Identification and characterisation of carbapenem-resistant sp. nov. isolated from blood culture.

Background: This study aimed to investigate a highly resistant strain of sp. isolated from a patient with bloodstream infection and determine its taxonomic classification.

Methods: The strain was isolated from blood culture from a 65-year-old male patient admitted to St. Olavs University hospital, Trondheim, Norway, in 2023. Antimicrobial susceptibility testing as well as phenotypic and biochemical characterization were performed. Whole genome sequencing was conducted and genomic comparison to type strains was carried out.

Results: The strain was initially identified as / but showed significant genetic differences, suggesting that it belonged to an undescribed species within the genus. Phenotypic and biochemical characterization identified the strain as a non-motile, facultative anaerobic bacterium with α-hemolysis. Antimicrobial susceptibility testing showed resistance to all beta-lactams tested. Genomic analyses confirmed the classification of the strain as a novel species, which was designated .

Conclusion: This study combines conventional phenotypic tests with whole genome sequencing for accurate taxonomic classification of a bacterial strain isolated from blood culture. The identification of a novel species within the genus contributes to the understanding of microbial diversity and antibiotic resistance of the genus in clinical settings.