Presence and Characterization of Extraintestinal Pathogenic Escherichia coli Virulence Genes in F165-Positive E. coli Strains Isolated from Diseased Calves and Pigs

Abstract

The virulence genotype profile and presence of a pathogenicity island(s) (PAI) were studied in 18 strains of F165-positive Escherichia coli originally isolated from diseased calves or piglets. On the basis of their adhesion phenotypes and genotypes, these extraintestinal pathogenic strains were classified into three groups. The F165 fimbrial complex consists of at least two serologically and genetically distinct fimbriae: F165 1 and F165 2 . F165 1 is encoded by the foo operon (pap-like), and F165 2 is encoded by fot (sfa related). Strains in group 1 were foo and fot positive, strains in group 2 were foo and afa positive, and strains in group 3 were foo positive only. The strains were tested for the presence of virulence genes found mainly in extraintestinal pathogenic E. coli (ExPEC) strains. Although all the strains were positive for the papA variant encoding F11 fimbriae incD, traT, and papC, the prevalence of virulence genes commonly found in PAIs associated with ExPEC strains was highly variable, with strains of group 2 harboring most of the virulence genes tested. papG allele III was detected in all strains in group 1 and in one strain in group 3. All other strains were negative for the known alleles encoding PapG adhesins. The association of virulence genes with tRNA genes was characterized in these strains by using pulsed-field gel electrophoresis and DNA hybridization. The insertion site of the foo operon was found at the pheU tRNA locus in 16 of the 18 strains and at the selC tRNA locus in the other 2 strains. Furthermore, 8 of the 18 strains harbored a high-pathogenicity island which was inserted in either the asnT or the asnV/U tRNA locus. These results suggest the presence of one or more PAIs in septicemic strains from animals and the association of the foo operon with at least one of these islands. F165-positive strains share certain virulence traits with ExPEC, and most of them are pathogenic in piglets, as tested in experimental infections.Escherichia coli is a frequent cause of intestinal and extraintestinal diseases in humans and animals. Typical extraintestinal infections include urinary tract infections, newborn meningitis, polyserositis, and septicemia. All these groups of pathogenic E. coli strains have been called extraintestinal pathogenic E. coli (ExPEC). The recognized virulence factors of ExPEC include diverse adhesins (e.g., P fimbriae, S/F1C fimbriae, F165 fimbriae, Afa/Dr adhesins, and type 1 fimbriae), toxins (e.g., hemolysin, cytotoxic necrotizing factor, and cytolethal distending toxin), surface antigens (e.g., group II and group III capsules and lipopolysaccharide), invasins (e.g., an invasin responsible for invasion of brain endothelium [IbeA, also called Ibe10]), iron uptake systems (e.g., the aerobactin system), and secretion systems (e.g., type III secretion systems). These virulence factors facilitate colonization and invasion of the host, avoidance or disruption of host defense mechanisms, injury to host tissues, and/or stimulation of a noxious host inflammatory response (...

Characteristics and virulence genes of Escherichia coli isolated from septicemic calves in southeast of Iran

“…It has been established that typeable isolates from colisepticemia can belong to a relatively small number of O serogroups (Fecteau et al 2001). There are evidences that certain factors, such as O type (e.g., O115, O78) and K serotype (K1), are important in key steps for survival in the blood and resistance to bacterial killing by the host (Dezfulian et al 2003). According to results of the present study among 14 O-typeable isolates 57.14% (8 isolates) belonged to B1, 28.57% (4) to A and 14.28% (2) to D phylogenetic groups.…”

“…The nonfimbrial CS31A adhesin encoded by clpG gene has detected on E. coli isolates from calves with septicemia or diarrhea (Mercado et al 2003). F165-1 fimbrial antigen is produced by E. coli isolates associated with diarrhea and septicemia in calves and piglets (Dezfulian et al 2003). The pap/prs gene cluster (coding for P-fimbriae) is composed of genes coding for structural subunits (papA, papE, papF, and papG) and a gene (papC) coding for a transport protein (Van Bost et al 2003).…”

Clonal analysis and virulent traits of pathogenic extraintestinal Escherichia coliisolates from swine in China

“…The importance of swine ExPECs is not fully appreciated at present. This is mainly because the phylogenetic types present in swine differ considerably with the majority of ExPEC isolates in human, and because There have been much lower number of ExPECs isolated from pork compared with poultry meat [10,11]. …”

Characterization and virulence clustering analysis of extraintestinal pathogenic Escherichia coli isolated from swine in China

“…It can lead to many kinds of extraintestinal diseases, including newborn meningitis, sepsis, and urinary tract disease [1]. It has been reported to cause death in animals and humans in Europe and North America [2, 3]. ExPEC can be distinguished from intestinal pathogenic E. coli and commensal E. coli by isolation site and genetic patterns [4].…”