The effects of 6 antibiotics and berberine on releasing of Shiga-toxin from Escherichia O157∶H7 strains isolated in China
Objective To study the effects of six antibiotics and berberine on production and release of Shiga-toxin of E.coli O157∶H7, which have been frequently used in the antibiotic therapy for bacterial diarrheal diseases in China. Methods The Shiga-toxin-induced cell death of Vero cells was determined by a colorimetric assay based on the measurement of lactate dehydrogenase (LDH) released into the supernatant from the cytosol of damaged cells. Results Growth of all 8 Shiga-toxin(Stx)-producing E.coli O157∶H7 strains in broth containing subinhibitory concentrations of ciprofloxacin, gentamycin, ampicillin, pencillin, streptomycin or erythromycin caused marked increase in the release of Stx. Morever, exposure of E.coli O157∶H7 to berberine also caused observable increase of Stx releases, which has been used wieldy in treatment of diarrheal disease in China for hundreds years. Conclusion Since all of the six antibiotics tested and berberine increased Shiga-toxin production and release from E.coli O157∶H7 in vitro, it is suggested that treatment of Stx-producing E.coli infection by these antibiotics at subinhibitory dosage may have significant adverse clinical consequences, such as increasing the possibility of patient developing hemolytic uremic syndrome.