Infections and Infestations Flashcards
What is the pathogenesis of the herpes simplex virus?
Infection becomes latent after primary exposure - with or without a clinical episode
After infeciton is latent a trigger causes a clinical episode (trauma, menstruation, sunlight, fever)
The first clinical episode is likely to be the most severe
Where does the herpes simplex virus reside?
Usually resides in the dorsal root ganglion after travelling up the peripheral nerves
Who is likely to suffer from worse cinical episodes from the herpes simplex virus?
The immunosuppressed
Those with atopic eczema
What is the pathogenesis of the herpes zoster virus?
Primary exposure
Chicken pox
Latent infection
Reactivation
Shingles
(pain / constitutional symptoms)
about 4 days after - rash
The rash usually tracks around the body - however it does not cross the midline of the body
What are the common infective agents of the skin?
Staph aureus and strep
Desribe the depth of infection of impetigo
Very superficial
What is a furuncle?
Abscess in a hair follicle
What is a carbuncle?
Several furuncles joined together
Define erysipelas
an acute, sometimes recurrent disease caused by a bacterial infection, characterized by large raised red patches on the skin.
More superficial than cellulitis
Caused by strep
Skin is raised and inflamed over infected area
What is the causative organism for cellulitis?
Staph
What does impetigo look like on dry skin?
Golden and crusten, although it does look slightly different over a moist area (e.g underneath the armpit)
Very contagous
The causative organism os usually staph - however it may be strep (20%) sometimes a mixture of both
Who is more susceptible to rcurrent furuncles?
People with diabetes
What is ecthyma?
Ecthyma is a variation of impetigo, presenting at a deeper level of tissue. It is usually associated with Group A (beta-hemolytic) Streptococcus (abbreviated GAS).
Where is cellulitis common?
Lower limb - below the knee
What are the symptoms of cellulitis?
Tender and hot
If the infection is extensive then fever as well
What is the most common yeast infection?
Candida albicans- grows on moist areas
(obese people who are unable to wash well)
What does candida albicans look like?
Brick red erythema
Satellite pustules
(commonly foound underneath the breasts or inbetween the fingers of people who have a lot of wetness on their hands - occupation related)
What is paronychia?
Inflammation of the folds of tissue surrounding the nail due to infection or inflammation. The infection may be bacterial (most commonly, staph or strep) or fungal pathogens.
Most common infective agent is candida
What does athletes foot look like?
(tinea pedis)
Lots of white lacerated skin - flaky bits around the edge
What are the fungi responsible for athletes foot?
Usually caused by dermatophyte fungi
What are the best agents to treat tinea pedis (dermatophyte fungi)?
Clotrimazole or terbinafine
What is the name given to athletes foot but on the body?
Tinea corporis
What is the relevant investigation for tinea infections?
Scrapings are sent to the lab for culture
What is the name of athletes foot in the crotch area?
Tinea cruris
