Dataset Information

Diversity of virulence level phenotype of hypervirulent Klebsiella pneumoniae from different sequence type lineage.

ABSTRACT:

Background

Hypervirulent Klebsiella pneumoniae (hvKP) is emerging around the Asian-Pacific region and it is the major cause of the community-acquired pyogenic liver abscesses. Multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-hvKP) isolates were reported in France, China and Taiwan. However, the international-ally agreed definition for hvKP and the virulence level of hvKP are not clear.

Results

In this study, 56 hvKP isolates were collected from March 2008 to June 2012 and investigated by string test, capsule serotyping, multilocus sequence typing (MLST), virulence gene detection and serum resistance assay. Among the 56 K. pneumoniae isolates, 64.3% had the hypermucoviscosity phenotype, meanwhile, 64.3% were the K1 serotype and 19.6% were the K2 serotype. Within the K1 serotype, 94.4% were ST23, and within the K2 serotype, ST65, ST86 and ST375 accounted for the same percentage 27.3%. The serum resistance showed statistically normal distribution. According to the 50% lethal dose of Galleria. mellonella infection model, hvKP isolates were divided into high virulence level group and moderate virulence level group. The ability of each method evaluating the virulence level of hvKP was assessed using the area under the receiver operating characteristic curve.

Conclusions

K1 ST23 K. pneumoniae was the most prevalent clone of the hvKP. However, K1 ST23 K. pneumoniae was the dominant clone in the moderate virulence level group. MLST was a relatively reliable evaluation method to discriminate the virulence level of hvKP in our study.

SUBMITTER: Shi Q

PROVIDER: S-EPMC6116568 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Publications

Diversity of virulence level phenotype of hypervirulent Klebsiella pneumoniae from different sequence type lineage.

Shi Qiucheng Q Lan Peng P Huang Danyan D Hua Xiaoting X Jiang Yan Y Zhou Jiancang J Yu Yunsong Y

BMC microbiology 20180829 1

<h4>Background</h4>Hypervirulent Klebsiella pneumoniae (hvKP) is emerging around the Asian-Pacific region and it is the major cause of the community-acquired pyogenic liver abscesses. Multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-hvKP) isolates were reported in France, China and Taiwan. However, the international-ally agreed definition for hvKP and the virulence level of hvKP are not clear.<h4>Results</h4>In this study, 56 hvKP isolates were collected from March 2008 to June 2012 ...[more]

PMID: 30157774

Similar Datasets

Project description:BackgroundKlebsiella pneumoniae, as a global priority pathogen, is well known for its capability of acquiring mobile genetic elements that carry resistance and/or virulence genes. Its virulence plasmid, previously deemed nonconjugative and restricted within hypervirulent K. pneumoniae (hvKP), has disseminated into classic K. pneumoniae (cKP), particularly carbapenem-resistant K. pneumoniae (CRKP), which poses alarming challenges to public health. However, the mechanism underlying its transfer from hvKP to CRKP is unclear.MethodsA total of 28 sequence type (ST) 11 bloodstream infection-causing CRKP strains were collected from Ruijin Hospital in Shanghai, China, and used as recipients in conjugation assays. Transconjugants obtained from conjugation assays were confirmed by XbaI and S1 nuclease pulsed-field gel electrophoresis, PCR detection and/or whole-genome sequencing. The plasmid stability of the transconjugants was evaluated by serial culture. Genetically modified strains and constructed mimic virulence plasmids were employed to investigate the mechanisms underlying mobilization. The level of extracellular polysaccharides was measured by mucoviscosity assays and uronic acid quantification. An in silico analysis of 2608 plasmids derived from 814 completely sequenced K. pneumoniae strains available in GenBank was performed to investigate the distribution of putative helper plasmids and mobilizable virulence plasmids.ResultsA nonconjugative virulence plasmid was mobilized by the conjugative plasmid belonging to incompatibility group F (IncF) from the hvKP strain into ST11 CRKP strains under low extracellular polysaccharide-producing conditions or by employing intermediate E. coli strains. The virulence plasmid was mobilized via four modes: transfer alone, cotransfer with the conjugative IncF plasmid, hybrid plasmid formation due to two rounds of single-strand exchanges at specific 28-bp fusion sites or homologous recombination. According to the in silico analysis, 31.8% (242) of the putative helper plasmids and 98.8% (84/85) of the virulence plasmids carry the 28-bp fusion site. All virulence plasmids carry the origin of the transfer site.ConclusionsThe nonconjugative virulence plasmid in ST11 CRKP strains is putatively mobilized from hvKP or E. coli intermediates with the help of conjugative IncF plasmids. Our findings emphasize the importance of raising public awareness of the rapid dissemination of virulence plasmids and the consistent emergence of hypervirulent carbapenem-resistant K. pneumoniae (hv-CRKP) strains.

Project description:The emergence of nosocomial infections caused by hypervirulent and carbapenem-resistant K. pneumoniae (hv-CRKP) has become a significant public health challenge. The genetic traits of virulence and resistance plasmids in hv-CRKP have been extensively studied; however, research on the adaptive evolution strategies of clinical strains inside the host was scarce. This study aimed to understand the effects of antibiotic treatment on the phenotype and genotype characteristics of hv-CRKP. We investigated the evolution of hv-CRKP strains isolated from the same patient to elucidate the transition between hospital invasion and colonization. A comparative genomics analysis was performed to identify single nucleotide polymorphisms in the rmpA promoter. Subsequent validation through RNA-seq and gene deletion confirmed that distinct rmpA promoter sequences exert control over the mucoid phenotype. Additionally, biofilm experiments, cell adhesion assays, and animal infection models were conducted to illuminate the influence of rmpA promoter diversity on virulence changes. We demonstrated that the P12T and P11T promoters of rmpA possess strong activity, which leads to the evolution of CRKP into infectious and virulent strains. Meanwhile, the specific sequence of polyT motifs in the rmpA promoter led to a decrease in the lethality of hv-CRKP and enhanced cell adhesion and colonization. To summarize, the rmpA promoter of hv-CRKP is utilized to control capsule production, thereby modifying pathogenicity to better suit the host's ecological environment.IMPORTANCEThe prevalence of hospital-acquired illness caused by hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) is significant, leading to prolonged antibiotic treatment. However, there are few reports on the phenotypic changes of hv-CRKP in patients undergoing antibiotic treatment. We performed a comprehensive examination of the genetic evolutionary traits of hv-CRKP obtained from the same patient and observed variations in the promoter sequences of the virulence factor rmpA. The strong activity of the promoter sequences P11T and P12T enhances the consistent production of capsule polysaccharides, resulting in an invasive strain. Conversely, weak promoter activity of P9T and P10T is advantageous for exposing pili, hence improving bacterial cell attachment ability and facilitating bacterial colonization. This finding also explains the confusion of some clinical strains carrying wild-type rmpA but exhibiting a low mucoid phenotype. This adaptive alteration facilitates the dissemination of K. pneumoniae within the hospital setting.

Dataset Information

Diversity of virulence level phenotype of hypervirulent Klebsiella pneumoniae from different sequence type lineage.

Background

Results

Conclusions

Publications

Diversity of virulence level phenotype of hypervirulent Klebsiella pneumoniae from different sequence type lineage.

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