OBJECTIVE To explore the change of adaptive cost of Klebsiella pneumoniae in subinhibitory concentration of Epigallocatechin gallate (EGCG) for subculture of 14 days so as to provide experimental support for clinical transformation of EGCG.

METHODS The drug resistance genes in the K. pneumoniae strains were analyzed by whole genome sequencing technology. The change of biofilm formation ability was detected by crystal violet staining, the transcriptional levels of quorum sensing gene luxS and its regulatory genes(lsrK and lsrR) as well as virulence genes(aerobactin and rmpA) were detected by means of fluorescent quantitative polymerase chain reaction (PCR). The pathogenicity of the K. pneumoniae was tested through survival assay of greater wax moth.

RESULTS The whole genome sequencing showed that 1 strain of non-mucous CRKP and 2 strains of mucous CRKP were ST11, all of which carried bla_KPC-2 gene. There was no change in the growth curve of subculture after treatment with subinhibitory concentration of EGCG; the biofilm forming ability was reduced. The expression level of luxS gene was higher in the non-treatment group. The transcriptional level of ionophore aerobactin was inhibited with the increase of subculture days and subinhibitory concentration; the transcription ability of the virulence gene mucous phenotype regulatory gene rmpA was inhibited as well. The survival rate of greater wax moth increased, and there was significant difference (P < 0.05).

CONCLUSIONS The growth rate of K. pneumoniae strains dose not change after the treatment with the subinhibitory concentration of EGCG. The biofilm formation and the transcriptional levels of virulence genes and quorum sensing genes as well as the pathogenicity are inhibited, which may provide experimental bases for clinical application of EGCG.