Skin infections Flashcards
(31 cards)
What are the two most common organisms that cause skin infections?
Staphylococcus aureus
Streptococcal pyrogens (GAS) Group A streptococcal)
How would you differentiate staphylococcus aureus from other staph organisms?
Staph aureus produces a coagulase enzyme (activator of fibrinogen - important in abscess formation)
How do the streptococcal pyogens overcome the skin protection barriers ? Name 2 ways.
- Strep pyrogens have an extracellular capsule similar to the connective tissue of the host - easy to invade
- M protein on the bacteria rises phagocytosis
Define Impetigo. How does it present?
What are the causative agents?
How would you treat?
Is a skin infection, presenting with superficial yellow thick crusts
Causative agents - staph aureus and strep pyogens
Treatment - topical or if severe oral flucloxicillin
Describe the difference between the folliculitis, furuncles and carbuncles
All caused by Staph aureus
Folliculitis - infection of the follicles - epidermis
Furuncles - infection is deeper - dermis
Carbuncles - several joint infected follicles, in diabetics or immunocompromised - usually on the neck
Define erysipelas
Skin infection caused by strep pyogens mainly
similar to cellulitis - lesions with red, hot, swollen skin around
systemic flu like symptoms just like cellulitis
Define cellulitis. How does it present?
Spreading inflammation of dermis and subcutaneous tissue
Flu like symptoms
Red, hot, swollen
UNILATERAL
What organism causes infection after a dog or cat bite?
How would you treat?
Pasteurella multocida (normal organisms of the mouth flora in cats and dogs)
Co amoxiclav
(if allergic - ciprofloxacin and clindamycin )
How would you treat a post-surgical infection?
Depends on the type of surgery:
- clean (usually staph aureus cause) - flucloxicillin
- contaminated/dirty (various number of agents) - broader spectrum of organisms - co-amoxiclav
Describe an arterial ulcer.
- well defined border
- decreased/absent pulses
- hairless, cold peripheries)
- symptoms of intermittent claudication
- reduced ABPI
Where on the leg are the venous ulcers more common?
Above the medial malleolus - great saphenous vein
What is the difference between wet and dry gangrene?
Gangrene - death of the tissue
Wet gangrene - infection is present - oozing fluid or pus
Dry gangrene - no infection usually
Define necrotising fasciitis.
What are the typical causes?
Rapidly spreading infection below the dermis that result in the necrosis of the tissues.
Strep pyogens and anaerobes?
Define a gas gangrene
Infection of the deep tissue by the clostridium perfingens that results in producing gas bubbles underneath
What organism causes gas gangrene ?
Clostridium perfingens
How would you treat necrotising fasciitis or a gas gangrene?
Surgical emergency - debriment
antibiotics - benzylpenicillin covers Strep but clindamycin covers Strep, Staph and anaerobes
What are the risk factors for hospital acquired MRSA?
- increased age
- number of hospitalisation
- surgical wounds
- nursing home residency
What is a Panton–Valentine leukocidin toxin?
Toxin present in majority of community acquired MRSA
What organism causes Carbuncles?
Staph aureus
Which viruses cause macular, maculopapular and vesico-pustular rash?
macular - Erythrovirus B19
maculopapular - Measles
vesico-pustular - VZV and HSV
What are the tests carried out for VZV?
PCR
Serology - IgM (4 days after the onset of rash)
In VZV which immunoglobulin indicates immunity? And which one past infection?
IgG - immunity
IgM - past infection
What complications will Erythrovirus B19 and rubella cause in utero?
Erythrovirus B19 - hydros faetalis
rubella - congenital rubella syndrome
Which condition is known as a slapped cheek virus?
Erythrovirus B19
