Osteomyelitis

Question 1

What makes osteomyelitis different than a septic joint?

Answer 1

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

Question 2

What organism is most commonly recovered from osteomyelitis infections?
• Why is this organism so prolific in this type of infection?

Answer 2

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.

Question 3

Osteomyelitis:
• what key symptoms are you looking for?
• What are you NOT looking for?

Answer 3

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**

Question 4

People with septic arthritis typically present acutely due to rapid proliferation of bacterial pathogens in synovial fluid. Is the same true for osteomyelitis?

Answer 4

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***

Question 5

What are the steps to diagnosing an osteomyelitis?
• what are going to be your most sensitive tests in detecting this infection?

Answer 5

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

Question 6

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?

Answer 6

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.

Question 7

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?

Answer 7

Hematogenous or Continguous:
• Hematogenous spread then you’ll most likely see MONObacterial infection

• Continguous spread then you’ll most likely see POLYmicrobial infection

Question 8

What are the most common causes of osteomyelitis other than staph aureus?

Answer 8

Common (>50% of cases)
• S. aureus
• S. epidermidus - coagulase negative staph

Occasional (>25%)
• Streptococci
• Enterococci
• Gram Negatives like Pseudomonas
• Anaerobes
• MTB

Question 9

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?

Answer 9

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

Question 10

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 -)?

Answer 10

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

Question 11

Why do you wan to limit your use of linezolid to Vancomycin Resistant Enterococcus?
• Side Effects
• Oral Bioavailability?

Answer 11

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

Question 12

T or F: people with vertebral osteomyelitis often present with motor and sensory deficit in the spinal cord.

Answer 12

False, this is not a common symptom, but is known to occur in about 15% of pts.

Question 13

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?

Answer 13

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

Question 14

How long is the treatment for Vertebral Osteomyelitis?

Answer 14

• At least 6 weeks of IV antibiotics required

Question 15

What are the 4 most likely pathogens to cause these changes on MRI?

Answer 15

• Staph Aureus
• Staph Epidermitus
• Brucella
• MTB

Question 16

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?

Answer 16

• Hyperglycemia
• Peripheral Neuropathy
• Poor vascular Supply - also prevents antibiotic access to affected sites.

Question 17

What factors put a person who is already diabetic at an increased risk of getting osteomyelitis?

Answer 17

Risks:
• Diabetes for more than 10 years
• CV disease
• Poor Glucose Control
• Renal/Retinal Disease

Question 18

You culture osteomyelitis from the foot of a diabetic. What are you likely to see?
• generally how will you treat these patients?

Answer 18

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

Question 19

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

Answer 19

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

Question 20

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?

Answer 20

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

Question 21

Why are children more likely to experience osteomyelitis in their metaphyses?
• Explain the underlying pathophysiology.

Answer 21

• 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.

Question 22

What are the most common causes of Acute Hematogenous Osteomyelitis in Children?
• Neonates?

Answer 22

Children:
• S. aureus
• S. pneumoniae
• H. influenzae (B) - not that common anymore now that we have a vaccine

Neonates:
• Groups B Step.
• E. coli

Question 23

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?

Answer 23

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

Question 24

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?

Answer 24

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.

Question 25

A sickle cell patient presents to the ER with osteomyelitis.
• Based on odds where his their infection located?
• What pathogens are likely responsible?

Answer 25

Sickle Cell patients typically get ACUTE osteomyelitis from Salmonella or S. aureus

Question 26

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?

Answer 26

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.

Question 27

What are some common places to see osteomyelitis manifest in an IVDU?

Answer 27

Hematogenous spread in IVDUs often localizes in weird places for example:

• Sternoclavicular Joint
• Sternochondral Joint
• Pubic Symphysis

Question 28

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.

Answer 28

Biggest Risk Factor:
• IVDU

Pathogens:
• S. aureus
• Pseudomonas
• Candida

Question 29

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

Answer 29

Gram Negative organsims:
• Pseudomonas

Gram Positive organisms:
• S. aureus

No organisms:
• Candida (do a silver stain)

Question 30

Tom likes to lick the needle before he shoots up. What pathogen may cause osteomyelitis in this patient?

Answer 30

Eikenella corrodens causes needle licker osteomyelitis

Question 31

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?

Answer 31

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

Question 32

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?

Answer 32

Systemic Symptoms are commonly abscent in people with TB (Pott’s disease)

• Pott’s disease usually occurs via Hematogenous spread from a pulmonary source

Question 33

When should you suspect Pott’s disease opposed to regular osteomyelitis?

Answer 33

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

Question 34

What do you need to DIAGNOSE TB osteomyelitis in a patient?

Answer 34

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.