OBJECTIVE To investigate the drug resistance genes, virulence genes and capsule serotypes of hypermucoviscous Klebsiella pneumoniae (HMKP) from a hospital, providing a reference for clinical anti-infective treatment.
METHODS A total of 46 non-repetitive HMKP strains, isolated and identified from clinical samples in the First People′s Hospital of Chuzhou from Jul. to Dec. 2023, were collected. Drug susceptibility testing was performed, and drug resistance genes, virulence genes and capsule serotypes were amplified by polymerase chain reaction (PCR). The PCR products were determined by genetic sequencing and comparison. Multilocus sequence typing (MLST) was used for molecular epidemiological typing, and eBURST was used to analyze strain homology.
RESULTS The 46 HMKP strains were mainly isolated from ICU (28.26%, 13 strains) and respiratory departments (23.91%, 11 strains). The primary specimen type was respiratory specimens (91.30%, 42 strains). The drug resistance rates of HMKP to the monitored antibacterial drugs were all < 10%. PCR results showed that only 1 strain carried the CTX-M1 drug resistance gene. The predominant capsule serotypes were K2 (16 strains, 34.78%), K1 (7 strains, 15.22%) and K57 (7 strains, 15.22%). The detection rates of the five virulence genes were as follows: aerobactin (46 strains, 100.00%), kfu (46 strains, 100.00%), rmpA (43 strains, 93.48%), iroNB (42 strains, 91.30%), rmpA2 (37 strains, 80.43%) and magA (31 strains, 67.39%). Among the 46 HMKP strains, 22 sequence types (STs) were identified, with ST86 (9 strains, 19.56%), ST25 (8 strains, 17.39%), ST23 (5 strains, 10.87%), ST412 (5 strains, 10.87%) and ST65 (2 strains, 4.35%) being the most prevalent. Homology analysis conducted by eBURST software revealed that 18 STs had relatively close genetic relationships.
CONCLUSIONS Only 1 strain of clinically isolated HMKP carries the CTX-M1 gene, with the predominant capsule serotypes being K2, K1 and K57. The detection rates of virulence genes aerobactin and kfu are 100.00%. The K2 serotype carries multiple virulence gene patterns, and the STs are mainly ST86, ST25, ST23 and ST412. There is a clear evolutionary relationship among HMKP strains.
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