The stimulating effect of fosfomycin, an antibiotic in common use in Japan, on the production/release of verotoxin-1 from enterohaemorrhagic Escherichia coli O157:H7 in vitro.

In 1996 Japan had a big outbreak of enterohaemorrhagic Escherichia coli (EHEC) O157:H7, especially in Osaka prefecture where about 6000 patients (mainly schoolchildren) suffered from diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome (HUS) due to EHEC infection via school lunch. Our survey of doctors who took care of those patients showed that most patients had received antibiotics, especially fosfomycin which comprised 84% of the prescribed treatment. Since the administration of antibiotics for EHEC infection is under discussion, we analysed the effect of fosfomycin on production/release of verotoxins (VTs). Addition of fosfomycin into EHEC culture in CAYE broth at 2 and 5 h after start of incubation caused marked increase of VT1 release. This observation warns of the possibility of fosfomycin treatment making the disease worse.