A case of bacteremia caused by Roseomonas gilardii subsp. gilardii from blood culture

Abstract

Roseomonas is a pink-pigmented, nonfermentative, Gram-negative bacillus having clinical importance as an opportunistic pathogen that can lead to infection, especially in immunosuppressed individuals. Here, we report a case of bacteremia caused by R. gilardii subsp. gilardii from blood culture. An 82-year-old man was diagnosed as having pneumonia and was hospitalized. When the patient developed fever after ten days of hospitalization, blood was collected for two sets of bacterial culture. Gram-negative bacillus cells were observed in one of the sets, and pink mucoid colonies grew on sheep blood agar, chocolate agar, and modified Drigalski agar. The strain was identified using automated WalkAway40SI and IDtestNF-18. However, it could not be parsed. By sequencing analysis of the 16S rRNA gene, the bacillus was identified as R. gilardii subsp. gilardii. Sulfamethoxazole-trimethoprim was administered on the basis of the antimicrobial susceptibility results and the patient’s condition improved. In many laboratories, it is difficult to identify the species of the genus Roseomonas by routine microbial tests. Therefore, their clinical significance in immunocompromised hosts is not known. However, it is important to integrate the antimicrobial susceptibility and infection treatment data of Roseomonas infection.