Question 224

Question:

A 12-year-old girl with sickle cell disease has pain in her right arm. An x-ray of the right upper extremity shows bony lesions consistent with osteomyelitis. Which of the following is the most likely causal organism?

Correct Answer: E.  Salmonella enteritidis

You need to know the likely organisms that cause osteomyelitis, and determine which of these are associated with sickle cell disease.
In general, Staph aureus and Salmonella enteritidis are the two most common causes of osteomyelitis in general. The vaso-occlusive bone disease related to sickle cell leaves the bone prone to infection. Here, the best answer choice is (E) Salmonella enteritidis.
(A) Clostridium family bugs cause Gas Gangrene, myonecrosis and septicemia, NOT osteomyelitis.
(B) Enterococcus faecalis is a Gram-Positive bacterium that normally inhabits the human gastrointestinal tract. It can exhibit antibiotic resistance and cause endocarditis and bladder or prostate infections.
(C) Listeria monocytogenes is a Gram positive, motile (with flagella) organism. It causes the disease Listerosis, which is characterized by septicemia, encephalitis and uterine/cervical infections.
(D) Proteus mirabilis is a Gram-negative, facultatively anaerobic bacterium. It shows swarming, motility, and urease activity. So, Proteus infection commonly results in struvite or calcium carbonate crystals in the urine, and to the formation of kidney stones.