Taxonomic and phenotypic characterization of a novel Providencia species: Providencia lanzhouensis sp. nov.

The genus Providencia includes species of ecological and clinical significance, with several members acting as opportunistic pathogens in hospital-acquired infections, particularly urinary tract infections (UTIs). However, overlapping phenotypic traits and genetic similarities among species pose challenges for accurate identification. In this study, we isolated strain PAZ2 from a urine sample of a hospitalized patient in Lanzhou, Gansu Province, China. While initial mass spectrometry analysis identified the strain as Providencia alcalifaciens, comprehensive genomic analysis revealed distinct characteristics suggesting a novel species. Comparative genomic analyses showed average nucleotide identity (ANI) values ranging from 79.92% to 94.73% and digital DNA-DNA hybridization (dDDH) values between 21.2% and 57.6% when compared with known Providencia species. The strain exhibited resistance to multiple antibiotics, including ampicillin, tetracycline, tigecycline, polymyxin B, colistin, trimethoprim-sulfamethoxazole, and ciprofloxacin. Biochemical characterization revealed distinct properties that differentiated PAZ2 from previously described species within the genus. Based on genomic and phenotypic evidence, we propose strain PAZ2 as the type strain of a novel species, Providencia lanzhouensis sp. nov. Geographic distribution analysis indicated P. lanzhouensis presence in five countries, with predominance in China. Notably, comparative genomic analysis revealed that P. lanzhouensis PAZ2 harbors an expanded repertoire of antimicrobial resistance genes compared to other Providencia strains with high ANI values. This discovery expands our understanding of Providencia taxonomy and highlights its clinical significance. Further studies investigating its pathogenicity mechanisms, antimicrobial resistance profiles, and epidemiological patterns will be crucial for developing effective treatment strategies.IMPORTANCEAccurate identification of bacterial pathogens is crucial for effective clinical treatment, yet current diagnostic methods sometimes fall short when encountering novel species. This study describes Providencia lanzhouensis, a new bacterial species isolated from a clinical setting in China, which was initially misidentified by conventional methods. Our discovery not only expands the known diversity of the Providencia genus but also reveals important insights about antimicrobial resistance in emerging pathogens. P. lanzhouensis carries multiple resistance genes, highlighting potential clinical challenges and the need for accurate identification in healthcare settings. This work demonstrates the importance of integrating multiple analytical approaches for bacterial identification and underscores the dynamic nature of bacterial evolution. These findings have significant implications for improving pathogen identification systems and developing effective treatment strategies in clinical practice.