Micro 4: skin infection COPY Flashcards
When are skin infections more commonly seen- GP or hospital
In GP it’s 25% In hospital 5%
Where are high and low rates of skin infection seen
* High rates of skin infection are seen in hot, humid and poor populations * Low rates are see in dry, temperate conditions, and rich populations
What type of bacterium is S. Aureus
Gram pos (cocci, fro name)
What toxins does S. Aureus produce
Panton Valentine Leuocidin, Exfoliative toxin, TSST-1 (Toxic Shock Syndrome Toxin 1) ,Enterotoxin
Is S. Aureus always harmful?
COMMENSAL 30% carry it, either in the nostrils or on the ski
Which AB is it commonly resistant to
MRSA Resistant to methicillin= flucoxicillin
What can S. Aureus infect
Bone, joint, lung infections
What is the structure of the S. Aureus
Cell wall, cell membrane Susceptible to penicillin treatment
What are panto valentina leucocidin
It is a virulence factor which makes the infection necrotising (it causes tissue death)
What is the exfoliative toxin
Cuases cleavage of the skin within the epidermis . involves the same antigen as bullous pemphigus. Causes skin to flake off
What is TSST-1
Toxic shock dynfrome 1 causes septicaemia type disease
What are enterotoxin
Food handler might have infected S. Aureus and an enterotoxin can get into the good and cause D and V in others
Where can S. Aureus cause infection
Bone joint lung infections But focus of infection ften starts on the skin
When can staphylococcal lung infection occur
Often after flu (so deaths due to flue can be caused by this)
Manifestations of S. Aureus
Impetigo: subcorneal layer(i.e. very superficial) Folliculitis: mouth of hair follicle… can progress to abcess Ecthyma: full thickness involvement of the epidermis, we see an (e.g. infected insect bite) NOT IN DERMIS . A boil: An abcess that often starts in the hair follicle. A carbuncle describes multiple abscesses next to each other, all coalescing( an abcess of multiple ajoining hair follicles.)
What kind of skin infection does insect bite cause
Ecthyma …. lesions look like firmly adherent crust on a background of erythema. The crust will not come off – the surface of the skin is dying. It commonly occurs after infected insect bites, or infected wounds.
What is it called if a folliculitis forms into abscess of hair follicle
Called boil
What is a carbuncle
Abscess of several adjacent hair follicles
Which S. Aureus infections are inthe spidermis and which in the dermis
Epidermis: Impetigo, folliculitis, ecthyma (might extend a tiny bit into the dermis) Dermis: Boil and carbuncles
Feature of S. Aureus
Aureus= gold because the crust is golden
Common locatios for impetigo What is bollous impetigo
It often occurs around the nose and mouth, but can occur anywhere (particularly groin/perineal region Blistering with S. Aureus Because of the exfoliative toxin from S. Aureus (against that desmoglein antigen) in addition to the impetigo which is just infection of the subcorneum and corneum
What can abscess start off as. How is it treated
Start as folliculitis treated with pus drainage
What can the exfoliative toxin from S Auerus casue
- Bollous impetigo 2. Staphylococcal scalded skin syndrome
Who does Staphylococcal scalded skin syndrome occur in
Ages under 5 Because the immune system of children hasn’t developed properly so the infection can spread and cause widespread erythema and epithelial release
How can you confirm it
Send away for lab
What is the treatment for S. Auerus
Give flucoxicillin/clindamycin/erythromycin Topic for impetigo
What infection causes symphylis
Treponema pallidum
What type of bacterium is Treponema pallidum
Gram neg spirochete (Syph Spiro)
What is coinfection with Treponema pallidum bad
Co-infection with syphilis increases the transmission of HIV
Phases of syphilis
Primary (3-8 weeks) Secondary (6-12) Latent Tertiary Congenital
Outline primary syphilis
Painless ulcer at inoculation site (Genital or oral)
Outline secondary syphilis
Disseminated infection Generalised rash and lymphadenopathy
Outline latent syph
(no clinical signs)
Outline teriary syph
Skin, neurological and vascular manifestations
Outline congenital syph
Acquired perinatally ( can cause miscarraiges|)Early and late manifestations
What happens to the baby in congenital syph
Miscarriage Still birth Prematurity Rashes Brain and neurological problems Bone disease
Does syph involve palms and hands
Yes
What is a chancre
An ulcer…. primary syph often genital region Lasts a few weeks then disappears Can take a swap
What type of rash is seen in syph
In econdary syph Macropapular rash (can be just a few) Involves palms and soles
Why do brothels have red lights
Can’t see the macropapular rash under it
What is Condyloma lata
NOT A WART But a wart type lesion seen in secondary syph Axilla and groin
Tertiary syphylis
Bone lesions Gummatous skin lesions Thoracic aneurysm Neurosyphilis
T/F Mother can pass syph onto the baby in a latent phase
T
Diagnosis of syph and treatment
For the chancre it’ll be microscopy ,Otherwise look for antibody against syph(blood test). Penicillin
How many human herpes viruses
8
What is HHV1, HHV2 and HHV3 What is the target cell
HHV1: HSV1 HHV2: HSV2 and HHV3: VZV macro-epithelial
What is the disease caused by HHV1, HHV2 and HHV3
1 &2: Oro-genital herpes 3: Chickenpox shingles
Site of latency for HHV1, HHV2 and HHV3
NEURONS
What disease does HHC-4 vauses What is the target cell, and what is it also known as. Where is the latency
also known as EBV. The target cell is B cells. Cuases Infectious mono nucelosis(gladular fever) . Site of latency :B cells.
