Watch out for the even eviler cousin—sorbitol-fermenting E coli O157

Abstract

Hugh Pennington's thorough review (Oct 23, p 1428)1Pennington H Escherichia coli O157.Lancet. 2010; 376: 1428-1435Summary Full Text Full Text PDF PubMed Scopus (296) Google Scholar focuses on classic (ie, non-sorbitol-fermenting) enterohaemorrhagic Escherichia coli O157:H7, the main cause of haemolytic uraemic syndrome (HUS) worldwide. However, its phylogenetically close relative, sorbitol-fermenting E coli O157:NM (non-motile), warrants note. Sorbitol-fermenting E coli O157 accounts for 17% of sporadic cases of HUS2Bielaszewska M Kock R Friedrich AW et al.Shiga toxin-mediated hemolytic uremic syndrome: time to change the diagnostic paradigm?.PLoS One. 2007; 2: e1024Crossref PubMed Scopus (120) Google Scholar and caused seven outbreaks in Germany between 1988 and 2009, the largest of which involved 38 cases of HUS.3Alpers K Werber D Frank C et al.Sorbitol-fermenting enterohaemorrhagic Escherichia coli O157:H- causes another outbreak of haemolytic uraemic syndrome in children.Epidemiol Infect. 2009; 137: 389-395Crossref PubMed Scopus (44) Google Scholar A large outbreak also occurred recently in the UK.4Pollock KG Locking ME Beattie TJ et al.Sorbitol-fermenting Escherichia coli O157, Scotland.Emerg Infect Dis. 2010; 16: 881-882Crossref PubMed Scopus (20) Google Scholar Several features distinguish sorbitol-fermenting E coli O157 from its prominent cousin, E coli O157:H7. First, outbreaks caused by sorbitol-fermenting O157 strains are dominated by children with HUS who require more sessions of haemodialysis and have a higher risk of dying (case-fatality 11%) than do HUS patients infected with E coli O157:H7.3Alpers K Werber D Frank C et al.Sorbitol-fermenting enterohaemorrhagic Escherichia coli O157:H- causes another outbreak of haemolytic uraemic syndrome in children.Epidemiol Infect. 2009; 137: 389-395Crossref PubMed Scopus (44) Google Scholar, 5Ammon A Petersen LR Karch H A large outbreak of hemolytic uremic syndrome caused by an unusual sorbitol-fermenting strain of Escherichia coli O157:H.J Infect Dis. 1999; 179: 1274-1277Crossref PubMed Scopus (122) Google Scholar Second, culture-based methods that make use of selective and differential media will not detect sorbitol-fermenting E coli O157.5Ammon A Petersen LR Karch H A large outbreak of hemolytic uremic syndrome caused by an unusual sorbitol-fermenting strain of Escherichia coli O157:H.J Infect Dis. 1999; 179: 1274-1277Crossref PubMed Scopus (122) Google Scholar Targeting of the sfp gene cluster (encoding Sfp fimbriae) as a marker can reliably screen for sorbitol-fermenting E coli O157, but is seldom applied even in specialised laboratories, resulting in underdiagnosis of this pathogen. Third, the reservoir and exposure routes of sorbitol-fermenting E coli O157 are still unknown, but they are likely to be different from those of E coli O157:H7. Consequently, existing prevention guidelines for E coli O157 might not be appropriate for sorbitol-fermenting E coli O157—a pathogen with probably greater virulence. Because no specific treatment is available for HUS, prevention is pivotal. Further epidemiological investigations on reservoirs and risk factors for sorbitol-fermenting E coli O157 infections are needed, which will require timely identification of cases. Therefore, we recommend sfp testing of stool specimens in all children with HUS, in addition to screening for E coli O157:H7 on sorbitol MacConkey agar. We declare that we have no conflicts of interest.