Flavobacterium ceti From Blood Samples of a Korean Patient With Alcoholic Liver Cirrhosis

Dear Editor Flavobacterium species are nonfastidious, oxidase-positive, glucose nonfermenting, gram-negative rods. Few Flavobacterium species have been extensively studied [1]. Flavobacterium ceti was first isolated from the lung and liver of two beaked whales, as described in 2007 by Vela et al. [2]. Flavobacterium species are mainly found in aquatic animals and are rarely isolated from human clinical specimens. We present a case in which F. ceti was identified in the blood of a patient admitted to Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea. A 43-yr-old man with alcoholic liver cirrhosis presented with mild fever and abdominal distension. Laboratory investigation revealed mild leukocytosis with neutrophilia (10.34×10/L; neutrophils, 83%) and hepatic dysfunction. Ascitic fluid showed leukocyte counts >1×10 cells/L (neutrophils, 62%), whereas the serum ascites albumin gradient was >1.1 g/dL, total protein was 0.8 g/dL, glucose was 107 mg/dL, and lactate dehydrogenase was 97 U/L. Blood culture was drawn from two separate sites on the day of admission, but ascites cultures were not performed. Intravenous antibiotics were administered from the day of admission: one day of cefotaxime followed by ceftriaxone for the next 20 days. Follow-up blood cultures on day 4, 11, and 14 were all negative. Ascitic cultures performed after 14 days of antibiotics revealed no organisms. Signs of inflammation were gradually resolved, and the patient was discharged 25 days after admission. After two days of incubation, bacterial growth was detected in aerobic culture bottles of two separate blood cultures. The next day, circular, orange-colored, non-hemolytic colonies were observed on the blood agar plates (Fig. 1A), and gram stain smear revealed gram-negative rods (Fig. 1B). No colonies were observed on MacConkey agar plates. Vitek2 GN system (bioMérieux, Marcy l’Etoile, France) identified the isolated organism as Brevundimonas diminuta/vesicularis with 95% probability. The contraindicating typical biopattern was phosphatase negative, enzyme activity that is almost always observed in Brevundimonas [3]. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS; BrukerDaltonik GmbH, Bremen, Germany) revealed the most matched pattern as Acinetobacter lwoffii, but showed no reliability with a score of 1.191 (Biotyper Version 3.1, Bremen, Germany). To confirm the identification, 16S rRNA sequence was analyzed by using polymerase chain reaction with 27F and 1492R primers and sequencing with 518F and 801R primers in order to span all bacteria [4]. Sequencing reactions were performed by using a DNA Engine Tetrad 2 Peltier Thermal Cycler (BioRad, Hercules, CA, USA)