Emergence of NDM-5-Producing Carbapenem-Resistant and SIM-Producing Hypervirulent Isolated from Aseptic Body Fluid in a Large Tertiary Hospital, 2017-2018: Genetic Traits of NDM-Like and SIM-Like Genes as Determined by NGS.

PURPOSE

To characterize the clinical, resistance, and virulence features of carbapenem-resistant (CRKP) and hypervirulent (hvKP) and also provide an effective selection of drug in CRKP and hvKP treatment.

MATERIALS AND METHODS

Twelve strains were collected and investigated these isolates for their antimicrobial susceptibility and molecular features. Resistance mechanisms, virulence-associated genes, multilocus sequence typing (MLST), and serotypes were detected by PCR and sequencing. Next general sequencing (NGS) was carried out to determine the features of carbapenem resistance and virulence. The synergistic activity of tigecycline-imipenem (TGC+IPM), tigecycline-meropenem (TGC+MEM), and tigecycline-aztreonam (TGC+ATM) combinations were performed by microdilution checkerboard method.

RESULTS

Eleven CRKP and one hvKP strains were collected. All strains showed highly sensitive rates to tigecycline (TGC) and amikacin (AMK). NDM (33.3%, 4/12) was the main resistance mechanism and MLST assigned 3 of them to ST11. CTX-M-producing (n = 1) and KPC-2-producing (n = 1) isolates belonged to ST147 and ST11, respectively. The MICs of ATM and quinolones in NDM-1 CRKP and NDM-5 CRKP strains were different. The serotype of the majority strains was KL22KL137 (58.3%, 7/12), hvKP stain belonged to K64. CRKP strains harbored plasmid-mediated quinolone resistance genes (oqxA, oqxB, qnrS, qnrB), β-lactams ( ), aminoglycosides, type I and type III fimbriae genes, siderophore genes, and transporter and pumps. SIM-producing ST1764 K64 showed typical features of hvKP, showing hypermucoviscosity phenotype. The virulence genes, including and aerobactin genes, linked to hvKP, were found in ST1764 hvKP. hvKP was sensitive to quinolone; also, gene was detected. All TGC combinations showed highly synergistic effects and TGC+IPM was more effective treatment.

CONCLUSION

We first identified the NDM-5-producing ST690 CRKP and SIM-producing ST1764 hvKP strains in Shanxi province. Tigecycline-carbapenem combinations were available treatments for CRKP.