Bacterial and viral infections Flashcards
Is staphylococcus aureus pathogenic?
It is often pathogenic, but can
inhabit the inner nose as a
symptomless resevoir.
Is streptococcus pyogenes pathogenic?
It’s always pathogenic
Name the different skin conditions that can be caused by S.aureus and S.pyogenes.
Impetigo
erysipelas
cellulitis
folliculitis
ecthyma
staphylococcal scalded skin syndrome
Name the different skin conditions that are 2ry to skin infection.
erythema nodosum
erythema multiforme
vasculitis
necrotising fasciitis
cold sore (herpes simplex)
eczema
Who is impetigo common in?
Young children
Which organisms often cause impetigo?
staphylococcus aureus and
streptococcus pyogenes
What is the Ix/Mx for impetigo?
Swap and culture
Topical antiseptics/biotics (systemic if severe)
Soak off curst with soap and water (as full of bacteria)
Who is ecthyma common in?
Diabetics
Immunosuppressed
What is the resolution of ecthyma like?
Tends to leave a scar
How is ecthyma treated?
Long course (2-4 weeks) of
oral antibiotics
Which layers of the skin does impetigo infect?
The epidermis
What layer of skin does ecythma infect and what is it linked to?
Linked to impetigo but extends from epidermis to dermis
Which layers of the skin are infected in cellulitis?
deeper dermis as well as
the subcutaneous tissues
What layers of the skin does erysipelas infect and what is it linked to?
It is linked to cellultis
It is infection of the upper dermis
What generally are the causes of cellulitis?
by staphylococcal or
streptococcal disease
What is the treatment for cellulitis?
systemic antibiotics
What is a common port of entry for cellulitis?
Tinea pedis (which is treatable)
How can you distinguish erysipelas and cellulitis?
Erisipelas is more superficial and
has more defined edges
What is staphylococcal scalded skin syndrome caused by?
staphylococcal toxins
What is the treatment for staphylococcal scalded skin syndrome?
Find source of infection
I.V. antibiotics
Supportive care:
1) Fluids
2) Analgesia
3) Liberal emollients
What are the common causes of erythema nodosum?
Streptococcal infection (type IV delayed hypersensitivity response to numerous antigens)
Sarcoidosis
IBD
What is the treatment for erythema nodosum?
Treat any underlying condition
NSAIDs
How is erthema multiforme treated?
Remove trigger such as:
HSV
Streptococcus
Meds
and it will settle within 2 weeks
What is the treatment for vasculitis?
screening for extra-cutaneous disease and
treatment of the underlying problem
Other than a rash what symptoms occur in necrotising fasciitis?
Pyrexia
Pain in affected area
What speed is the progression of the rash in necrotising fasciitis?
rapid progression
What is the treatment for necrotising fasciitis?
Life-threatening - thus surgical debridement required
Which conditions can be caused by hypersensitivity to streptococcal antigens?
Erythema nodosum
erythema multiforme
guttate psoriasis
vasculitis
glomerulonephritis
What does HSV cause?
Cold sores and gential herpes
What are the lesions caused by HSV called (on the face)?
Vesicles
What is the treatment for cold sores?
Topical of systemic acyclovir
What areas of the lip will be infected by HSV?
It will affect the same part of a single pt repeatedly
What is the treatment for eczema herpeticum?
systemic aciclovir
treat the eczema with topical steroids
How is varicella zoster virus transmitted and how long does it incubated for?
Respiratory droplets
Incubation period of 14-17 days
How long is a patient with varicella zoster virus infection (chicken pox) infectious for?
2 days before eruption
to a week after onset of eruption
What is the risk of adults have chickenpox?
Much higher risk of
internal organ involvement
What is the risk of shingles of the nasal tip?
involvement of the
naso-ciliary nerve (a branch of the ophthalmic nerve (CN V1))
is likely to cause ocular disease
which may be sight-threatening
What causes shingles?
reactivation of varicella zoster virus (a.k.a. herpes zoster)
What is the risk of herpes zoster around the external auditory meatus?
May indicate Ramsay Hunt syndrome,
should have associated:
facial palsy
deafness
vertigo
What are the risks of shingles infection?
Nasal tip - naso-ciliary nerve involvement + subsequent sight loss
Ramsay Hunt syndrome
Post-herpetic neuralgia
2ry bacterial infection
Encephalitis
What is the treatment of shingles?
Must treat before vesicles have stopped forming or its too late.
Treatment is aciclovir
Where does the varicella zoster virus lay dormant from chickenpox to cause shingles?
The dorsal route ganglion
Which type of HPV warts are very resistant to treatment?
Mosaic warts
What is the treatment for HPV warts?
cryotherapy or
curettage
(should eventually spontaneously resolve)
What are the typical lesions of molluscum contagiosum like?
Umbilicated papules
What are the symptoms associated with the umbilicated papules of molluscum contagiosum?
They are asymptomatic
What is the treatment for molluscum contagiosum?
Generally no treatment is required
Who does molluscum contagiosum commonly occur in and who is it worse in?
Common in children
Worse in atopics
