Using antibiotics in suspected haemolytic-uraemic syndrome

Editor—By uncritically quoting the meta-analysis of Safdar et al in their evidence based case report, Phillips et al perpetuate an error about antibiotic treatment of Escherichia coli O157:H7 infections.¹,²

Specifically, Safdar et al mischaracterised a study by Ikeda et al as showing that treatment of E coli O157:H7 infections with fosfomycin diminished the risk of haemolytic-uraemic syndrome compared with no antibiotic treatment.³ However, Ikeda et al did not show that antibiotics prevent the syndrome because two of the 256 patients were not treated. Moreover, statistically significant benefit emerged only after subgroup analysis, with the implication that treatment had value only if started on day 2 of illness. In practice, this subgroup would be nearly impossible to identify; the plausibility of antibiotics' benefit only on the second day of illness seems lacking.

Without more clinical data, including the nature of the “clotting abnormality” (beyond expected thrombocytopenia), we do not know if a consideration of sepsis in the patient Phillips et al described, who seems to have had haemolytic-uraemic syndrome at presentation, was warranted. However, Safdar et al substantiate neither the efficacy nor the safety of using antibiotics to treat E coli O157:H7 infections because their analysis relied disproportionately on a misclassified study.

People performing meta-analyses and people using them in derivative communications are advised to scrutinise the original investigations on which such exercises are based. Most studies show either no benefit, or harm, to E coli O157:H7 infected patients treated with antibiotics. On the basis of current data, such agents should not be used.