Sequence analysis and characterization of a transferable hybrid plasmid encoding multidrug resistance and enabling zoonotic potential for extraintestinal Escherichia coli.

ColV plasmids of extraintestinal pathogenic Escherichia coli (ExPEC) encode a variety of fitness and virulence factors and have long been associated with septicemia and avian colibacillosis. These plasmids are found significantly more often in ExPEC, including ExPEC associated with human neonatal meningitis and avian colibacillosis, than in commensal E. coli. Here we describe pAPEC-O103-ColBM, a hybrid RepFIIA/FIB plasmid harboring components of the ColV pathogenicity island and a multidrug resistance (MDR)-encoding island. This plasmid is mobilizable and confers the ability to cause septicemia in chickens, the ability to cause bacteremia resulting in meningitis in the rat model of human disease, and the ability to resist the killing effects of multiple antimicrobial agents and human serum. The results of a sequence analysis of this and other ColV plasmids supported previous findings which indicated that these plasmid types arose from a RepFIIA/FIB plasmid backbone on multiple occasions. Comparisons of pAPEC-O103-ColBM with other sequenced ColV and ColBM plasmids indicated that there is a core repertoire of virulence genes that might contribute to the ability of some ExPEC strains to cause high-level bacteremia and meningitis in a rat model. Examination of a neonatal meningitis E. coli (NMEC) population revealed that approximately 58% of the isolates examined harbored ColV-type plasmids and that 26% of these plasmids had genetic contents similar to that of pAPEC-O103-ColBM. The linkage of the ability to confer MDR and the ability contribute to multiple forms of human and animal disease on a single plasmid presents further challenges for preventing and treating ExPEC infections.

Complete sequence of pEC14_114, a highly conserved IncFIB/FIIA plasmid associated with uropathogenic Escherichia coli cystitis strains.

Extraintestinal pathogenic Escherichia coli (ExPEC) are known to cause important diseases of humans and animals, and they have been shown to carry a variety of plasmids associated with increased virulence and decreased antimicrobial susceptibility. Here, the completed DNA sequence of a human uropathogenic E. coli (UPEC; O6:H31 isolate) plasmid, pEC14_114, was determined. The plasmid was 114,222bp in length and was highly similar to plasmid sequences or draft contiguous sequences from three other human cystitis-associated UPEC isolates. pEC14_114 contained 141 coding regions, including a number of genes associated with mobile genetic elements, F-type transfer, plasmid maintenance and stability, colicin immunity, and plasmid replication. This plasmid also possessed a "genetic load" region containing genes with predicted similarity to iron acquisition systems and virulence factors. The prevalence of pEC14-associated genes was determined for a collection of 1456 E. coli isolates, including those from food products, humans, dogs, cats, pigs, chickens, and turkeys. pEC14_114-associated genes were found significantly more often (16-35%) among human UPEC and neonatal meningitis-associated isolates than among food- and animal-source isolates (0-8%). Overall, this plasmid represents a novel IncFIB/FIIA plasmid type associated with human ExPEC belonging to the B2 phylogenetic group. The overall role of this plasmid, if any, in human ExPEC infections remains to be determined.