[Activity of bicozamycin against Escherichia coli O157:H7 producing Vero toxin]

Bicozamycin (BCM) which inhibits protein synthesis by inhibiting Rho-dependent transcription termination factor ATPase activity is used for treatment of animal infections. BCM had moderate activity of MIC 16-32 micrograms/ml against enterohemorrhagic Verotoxin (VT)-producing Escherichia coli (EHEC) O157:H7 and inhibited production of VT1 and VT2. The activity of BCM against EHEC was slightly higher in anaerobic conditions, and was more evident in vivo. BCM decreased CFUs of EHEC in caecum more effectively than fosfomycin, cefixime and norfloxacin in a mouse infection model. Moreover, BCM did not increase the amount of either VT1 or VT2 in caecum in mice. In contrast, norfloxacin increased mortality of mice infected with EHEC by inducing VT production. The results suggest that BCM is useful for the treatment of EHEC infection and eradication of EHEC. Dairy live stock, especially young animals, have been implicated as a principal reservoir of EHEC. Eradication of EHEC from live stock will become an important problem in the near future. The narrow spectrum antibiotic BCM is expected to be a safe and effective antibiotic to eradicate EHEC from live stock.