Bone and Soft Tissue Infection Flashcards
What is osteomyelitis?
Infection of bone
Acute or Chronic
Specific e.g. TB
Non-specific (more common)
How does acute osteomyelitis present in infants?
Most commonly in knee
Vague, systemic symptoms (failure to thrive, drowsy, irritable, unwell)
Metaphyseal tenderness/swelling (hard to see/feel due to chubby babies!)
Decreased ROM (Unusual positioning)
How does acute osteomyelitis present in children?
Boys > Girls Severe pain Reluctant to move Unable to weight-bear Flexed neighbouring joint Swinging pyrexia, tachycardia, fatigue, nausea, vomiting, distress toxaemia
How does acute osteomyelitis present in adults?
Commonly thoracolumbar spine (backache) in haematogenous/primary spread
UTI/urological procedure history
Elderly, diabetic, immunocompromised
Local/secondary after open fracture or ORIF
Source of infection in osteomyelitis
Infants, Children, Adults
Infants: infected umbilical cord
Children: boils, tonsillitis, skin abrasions
Adults: UTI, arterial line
Why are children susceptible to osteomyelitis?
Rich blood supply to growing tissue
How does osteomyelitis spread?
Haematogenous spread (children and elderly) Local from adjacent infected site (trauma/open fracture, ORIF, joint replacement) Secondary to vascular insufficiency (not cleared, chronic more likely)
Organisms in acute osteomyelitis - Infant, children, adults
Most commonly staph. aureus E. coli possible in infants Children: Strep. pyogenes or H. influenzae Adults: Propionibacterium (prostheses) M. tuberculosis, Pseudomonas (IVDUs) mixed in diabetes salmonella in sickle cell candida in immunocompromised
Where is acute osteomyelitis found?
Metaphysis of long bones (femur, tibia, humerus)
Joints with intraarticular metaphysis (hip, radial head of elbow)
Process of acute osteomyelitis
Starts at metaphysis; possible trauma
Blood flow stops (venous congestion, arterial thrombosis)
Acute inflammation increases pressure
Suppuration (pus formation)
Pressure released into medulla, into joint
Necrosis and new formation of bone
Resolution (if acute, single episode)
Investigating acute osteomyelitis
History and examination (pyrexial, high HR)
Bloods: FBC, WBC (neutrophils high) ESR, CRP
Blood culture
U&Es (dehydrated)
X-ray (two weeks normal, then early periosteal changes)
Ultrasound
Aspiration
Isotope bone scan
Labelled white cell scan
MRI
What is cellulitis?
Deep infection of subcutaneous tissue (dermis and subcutaneous fat)
Usually group A strep infection
What is Erysipelas?
Superficial infection Upper dermis
Subcutaneous lymph vessels Raised
Demarcated red ‘leathery’ plaque
Usually group A strep infection
What is necrotising fasciitis?
Aggressive fascial infection ‘Flesh eating disease’ Infection enters via burn or wound
Intense pain
Usually group A strep or clostridia
What is Gas Gangrene?
Grossly contaminated trauma
Deep infection
Bacteria responsible produce gas
Clostridium perfringens
What is toxic shock syndrome?
Secondary wound colonisation
Bacteria produce toxins
Desquamating rash
Usually staph. aureus (otherwise healthy people) OR strep pyogenes (pre-existing skin infection)
X-rays of osteomyelitis show…?
Early: minimal changes
Two weeks: early periosteal changes
Changes in medulla: lysis
Late: bone necrosis (sequestrum), new bone (involucrum)
Microbiology for osteomyelitis?
Blood cultures (if haematogenous, or suspected septic arthritis)
Bone biopsy
Tissues or swabs from sites around implant if prosthetic
Treating osteomyelitis
Fluids, analgesia
Rest, splint
Antibiotics (IV, oral, 4-6 weeks depending on response)
Which antibiotics to use for osteomyelitis?
Empirical while waiting (flucloxacillin, benzylpenicillin)
Depends on organism (resistant or persistent organisms, poor absorption or penetration)
When to operate on cases of osteomyelitis
Aspirated pus
Need to drain abscess
Debridement of dead/infected tissue
Not responding to antibiotics
What is chronic Osteomyelitis?
Due to the presence of intracellular bacteria (following operation, open fracture (even years prior)
Presentation: immunosuppressed, diabetics, elderly, IVDUs
‘Healed’ wounds repeatedly break down
Organisms of chronic osteomyelitis
Mixed: Usually same organisms for each flare-up Staph aureus E. coli Strep. pyogenes proteus
Pathological appearance of chronic osteomyelitis
Cavities Dead bone (former sequestra necrosis)
Involucrum (new bone formation)
Chronic inflammation on histology
Chronic osteomyelitis complications
Chronic discharge of pus via sinus Flare-ups
Ongoing infection Possible metastasis/abscesses
Fractures
Disturbed/deformed growth of bone
Squamous cell carcinoma
Treating chronic osteomyelitis
Long-term antibiotics (local or systemic) Surgically eradicate infection Treat soft tissue problems Correct deformities Amputation
Antibiotics for chronic osteomyelitis
Local: gentamicin cement or beads, sponge
Systemic: oral, IV (keep at home for flares)
