Skin And Soft Tissue Infections Flashcards
State how infections are classified?
- By microbe:
- bacteria
- virus
- fungi - By anatomy:
- superficial
- deeper tissues - Treatment principles
Describe the microbe s.aureus
- basic description
- virulence factor
- disease
- Basic description
- cocci (round)
- gram positive (purple)
- often clumped together (similar to grapes) - Virulence factor
- Panton Valentine leukocidin toxin - Disease
- angular cheilitis
What is a leukocidin?
A toxin that kills white blood cells
What are the two types of s.aureus?
- Methicillin sensitive s.aureus
2. Methicillin resistant s.aureus
MRSA
Briefly describe how panto-Valentine leukotoxins work (in association with s.aureus
- Positive s.aureus will release PVL sub units
- These sub units will conglomerate to form pores on the target cell which allow its contents to “leak” out
- Leukocytes (white cells) contain inflammatory mediators which can cause problems when they leak out of the cell
What is a very dangerous disease caused by MRSA that also effects young healthy people
Necrotising pneumonia
Describe s.pyogenes
- Basic description:
- cocci
- gram positive
- form chains - Virulence factors:
- superantigens and toxic shock syndrome - Disease:
- cellulitis
What is a superantigen?
An antigen that causes huge dysregulation in its host compared to the amount of the antigen that is released by the bacteria
Describe the s.anginosis group
- Basic description
- cocci
- gram positive
- usually seem in chains but can clump together - Virulence factors:
- intermedilysin (cytotoxin)
- leads to lysis of cells - Disease
- (periapical) periodontitis
Describe c.welchii
- ## Basic description
- Virulence factor
- alpha toxin (lecithinase) - Disease:
- clostridial myonecrosis - “gas gangrene”
What laboratory test is used to detect alpha toxin and help confirm the identity of C.welchii?
The nagler reaction
Describe the herpes simplex group of viruses
- Basic description
- DNA virus
- nuclear capsid surrounded by lipid membrane - Virulence factor
- cell lysis - Disease
- herpes infection
(i. e herpes labiales)
Describe the fungi Candida albicans
- Basic description
- 10x larger than bacteria
- circular yeast cells
- special stain normally used but can stain gram positive (purple) - Virulence factor
- phospholipase - Disease
- candidiasis
PART 2
PART 2
What are the 3 main anatomical classifications for skin and soft tissue infections?
- Epidermis
- Dermis
- Sub cutaneous
List two examples of diseases that infect the epidermis
- Impetigo
2. Angular cheilitis
Give an example of a disease that infects the dermis of the skin and describe how it can present
Disease:
- erysipelas
Description:
- “butterfly erythema” on the face
- looks like a large red rash
- caused by S.pyrogenes (group A strep)
What disease in the dermis is commonly caused by S.aureus and how does it present?
- Folliculitis
- infection of hair follicles
Description:
- red spots containing discharge on the surface of skin
- in more severe cases boils can form
- in even more Severe cases carbuncles (multiple heads) can form
Give an example of a subcutaneous infection and briefly describe it
- Disease:
- cellulitis - Clinical description
- erythema and swelling of infected tissue
What microorganism is a common cause of severe Odontogenic infection?
Streptococcus anginosis
- may be others involved
- including anaerobic bacteria
Describe another sub cutaneous infection which presents with severe necrosis of infected tissue
- Fascia - necrotising fasciitis
What is a common cause of surgical wound infections
Staph. Aureus
What microorganism is often present in bite wounds from animals?
Pasteurella multicoda
List the order of events in treatment of skin and soft tissue infections
- Diagnosis
- Surgical debridement
- Microbiological specimens
- Antibiotics
- Review
