The Characteristic of Biofilm Formation in ESBL-Producing K. pneumoniae Isolates

Abstract

Klebsiella pneumoniae is a pathogen that commonly causes hospital-acquired infections. Bacterial bioflms are structured bacterial communities that adhere to the surface of objects or biological tissues. In this study, we investigated the genome homology and bioflm formation capacity of ESBL-producing K. pneumoniae. Tirty ESBL-producing K. pneumoniae isolates from 25 inpatients at Ruijin Hospital, Shanghai, were subjected to pulsed-feld gel electrophoresis (PFGE) to estimate genomic relatedness. Based on the chromosomal DNA patterns we obtained, we identifed 21 PFGE profles from the 30 isolates, eight of which had high homology indicating that they may have genetic relationships and/or potential clonal advantages within the hospital. Approximately 84% (21/25) of the clinical patients had a history of surgery, urinary tract catheterization, and/or arteriovenous intubation, all of which may have increased the risk for nosocomial infections. Bioflms were observed in 73% (22/30) of the isolates and that strains did not express type 3 fmbriae did not have bioflm formation capacity. Above fndings indicated that a high percentage of ESBL-producing K. pneumoniae isolates formed bioflms in vitro and even though two strains with cut-of of PFGE reached 100% similarity, they generated bioflms differently. Besides, the variability in bioflm formation ability may be correlated with the expression of type 3 fmbriae. Tus, we next screened four ESBL-producing K. pneumoniae isolates (Kpn5, Kpn7, Kpn11, and Kpn16) with high homology and signifcant diferences in bioflm formation using PFGE molecular typing, colony morphology, and crystal violet tests. Kpn7 and Kpn16 had stronger bioflm formation abilities compared with Kpn5 and Kpn11. Te ability of above four ESBL-producing K. pneumoniae isolates to agglutinate in a mannose-resistant manner or in a mannose-sensitive manner, as well as RNA sequencing-based transcriptome results, showed that type 3 fmbriae play a signifcant role in bioflm formation. In contrast, type 1 fmbriae were downregulated during bioflm formation. Further research is needed to fully understand the regulatory mechanisms which underlie these processes.