What is HHV8 What is the target cell, and what is the site of latency
Karposi sarcoma associated herpes virus Target cell is lymphocyte Latency in B cells
What does HV1 and HV2 usually cause
General HSV 1= Oral coldsores HSV 2: Genital herpes
What does HHV5 cause, what is the target cell, disease and latency
CMV, Monocyte, epithelial cell, infectious mononucleosis type sndome Lymphocyte latency
What is HHV6 Target cell? disease? latency?
Roseola virus Lymphocyte latency and target cell Roseola
What is HHV 7 target cell and latency
T cell is target cell Pityriasis rosea is the disease Lymphocyte site of latency
What does KS affect and which patients
Endothelial cells of the lymphatics and affects HIV patients in partivular
Clinical presentation of Herpes simplex
Can cause Vesicular rash: grouped vesicles( these can break up to form an ulcer) on an erythematous base, then clears up .
Can cause eczema herpeticum: igf the patient has eczema.
Can cause herpes encephalitis: where it has a global effect on the brain.
What can happen with primary HSV
Can be worse and form stomatitis (who mouth not just lips) hard to eat
What is stephen-hojnsons syndrom
Often cause by drug reaction can also get inflammation of mouth
What are herpetic lesions
Can be seen in eczema herpeticum, little punched out ulcers in the skin following the vesicle formation
What can latent HSV reactivate
Times of stress, sun exposure, other infection etc
HHV3 causes whatt
Chickenpox/ singles
What type of rash in chicken pox VCV
Looks like vesicles on erthymatous base scattered all ofver the body, most concentrated on the face, ess concentrated on the body and least concentrated on arms and legs Ask if they are feeling unwell if they are adults… found in mouth
Treatment for chikcen pox
Normally will get better by itself… can cause encephalitis
What is Herpes Zoster
This is shingles (i.e like chicken pox and herpes zoster both caused by VZV HHV3)
Distribution of rash in VZV
Comes after latency at times of stress or low immune function and spreads along 1 dermatome Vesicular
How do people feel with shingles
Can feel nothing or terrible
Does the rash in shingles cross the midline?
No ,because it’s in dermatome
Can herpes zoster cross dermatomes
Yes it can partocilarly in immunosuppressed people like HIV
Why is involvement of the tip of the nose bad in herpes zoster
Because it can inidcate involvement of the nasociliary branch of V1 This could mean that the back of the eye is involved, and this needs more serious treatment to prevent blindness Acyclovir
Types of fungal infections
Superficial and deep (deep is in ID)
Types of superficial skin fungal infections
Dermatophytes Yeasts
Example of dermatophytes, where they grow
eg Trichophyton rubrum (often causes athletes foot) Grow in keratin Skin hair and nails
How do dermatophytes grow
Long hyphae, grow from tip
Example of yeast and where they grow and how they grow
eg Candida Grow on warm wet surfaces single cell and bud Groin genitals under breast, axilla and groins
What is tinea unguium and what is it usually caused by What does it look like
This is the disease not the fungus Funal infection of the nails Usually caused by dermatophytes but sometimes yeast Yellow and crumbly
How to treat tinea unguium
Anti-fungal IV Topical probably won’t work because it’s deep in the nail
Cause of tinea capitis
Funal infection on the head
Who does tinea capitis occur on
Kids not adults At around puberty sebum produces antifungals Agro-caribbean kids due to shape of hair shaft makes suceptible to fungal infection
Types of lesion in tinea capitis
Kerion (abscess type lesion, well defined) … dermatophyte Diffuse across scalp
Waht is fungal superficial infection of the hadn called
Tinea mannum Vets get it and kids with pets. Fungus transferred from the pet to the kid
What is tinea curis
Fungal infection of skin around the groin Not involving scrotum
Tinea facei
Funal infection of the face (on chin may be pet related)
Candida intertrigo
Yeast infection often on top of somme eczema Some satellite regions Wet rash Intertrigo means inflammation within a body crease
Tinea pedis
Between toes (usually due to Trichophyton rubrum (athletes foot)
An area that tinea doesn’t appear on
The scrotum, only the groin
Treamtnet of the superficial fungal infections
SKIN only -> topical cream (clotrimazole antidngal) HAIR OR NAIL –> the infection has gone deeper and needs tablet… it goes down the hair follice
Latin name for scabies
Sarcoptes scabei A mite
Where do scabies burrow
Deep in surface off epidermis Finger, axillae, genital area, insteps of the feet Widepsread itchy rash
What happens after the scabies infectin
After the burrows, two weeks later eczema reaction ot the eggs and faeces
Does tinea infection include yeast
Strictly speaking no, just dermatophyte General fungal nail infection (ie yeast or dermatophyte= onchynychhya mycosis) Dermatophyte infection nail= tinea unguium
Terminology:
explain tinea and candida terminology
the tinea teminology is to describe disease. tinea means fungal( and it is usually for dermatophytes , but can also include yeast sometimes) and the next part of the word describes where it occurs in. Candida is always for yeast.
