Abstract
To the Editor:
Infective endocarditis (IE) is a serious and life-threatening disease, with a yearly incidence of approximately three to 10 per 100,000. 1 Anti-infection is the cornerstone of the treatment of IE. It is important to obtain pathogens as early as possible. The frequently isolated micro-organisms associated with IE are Streptococcus, Staphylococcus, Colibacterium, Chlamydia, Corynebacterium, Brucella, Enterobacteriaceae, and fungi 2 ; Bartonella endocarditis (BE) is rare. Here, we report a case of blood culture-negative IE caused by Bartonella henselae. The pathogen was identified by metagenomics next-generation sequencing (mNGS).
A 23-year-old female presented to the hospital with fever for more than one month. She denied history of hypertension, diabetes mellitus, or any infectious disease. After her diagnosis was confirmed, we asked again about the epidemiologic history, she reported that she has a pet cat.
On physical examination, a systolic murmur was heard in the mitral valve area. Results of laboratory studies showed that white blood cell count was 19.91 × 109/L, neutrophil count was 18.68 × 109/L, neutrophil rate was 93.8%, and procalcitonin was 24.39 ng/mL. Liver and kidney function were normal. Echocardiography showed mitral valve neoplasm. The patient was treated with ceftriaxone but her condition did not improve. Multiple blood cultures were negative. The patient then underwent mitral valve neoplasm removal and mitral valve replacement. The neoplasm was sent for culture and mNGS detection; mNGS detected Bartonella henselae and no other pathogens were detected, the neoplasm culture was negative. The anti-infective regimen was changed to doxycycline combined with gentamicin, and the patient's fever was controlled.
Bartonella grows slowly, requires harsh nutritional conditions, and is difficult to isolate and culture, which makes the diagnosis of BE difficult. Bartonella endocarditis has no obvious clinical features, and many cases may have not been identified. For culture-negative IE patients, BE should be suspected if the individuals have epidemiologic history of possible exposure to Bartonella. Metagenomics next-generation sequencing may be an effective method for early acquisition of pathogenic bacteria of culture-negative IE, especially for some rare pathogens.