Virulence of urinary and faecalEscherichia coliin relation to serotype, haemolysis and haemagglutination

Abstract

SUMMARYThe virulence offaecal and urinary Escherichia coli strains was studied in relation to serotype, haemolysin production and haemagglutination pattern. By means of an experimental mouse model E. coli strains can be divided into avirulent (I), mouse nephropathogenic (II), and generally virulent (III) strains. Virulent group II and group III strains were more often haemolytic and haemagglutinating than avirulent group I strains. Presence of K antigen could not be associated with virulence. Discriminant analysis for qualitative variables revealed that no combination of the investigated properties contributed more to a strain's virulence level than did one single property. It is concluded that other virulence factors, apart from haemolysin production in group II strains and haemagglutinins in group III strains, must be involved in the determination of a strain's virulence level.All 02, 06 and 018 ac strains tested were virulent, and by far the most 075 strains were avirulent, whereas other 0 groups were more variable with regard to virulence. Pyelonephritis strains were more often mannose-resistant haemagglutinating than faecal and other urinary isolates, indicating that mannoseresistant adhesins may be important in the pathogenesis of pyelonephritis.

Virulence factors in Escherichia coli urinary tract infection

“…However, using more-sensitive methods and morecareful patient selection, others have found evidence of fimbriation and adherence in bacteria in a substantial proportion of urine specimens from infected patients (313,390,427) (181,198,338,469,470,472,509,512,518,527). Hemagglutination testing yields similar results, with the highest proportion of MRHA strains among pyelonephritis patient isolates (50 to 81%) and progressively lower proportions among cystitis patient isolates (17 to 52%), ABU patient isolates (11 to 19%), and fecal isolates (2 to 29%) (48, 49,102,139,162,181,315,316,354,399,423,509,566). This evidence indicates that mannose-resistant uroepithelial-cell adherence and MRHA are characteristic of strains with an increased ability to cause UTI (especially the more clinically severe forms) and suggests that these properties may contribute directly to urovirulence.…”

“…Association of Adherence With Other VFs MRHA or type VI hemagglutination (123) and uroepithelial-cell adherence are more prevalent among strains of certain 0 serogroups, especially 01, 02, 04, 06, 07, 08, and 018 (102,122,123,162,512,518,566). These adherence properties are also associated with the E. coli Kl (77,123) or K12 (518) capsular antigen, although the 0-group association may be primary (518).…”

“…This evidence indicates that mannose-resistant uroepithelial-cell adherence and MRHA are characteristic of strains with an increased ability to cause UTI (especially the more clinically severe forms) and suggests that these properties may contribute directly to urovirulence. Strains mediating MRHA were more virulent than non-MRHA strains in animal models in some (198,264,566,567) but not all (360) studies. Confirmation that E. coli adhesins mediating MRHA and mannose-resistant uroepithelial-cell adherence contribute to uropathogenicity followed further elucidation of the binding specificities, structure, and genetics of these adhesins (see below) (Table 1).…”

“…In mice, P fimbriae are a major determinant of bacterial colonization or invasion both of the upper urinary tract and, in the absence of type 1 fimbriae, of the bladder (97,180,264,391). P-fimbriated organisms produce disseminated infection when administered intravenously to mice (566), suggesting that P fimbriae may also play an important role outside the urinary tract. Administration of globoside along with the bacterial inoculum protects mice from urinary tract colonization with P-fimbriated organisms (520), and immunization against P fimbriae from a wild-type strain confers protection against subsequent renal infection with the same wild-type strain (182, 391).…”

“…Animal Studies Hemolytic strains are more lethal than nonhemolytic strains for chicken embryos (116,173,206,275,353) and for mice or rats in models of peritonitis (116,173,175,198,275,500,603,604), respiratory infection (115,173), and hematogenous pyelonephritis (136,137,173,310,565,566,587,589,590), causing hemorrhagic lung lesions and hemoglobinuria in mice in addition to increased mortality (116,500). In mouse and rat models of ascending UTI, hemolysin production is associated with increased bladder colonization and nephropathogenicity (97,212,265,340).…”