LAUSR

Dear Editor, Cruoricaptor ignavus, belonging to the family Flavobacteriaceae, is a gram-negative, non-motile, non-spore-forming coccoidor coccobacilli-shaped bacterium first isolated from a human blood culture in 2012 and proposed as a novel genus and species [1]. With approval from Samsung Medical Center institutional review board (IRB; approval number: 2018-01-112), we report the second case worldwide of C. ignavus, isolated from the blood culture of a 16-year-old boy with Ewing sarcoma and identified by DNA target sequencing. The IRB waived the need for informed consent for this study. The patient underwent wide excision of sarcoma and additional chemotherapy. On day 13 of chemotherapy, he developed fever with abdominal pain and visited the emergency room. His temperature was 38.3°C, blood pressure was 116/59 mmHg, pulse rate was 67 beats per minute, and respiratory rate was 18 breaths per minute. The C-reactive protein concentration was 146.7 nmol/L, and leukocyte count was 0.21×10/L with neutropenia (0.07×10/L). Blood, urine, and stool cultures were performed, and cefepime was administered. Positive growth was observed in one of two sets of blood cultures after two days of incubation. Microscopic examination revealed gram-variable cocci or coccobacilli (Fig. 1), which grew as tiny, yellowish colonies on blood agar plates (Fig. 2). The microorganism could not be identified using the GP, GN, and NH cards of the VITEK 2 system (bioMérieux, Marcy l’Etoile, France) or by matrix-assisted laser desorption/ionization time-offlight mass spectrometry (MALDI-TOF MS) with the Bruker MALDI Biotyper system (Bruker Daltonics GmbH, Leipzig, Germany). The VITEK MS system identified the organism as Alloiococcus otitis (99.9% confidence), but Gram staining and colony morphology showed that this identification was not accurate. To identify the strain, we performed 16S ribosomal RNA (rRNA) target sequencing according to the CLSI guidelines [2]. Subregions of the 16S rRNA gene were amplified using the following primer pairs: forward, 4F: 5 ́-TTG GAG AGT TTG ATC CTG GCT C-3 ́ and reverse, 534R: 5 ́-TAC CGC GGC TGC TGG CAC-3 ́ and forward, 27F: 5 ́-AGA GTT TGA TCM TGG CTC AG3 ́ and reverse, 801R: 5 ́-GGC GTG GAC TTC CAG GGT ATC T-3 ́ [2]. The amplified sequence was compared with the GenBank (National Center for Biotechnology Information) database, using the basic local alignment search tool (BLAST) algorithm. The 16S rRNA sequence of the isolate exhibited 99.72% (722/724 bp) similarity to C. ignavus (GenBank accession number NR_108875.1, Strain IMMIB L-12475). The second highest match was Epilithonimonas xixisoli with 87.07% (653/750 bp) similarity. When the sequence (724 bp) was submitted to the EzTaxon database v2.1 (http://www.ezbiocloud.net), the best-