Lysinibacillus massiliensis is an aerobic, endospore-forming, gram-negative staining bacterium with peritrichous flagella belonging to the Bacillaceae family. A few cases of L. massiliensis isolated from the cerebrospinal fluid and tissue have been reported. In this study, we aimed to describe a case of L. massiliensis isolated from the synovial fluid. The synovial fluid from a 74-year-old female patient was inoculated into blood culture bottle. Gram-negative rods were observed in a gram-stained smear from a positive blood culture bottle. The bacterium was identified as Lysinibacillus sphaericus/Lysinibacillus fusiformis, with a probability of 89% using an automated bacterial identification system (VITEK2; Biomerieux, France). Subsequently, 16S rRNA gene sequencing was performed, and the sequence was analyzed using the Basic Local Alignment Search Tool. The sequence had 99.9% (1426/1427) identity with the strain L. massiliensis (GenBank ID: NR_043092.1). To our knowledge, this is the first reported case of L. massiliensis isolated from the synovial fluid. When an endospore-forming gram-negative staining bacterium can not be identified by phenotypic characterization, L. massiliensis should be considered, and different microbiological methods should be used for identification.
Floating fungus balls in a blood culture bottle
