Osteomyelitis Flashcards
What makes osteomyelitis different than a septic joint?
Osteomyelitis is an actual infection of the bone that is localized to the bone and involves boney distruction of the joint and the formation of sequestra
What organism is most commonly recovered from osteomyelitis infections?
• Why is this organism so prolific in this type of infection?
Staph aureus is the most common cause of osteomyelitis.
• It ability to infect bone relates to the many adhesins that is has which can bind fibronectin, Laminin, Collagen etc. and allow it to stick to bone.
Osteomyelitis:
• what key symptoms are you looking for?
• What are you NOT looking for?
Osteomyelitis Key Symptoms:
• Draining Sinus Tract and Non-specific pain around the site of infection.
Symptoms that are usually Absent:
_• NO fever/chills
• NO swelling
• NO erthema_
**Note: these final two are key in telling this disease from septic arthritis**
People with septic arthritis typically present acutely due to rapid proliferation of bacterial pathogens in synovial fluid. Is the same true for osteomyelitis?
No, osteomyelitis doesn’t typically present acutely instead we’re looking for a subacute to chronic presentation.
***Presence of a sinus tract means this infection has been around for awhile by the time it gets to you***
What are the steps to diagnosing an osteomyelitis?
• what are going to be your most sensitive tests in detecting this infection?
Diagnosis:
Imaging:
• Standard radiograph will work and CT is better but an MRI is the GOLD Standard
Labs:
• ESR and CRP typically elevated
Cultures:
• Aspiration of the bone under radiologic guidance is needed to optimize therapy
Ophilia presents with a two month history pain over her left femur. She denies any chills, fever, or malaise. On insepection no inflammation, erythema, or calor is detected. A small lesion draining pus is noted.
• Assuming the etiologic agent is a bacteria, what is the infection?
• What is the most likely bacteria?
• What imaging should you order to proceed?
This is most likely a staph aureus osteomyelitis because she is not inflammed but does a draining sinus tract from the infection. Appropriate imaging studies would be an MRI, it would likely show bone destruction and inflammation.
Ophilia presents with a two month history pain over her left femur. She denies any chills, fever, or malaise. On insepection no inflammation, erythema, or calor is detected. A small lesion draining pus is noted.
• Assuming the etiologic agent is a bacteria, what are 2 ways it could have gotten there?
• How do these two methods of infection affect what we’ll see on culture?
Hematogenous or Continguous:
• Hematogenous spread then you’ll most likely see MONObacterial infection
• Continguous spread then you’ll most likely see POLYmicrobial infection
What are the most common causes of osteomyelitis other than staph aureus?
Common (>50% of cases)
• S. aureus
• S. epidermidus - coagulase negative staph
Occasional (>25%)
• Streptococci
• Enterococci
• Gram Negatives like Pseudomonas
• Anaerobes
• MTB
Jane presents with pain in her back that has onset over the past few weeks and she is currently experiencing pain and tenderness localized to her cervical region. MRI shows localized destruction of boney vertebral tissue. She is currently experiencing a fever of 100 degrees.
• How did this infection likely spread to her vertebrae?
• What are some potential sources of the infection?
She has a Vertebral Osteomyelitis. The most common method of seeding in this infection is Hematogenous spread.
Risk Factors for Vertebral Osteomyelitis:
• Skin/Soft tissue infection
• GU tract infection
• Infective Endocarditis
• IVDU
• Recent operation
Jane presents with pain in her back that has onset over the past few weeks and she is currently experiencing pain and tenderness localized to her cervical region. MRI shows localized destruction of boney vertebral tissue. She is currently experiencing a fever of 100 degrees.
• How will you manage this infection?
• How will you tailor management on the basis of blood cultures (MRSA, VRE, Gram +, Gram -)?
Management is via Surgery and Abx.
Surgical:
• Removal if Hardware (if any, if possible)
• Adequate drainage/Debridement of all infected tissue
ABX:
• Beta Lactams (gram + or -) and Vanc (MRSA, Gram +) are most commonly used.
