Osteomyelitis Flashcards
Osteomyelitis refers to …
Osteomyelitis refers to infection of the bone.
What is the most commonly identified infecting organism in osteomyelitis?
Staphylococcus aureus is the most commonly identified infecting organism. Treatment involves long courses of antibiotics (normally a minimum of 4-6 weeks) and at times surgical debridement.
Causative organisms in osteomyelitis
Staphylococcus aureus: A gram-positive cocci. Includes MRSA (Methicillin Resistant Staphylococcus Aureus) a penicillin resistant organism.
Pseudomonas aeruginosa: A gram-negative rod. More commonly seen in IV drug users.
Salmonella spp.: Gram-negative rods. Most commonly seen in patients with sickle cell anaemia.
Neisseria gonorrhoeae: A gram-negative diplococci. Seen in the sexually active where rarely may cause a disseminated infection.
Mycobacterium tuberculosis: Acid fast bacilli. May cause osteomyelitis - characteristically in Pott’s disease (TB affecting the spine).
Polymicrobial: More commonly seen in those with ulcers secondary to vascular disease, neuropathy and diabetes.
Staphylococcus aureus: A gram-… …. Includes MRSA (Methicillin Resistant Staphylococcus Aureus) a penicillin resistant organism.
Staphylococcus aureus: A gram-positive cocci. Includes MRSA (Methicillin Resistant Staphylococcus Aureus) a penicillin resistant organism.
Staphylococcus aureus: A gram-positive cocci. Includes MRSA (Methicillin Resistant Staphylococcus Aureus) a … resistant organism.
Staphylococcus aureus: A gram-positive cocci. Includes MRSA (Methicillin Resistant Staphylococcus Aureus) a penicillin resistant organism.
Pseudomonas aeruginosa: A gram-negative rod. More commonly seen in … users.
Pseudomonas aeruginosa: A gram-negative rod. More commonly seen in IV drug users.
Salmonella spp.: Gram-negative rods. Most commonly seen in patients with …
Salmonella spp.: Gram-negative rods. Most commonly seen in patients with sickle cell anaemia.
Neisseria gonorrhoeae: A gram-negative …. Seen in the sexually active where rarely may cause a disseminated infection.
Neisseria gonorrhoeae: A gram-negative diplococci. Seen in the sexually active where rarely may cause a disseminated infection.
Mycobacterium tuberculosis: … fast ….. May cause osteomyelitis - characteristically in Pott’s disease (TB affecting the spine).
Mycobacterium tuberculosis: Acid fast bacilli. May cause osteomyelitis - characteristically in Pott’s disease (TB affecting the spine).
… osteomyelitis: More commonly seen in those with ulcers secondary to vascular disease, neuropathy and diabetes.
Polymicrobial osteomyelitis: More commonly seen in those with ulcers secondary to vascular disease, neuropathy and diabetes.
Haematogenous spread refers to the spread of a pathogen via the …
Haematogenous spread refers to the spread of a pathogen via the blood. Risk factors for such infections include:
Indwelling intravascular catheter (e.g. Hickman line)
Haemodialysis
Endocarditis
IV drug use
Haematogenous spread refers to the spread of a pathogen via the blood. Risk factors for such infections include:
… (e.g. Hickman line)
H…
E…
… … use
Haematogenous spread refers to the spread of a pathogen via the blood. Risk factors for such infections include:
Indwelling intravascular catheter (e.g. Hickman line)
Haemodialysis
Endocarditis
IV drug use
Osteomyelitis occurring secondary to haematogenous spread in adults most commonly affects the axial skeleton, primarily the … bones.
Osteomyelitis occurring secondary to haematogenous spread in adults most commonly affects the axial skeleton, primarily the vertebral bones. After the vertebral bones the next most frequently affected sites are other axial bones like the sternum and pelvis. Less commonly (in adults) long-bone osteomyelitis is seen - which when affecting the metaphysis may lead to septic arthritis.
What is the most commonly affected site in haematogenous spread osteomyelitis in adults?
Vertebrae
Non-haematogenous spread (osteomyelitis)
Non-haematogenous spread occurs due to breakdown or removal of the normal protective barriers of skin and soft tissue or spread from a contiguous focus of infection. This may occur for a number of reasons: (4)
Skin ulcers
Trauma
Surgery (especially when foreign material is placed)
Animal / insect bites
Osteomyelitis may present with …, pain and signs of local ….
Osteomyelitis may present with fever, pain and signs of local inflammation.
Symptoms of osteomyelitis (5)
Fever Pain Overlying redness Swelling Malaise
Signs of osteomyelitis (6)
Erythema Swelling Evidence of previous surgery or trauma Tenderness Discharging sinus Ulcers / skin breaks
Osteomyelitis - what will blood tests usually reveal?
Blood tests will normally reveal a non-specific rise in inflammatory markers.
Osteomyelitis is normally diagnosed how?
Osteomyelitis is normally diagnosed on MRI imaging.
…: Refers to a dead piece of devitalised bone that has been separated due to necrosis from the surrounding bone.
Sequestrum: Refers to a dead piece of devitalised bone that has been separated (i.e. sequestered) due to necrosis from the surrounding bone.
…: New growth of periosteal bone around a sequestrum.
Involucrum: New growth of periosteal bone around a sequestrum.
…: An opening in an involuvcrum that allows the internal necrotic bone and pus to discharge out.
Cloaca: An opening in an involuvcrum that allows the internal necrotic bone and pus to discharge out.
Pros and cons of X-ray (osteomyelitis imaging)
Cheap and easy
Poor sensitivity - Osteopenia, bone lysis and cortical loss may be seen
Pros and cons of CT (osteomyelitis imaging)
Poor sensitivity compared to MRI
Good for small sequestrum
Why is MRI the imaging modality of choice in osteomyelitis?
Modality of choice
Excellent bone and soft tissue views
Bone marrow oedema seen early
What forms the mainstay of management in osteomyelitis?
Antibiotics +/- surgical debridement forms the mainstay of management.
In osteomyelitis what should be done before antibiotics are given? (Whenever possible)
Whenever possible antibiotics should be held until bone cultures (or at least blood cultures and any relevant tissue swabs) have been taken.
Antibiotic courses tend to be a minimum of 4-6 weeks and are guided by microbiology. Where possible and appropriate these can be administered as an outpatient.
Patients with vertebral osteomyelitis may receive symptomatic relief from back ….
Patients with vertebral osteomyelitis may receive symptomatic relief from back braces.
An example empirical regimen for osteomyelitis would be once-daily … and …. This offers good coverage for S. aureus with the … active against MRSA.
An example empirical regimen would be once-daily ceftriaxone and vancomycin. This offers good coverage for S. aureus with the vancomycin active against MRSA.
Surgical debridement is more commonly indicated in … spread osteomyelitis, although acute antibiotic therapy may be trialled first.
Surgical debridement is more commonly indicated in non-haematogenous spread osteomyelitis, although acute antibiotic therapy may be trialled first.
In many cases of haematogenous spread osteomyelitis, which in adults most commonly affects the vertebrae, an attempt will be made to treat with antibiotics first. Indications for surgery include:
(3)
Failure to respond to antibiotic therapy
Formation of discrete abscess
Neurological deficit (vertebral osteomyelitis)
