Virulence-related genes in ColV plasmids of Escherichia coli isolated from human blood and intestines

Abstract

DNA probes for the colicin V, traT, iss, and iu genes were used in this study of four representative ColV plasmids together with 200 Escherichia coli strains isolated from the stools of patients with diarrhea and 146 E. coli strains isolated from the blood of patients with bacteremia. The study indicated that the ColV plasmids are heterogeneous. Southern and colony hybridization analyses showed that in most of the colicin V-producing intestinal E. coli strains, the colicin V genes are located in the chromosome (14 of 16); in most of the colicin V-producing E. coli strains isolated from the blood, they are located in plasmids (18 of 22). In both intestinal and blood E. coli isolates, the traT, iss, and aerobactin receptor genes were present at similar frequencies, but the frequency of the aerobactin synthesis genes was significantly different. The aerobactin receptor gene was present in 25% of the intestinal E. coli strains that lack the aerobactin synthesis gene. In the blood isolates, the aerobactin synthesis and receptor genes were present at almost equal frequencies. Among the colicin V-producing isolates, the iss, traT, and iu genes were present in 95.5, 86.4, and 90.9% of the blood isolates and in only 68.8, 43.8, and 81.3% of the intestinal isolates, respectively. The ColV plasmids from blood isolates that were tested for the presence of traT, iss, and iu genes were homogeneous and had DNA sequences that hybridized with each of the probes. On the other hand, the two intestinal strains containing ColV genes in a plasmid were heterogeneous in regard to the carriage of these genes. The presence of ColV is not restricted to specific O types.

Genotypic characterization of multiple drug resistant Escherichia coli isolates from a pediatric cancer hospital in Egypt

“…www.nature.com/scientificreports www.nature.com/scientificreports/ Isolate E1714 contained five virulence genes iroB, iroC, iroD, iroE, and iroN, commonly present in E. coli, involved in iron ion binding and signaling receptor activity. They are commonly present on IncFI and ColV2-K94 plasmids 25 . They act through formation of iroA gene cluster that permits the pathogen to acquire iron from the host avoiding the innate immune system proteins such as NGAL (also known as lipocalin 2) that sequester the bacterial iron siderophores.…”

Colicin V virulence plasmids.

“…The transfer region appears to encompass about 30 kb, as in the F plasmid, and the colicin V genes encompass about 4 kb, leaving 70 kb of DNA uncharted. In addition to the aerobactin iron uptake system and colicin V genes of pColV-K30, genetic probes have identified regions homologous to traT but not to iss (37). From our genetic survey came the discovery of the following highly conserved genetically linked unit: the IncFI-correlated replication region REPI, the aerobactin iron uptake system flanked by inverted copies of the insertion sequence IS], and a stability locus par which maintains REPI-driven clones (Fig.…”

Structure and Function of Plasmid pColD157 of Enterohemorrhagic Escherichia coli O157 and Its Distribution among Strains from Patients with Diarrhea and Hemolytic-Uremic Syndrome

“…In addition, colicinogeny could be shown in Shigella spp. (20), uropathogenic E. coli, and E. coli isolated from human blood (13). Although the production of bacteriocins by a wide range of gram-negative and gram-positive bacteria has Fresh colonies of the strains were transferred with a sterile toothpick onto a lawn of 10 6 E. coli C600 indicator cells and were incubated overnight at 37°C.…”