6. Skin Infections Flashcards
What is the epidemiology of skin disease?
Where is it more common?
- Skin disease is common – 15% of GP appointments are skin related (25% due to skin infection).
- 5% of dermatologist appointments are due to skin infections.
- Skin conditions are more common in hot, humid climates amongst poorer populations (opposite in dry/rich).
What are the features of Staphylococcus aureus?
Features of SA:
- A gram+ bacteria, commensal in approx. 30% of humans with colonisation in the nose, axilla and groin.
- SA is the most common bacterial cause of skin infections including – impetigo (and bullous (blistering) impetigo), folliculitis, ecthyma, boils and carbuncles.
Commensal: can be part of the normal part of the microflora
Lives in the nose, armpits, groins
The most important cause of infections
It is the same bacteria as toxin production
MRSA: not a more serious confition, just harder to treat
Also producs toxins
PVL , if it produces more toxins= necrotsising and necrotic
Exfolatative
Blistters
Staphylococcus
Can produce blisters
Toxin 1
Can produce
And patient becomes more septic
Staphylaureus, someone has it, makes food, someone eats it = diarrhea due to the toxins
Describe this
Bullous impetigo
Produces toxins
Exfloative ; produces pusses within blisters
Blisters with puss inside
Same toxins will cause skin syndrome
Describe this?
Exthyma: full thickness
Thic lesion
Surface of the skin has died/necrotizing
Infected bite
What are some complciations of syphilis?
Tertairy syphylisis- thoracic aneurysm
Neurosyphilis: one of the most common casues of dementia
What diseases can Staphylococcus aureus cause?
What are the treatments? What is itcalled when it affectes different layers
Diseases caused
– via the production of toxins, SA can cause:
- o Staphylococcal Scalded Skin Syndrome – Exfoliative toxin.
- o Toxic shock Syndrome – Toxic Shock Syndrome Toxin 1 (TSST-1).
- o Food poisoning – Enterotoxin.
- o Necrotising soft tissue infections – Panton Valentine Leucocidin virulence factor.
Treatment – infections all treated with antibiotics, there is no vaccine.
What are the features of treponema pallidum and what does it cause?
Features of TP:
- A gram- spirochaete and the cause of Syphilis (which is usually an STI).
- Syphilis
Bacteria spiral shaped bacteria
Std
What is congenital syphilis?
Congetital
Acirve transmitted to the babies
If survivied: rashes like secondary
And some teratiary features such as brain
Some will survive
Saddle shaped nose
Blindess
Destrctive lesions
What are the stages of syphilis?
How can it be transmitted and what is its treatment?
Stages of Syphilis:
- o Primary – painless ulcers (chancre) at site of inoculation.
- o Secondary – disseminated infection with rash (maculopapular) and lymphadenopathy. Red notchy. Can be quite a few. Plasma and soles.
- o Latent – asymptomatic period.
- o Tertiary – skin (gummatous skin lesions, bone lesions), neurological and vascular manifestations. Inflammatory lesions. Destruct bones, skin
Transmission: Syphilis can be VERTICALLY transmitted and cause congenital syphilis.
Treatment: No vaccine is available but the infection can be treated with antibiotics.
3 pahses
Primary: 3-8 weeks, after [ainless ulcer= shangre, this gets better and gets better.
Primary: ulcer , paitient don’t really know about it
Serology would be negative
Field microscopy
6-12 weeks: secndoayr: rapid proliferation and dissmenationa dn ptient will have a rash , lasta. Few weeks
Reactivate
Go to a latent phase: no clinical features, but they do have syphilis, theroeatically it can be transmitted
Can reactivate by terityr: can affect any organs incl brain heart
Conegnitsl:
Can transfer across the plcaneta
diagnosis
Filed microscopy: spiral shaped organisms can be seen
What are the features of HSV and what are the two types?
Herpes Simplex Viruses 1 & 2
Features of HSV:
- o Members of the human herpes virus (HHV) family which are DNA viruses.
- o Type 1 – causes oral infections.
- o Type 2 – causes genital infections.