• Linezolid => ONLY IF VRE
• Daptomycin ($$$) => Gram Positives
Why do you wan to limit your use of linezolid to Vancomycin Resistant Enterococcus?
• Side Effects
• Oral Bioavailability?
Linezolid has LOTS of severe side effects and the prolonged treatment needed to combat osteomyelitis means pts. are more likely to experience these symptoms
Side Effects:
• Pancytopenia
• Peripheral Neuropathies/Optic Neurtitis
• Lactic Acidosis
T or F: people with vertebral osteomyelitis often present with motor and sensory deficit in the spinal cord.
False, this is not a common symptom, but is known to occur in about 15% of pts.
John presents with generalized pain in his lower back that has not resolved by taking NSAIDs. His history is positive for a recent trip to India where he consumed copius amounts of cheese and goat milk. MRI indicates the presence of osteodegradation and inflammation in the vertebrae. He denies any IVDU, but his urinary drug screen is positive for opiates.
• What are his risk factors for his current infection?
• What are some possible etiologic agents for infection?
Risk Factors:
• Travel outside of the country (brings TB, and Brucella into ddx)
• IVDU potentially (brings TB, S. aureus and S. epidermitus into ddx)
Etiololgy:
• Staph Aureus - MOST LIKELY
• Staph Epidermitus - Fairly Likely
• MTB
• Brucella
How long is the treatment for Vertebral Osteomyelitis?
• At least 6 weeks of IV antibiotics required
What are the 4 most likely pathogens to cause these changes on MRI?
- Staph Aureus
- Staph Epidermitus
- Brucella
- MTB
Why are people with diabetes at an increased risk of osteomyelitis?
• which of these risk factors is also a reason for poor treatment outcomes in these patients?
• Hyperglycemia
• Peripheral Neuropathy
• Poor vascular Supply - also prevents antibiotic access to affected sites.
What factors put a person who is already diabetic at an increased risk of getting osteomyelitis?
Risks:
• Diabetes for more than 10 years
• CV disease
• Poor Glucose Control
• Renal/Retinal Disease
You culture osteomyelitis from the foot of a diabetic. What are you likely to see?
• generally how will you treat these patients?
Diabetics typically have open foot ulcers that will be colonized by SEVERAL types of bacteria
You need to use surgery and BROAD SPECTRUM ABx. because the disease is polymicrobial
What exception is there to the rule that osteomyelitis that has been caused by hematogenous spread is manifested in the vertebral column?
• name 4 groups that may be exceptions
Exception is KIDS with ACUTE HEMATOGENOUS OSTEOMYELITIS, they’ll get infections in the METAPHYSES long bones with tibia and femur affected in most cases.
• Elderly, IVDUs, and ppl. with indwelling central lines may also get Osteomyelitis in these locations
A nearly 1 month old presents with severe hip pain is is holding his hip in an externally rotated position. You aspirate the joint and find WBCs are 100,000.
• What might this kid have in addition to a septic joint?
• Most likely pathogens?
This kid probably could have Osteomyelitis that is also involving the adjacent joint **This happens 50% in neonatal osteomyelitis**
Pathogens:
• Group B step and E. coli are the most common causes of osteomyelitis in neonates
Why are children more likely to experience osteomyelitis in their metaphyses?
• Explain the underlying pathophysiology.
- Capillary ends of the nutrient artery make sharp loops under the growth plate. This capillary feeds into large sinusoids where blood flow becomes slow and turbulent.
- Any minor trauma may lead to hematoma and vascular destruction, this will not be removed quickly because capillaries lack phagocytic lining cells
• Avascular necrosis occurs and you now have the appropriate setting for a Transient Bacteremia to seed.
What are the most common causes of Acute Hematogenous Osteomyelitis in Children?
• Neonates?
Children:
• S. aureus
• S. pneumoniae
• H. influenzae (B) - not that common anymore now that we have a vaccine
Neonates:
• Groups B Step.
• E. coli
You have an 8 year old girl with a draining sinus tract near here knee. She also has a fever. ROM is normal and she is afebrile with non-localized lower leg pain.
• What does she have?
• How did it probably get there?
• What do you need to make the diagnosis?
