A case of Streptobacillus moniliformis bacteremia in which information provided by the biomedical laboratory scientist led to rapid identification

Abstract

Here, we report a case of bacteremia caused by Streptobacillus moniliformis, in which information provided by the biomedical laboratory scientist led to the rapid identification and selection of appropriate antimicrobial agents. A 50-year-old man with diabetes was admitted to our hospital with the chief complaint of arthritis. Owing to the elevated levels of inflammatory markers, he was hospitalized and underwent a thorough examination. Culture of blood and articular fluid on admission revealed a filamentous gram-negative bacillus and small colonies measuring 1–2 mm on blood/chocolate agar. Gram staining of colonies showed pleomorphic gram-negative bacillus with chaining and clumping. The information provided by the biomedical laboratory scientist led to the finding that the patient had a history of contact with mice. This information also led to the early identification of the bacterium as S. moniliformis. Identification and susceptibility testing are important because incomplete treatment of infection with this organism has been reported to lead to relapse. However, mass spectrometry and genetic analysis are necessary to definitively identify the species. Although S. moniliformis is considered a causative agent of rat-bite fever, the entry route is unknown in many cases without a history of rat bites. This case highlighted the importance of the biomedical laboratory scientist and questioning patients about animal contact history in the treatment of infectious diseases.