Theme 10 L3: Clinical infections - orthopaedic, skin and soft tissue Flashcards
Which microorganisms colonise the skin?
- coagulase-negative staphyloccoci
- S.aureus
- propionibacterium
- cornyebacterium spp
What are viral warts?
small asymptomatic growths of skin (hands, genitals, feet, around nails, throat)
What is the causative agent of viral warts?
HPV
Explain the pathogenesis of viral warts
proliferation and thickening of stratum corneum, granulosum and spinosum
What is the treatment of viral warts/
topical - salicyclic acid, silver nitrate, cryosurgery
How do we prevent viral warts?
gardasil (types 16, 18, 6 and 11) and genital: barrier protection
What is a pilonidal cyst or abscesss?
- cysts or abscesses in natal cleft
- contain hair and debris
- present with pain, swelling, pus
What is impetigo?
- crusting, around nares and corners of mouth
- superficial skin
- transmissible
What is the causative organism for impetigo?
staph aureus
What is erisipelas?
- raised and demarcated rash over face
- upper epidermis
What is the causative organism of erisipelas?
strep pyogenes
What similar condition is more severe than erysipelas?
cellulitis
What is cellulitis?
infection affecting the inner layers of the skin - dermis and subcutaenous fat, into lymphatics
What are some causative agent?
bacterial - S.aureus, group A strep, other B-haemolytic streptococci
How does cellulitis develop?
- bugs enter through breaks in skin
- wound, insect bite
- pre-existing condition e.g eczema, athletes foot
What is the clinical presentation of cellulitis?
- Rubour (red), calor (heat), dolor (pain), tumor (swelling)
* Loss of skin creases, blistering, pus/exudate, fever
What is orbital cellulitis?
infection of soft tissues around and behind eye
what is the clinical presentation of orbital cellulitis?
erythema, swelling with induration and pain on eye moveemnt, bulging
What are the causes of orbital cellulitis?
S.aureus, S.pyogenes
How do we treat orbital cellulitis?
iV antibiotics
What are the 4 types of necrotising fasciitis?
Type 1: synergitis/ poly-microbial
Type 2: Group A strep (s.pyogenese mediated)
Type 3: Vibrio vulnificus
Type 4: Fungal
Explain the pathogenesis of type I necrotising fasciitis?
ischamic tissue, colonisation then infection resulting in further ischaemia and necrosis
Explain the pathogenesis of type II necrotising fasciitis?
infection, toxin release - disruption in blood supply - necrosis
What is the clinical presentation of necrotising fasciitis?
swelling, erythema, pain
, crepitus , sepsis, necrosis
What is gangrene?
necrosis caused by inadequate blood supplyq
What are the causes of gangrene?
atherosclerosis
smoking
DM
autoimmune
What are the three types of gangrene?
- Dry gangrene - “mummified”
- Wet gangrene - exudate, surrounding erythema, swollen (dactylitis)
- Gas gangrene - crepitus
Explain the pathogenesis of gangrene
poor blood flow tissue necrosis colonisation infection synergistic infection further necrosis
What is diabetic foot infection?
spectrum of disease from superficial through to deep bone infection in patients with diabetes
Explain the pathogenesis of diabetic foot infection
- Damage to blood vessels – ischaemia, impaired immunity and poor wound healing
- Damage to nerves – neuropathy, trauma
- High blood sugars – prone to bacterial infection
What are the causative organisms of diabetic foot infection?
superficial - skin flora: S.aureus, streps, corynebacterium
deeper - skin and enteric flora: above + GNB, anaerobes
How do we treat diabetic foot infection?
- Surgical debridement
- Revascularisation
- Antibiotics
- Off-loading
- Diabetic control
What is osteomylelitis?
infection of bone
What is the difference between acute vs chronic osteomyelitis?
Acute: associated with inflammatory reaction, fulminant, sepsis
Chronic: present for > 1 month
What is the clinical presentation of osteomyelitis?
acute pain, swelling, erythema, sinus, pathological fracture,
What is septic (or pyogenic) arthritis?
infection of the joint (usually bacterial but can also be caused by viruses, mycobacterium and fungi)
What is a prosthetic joint infection?
“PERI” prosthetic joint infection - infection of tissue and bone surrounding a prosthetic joint
How would a patient with prosthetic joint infection present?
pain, instability, swelling/ erythema, sinus formation - pus
What is syphilis caused by?
treponema pallidum - a spirochete
What is the treatment for syphilis?
penicillin
What are the 3 stages of syphilis?
- Primary
- painless, firm non-itchy ulcer (chancre)
- at point of contact
- lasts 3-6 weeks
- lymphadenopathy - Secondary
- 4-10 weeks after ulcer (chancre)
- symmetrical, red/pink, non-itchy rash
- everywhere including soles, palms, mucous membranes
- maculopapular or pustular rash that contains treponema - Tertiary
- 3 to 15 years after initial infection
What are the 3 forms of tertiary syphillis?
- Gummatous (late benign) - granulomatous lesions affecting mainly liver and bone
- Neuro
- Cardiovascular
