A case of Chryseobacterium taklimakanense bacteremia.

Chryseobacterium is an obligate aerobic, non-glucose-fermenting, Gram-negative bacillus belonging to the family Flavobacteriaceae. Chryseobacterium species have rarely been isolated from clinical samples. Chryseobacterium indologenes and Chryseobacterium gleum are the most frequently isolated species. Chryseobacterium taklimakanense was first reported in 2009. Reports of C. taklimakanense isolation from blood cultures are rare and no case reports exist, leaving no established susceptibility data. An 80-year-old man with multiple underlying conditions, including appendiceal cancer, chronic heart failure, and type 2 diabetes mellitus, visited our hospital with exertional dyspnea and orthopnea. Upon admission, the patient had low oxygen saturation, a fever, and diarrhea. Acute exacerbation of chronic heart failure was suspected to be due to bacteremia. Blood cultures revealed Gram-negative bacilli, which were identified as Chryseobacterium taklimakanense by an 16 S rRNA analysis. Whole-genome sequencing was performed later, but no resistance genes were detected. The patient was treated with piperacillin-tazobactam for two weeks, which led to symptom improvement. Since no other infection sources were identified, bacteremia was attributed to bacterial translocation from the gastrointestinal tract. The isolate in this case was susceptible to meropenem, levofloxacin, and piperacillin-tazobactam, but resistant to minocycline and sulfamethoxazole-trimethoprim. This susceptibility pattern was different from that commonly observed in C. indologenes and C. gleum. This case highlights the antimicrobial susceptibility profile and treatment approach for infections caused by the rare bacterium C. taklimakanense.