Skin + soft tissue infections Flashcards
What is impetigo?
Skin infection of the epidermis, commonly caused by Staphylococcal
What is erysipelas?
Skin infection of the epidermis, commonly caused by Streptococcal
What is cellulitis?
Skin infection of the dermis (+/- subcutaneous fat), commonly caused by either Staphylococcal or Streptococcal
What is furuncle?
A deep infection of a hair follicle causing a ‘boil’ - commonly caused by Staphylococcal
What is carbuncle?
Connecting collections of furuncles, commonly caused by Staphylococcal
What is necrotising fasciitis?
A deep infection of the fascia (+/- muscle), commonly caused by Streptococcal or mixed bacterias
What viruses commonly affect the skin?
Viral warts
Herpes
Viral exanthems (e.g. chickenpox, shingles)
What bacteria commonly affect the skin?
Streptococcus species
Staphylococcus aureus
Opportunistic bacterias (e.g. in diabetic foot ulcers)
What is a commensal host-microbe interaction?
Symbiotic relationship between two different species where one derives some benefit and the other is unaffected
What is colonisation?
When a microbe grows on (or in) another organism without causing any disease
What is a pathogen?
Microbe that is able to cause disease
Define infection
The invasion and multiplication of microbes in an area of the body where they are not normally present, usually leading to disease
What bacteria dominates the normal flora of the skin?
Gram positive bacteria species
What areas of the body are normally sterile from bacteria?
Lungs
Internal tissue
Urinary tract (except distal region of urethra)
What bacteria dominates the normal flora of the vagina?
Lactobacilli
What are the risk factors for SSTIs?
Direct inoculation (trauma, medical procedures, skin ulcers etc.) Previous colonisation (poor hygiene, MRSA etc.) Immunosuppression (e.g. DM, renal failure)
What characteristics should be used to describe a skin lesion or rash?
Shape Size Edge Colour Surface Distribution
What is the diagnostic process for SSTIs?
- History
- Examination
- Differentials
- Investigations
- Diagnosis
- Treatment
What microbiology samples can be used to aid diagnosis of SSTIs?
Swabs (e.g. pus or skin) Body fluids (e.g. pus, vesicle fluid, blood) Body tissues (biopsies)
How should viral SSTIs be treated?
Generally self-limiting and therefore do not require treatment.
Antivirals (e.g. aciclovir) can be used to treat herpes, chickenpox and shingles
How is impetigo normally treated?
Topical Fuscidin
How is Staphylococcus Aureus usually treated?
Sampling recommended + Flucloxacillin initially
[These types of infection are often abx resistant e.g. MRSA]
How are Streptococcus species skin infections usually treated?
Penicillin recommended
How are opportunistic bacterial skin infections (e.g. diabetic ulcers) usually treated?
Often polymicrobial so sampling is recommended and Co-Amoxiclav used initially
How are fungal skin infections usually treated?
Topical Terbinafine often used
What factors need to be taken into account when deciding how to treat an SSTI?
Allergy/ intolerance Renal/ liver function Severity of infection Immunocompromised? Risk of antibiotic-associated infections Route of administration Drug interactions Age/ ethnic group Pregnancy/ breast-feeding/ contraception
Is Staph Epidermis usually a pathogen?
No, normally considered a commensal bacteria
Only causes infection only if reaching internal prosthetic material
Which type of Staphylococcus bacteria is normally considered a pathogen?
Staph. Aureus
