Production of cytotoxic necrotizing factor, verocytotoxin and haemolysin by pyelonephritogenicEscherichia coli

Abstract

Two hundred and thirty-two strains of Escherichia coli isolated from children with non-obstructive acute pyelonephritis (n = 65), women with non-obstructive acute pyelonephritis (n = 63) and the faecal flora of healthy children (n = 33) and adults (n = 71) were examined for cytotoxic necrotizing factor production, haemolysin synthesis, verocytotoxin production and expression of mannose-resistant haemaglutination of human erythrocytes. Forty-eight per cent of the pyelonephritogenic Escherichia coli strains produced cytotoxic necrotizing factor and 61% produced haemolysin compared to 25% and 27% of faecal control strains (p less than 0.001 and p less than 0.001 respectively). Cytotoxic necrotizing factor production did not occur among the non-haemolytic Escherichia coli strains which confirms the close association between these two toxic factors. The bacterial phenotypes producing both haemolysin and cytotoxic necrotizing factor, and the phenotype expressing both these toxic factors and mannose-resistant haemagglutination occurred significantly more often in pyelonephritogenic strains than in faecal isolates (p less than 0.001). Haemolytic strains without the ability to produce cytotoxic necrotizing factor were more common in faecal isolates than in uropathogenic strains (p = 0.05). Strains lacking the ability to synthesize both these toxins were also over-represented in faecal isolates (p less than 0.01).

Adherence Assay of UropathogenicEscherichia coliIn Vivo and In Vitro

“…The surface hydrophobicity of bacteria confers loose attachment to the epithelial surface on themselves; however, many kinds of adhesins of bacteria and reciprocal receptors of the host cells are known to mediate strong adherence of E. coli strains to the epithelial surfaces [13,14].…”

Dysregulation ofEscherichia coliα-hemolysin expression alters the course of acute and persistent urinary tract infection

“…In contrast, ∼50% of UPEC strains harbor and express HlyA (46,47) as part of their toxin repertoire. One of the reasons why hlyA is not harbored by all E. coli may be the toxin armamentarium of each strain.…”

Mycotoxin Fumonisin B 1 Increases Intestinal Colonization by Pathogenic Escherichia coli in Pigs

“…Extraintestinal pathogenic E. coli (ExPEC) strains usually possess virulence determinants that allow them to persist in the intestine, cross epithelial barriers, resist nonspecific host defense mechanisms, establish specifically in extraintestinal tissues, and potentially cause damage at these sites (50,55). For instance, ExPEC strains with similar virulence determinants have been associated with urinary tract diseases in humans and septicemia in pigs (7,15,23). We have established a septicemia model involving oral inoculation of porcine ExPEC strains in newborn, colostrum-deprived, germfree pigs to study the pathogenic mechanisms of these bacteria in the natural host when it is highly susceptible to bacterial infection (17).…”