Identification of a novel Providencia species showing multi-drug-resistant in three patients with hospital-acquired infection.

Providencia species are important opportunistic pathogens for humans and are associated with several infectious diseases. In this study, we found three clinical strains belonging to a novel Providencia species, namely Providencia huashanensis, including strains CRE-3FA-0001, CRE-138-0026, and CRE-138-0111. These strains were recovered from three patients, and all of them were associated with nosocomial infections, including incision infection, urinary tract infection, and intracranial infection. The three strains showed high-level resistance to many types of antimicrobials, including amikacin, aztreonam, ceftazidime, cefepime, ciprofloxacin, colistin, polymyxin B, imipenem, meropenem, ceftazidime-avibactam, imipenem-relebactam. Investigation of the resistance mechanism revealed that acquired resistance genes such as bla, bla, bla, bla, aac, ant, and qnrD, played an important role in the multi-drug-resistant phenotype for the three strains. The phylogenetic trees were reconstructed based on the 16S rRNA gene sequences, multi-locus sequence analysis, and core single nucleotide polymorphisms. The genome sequence of the strains had a range of 83.5%-85.8% average nucleotide identity and 21%-25.5% in silico DNA-DNA hybridization scores with other Providencia type strains. The average nucleotide identity and in silico DNA-DNA hybridization values and the phylogenetic trees indicated that the strains CRE-3FA-0001, CRE-138-0026, and CRE-138-0111 strains should be considered as a novel species of the genus Providencia, for which the name P. huashanensis sp. nov. is proposed. The type strain is CRE-3FA-0001 = China Center for Type Culture Collection AB 2023186 = Korean Collection for Type Cultures 8373.