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Non-O157:H7 Stx2-producing Escherichia coli strains associated with sporadic cases of HUS

Non-O157:H7 Stx2-producing Escherichia coli strains associated with sporadic cases of hemolytic-uremic syndrome in adults. Bonnet R, Souweine B, Gauthier G, Rich C, Livrelli V, Sirot J, Joly B, Forestier C. Journal of Clinical Microbiology 1998 Jun;36(6):1777-80.

ABSTRACT:

The association between hemolytic uremic syndrome (HUS) and verotoxin-producing Escherichia coli (VTEC) infection is now well established. Cases of HUS caused by VTEC have been identified in all age groups but most frequently in infants and young children, and they are observed either during the course of outbreaks of VTEC infections or as sporadic cases. Most of the clinical signs observed are due to the absorption from the gastrointestinal tract of Shiga-like toxins (Stx) produced by the bacteria. Two types of Shiga-like toxins (also called verotoxins), Stx1 and Stx2, which presumably cause microangiopathic hemolytic anemia as a result of endothelial-cell injury, have been isolated. Other bacterial virulence factors may play a role in the pathological process as well, such as intimin, a protein product of the gene eae, which is involved in bacterial adhesion to intestinal cells, and an enterohemolysin (Ehly) which has a cytolytic effect. This paper reviews the adult cases of HUS admitted to the study hospital. The average number of adults with HUS admitted to the medical intensive care unit at this French hospital had been one every 18 months. Between August 1996 to May 1997, 14 HUS patients were admitted. In six cases, verotoxin-producing Escherichia coli (VTEC) strains were isolated from stool specimens. The following findings were attributed to these six cases. The male-to-female ratio was 1:5 and the mean age was 64 years. Acute renal failure occurred in all the patients; four required renal replacement therapy. All were treated with plasma exchanges and none died. All the isolates were stx2 positive and belonged to different serotypes: O6:H4, O91:H10, O91:H21, O rough:H16, OX3:H2, and O nontypeable:H2. The Ehly-encoding genes were detected in two isolates, and none of the isolates harbored the intimin (Eae)-encoding gene. These findings suggest that stx2-positive non-O157:H7 VTEC is a major cause of HUS in adults and that several sources of pathogens are responsible for local endemic infections. The development of diagnostic tools allowing detection of VTEC regardless of serotype is thought to be urgently needed. The authors suggest that rapid and efficient detection of VTEC should be performed in all cases of bloody diarrhea in order to prevent both severe development of the disease and further spread to others.