stress it reemerges
how is herpes virus transmitted?
Transmission by direct contact
how is herpes treated?
there is no vaccine available
treated with anti-viral medication such as acyclovir
what are the features of the Varicella-Zoster Virus?
- it is another version of the human herpes virus
what are the features of the primary infection with VZV?
- causes chickenpox
- fever and malaise followed by a vesicular rash that usually lasts for 2 weeks and then becomes latent
- Can reactivate later on in life as shingles.
how does shingles present?
- painful vesicular rash along a dermatome
- There can be serious consequences if CN V ophthalmic branch affected (blindness)
what is the treatment for VZV?
- vaccine available
- anti-viral medication can be given
Features of Trichophytum?
- A common cause of superficial fungal infections
- It is a dermatophyte = a type of fungus that particularly affects parts of the body that have keratin
what are fungal clinical infections called? examples?
Tinea… something
Tinea capitis -eg. Kerion
Tinea manuum - a fungal infection that affects the dorsum of the hand.
example of Yeast infection?
candida (grows in warm wet places)
what are the main clinical manifestations of fungal infections?
- eryhthromatous (red) scaly rash on skin
- discoloured or crumbly nails.
how to treat fungal skin infections?
anti-fungal medications such as Terbinafine.
what is scabies caused by?
- A skin infestation by the mite Sarcoptes scabei.
what is the pathogenesis of scabies?
- The mite burrows into the surface of the skin
- exposure to the mite faeces causes a delayed-type allergic reaction resulting in a widespread eczematous rash (very itchy)
- this occurs 4 weeks after the first infestation
clinical features of scabies?
- very itchy
- The burrow sites are usually at genital regions, nipples, wrists, finger webs, the instep of feet, axilla
- often causes a secondary bacterial infection
how is scabies transmitted?
skin-skin contact
how is scabies treated?
topical systemic insecticides.
