A 4-year-old boy is brought to the office with right leg pain. The pain began about a week ago when the patient bumped his leg into a coffee table. At the time, his parents were not concerned as he "cried for only a few minutes" and was able to walk normally afterward. However, the pain has worsened over the past few days and the patient is now limping. He also developed a persistent fever 4 days ago that is not improving despite ibuprofen and acetaminophen. The patient has had no cough, vomiting, diarrhea, or rash. Medical history is notable for sickle cell disease, and he has been hospitalized several times for vaso-occlusive pain crises. He has no history of splenic sequestration or acute chest syndrome. The patient takes no medications other than the antipyretics. Immunizations are up to date. Temperature is 39.4 C (103 F), blood pressure is 95/60 mm Hg, pulse is 158/min, and respirations are 30/min. Physical examination shows warmth and swelling of the right distal thigh with decreased spontaneous movements, although the patient has full range of motion in his hips and knees. The lungs are clear to auscultation with no increased work of breathing, and the abdomen is soft and nontender with no organomegaly. Laboratory results are as follows: Additional diagnostic testing is pending. Which of the following is the most appropriate empiric antibiotic therapy for this patient?

Question

A 4-year-old boy is brought to the office with right leg pain.  The pain began about a week ago when the patient bumped his leg into a coffee table.  At the time, his parents were not concerned as he "cried for only a few minutes" and was able to walk normally afterward.  However, the pain has worsened over the past few days and the patient is now limping.  He also developed a persistent fever 4 days ago that is not improving despite ibuprofen and acetaminophen.  The patient has had no cough, vomiting, diarrhea, or rash.  Medical history is notable for sickle cell disease, and he has been hospitalized several times for vaso-occlusive pain crises.  He has no history of splenic sequestration or acute chest syndrome.  The patient takes no medications other than the antipyretics.  Immunizations are up to date.  Temperature is 39.4 C (103 F), blood pressure is 95/60 mm Hg, pulse is 158/min, and respirations are 30/min.  Physical examination shows warmth and swelling of the right distal thigh with decreased spontaneous movements, although the patient has full range of motion in his hips and knees.  The lungs are clear to auscultation with no increased work of breathing, and the abdomen is soft and nontender with no organomegaly.  Laboratory results are as follows:  Additional diagnostic testing is pending.  Which of the following is the most appropriate empiric antibiotic therapy for this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bf74_67a6_8f63_51ea55ffb2ba_MD0005_00 This patient with sickle cell disease (SCD) has fever, focal bone pain, and elevated inflammatory markers (eg, C-reactive protein >8 mg/L [2 mg/dL]), after mild trauma. The etiology is likely osteomyelitis, a bone infection that is most commonly spread hematogenously in children. Initial diagnostic testing should include complete blood count, C-reactive protein, erythrocyte sedimentation rate, and blood culture. X-rays should be obtained to evaluate for alternate causes of pain and the late finding of periosteal reaction/elevation seen in osteomyelitis. MRI has excellent sensitivity for osteomyelitis if the diagnosis is unclear. The most common etiology is the gram-positive cocci Staphylococcus aureus, including methicillin-resistant S aureus (MRSA). However, this patient's history of SCD raises his risk of osteomyelitis due to gram-negative organisms, including Salmonella. Patients with SCD have functional asplenia due to repeated splenic microinfarctions, rendering vulnerability to encapsulated organisms. Empiric antibiotic therapy should therefore include gram-positive coverage with nafcillin, oxacillin, or cefazolin if rates of MRSA are low or clindamycin or vancomycin if MRSA is suspected. In addition, this patient's history of SCD necessitates additional treatment with a third-generation cephalosporin (eg, ceftriaxone, cefotaxime) for gram-negative coverage. Antibiotic therapy should begin promptly after initial laboratory studies are drawn to reduce the risk of further morbidity and mortality. (Choice A) Azithromycin plus ceftriaxone is an appropriate empiric antibiotic regimen for patients who have SCD with acute chest syndrome. Ceftriaxone covers common causes of community-acquired pneumonia (eg, Streptococcus pneumoniae), and azithromycin provides coverage for atypical organisms (eg, Mycoplasma pneumoniae). (Choices B and E) Ceftriaxone alone in this patient would fail to cover S aureus, a common cause of osteomyelitis in all patients, including those with SCD. Similarly, vancomycin alone would not provide coverage for gram-negative organisms. (Choice D) Because of functional asplenia, prophylactic penicillin is recommended for all children between age 2 months and 5 years to prevent infection from encapsulated organisms. However, penicillin has a narrow spectrum of activity and would not provide coverage for S aureus. Educational objective: Osteomyelitis should be suspected in any patient with fever, focal bone pain, and elevated inflammatory markers. Patients with sickle cell disease who have osteomyelitis should receive empiric antibiotic coverage for Staphylococcus aureus and Salmonella. References: Musculoskeletal manifestations of sickle cell disease: a review. (http://www.ncbi.nlm.nih.gov/pubmed/26623213)

A 4-Year-Old Boy Is Brought to the Office with Right