Bartonella henselae Endocarditis: An Usual Presentation of an Unusual Disease

Bartonella species are an emerging cause of culture-negative endocarditis with more cases being diagnosed now than 25 years ago when Bartonella quintana endocarditis was first described in a patient infected with human immunodeficiency virus (HIV). Despite the disease being increasingly reported, the exact epidemiological features are not clear, with prevalence rates ranging between 2% and 10% of all cases of culture-negative endocarditis. Moreover, the mortality rate is still high, presumably because of the subacute nature and relative rareness of the disease. Bartonella endocarditis occurs more often in men, and previous valvular surgery is a major risk factor. There is insufficient data to guide definitive treatment due to the paucity of literature. A previous study demonstrated that effective antibiotic therapy for Bartonella endocarditis should include an aminoglycoside prescribed for a minimum of 2 weeks. However, the treatment strategy is a matter of expert opinion.

Bartonella endocarditis is considered one of the most common causes of culture-negative endocarditis, yet tardy diagnosis of the disease is usually made, thus carrying a high mortality rate.Awareness of the unusual presentation of Bartonella endocarditis could potentially decrease complications and mortality rates.Contact with animals, and cats in particular, is a prominent risk factor for Bartonella henselae infection. Physicians should therefore routinely enquire about such exposure when endocarditis and especially culture-negative endocarditis is suspected.Empirical therapy should be started when culture-negative endocarditis is suspected and even when Duke criteria are not met; watchful waiting for final serological tests might be harmful, as recommended by some international authors.Most organisms causing culture-negative endocarditis are not covered in the initial treatment of infective endocarditis before or without pathogen identification recommended by the European Society of Cardiology.