Case report of Enterococcus thailandicus bacteremia, with genomic characterization of its clinical isolate

Enterococcus thailandicus was initially isolated from food in Thailand, and a single clinical case involving an intra-abdominal abscess was reported. No reports on the bacteremia or whole-genome sequencing of clinically isolated E. thailandicus have been published.

A 50-year-old woman with intestinal Crohn's disease was admitted because of bloody stools. She had been treated twice previously for a perianal abscess. She developed a fever on day 15 of hospitalization. Both blood and urine cultures were polymicrobial and included E. thailandicus, which was susceptible to penicillins. She was treated for the perianal abscess and pyelonephritis with intravenous penicillins combined with beta-lactamase inhibitors for 2 weeks, followed by oral amoxicillin-clavulanic acid for 4 weeks. The identities of the isolates in the blood and urine cultures were confirmed using whole-genome analysis. No antimicrobial resistance genes, virulence genes, or plasmid replicons were identified in these isolates. Phylogenetic analysis of the clinical isolates and 21 E. thailandicus isolates in public databases indicated a relatively close lineage to that obtained from pig stool samples in Japan. No antimicrobial resistance genes conferring resistance to penicillins were identified in any of the E. thailandicus genomes.

Phylogenetic analysis suggested that infection with E. thailandicus in this patient may have originated in Japan. The prognosis after treatment with penicillins was favorable.