The objective of this study was to characterize the virulence characteristics of a collection of Klebsiella pneumoniae isolates collected from different clinical sources. A collection of 60 non-repetitive K. pneumoniae isolates, was studied. In vitro, virulence was analyzed by testing the survival of bacteria in pooled human serum. Isolates were typed by MLST. The genomes of 23 K. pneumoniae isolates, representatives of different STs and virulence profiles, were completely sequenced using the Illumina platform. Of note, 26/60 of K. pneumoniae isolates were resistant to killing by complement. Serum-resistant isolates belonged to distinct STs. Analysis of WGS data with VFDB showed the presence of several virulence genes related various virulence functions. Specifically, serum-resistant isolates carried a higher number of ORFs, which were associated with serum resistance, compared to serum-sensitive isolates. Additionally, analysis of WGS data showed the presence of multiple plasmid replicons that could be involved with the spread and acquisition of resistance and virulence genes. In conclusion, analysis of virulence characteristics showed that an important percentage (31.6%) of K. pneumoniae isolates were in vitro virulent by exhibiting resistance to serum. Thus, the presence of several virulence factors, in combination with the presence of multidrug resistance, could challenge antimicrobial therapy of infections caused by such bacteria.

• Keywords
• Klebsiella pneumoniae, Biofilm formation, Carbapenemases, Multidrug resistance, Serum resistant, Virulence,
• MeSH
• Virulence Factors * genetics   MeSH
• Genome, Bacterial MeSH
• Klebsiella Infections * microbiology   genetics   MeSH
• Klebsiella pneumoniae * genetics   pathogenicity   isolation & purification   MeSH
• Humans MeSH
• Multilocus Sequence Typing MeSH
• Hospitals MeSH
• Plasmids genetics   MeSH
• Whole Genome Sequencing MeSH
• Virulence genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Greece MeSH
• Names of Substances
• Virulence Factors * MeSH

The aim of the present study is to describe the ongoing spread of the KPC-producing strains, which is evolving to an epidemic in Czech hospitals. During the period of 2018-2019, a total of 108 KPC-producing Enterobacterales were recovered from 20 hospitals. Analysis of long-read sequencing data revealed the presence of several types of blaKPC-carrying plasmids; 19 out of 25 blaKPC-carrying plasmids could be assigned to R (n = 12), N (n = 5), C (n = 1) and P6 (n = 1) incompatibility (Inc) groups. Five of the remaining blaKPC-carrying plasmids were multireplicon, while one plasmid couldn't be typed. Additionally, phylogenetic analysis confirmed the spread of blaKPC-carrying plasmids among different clones of diverse Enterobacterales species. Our findings demonstrated that the increased prevalence of KPC-producing isolates was due to plasmids spreading among different species. In some districts, the local dissemination of IncR and IncN plasmids was observed. Additionally, the ongoing evolution of blaKPC-carrying plasmids, through genetic rearrangements, favours the preservation and further dissemination of these mobile genetic elements. Therefore, the situation should be monitored, and immediate infection control should be implemented in hospitals reporting KPC-producing strains.

• MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Drug Resistance, Bacterial * MeSH
• Bacterial Proteins genetics   metabolism   MeSH
• beta-Lactamases metabolism   MeSH
• Epidemics MeSH
• Klebsiella Infections epidemiology   microbiology   MeSH
• Klebsiella pneumoniae isolation & purification   metabolism   MeSH
• Humans MeSH
• Hospitals statistics & numerical data   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Bacterial Proteins MeSH
• beta-Lactamases MeSH
• carbapenemase MeSH Browser

Ten Enterobacteriaceae isolates collected in a Czech hospital carried blaKPC-positive plasmids of different sizes (∼30, ∼45, and ∼80 kb). Sequencing revealed three types of plasmids (A to C) with the Tn4401a transposon. Type A plasmids comprised an IncR backbone and a KPC-2-encoding multidrug resistance (MDR) region. Type B plasmids were derivatives of type A plasmids carrying an IncN3-like segment, while type C plasmids were IncP6 plasmids sharing the same KPC-2-encoding MDR region with type A and B plasmids.

• Keywords
• Citrobacter freundii, Illumina sequencing, IncR, ST18, Tn4401a,
• MeSH
• Anti-Bacterial Agents therapeutic use   MeSH
• beta-Lactamases genetics   metabolism   MeSH
• Citrobacter freundii drug effects   enzymology   genetics   isolation & purification   MeSH
• Enterobacteriaceae Infections drug therapy   epidemiology   microbiology   MeSH
• Escherichia coli drug effects   enzymology   genetics   isolation & purification   MeSH
• Gene Expression MeSH
• Isoenzymes genetics   metabolism   MeSH
• Carbapenems therapeutic use   MeSH
• Klebsiella pneumoniae drug effects   enzymology   genetics   isolation & purification   MeSH
• Humans MeSH
• Microbial Sensitivity Tests MeSH
• Drug Resistance, Multiple, Bacterial genetics   MeSH
• Morganella morganii drug effects   enzymology   genetics   isolation & purification   MeSH
• Hospitals MeSH
• Open Reading Frames MeSH
• Plasmids chemistry   classification   metabolism   MeSH
• Base Sequence MeSH
• Sequence Analysis, DNA MeSH
• DNA Transposable Elements MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• beta-lactamase KPC-2 MeSH Browser
• beta-Lactamases MeSH
• Isoenzymes MeSH
• Carbapenems MeSH
• DNA Transposable Elements MeSH