Ann Lab Med.  2018 May;38(3):271-273. 10.3343/alm.2018.38.3.271.

Prevalence of Escherichia coli Carrying pks Islands in Bacteremia Patients

• Lee E
• Lee Y

• KMID: 2403463
• DOI: http://doi.org/10.3343/alm.2018.38.3.271

Abstract

Escherichia coli can harbor genomic pks islands that code for a polyketide-peptide genotoxin known as colibactin. E. coli strains carrying pks islands trigger genetic instability. pks islands have been significantly associated with bacteremia. We investigated the molecular epidemiology of bacteremic E. coli isolates and the prevalence of bacteremia-causing E. coli carrying pks islands. A total of 146 E. coli isolates were collected at a tertiary-care hospital from January 2015 to December 2016. The phylogenetic groups were determined by multiplex PCR. All isolates were screened by PCR for sequence type 131 (ST131)-associated single-nucleotide polymorphisms (SNPs) in mdh and gyrB. For detection of pks islands, we performed PCR for the clbB and clbN genes as colibactin system markers. Phylogenetic group B2 was the most common, accounting for 54.1% (N=79) of the isolates, followed by group D with 29.5% (N=43), group A with 11.6% (N=17), and group B1 with 4.8%. Of the group B2 isolates, 40.5% were ST131 strains and 32.9% carried pks islands. Only three ST131 isolates in group B2 carried the clbB and clbN genes, while the other 23 ST131 isolates did not. The pks gene might not be associated with ST131 strains.

Keyword

Escherichia coli; pks islands; clbB; Bacteremia; ST131

MeSH Terms

Bacteremia*
Escherichia coli*
Escherichia*
Humans
Islands*
Molecular Epidemiology
Multiplex Polymerase Chain Reaction
Polymerase Chain Reaction
Prevalence*

Figure

• 

  Fig. 1 Isolates carrying pks islands and those identified as strain ST131, arranged by phylogenetic group. Phylogenetic groups were determined by multiplex PCR using a combination of three genes (chuA, yjaA, and TSPE4.C2), and the isolates were clustered into four main phylogenetic groups, A, B1, B2, and D. The numbers in the dotted circle and the small dotted circle indicate ST131 positive isolates and pks-carrying isolates, respectively.

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