Drug Resistance and Molecular Characteristics of Carbapenem-Resistant OXA-48-Producing Klebsiella pneumoniae Strains in Hainan, China.

BACKGROUND: The emergence and global spread of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) are of great concern to health services worldwide. These β-lactamases hydrolyze almost all β-lactams, are plasmid-encoded, and are easily transferable among bacterial species. They are mostly of the KPC types in CR-hvKp. OXA-48-producing hvKP strains have been rarely reported in the literature.

METHODS: OXA-48-producing hvKP strains were collected from clinical specimens at the First Affiliated Hospital of Hainan Medical University from January 2022 to March 2023. Hypervirulent strains were tested for virulence in a mouse lethality study and underwent whole genome sequencing to identify genomic features.

RESULTS: A total of 42 unique OXA-48-bearing K. pneumoniae strains were identified, including three CR-hvKP strains (KP2683-1, NCRE61, and KP2185), which were isolated from bacteremia, pulmonary abscess, and liver abscess separately. The three CR-hvKP strains belonged to two different clones of ST11 KL64 (KP2185 and NCRE61) and ST23 K1 (KP2683-1). The KP2683-1 strain had the highest virulence. Whole genome sequencing analysis indicated that NCRE61 and KP2185 acquired IncFIB-type plasmids with a set of virulence genes ( iroBCDN , iucABCD , iutA , rmpA , and rmpA2 ), while KP2683-1 acquired an IncL-type bla OXA-48 -harboring plasmid. Consecutive cultures showed that the bla OXA-48 -harboring plasmids were highly stable in the three hvKP strains and could be transmitted to Escherichia coli J53 by conjugation. The drug susceptibility testing results show that Ceftazidime/avibactam is sensitive for OXA-48-producing hvKP.

CONCLUSIONS: Our study highlighted the two evolutionary pathways of OXA-48-producing hvKP strains and confirmed their virulence through in vivo testing. Ceftazidime/avibactam may be a viable option for treating OXA-48-producing hvKP strains.