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A 35-year-old man comes to the physician for evaluation of left thigh pain, which has been ongoing for the last five days. The pain has been progressively increasing in severity. In addition, he has been experiencing fevers and chills. Physical examination reveals swelling, warmth, and erythema in the thigh above the knee joint. In addition, several track marks are noted on the forearms. Temperature is 38.5°C (101.3°F), pulse is 110/minute, and blood pressure is 130/80 mmHg. Radiography reveals findings suggestive of osteomyelitis of the femur. The patient is subsequently started on antibiotics. The microorganism most likely responsible for this patient’s infection has which of the following characteristics?  

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Candida spp.

osteomyelitis p. 177

Mycobacterium avium-intracellulare p. , 138

vertebral osteomyelitis p. 177

Mycobacterium tuberculosis p. , 138

osteomyelitis p. 177

Neisseria gonorrhoeae p. , 140

osteomyelitis p. 177

Osteomyelitis p. 177

diagnostic findings p. 722

Pseudomonas aeruginosa p. , 141

sickle cell anemia p. 417

Staphylococcus aureus p. , 133

Pasteurella multocida

osteomyelitis p. 177

Pseudomonas spp.

osteomyelitis p. 177

Salmonella spp.

osteomyelitis p. 177

Staphylococcus aureus p. , 133

osteomyelitis and p. 177

Staphylococcus epidermidis p. , 133

osteomyelitis p. 177


Osteomyelitis can be broken down. Osteo- refers to bones, –myel stands for myelo and relates to the bone marrow, and lastly, –itis refers to inflammation.

So, osteomyelitis is an inflammation of the bone or bone marrow, and it typically results from an infection.

Normally, if we look at a cross-section of a bone, we can see that it has a hard-external layer known as the cortical bone and a softer internal layer of spongy bone that looks like honeycombs.

There’s also another layer called the periosteum that covers the cortical bone - like the lamination of a basketball card - and it's where the muscles, tendons, and ligaments are attached.

If we zoom into a cross-section of cortical bone, we can see that it has many pipe-like structures called osteons running through the length of the bone.

Each pipe has an empty center called a Haversian canal which contains the nerves and blood vessels that supply the osteon.

At the outer-border of the osteon is a ring of cells called osteoblasts which synthesize bone.

Along with these cells are osteoclasts that break down bone.

In bones, like the long femur bones, the tips of the bone are called the epiphysis, while the shaft is called the diaphysis of the bone.

Between the epiphysis and diaphysis, we have the metaphysis. It contains the growth plate, the part of the bone that grows during childhood.

In osteomyelitis, microorganisms, such as bacteria, reach the bone to cause an infection in a few different ways.

Bacteria particularly affect certain high-risk individuals like those with a weak immune system, and those with poor blood circulation due to uncontrolled diabetes.

In fact, a major way that bacteria reach the bone is through the bloodstream, and it's called hematogenous spread. For example, this might happen in a person who uses contaminated needles to inject drugs or in individuals undergoing hemodialysis that may be contaminated by a bacteria or even through the dental extraction of an infected tooth.


Osteomyelitis is an infection and inflammation of the bone or bone marrow. It is often caused by bacteria like Staphylococcus aureus, which enters the bone through an injury, surgery, or a blood infection. Common symptoms of osteomyelitis include pain, swelling, swelling, and warmth around the affected bone. People can also have fever and chills, and weakness. The treatment typically involves weeks of antibiotics directed at the organism causing the infection.


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  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 7/E (ENHANCED EBOOK)" McGraw Hill Professional (2014)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw Hill Professional (2019)
  5. "Osteomyelitis" Infectious Disease Clinics of North America (2017)
  6. "Etiology of Osteomyelitis Complicating Sickle Cell Disease" Pediatrics (1998)
  7. "T1-weighted MRI Imaging Features of Pathologically Proven Non-pedal Osteomyelitis" Academic Radiology (2013)

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