In their important retrospective study, Menne and colleagues demonstrate that antibiotic treatment of patients with established Escherichia coli O104:H4 associated haemolytic uraemic syndrome had clinical benefit [1].

The study introduces interesting hypotheses and contributes significantly to the debate on how to best treat such cases. The authors and F. Artunc in an accompanying editorial [2], recommend that the hypotheses generated should be investigated in a future randomised trial.

Enterohaemorrhagic E. coli (EHEC) represents a diverse group of bacteria. It should be emphasized that haemolytic uraemic syndrome may be associated with various serotypes of EHEC, as well as Shigella, Salmonella, and non-gastrointestinal infections [3, 4]. It may be that the results presented are restricted to some serotypes of E. coli or even O104:H4 alone. It is therefore important that future studies include thorough microbiological characteristics of the infectious agents, like those given by Menne and colleagues.

Shiga toxins (stx) are a family of related toxins and subtyping should also be welcomed. Studies suggests that the clinical presentation and outcome of infections caused by stx-producing E. coli depends on the stx-genotype of the infecting strain [5]. Particularly virulent strains may be found among numerous E. coli variants, including the very rare ones. In Norway, 10 of 17 patients developed haemolytic uraemic syndrome after infection with E. coli O103:H25, stx2-positive [6].

E. coli identification and serotyping is challenging and stx-production may be lost both in vivo and in vitro. Thus, microbiological examination should therefore also include examination for the eae-genes, which encode for the adherence factor intimin which also represents an important virulence marker.

Microbiological diagnosis of cases with haemolytic uraemic syndrome is valuable not only for individual diagnosis, outbreak investigation and other public health aspects, but also for evaluating the effects of various treatments offered in different cases.

References
1. Menne J, Nitschke M, Stingele R, Abu-Tair M, Beneke J, Bramstedt J, et al. Validation of treatment strategies for enterohaemorrhagic Escherichia coli O104:H4 induced haemolytic uraemic syndrome: case-control study. BMJ 2012;345:e4565

2. Artunc F. Treating Shiga toxin induced haemolytic uraemic syndrome. BMJ 2012;345:e4598

3. Noris M, Remuzzi G. Hemolytic uremic syndrome. J Am Soc Nephrol2005;16:1035-50

4. Ruzante JM, Majowicz SE, Fazil A, Davidson VJ. Hospitalization and deaths for select enteric illnesses and associated sequelae in Canada, 2001–2004. Epidemiol Infect. 2011;139:937-45

5. Bitzan M, Schaefer F, Reymond D. Treatment of typical (enteropathic) hemolytic uremic syndrome. Semin Thromb Hemost. 2010;36(6):594-610.

6. Schimmer B, Nygard K, Eriksen HM, Lassen J, Lindstedt BA, et al. Outbreak of haemolytic uraemic syndrome in Norway caused by stx2-positive Escherichia coli O103:H25 traced to cured mutton sausages. BMC Infect Dis. 2008;8:41

Competing interests: None declared