A 28-year-old woman comes to the emergency department with fever, chills, and generalized weakness for the past week. Her only other medical problem was a hospital admission for right arm cellulitis 6 months ago. Temperature is 40.0° C (104° F), blood pressure is 110/65 mm Hg, pulse is 110/min, and respirations are 18/min. Examination shows a normal oropharynx, and lungs are clear to auscultation. A holosystolic murmur is heard at the lower sternum which increases in intensity with inspiration. Examination of the right arm is shown in the image below. Blood is drawn and sent for culture. Which of the following is the most appropriate initial antibiotic therapy for this patient?

Question

A 28-year-old woman comes to the emergency department with fever, chills, and generalized weakness for the past week.  Her only other medical problem was a hospital admission for right arm cellulitis 6 months ago.  Temperature is 40.0° C (104° F), blood pressure is 110/65 mm Hg, pulse is 110/min, and respirations are 18/min.  Examination shows a normal oropharynx, and lungs are clear to auscultation.  A holosystolic murmur is heard at the lower sternum which increases in intensity with inspiration.  Examination of the right arm is shown in the image below.  Blood is drawn and sent for culture.  Which of the following is the most appropriate initial antibiotic therapy for this patient?

Quizplus · Accepted Answer

11ec25c8_d44c_2702_bc81_5dad7e83593a_MD0003_00 This patient's holosystolic murmur at the lower sternum, which increases in intensity with inspiration, is likely due to tricuspid regurgitation. In addition, arm cellulitis in a young adult with track marks also suggests intravenous drug use (IVDU). The combination of fever, generalized weakness, tricuspid regurgitation, and IVDU indicates likely right-sided infective endocarditis (IE). Staphylococcus aureus is the responsible pathogen for more than half of IE cases in IVDU. tricuspid regurgitation Empiric antibiotic treatment should be based on the conditions of the valves (prosthetic versus native) and prior history of IVDU. Empiric therapy in a native valve should cover methicillin-susceptible and -resistant staphylococci, streptococci, and enterococci. Vancomycin therefore is the most appropriate antibiotic for empiric therapy in these patients due to its broad spectrum of activity. Once the organism is identified in blood cultures, antibiotics can be changed to cover the appropriate organism. (Choice A) Ampicillin-sulbactam is generally not recommended for empiric therapy in patients with suspected or diagnosed IE. However, it is recommended for penicillin-resistant enterococcus and HACEK organisms once culture sensitivity results are available. (Choice B) Clindamycin is occasionally used for the treatment of cellulitis due to methicillin-resistant S aureus (MRSA) infection and also for prophylaxis against IE in high-risk patients undergoing invasive dental procedures. Vancomycin is a better initial choice for S aureus endocarditis as clindamycin has been associated with IE relapse. (Choice C) Oxacillin is not routinely used for treating native-valve IE due to MRSA infection. In the absence of culture sensitivity results, vancomycin is the most appropriate agent to cover the possibility of MRSA endocarditis. (Choice D) Aqueous penicillin G is the drug of choice in patients with native-valve IE due to penicillin-susceptible Viridans streptococci. Penicillin G has essentially no staphylococcal coverage. Aminoglycosides (gentamicin) are also not indicated for empiric therapy for suspected native-valve IE but can be used for specific organisms once culture results are available. Educational objective: Right-sided endocarditis should be considered in patients with presumed history of intravenous drug use. Empiric antibiotic treatment of native-valve endocarditis should be geared toward methicillin-resistant Staphylococcus aureus, streptococci, and enterococci. Vancomycin is the most appropriate empiric antibiotic for these patients. References: Staphylococcal endocarditis. Laboratory and clinical basis for antibiotic therapy. (http://www.ncbi.nlm.nih.gov/pubmed/3893113) Infectious endocarditis: diagnosis and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/22612050)

A 28-Year-Old Woman Comes to the Emergency Department with Fever