culture-negative endocarditis and Bartonella

 Q: Describe a few associated risk factors in culture-negative endocarditis where Bartonella should be covered with antibiotics?

Answer:  Bartonella is considered a significant cause of culture-negative endocarditis. Interestingly more than two-third of cases involved are in men. Other risk factors are

• homelessness
• alcoholism
• infestation with body lice 
• contact with cats
• valvular heart disease 
• history of HIV

Clinical significance: Clinical suspicion to cover Bartonella is important in culture-negative endocarditis. It takes time for the blood culture for Bartonella to turn positive. Also, it requires a special stain and PCR to establish the diagnosis. Antibiotic coverage requires doxycycline, aminoglycoside, and +/- ceftriaxone. 

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References:

1. Spach DH, Callis KP, Paauw DS, et al. Endocarditis caused by Rochalimaea quintana in a patient infected with human immunodeficiency virus. J Clin Microbiol 1993; 31:692.

2. Raoult D, Fournier PE, Vandenesch F, et al. Outcome and treatment of Bartonella endocarditis. Arch Intern Med 2003; 163:226.

3. Ghidey FY, Igbinosa O, Mills K, et al. Case series of Bartonella quintana blood culture-negative endocarditis in Washington, DC. JMM Case Rep 2016; 3:e005049. 

4. Fournier PE, Lelievre H, Eykyn SJ, et al. Epidemiologic and clinical characteristics of Bartonella quintana and Bartonella henselae endocarditis: a study of 48 patients. Medicine (Baltimore) 2001; 80:245.