Clinical infections: Orthopaedic, Skin and Soft Tissue Flashcards
Functions of the skin
- Physical barrier
- homeostasis
- Immunological function
Normal flora of the skin =
- Coagulase-negative Staphylococci
- Staph aureus
Viral warts definition
Small asymptomatic growths of skin; on hands, genitals, feet, around nails, throat
Viral warts features
- Aetiology = HPV
- Pathogenesis = proliferation and thickening of stratum corneum, granulosum and spinosum
- Clinical presentation = asymptomatic, mechanical, cervical cancer
Viral warts treatment
- Topical – salicylic acid, silver nitrate, cryosurgery
- Gardasil immunisation for HPV
Pilonidal Cysts or Abscesses
- In natal cleft; caused by ingrowing hair
- Contains hair and debris
- Discharge to form sinus
- Clinical presentation = pain, swelling, pus
- Treatment – hot compress, analgesia, antibiotics, surgical excision
Impetigo
- Superficial skin infection with crusting around nostrils or corners of mouth
- Aetiology = S. aureus
- Transmissible
- Treatment = topical or oral antibiotics
Cellulitis definition
Infection affecting inner layers of skin – dermis, subcutaneous fat into lymphatics
Cellulitis aetiology
S. aureus, group A strep, group B strep
Cellulitis features
- Bacteria enter through breaks in skin
- Rubor (red), calor (heat), dolor (pain), tumor (swelling) - inflammation
Cellulitis treatment
- Elevation, rest, antibiotics, source control (e.g. drain pus)
Necrotising Fasciitis definition
- Flesh eating bug, rapidly progressive, life threatening
- Tracking along fascia, cutting off blood supply leads to necrosis
Main types of necrotising fasciitis
- Type 1: synergistic/poly-microbial, Presence of host impairment, RFs – diabetes, obesity
- Type 2: group A strep mediated, Younger people, associated with cut or injury
- Type 3: vibrio vulnificus – sea water, coral
- Type 4: fungal – rare
Necrotising Fasciitis pathogenesis
- Type 1 – ischaemic tissue, colonisation then infection resulting in further ischaemia and necrosis.
- Type 2 – infection, toxin release, disruption in blood supply = necrosis
Necrotising Fasciitis clinical presentation + treatment
- Clinical presentation = swelling, erythema, pain, crepitus, sepsis/toxaemia
- Treatment = debridement and antibiotics
Gangrene pathogenesis
- poor blood flow
- tissue necrosis
- colonisation
- infection
- further necrosis
Gangrene risk factors
- Dry = mummified, auto-amputate
- Wet = boggy, swollen “dactylitis”
- Gas = crepitus due to gas in tissue
Gangrene aetiology + treatment
- Aetiology:
o Skin – Staph, streps
o Enteric – gram negative bacilli, anaerobes (incl. Clostridium) - Treatment – surgical source control, revascularisation +/- antibiotics (if infectious)
Fournier gangrene
- Necrotising fasciitis of the external genetalia
- +/- perineum
- M>F
Diabetic foot definition
- Spectrum of disease from superficial to deep bone infection
- Caused by organisms that are superficial or deep
Orbital cellulitis
- Infection of soft tissue around and behind eye via Infection from skin or sinuses
- Presentation = erythema, swelling with induration, pain on eye movement, bulging
- Aetiology = S aureus, group A strep, S pneumoniae, H influenzae
- Treatment = IV antibiotics
Diabetic foot pathogenesis
- Damage to blood vessels – ischaemia, impaired immunity, poor wound healing
- Damage to nerves – neuropathy, trauma
- High blood sugars – prone to bacterial infection
Osteomyelitis pathogenesis
- Infection of bone
Mechanism: - Contiguous - diabetic foot infection
- Haematogenous - bacteraemia
- Penetrating
Acute - associated with inflammatory reaction, fulminant, sepsis
Chronic - present for >1 month, smouldering, acute flares - Infection results in bone death and new bone formation
Osteomyelitis aetiology
- Haematogenous (mostly children) – S aureus
- Contiguous – skin (staph, strep) or enteric (gram negative bacilli)
- Penetrating – surgical, open fracture
- Sickle cell – Salmonella
Osteomyelitis presentation + treatment
Presentation = acute pain, swelling, erythema, sinus, pathological fracture
- Treatment = 4-6 weeks antibiotics, surgical debridement and stabilisation
Septic/Pyogenic Arthritis
- Infection of joint - usually bacterial (staph + strep)
- Haematogenous, local and penetrating spread
- Pain, swelling, unable to weight bear
- Treatment = 4-6 weeks of antibiotics and surgical source control
Prosthetic joint infection pathogenesis
- Infection of prosthetic joint or tissue and bone surrounding it
- Bugs get onto surface of foreign body
- Immune system cannot reach
- Early – implanted at time or surgery or shortly after via wound
- Late – haematogenous or late presenting early infection
Prosthetic joint infection aetiology
- Early – S aureus, S epidermis
- Late – above AND E coli, B haemolytic streps, Strep viridans
Prosthetic joint infection presentation + treatment
- Presentation = instability, sinus formation + pus
- Treatment = Antibiotics with debridement, remove old joint and replace
Syphilis aetiology
- STI or congenital
- Aetiology = Treponema pallidum
Syphilis Primary
- Chancre – painless, firm, non-itchy ulcer at the point of contact
- Usually single; Lasts 3-6 weeks
- Lymphadenopathy
Syphilis Secondary
- 4-6 weeks after chancre
- Rash – symmetrical, red/pink, non-itchy
- Everywhere including soles/ palms/ mucous membranes
- Rash contains treponema
Syphilis Tertiary
- 3-15 years after initial infection
- 3 forms – gummatous, neurological, cardiovascular
- Gummatous (late benign) – chronic gummas: large inflammatory swellings of bone and liver