This is a case of acute hematogenous osteomyelitis in a child. This often occurs in the metaphysis of joints opposed to the vertebrae like is seen in adults.
Dx:
• Clinical Findings + MRI (that’s compatible) + Postive Blood Cultures
You have an 8 year old girl with a draining sinus tract near here knee. She presents with a mild fever as well. ROM is normal and she is afebrile with non-localized knee pain.
• Most likely pathogens?
• Treatment?
• Duration of Tx?
Pathogens:
• S. aureus (gram + cocci in clusters)
• S. pneumoniae (gram + diplococci)
Treatment:
• 3 weeks of therapy, you can switch from IV abx to PO abx when patient becomes afebrile.
A sickle cell patient presents to the ER with osteomyelitis.
• Based on odds where his their infection located?
• What pathogens are likely responsible?
Sickle Cell patients typically get ACUTE osteomyelitis from Salmonella or S. aureus
A sickle cell patient presents to the ER with osteomyelitis. Gram negative rods are present in high number in the bone aspirate.
• which of the two most common causes of sickle cell osteomyelitis has infected this patient?
• What pathological reason is there for infection?
Salmonella is the cause of this patient’s osteomyelitis. Sickle cell patients are susceptible to this pathogen because capillary occlusion secondary to intravascular sickling may infarct the gut. Salmonella can then invade and will be successful at staying in the blood stream due to suppressed spleen and liver function. Bone also commonly is infaracted in these patients and this serves as a good location for the infection to seed.
What are some common places to see osteomyelitis manifest in an IVDU?
Hematogenous spread in IVDUs often localizes in weird places for example:
• Sternoclavicular Joint
• Sternochondral Joint
• Pubic Symphysis
A patient presents with osteomyelitis of the pubic symphysis.
• what was (most likely) their biggest risk factor for infection?
• Name the 3 most commonly encounted pathogens in these patients.
Biggest Risk Factor:
• IVDU
Pathogens:
• S. aureus
• Pseudomonas
• Candida
A patient presents with an infection of there sternochondral joint. They are positive for opiates on there urine drug screen. What is the infectious agent if gram stain shows:
• Gram Negative organisms
• Gram Positive organisms
• No organisms
Gram Negative organsims:
• Pseudomonas
Gram Positive organisms:
• S. aureus
No organisms:
• Candida (do a silver stain)
Tom likes to lick the needle before he shoots up. What pathogen may cause osteomyelitis in this patient?
Eikenella corrodens causes needle licker osteomyelitis
Lester presents with new onset back stiffness following his recent trip to china. He denies any muscle or bone trauma in the affected region. He also denies fever, chills, night sweats, or malaise. CXR is clear.
• Could this patient have TB osteomyelitis?
• What gross findings would you be likely to see on physicial exam?
Yes - he has the risk factor of recent travel to a place where TB may be present and has no history of muscle or bone trauma. Additionally, CXR is clear in 50% of people with Pott’s Disease. TB osteomyelitis most often affects the spine.
Physical Findings:
• Pain
• Swelling
• Abcess
• Sinus Formation
Lester presents with new onset back stiffness following his recent trip to china. He denies any muscle or bone trauma in the affected region. He also denies fever, chills, night sweats, or malaise. CXR is clear.
• Is it common for people with TB to lack systemic symptoms?
• What is the most common way to get Pott’s disease?
Systemic Symptoms are commonly abscent in people with TB (Pott’s disease)
• Pott’s disease usually occurs via Hematogenous spread from a pulmonary source
When should you suspect Pott’s disease opposed to regular osteomyelitis?
Suspect TB osteomyelitis in:
• Negative Bacterial Cultures
• Biopsy showing granulomas
• Hx treated or untreated TB + new back pain
• Positive PPD, IGRA
• Young patients
• Travel to endemic area
• Those with TB contacts
What do you need to DIAGNOSE TB osteomyelitis in a patient?
You NEED to culture and stain for MTB, because only 50% of ppl. will have granulomas on biopsy and there is a lot of overlap with this and regular Staph/Strep Osteomyelitis.
