Correlation between antimicrobial resistance and virulence in carbapenem-resistant Klebsiella pneumoniae at colonization and infection stages.

OBJECTIVE

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as a critical global public health. To investigate the dynamic changes of drug resistance genes and virulence traits in carbapenem-resistant Klebsiella pneumoniae during colonization-infection transitions, supporting clinical prevention strategies.

METHODS

A total of 18 cases each of CRKP colonization-to-infection and infection-to-colonization were enrolled from ICU patients. Genomic DNA from 72 isolates was used for PCR detection of resistance genes, virulence genes, and capsular serotype genes among the 72 isolates. KPC-positive isolates underwent Sanger sequencing for subtyping, and the string test was employed to assist in defining the hypervirulent phenotype.

RESULTS

No significant differences were observed in clinical features between groups. All isolates carried blaKPC-2 without other resistance genes. The colonization-to-infection group showed higher virulence gene detection rates (50.00% vs. 27.78%), with 4 cases exhibiting increased virulence genes during infection. Conversely, 2 cases in the infection-to-colonization group showed reduced virulence genes. Capsular serotyping identified three isolates (4.17%) carrying hypervirulence-associated serotypes: a K1 strain from a blood sample (Case 8) showing virulence gene increase during infection, and two K57 strains (Case 34) lacking virulence genes. 11 hypervirulent CRKP (15.28%) were identified, with 9 from the colonization-to-infection group.

CONCLUSION

CRKP maintains stable resistance genes during colonization-infection transitions, but dynamic virulence changes indicate higher infection risks when colonization converts to infection. Enhanced monitoring of virulence and resistance is critical to control hv-CRKP spread in ICUs.