Characterization of Integrative and Conjugative Element ICEKp1-Associated Genomic Heterogeneity in aKlebsiella pneumoniaeStrain Isolated from a Primary Liver Abscess

Abstract

Genomic heterogeneity has been shown to be associated with Klebsiella pneumoniae strains causing pyogenic liver abscesses (PLA) and metastatic infections. In order to explore the mechanism responsible for genomic heterogeneity in K. pneumoniae, we compared the complete genomic sequences of strains NTUH-K2044 and MGH78578. An ϳ76-kbp DNA fragment located adjacent to an asparagine (asn) tRNA gene was present in NTUH-K2044 but not in MGH78578. This fragment could be divided into three regions with different functions, and structurally it resembled a functional integrative and conjugative element (ICE), ICEEc1, in Escherichia coli. The 5 region of this fragment contained genes similar to a high-pathogenicity island (HPI) of Yersinia pestis and Yersinia pseudotuberculosis. The middle region was similar to part of a large plasmid in K. pneumoniae, and the 3 region contained genes responsible for DNA conjugative transfer. Therefore, this DNA fragment was designated ICEKp1. Precise excision and extrachromosomal circularization of ICEKp1 were detected in K. pneumoniae wild-type strain NTUH-K2044. ICEKp1 could integrate into the asn tRNA loci of the chromosome of another K. pneumoniae isolate. The prevalence of ICEKp1 was higher in PLA strains (38 of 42 strains) than in non-tissue-invasive strains (5 of 32 strains). Therefore, ICEKp1 may contribute to the transmission of the HPI and result in K. pneumoniae PLA infection-associated genomic heterogeneity.

Identification of resistance and virulence factors in an epidemic Enterobacter hormaechei outbreak strain

“…Indisputable evidence that HPI increased the virulence of the EHOS is lacking. However, in all Enterobacteriaceae tested, virulence was significantly increased by the HPI (Bearden et al, 1997;Carniel et al, 1992;de Almeida et al, 1993;Lin et al, 2008;Schubert et al, 2002). Other genes associated with the EHOS were those previously described on the pLVPK virulence plasmid of K. pneumoniae CG43 (Chen et al, 2004).…”

“…The HPI was first described in Yersinia spp., but has also been described in other Enterobacteriaceae (Bach et al, 2000;Koczura & Kaznowski, 2003;Mokracka et al, 2004;Petermann et al, 2008;Schubert et al, 1998Schubert et al, , 2000Schubert et al, , 2002. Yersinia spp., Escherichia coli, and possibly K. pneumoniae isolates containing the HPI are more virulent than isolates lacking this island (Bearden et al, 1997;Carniel et al, 1992;de Almeida et al, 1993;Lin et al, 2008;Schubert et al, 2002). The HPI was recently shown to be transferable by conjugation with HPI-ICEKp1 (Lin et al, 2008).…”

“…Yersinia spp., Escherichia coli, and possibly K. pneumoniae isolates containing the HPI are more virulent than isolates lacking this island (Bearden et al, 1997;Carniel et al, 1992;de Almeida et al, 1993;Lin et al, 2008;Schubert et al, 2002). The HPI was recently shown to be transferable by conjugation with HPI-ICEKp1 (Lin et al, 2008). This appears to be the first time that the HPI has been described in association with an outbreak of nosocomial pathogenic Enterobacteriaceae.…”

“…Thirty-two of the 100 DNA fragments were directly linked to transferable elements. Seven DNA fragments (size from 967 to 1511 bp) without any sequence overlap contained sequences present in the high pathogenicity island (HPI), which is a 35-76 kb large genomic island and a known virulence factor in Enterobacteriaceae (Bearden et al, 1997;Carniel et al, 1992;de Almeida et al, 1993;Lin et al, 2008;Schubert et al, 2002). Five of these seven DNA fragments belonged to the 25 DNA fragments most highly associated with the EHOS.…”

Enterotoxicity of a nonribosomal peptide causes antibiotic-associated colitis

“…1D). Comparison with other enterobacterial genomes revealed the location of the gene cluster to be a high-plasticity locus in the core genome typically harboring mobile DNA elements such as the polyketide synthase (pks) genotoxic island of Escherichia coli and determinants for the siderophore system yersiniabactin (29)(30)(31)(32). This genetic context implies that the toxin biosynthesis genes are part of a larger pathogenicity island (PAI).…”