Type 1 : around mouth
2: genitsl around
Painful blsiters, tingle burn
And break down to form ulcers
Healing might be a scar and thas it
But the virus can live on and racitave during times of stress or illness
What is the pathogenesis of HSV and what is its treatment?
Herpes Simplex Viruses 1 & 2
Pathogenesis:
- o Transmission by direct contact.
- o Clinical features involve – painful vesicular rash (heals over 2-4 weeks), eczema herpeticum, herpes encephalitis.
- o Due to latency in sensory involvement, there can be reactivation with reoccurrences of infection.
Treatment: No vaccine is available, outbreaks treated with anti-viral medication such as acyclovir.
Draw a table showing the 3 types of HHV (1,2,3) with their:
- synonym
- target cell
- disease
- site of latency
What are the features and pathogenesis of VZV?
What is its treatment?
Varicella Zoster Virus
Features of VZV:
- o Another human herpes virus as seen above.
Pathogenesis:
- o Primary infection – causes chicken pox – prodrome of fever and malaise followed by development of widespread vesicular rash. Usually lasts ~2 weeks and then becomes latent. Can reactivate in shingles.
Treatment: vaccine is available and anti-viral medication can be give
What is herpes zoster/shingles?
When can there be serious consequences?
Herpes Zoster or Shingles where there is reactivation of the VZV and a painful vesicular rash appears along the course of a dermatome – usually heals in 2-4 weeks.
- There can be serious consequences if CN V1 (ophthalmic division of trigeminal).
Chciken pox= 2 weeks
In adults: can cause inflammation of. The brain. Chickeck pox like .
Can also cause pneumonia: In the elderly
Gets better and lives in the dorsal root ganglion
Stress
Only one dermatome
Distrituion of the nerve roots
What are the features and pathogenesis of trichophytum?
What is its treatment?
Trichophytum – e.g. Trichophytum rubrum
Features of Trichophytum:
- o A common cause of superficial fungal infections.
- o It is a dermatophyte – a type of fungus that particularly affects parts of the body that have keratin.
- o The names of the clinical infections are prefixed with the Latin “tinea” followed by the body part:
- Tinea capitis – Kerion is a type of tinea capitis.
- Tinea manuum – dorsum of hand.
Yeasts are another form of fungal infection distinct from dermatophytes – e.g. candida (grow in warm/wet places).
Pathogenesis:
- o Clinical manifestations – eryhthromatous scaly rash on skin/scalp, discoloured or crumbly nails.
Treatment: with topical or systemic anti-fungal medications such as Terbinafin
Superirficial
Tropica: go deep
Trichopyton : fungus likes keratin: proten in skin , nails
Yeast are exmaples are candida , these love moist humid envirmonemts: cadida infection , places like body folds
What are the features and pathogenesis of scabies?
How is it transmitted and what is its treatment?
Features:
- o A skin infestation by the mite Sarcoptes scabei.
Pathogenesis:
- o The mite burrows into the surface of the skin and exposure to the mite faeces and eggs cause a delayed-type allergic reaction resulting in widespread eczematous rash occurring ~4 weeks after first infestation.
- o Usually very itchy.
- o The burrow sites are usually at – genital regions, nipples, wrists, finger webs, instep of feet, axilla.
- o Secondary bacterial infection is common.
Transmission: by skin-skin contact.
Treatment: with topical systemic insecticides.
Refeered to as sarcoptes
Electormigrohaph
Burrows into the skon ]
4-5 mm long
One end is a black dot: head of a mite
Scabies
Burrow
If you find them :
Can take a scarpings of it
Domatiscope
: extensive torch
Trianglualr shape ,
Hed of the mite
swiggle
Describe this layer of skin affected?
IMPETIGO
Aurues: looks gold/yellowy
Impetigo: common in children
Carrying staphyloccus aureus in the nose
Impetigo on top the skin disease
Staphylaurues = infectd eczema
Describe thecommon sites of burrows?
What complications can scabies often cause
Intial infection= aymptomatic
2 types of rashes
Looking for allergies against hem
Treatment: insecticide cream
From the neck down
Wash off
Ifamectine
Clean their beddings etc
5
Scabies: untreated= secondary bacterial infection, streptoccosus: renal failure
Renal failure fromt. He staphyloccus : glomerular
