Diagnosis of Cat-Scratch Disease by Metagenomic Next-Generation Sequencing

Cat-scratch disease caused by <i>Bartonella henselae</i> is a worldwide distributed zoonotic disease. Cats are the major reservoirs of <i>B. henselae</i>, and human infection cases are usually resulted from contact with pet cats. In this study, a 49-year-old woman presented to the hospital after 10 days of fever. She also complaint lymph node enlargement and pain. Laboratory tests indicated liver dysfunction and inflammation. Pathological examination of the lymph node suggested the possibility of cat-scratch disease, and then doxycycline was used. Metagenomic next-generation sequencing showed that 59496 sequences of <i>B. henselae</i> were identified, confirming the diagnosis of cat-scratch disease. Meanwhile, <i>Acinetobacter towneri</i> and Epstein-Barr virus were also identified. Doxycycline therapy was continued, and the enlargement of lymph node was apparently alleviated. Epidemiological investigation showed that she had a pet cat, and she was possibly infected through direct contact with the cat. Cat-scratch disease in China may be an underestimated disease. Although multiple methods for detecting <i>B. henselae</i> have been established, low bacteremia is still a key challenge to molecular diagnosis. mNGS is a preferable choice for the diagnosis of cat-scratch disease due to its feasibility, sensitivity, and timeliness.