Infections Flashcards
Which bugs can cause MSK infections?
Staph aureus Staph epidermidis Strep pyogenes Gram -ve Anaerobes
Define adult osteomyelitis
Inflammation of bone and medullary cavity, usually located in one of the long bones
What happens to the periosteum in infection?
Elevated due to infected pus filled abscess
What happens in chronic osteomyelitis?
Bone responds to injury by producing bone - the infected bone becomes enveloped in a shell of new bone
What is the gold standard investigation for osteomyelitis?
Bone biopsy
MRI/CT also useful
When would you be suspicious of an ulcer?
> 2cm >2 months
How are infections of bone treated?
Debridement and 6 weeks of antibiotics
What are the virulence factors of staph aureus?
Coagulase
Toxins - PVL, SSS, TSS
How are open fractures characterised?
Non-union and poor wound healing
What characterises a diabetic infection?
Probe to bone
Which drug is used for a true penicillin allergy?
Vancomycin
Doxycycline
Who is at risk of haematogenous infection?
Prepubertal children
PWID
Central lines/dialysis
Elderly
Where can haematogenous infection spread from?
Throat Skin UTI GI Lung
What are the characteristics of PWID bone infection?
Unusual sites - staph and strep
Sacroiliac and sternal joints
Unusual PWID - candida, pseudomonas, mycobacterium tuberculosis
Which bug are dialysis patients susceptible to?
Staph
Name four unusual patient groups
- sickle cell
- gauchers
- synovitis acne pustolosis hyper-stasis
- chronic recurrent multifocal osteomyelitis
How are vertebral infections usually acquired?
Haematogenous associated with epidural/psoas abscess
How does vertebral osteomyelitis present?
Insidious pain
Tenderness
Inflammatory markers increased
How is vertebral osteomyelitis treated?
Drainage of abscess
6 weeks antibiotics
What is the name for vertebral TB?
Pott’s disease
What are the risk factors for prosthetic joint infection?
- rheumatoid arthritis
- diabetes
- malnutrition
- obesity
Describe the mechanism of prosthetic joint infection
Direct innoculation, manipulation at time of surgery or seeding of joint at later time
Which pathogens cause prosthetic joint infection?
Staph aureus Staph epidermidis Propionibacterium acnes Strep/enterococcus E.coli
How is prosthetic joint infection diagnosed?
Culture preoperative tissue
Blood culture
CRP
Radiology
How is prosthetic joint infection treated?
Remove prosthesis for at least 6 weeks
Aggressive antibiotic therapy
Re-implant
What are the risk factors for arthroplasty?
- preoperative adjustment
- antibiotic prophylaxis
- laminar flow theatre
- doctors scrubbing technique
- anti-infective implant
- hydrogels
- antibiotic impregnated cement
- aftercare
- wound dressing
Which organisms cause septic arthritis?
Staph aureus Streptococci Coagulase -ve (prosthetic joint) Neisseria gonorrhoea (sexually active) H influenza (children)
How is septic arthritis investigated?
Aspirate joint fluid for microscopy
Blood culture if pyrexial
How is septic arthritis treated?
Flucloxacillin
<5 years old ceftriaxone
What can cause viral arthritis?
HBV
Paravirus B19
Rubella
Alphavirus
What is pyomyositis?
Muscle inflammation caused infection
What organism causes pyomyositis?
Staph
Describe tetanus
Clostridium tetani, spores in soil
Related to muscle spasm and paralysis
How is tetanus treated?
Antibiotics
Surgical debridement
Supportive measures
