Microbiology - Skin infections Flashcards
Epidemiology of skin infections
- 15% of GP consultations are skin related
- 6% of hospital outpatient attendances
- 1% of European population referred to dermatologist per year
- 20% of population have a skin disease requiring medical intervention
What is the difference in toxicity between MRSA and regular staphylococcus aureus
There is no difference its just harder to treat MRSA
What toxins are produced by staphylococcus aureus
- Panton valentine leukocidin
- exfoliating toxin (cleaves skin in epidermis)
- Toxic shock syndrome toxin 1
- Enterotoxin
What skin diseases are caused by staphylococcus aureus
- Impetigo - infection of subcorneal layer of epidermis
- Folliculitis - infection of mouth of hair follicle
- Ecthyma - infection of full thickness of epidermis (adherent crust or scab)
- Boil - abscess of hair follicle
- Carbuncle - abscess of several adjacent hair follicles
What is the most important treatment for an abscess
Release of the pus
What is staphylococcal scalded skin syndrome
- Only affects children under 5
- Staphylococcus aureus produces exfoliative toxin that causes shedding of the skin
What is treponema pallidum
- Gram negative spirochaete
- Cause of syphilis
- Most common STD - 12 million cases per year worldwide
- Increases transmission of HIV
What are the stages of syphilis
Primary (3-8 weeks) - painless ulcer called a chancre
Secondary (6-12 weeks) - maculopapular rash
- Disseminated infection
- Generalised rash and lymphadenopathy
- Palms and soles involved
Latent - asymptomatic period
Tertiary syphilis (years later)
- Skin, neurological, and vascular manifestations
- Bone lesions, thoracic aneurysm
Describe congenital syphilis
- Acquired perinatally
- Early and late miscarriages
- Stillbirth, prematurity, rashes, brain and neurological damage, bone disease
How many human herpes viruses are there
8
Describe the 3 main human herpes viruses
HHV-1
- HSV type 1
- Muco-epithelial
- Oro-genital herpes
- Latent in neuron
HHV-2
- HSV type 2
- Muco-epithelial
- Oro-genital herpes
- Latent in neuron
HHV-3
- Varicella zoster virus
- Muco-epithelial
- Chickenpox, shingles
- Latent in neuron
What is the clinical presentation of chickenpox
- Concentrated on face
- Some on trunk, arms and legs
- Check for small vesicles in mouth
- Severe cases can be lethal
Note : Vaccine available but not used in england
Describe the clinical presentation of shingles
- Rash following a nerve usually within a dermatome
- Immunosuppression can cause spreading between dermatomes
- Can cause encephalitis
What types of fungal infections are found in the UK
Only superficial fungi in the UK
- Dermatophytes (type of mould)
- Yeast infections
Describe dermatophyte infections
- Grow in and feed on keratin
- Long hyphae, grow from the tip
- Found in skin, hair, nails
e. g. trichiphyton rubrum
