WBR280

Author	PageAuthor::Gerald Chi (Reviewed by Serge Korjian)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Pharmacology
Sub Category	SubCategory::Head and Neck, SubCategory::Hematology, SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::An 8-year-old girl with a history of thalassaemia major presents to the emergency department with low-grade fever, leg pain, and malaise for the past week. Her blood pressure is 110/60 mm Hg, heart rate is 90/min, and temperature is 37.8 ᵒC (100 ᵒF). On physical examination, her anterior left shin is red, swollen, and tender to palpation. Following an extensive work-up, the diagnosis of tibial osteomyelitis is confirmed. Cultures from bone biopsies reveal gram-negative rods. Which of the following regimens is the most appropriate for the initial management of this patient?]]
Answer A	AnswerA::Ciprofloxacin
Answer A Explanation	[[AnswerAExp::Empiric treatment of hematogenous osteomyelitis in patients with hemoglobinopathies includes coverage for Salmonella, E. coli, and S. aureus species. Regimens should include ciprofloxacin and either oxacillin/nafcillin/ceftriaxone or vancomycin/linezolid depending on risk of MRSA.]]
Answer B	AnswerB::Linezolid
Answer B Explanation	AnswerBExp::Although linezolid provides adequate coverage for staphylococcal species, it does not cover ''Salmonella'' species, which are highly likely in this case given the history of thalassemia and the culture results.
Answer C	AnswerC::Ampicillin
Answer C Explanation	AnswerCExp::Although ampicillin provides adequate coverage for staphylococcal species, it does not cover ''Salmonella'' species, which are highly likely in this case given the history of thalassemia and the culture results.
Answer D	AnswerD::Vancomycin
Answer D Explanation	AnswerDExp::Although vancomycin provides adequate coverage for staphylococcal species, it does not cover ''Salmonella'' species, which are highly likely in this case given the history of thalassemia and the culture results.
Answer E	AnswerE::Clindamycin
Answer E Explanation	AnswerEExp::Although clindamycin provides adequate coverage for staphylococcal species, it does not cover ''Salmonella'' species, which are highly likely in this case given the history of thalassemia and the culture results.
Right Answer	RightAnswer::A
Explanation	[[Explanation::Beta-thalassemia major is and inherited autosomal-recessive blood disorder characterized by reduced or absent synthesis of beta hemoglobin chains resulting in severe anemia requiring transfusions, splenomegaly, and bone deformities due to marrow expansion. Beta-thalassemia major, and other hemoglobinopathies such as sickle cell disease, predispose patients to osteomyelitis secondary to Salmonella species. Among these patients, Salmonella osteomyelitis is more commonly observed than in the general population; however, S. aureus remains the predominant cause of osteomyelitis. Several hypotheses have been proposed to explain the higher incidence of Salmonella osteomyelitis in hemoglobinopathies. Given the impairment in effective oxygen delivery in these disorders, some have suggested that patchy ischemic infarction of the bowels may occur allowing transient mucosal barrier breakdown and passage of the bacteria into the bloodstream. Empiric treatment of hematogenous osteomyelitis in patients with hemoglobinopathies includes coverage for Salmonella, E. coli, and S. aureus species. Regimens should include ciprofloxacin and either oxacillin/nafcillin/ceftriaxone or vancomycin/linezolid, depending on risk of MRSA. In patients with bone biopsy diagnosis of Salmonella osteomyelitis, treatment with ciprofloxacin is recommended if susceptibility is documented. Educational Objective: Empiric treatment of hematogenous osteomyelitis in patients with hemoglobinopathies includes coverage for Salmonella, E. coli, and S. aureus species. Regimens should include ciprofloxacin and either oxacillin/nafcillin/ceftriaxone or vancomycin/linezolid depending on risk of MRSA. References: Burnett MW, Bass JW, Cook BA. Etiology of osteomyelitis complicating sickle cell disease. Pediatrics. 1998;101(2):296-7.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Salmonella, WBRKeyword::Osteomyelitis, WBRKeyword::Antibiotics, WBRKeyword::Thalassemia, WBRKeyword::Sickle cell disease
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::