The fatal case of “Pigmentibacter” bacteremia following aspiration pneumonia in elderly patient

Abstract

"Pigmentibacter ruber" was first reported in 2021, a novel bacterium of the family Silvanigrellaceae, isolated from human blood of the patient with aspiration pneumonia after the drowning accident in Republic of China. However, until now, there is only one report describing "P. ruber" infection, and no case of isolation from natural environment has been reported so far. Thus, the infectivity and pathogenicity of "Pigmentibacter" spp. has not been clearly understood. In this report, we described the fatal case of "Pigmentibacter" bacteremia subsequently occurred after aspiration pneumonia probably due to accidental ingestion of irrigation water in the elderly patient. Despite administration of broad-spectrum antibiotic, the patient dramatically deteriorated and eventually deceased. Whole-genome sequencing showed the strain isolated from the patient was identified as "Pigmentibacter" sp. (designated as strain Takaoka) and antimicrobial sensitivity testing showed it displayed high minimum inhibitory concentrations against various antibiotics including β-lactam. Further studies are needed to clarify the clinical characteristics of "Pigmentibacter" and its relative's infections and their antimicrobial sensitivity; however, the present case supported the clinical characteristics of "Pigmentibacter" infection, which can lead to bacteremia following aspiration pneumonia caused by mis-swallowing contaminated water, and poor outcome potentially due to multidrug resistances.