Bone and Joint Infections Flashcards
What is the source of most organisms getting into bone/joints ?
Definitely from outside, mainly from the skin
How do bones become infected (osteomyelitis)/what are possible access routes to the bone ?
- Haematogenous spread (in most cases)
- Local spread (e.g. from septic arthritis)
- Compound fracture
- Foreign body (mainly as a result of surgery)
Where, within the bone, does osteomyelitis tend to arise ? Why ?
In the epiphyseal plate/metaphysis, because that is an area of high vascularization so pathogens in the circulation often end of there.
What are some predisposing factors to osteomyelitis ?
- Younger people much more prone than older people
- Sickle cell disease (due to Salmonella)
- Travel/foreign born (due to Brucella)
- Prosthesis (due to Staphylococcus epidermis)
- Children under 5 (due to H.influenzae, so rare in countries with Hib vaccination programme)
- UTI (especially in older people, due to E.coli and others)
What are the organisms responsible for osteomyelitis ?
• S. aureus (>80%)
• S. pyogenes (~5%)
• M. tuberculosis
(Percentage applies to Scotland)
Which bones of the body are particularly prone to osteomyelitis ?
Bones with growing epiphyses.
- Femur
- Tibia
- Calcaneum
- Humerus
- Fibula
Define ostemyelitis.
Infection of the bone
Describe Haematogenous spread of infection to bones in osteomyelitis.
• Usually asymptomatic, but skin sepsis may be present (but is usually absent)
What are the main sources of foreign body infections in osteomyelitis.
- Orthopaedic implant (Knail) (most common)
- Trauma
- Shrapnel/Gun shot wound
Identify the main signs and symptoms of osteomyelitis.
- Painful swollen site
- Fever
- Reduced movement (may be the only sign in very young)
- Paraplegia
Identify the preliminary investigations for osteomyelitis.
- Fever
- WBC
- ESR (Erythrocyte Sedimentation Rate)
- CRP
Identify Investigation which should be undertaken for osteomyelitis diagnosis.
- Blood culture (Take 3 cultures. May be negative early on in the course of infection, but that does not rule out osteomyelitis because it may take weeks to show abnormalities)
- X-ray
- MRI/CT/Bonescan
- Pus (to help identify organism, from operative sample)
What would an X-ray of osteomyelitis show ?
- Reduced/absent space between vertebrae (vertebrae collapse)
- Demineralization of bones
What may a bone scan with osteomyelitis show ? Would this be a definite proof of osteomyelitis ?
- Areas with infection (osteomyelitis) hotter than rest of the body (noticeably darker on scan)
- Not definitive proof of osteomyelitis because anything that causes inflammation results in such ‘hotter’ areas
Describe the therapy required for osteomyelitis.
1) Standard Empirical Treatment
- Flucloxacillin/Fucidin (Flucloxacillin especially effective against staphylococcus aureus)
2) Alternative Empirical Treatment
- Fucidin/erythromycin or rifampicin (for ß- lactam allergy)
- Ciprofloxacin (for Salmonella infection)
- Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
(tuberculosis)
3) Drainage/Removal of involucrum
Define empirical therapy.
Therapy begun on the basis of a clinical educated guess in the absence of complete or perfect information, do not know causal organism
Identify the sites of Septic Arthritis.
- Knee
- Hip
- Lumbosacral spine
What are predisposing factors of Septic Arthritis ?
- Rheumatoid arthritis
- Injection of joint
- Prosthetic joint
Identify causative Organisms for Septic Arthritis.
- S. aureus
- S.pyogenes
- S. epidermis
- M. tuberculosis
- Salmonella
- Brucella
Identify investigation which should be undertaken for septic arthritis diagnosis.
- Blood culture
- Joint aspirate (Easier to get material out of septic arthritis than in OM)
- Joint X-ray
Describe the therapy required for septic arthritis.
Same organisms as OM so same approach
1) Standard empirical
- Flucloxacillin/Fucidin
2) Alternatives empirical
- Fucidin/erthromycin or rifampicin (for ß- lactam allergy)
- Ciprofloxacin (for Salmonella infection)
- Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
(tuberculosis)
Define reactive arthritis and identify the organisms involved. Also identify the main symptoms.
-=post infectious arthritide. Painful form of inflammatory arthritis, in reaction to an infection by certain bacteria.
-Most often, these bacteria are in the genitals (Chlamydia) or the bowel (Rubella, meningococcus, Yersinia, Salmonella, Shigella, Campylobacter, Mumps)
Used to be called Reiter’s Syndrome
• Synovitis
• Conjunctivitis
• Sacroiliitis
• Aortitis
• Circinatebalinitis
• Keratodermablennorrhagica
• Presence of HLA B27 antigen (associated with ankylosing spondylitis)
Identify the main risk factors for prosthetic joint infection, both in primary arthroplasty and revision (done for infection) arthroplasty.
PRIMARY: Rheumatoid Arthritis Diabetes Mellitus Poor Nutritional Status Obesity Concurrent UTI Steroid Therapy Malignancy Postoperative surgical site infection
REVISION Prior joint surgery Prolonged operating room time Preoperative infection (of teeth, skin, UTI)
Identify the main organisms responsible for prosthetic joint infections.
Staph. Aureus
Coagulase negative staphylococci
Streptococci
Describe the symptoms of Reitter’s Syndrome
- Synovitis
- Conjunctivitis
- Sacroiliitis
- Aortitis
- Circinatebalinitis
- Keratodermablennorrhagica
- HLA B27
- Associated with Clamydial infection
Describe rheumatic fever.
- An example of post-infectious arthritide
- Occurs after streptococcal infection
- 70% of those affected with rheumatic get arthritis
