Hemolysin Production as a Virulence Marker in Symptomatic and Asymptomatic Urinary Tract Infections Caused by Escherichia coli

Abstract

Potential virulence, as defined by combined levels of adhesion to urinary epithelial cells, serum resistance, and mouse toxicity, was assessed for Escherichia coli strains causing symptomatic and asymptomatic urinary tract infections in relation to the carriage of hemolysin and other suspected virulence determinants. Hemolysin production (Hly), associated with certain 0 (04, 06, 018, and 075), K (5), and hemagglutination (VI and VII) antigenic types but not colicin V production (Cva), was evident in 83 and 60% of isolates in groups possessing high potential virulence and in only 11 and 6% of those with low virulence. Strains of particular 0-types were not more virulent per se, but among the serotypes, specific combinations of virulence factors appeared decisive, e.g., 018 HAVI B/D/G Hly+ K5'/and 018 HAIII/IVB/V Hly-Cva'/-K1'/strains were, respectively, of high and low potential virulence. Isolates with high potential virulence were found to a similar extent in symptomatic and asymptomatic infections. 546 on July 3, 2020 by guest http://iai.asm.org/ Downloaded from

Molecular characterization of uropathogenic and diarrheagenic Escherichia coli pathotypes

“…On the other hand, hemolysin-positive enteroaggregative E. coli strains have been described and hemolysin production was supposed to play a role in EAEC pathogenesis since it was strongly associated with greater frequency and severity of diarrhea as well as more significant histopathological changes [17]. Hemolysin is a well known virulence factor among E. coli causing UTI and the expression among EAEC strains was previously observed [18,19]. These observations raised the hypothesis that at least some fecal EAEC strains might represent potential uropathogens.…”

Characterization of the hlyB gene and its role in the production of the EI Tor haemolysin of Vibrio choierae O1

“…Escherichia coli associated with extra-intestinal infections in humans commonly secrete an a-haemclysin (Hughes et al, 1985;Minshew et al. 1978), and its secretion into the extracellular medium is controlled by a group of genes that may be located either on the chromosome or on transmissible plasmids (Goebel ef al.. 1974).…”

Potent leukocidal action of Escherichia coli hemolysin mediated by permeabilization of target cell membranes.

“…Approximately 50% of Escherichia coli strains causing extra-intestinal infections in humans elaborate a cytolysin, designated E. coli hemolysin (ECH)t, which is responsible for the characteristic zones of (3-hemolysis surrounding bacterial colonies on blood agar (1)(2)(3)(4)(5)(6). Experimental support for a role of this cytolysin as a virulence factor derives from numerous studies with isogenic bacterial strains conducted in animal models (7)(8)(9)(10) .…”