Abstract: Objective　To investigate the methods for identifying Actinotignum schaalii and to analyze its biological characteristics in order to provide a basis for the diagnosis of urinary tract infections. Methods　The urine sample of a patient with urinary tract infection hospitalized in the First Teaching Hospital of Tianjin University of Traditional Chinese Medicine in January of 2020 was collected. Bacterial culture and Gram staining were used to observe the morphological characteristics. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA sequencing were used for the identification. The obtained sequences were compared with those in GenBank database for phylogenetic analysis. Results　The case was the first reported in China for a urinary tract infection caused by Actinotignum schaalii. MALDI-TOF MS and 16S rRNA sequencing identified the strain as Actinotignum schaalii, belonging to the genera Actinotignum, which was facultative anaerobic and Gram-positive bacterium. It was considered as a new type of pathogenic bacteria causing urinary tract infection. Conclusion　Actinotignum schaalii may be a new pathogen that causes urinary tract infection. 

Key words: Actinomyces, urinary tract infections, spectrometry, mass, matrix-assisted laser desorption-ionizationi, RNA, ribosomal,16S, sequence analysis, RNA, Actinotignum schaalii