Cephamycin C treatment of induced enterotoxigenic colibacillosis (scours) in calves and piglets.

Cephamycin C is a beta-lactam antibiotic that has broad gram-negative activity and is resistant to degradation by beta-lactamases and safe for use in animals. In colostrum-fed calves infected with Escherichia coli strain B44, cephamycin C administered by gavage at 31.3 to 1,000 mg per calf (0.75 to 24 mg/kg) twice a day for 6 days starting at 20 h post-inoculation eliminated the diarrhea and reduced the mortality from 90% in infected, nonmedicated calves to 14% in infected, medicated calves (P < 0.01). Comparable results were obtained with a shorter treatment regimen (30 mg of cephamycin C per calf [0.71 mg/kg] twice a day for 3 days). In colostrum-fed piglets infected with E. coli strain P155 and housed in cages, cephamycin C administered prophylactically by gavage at 12.5 mg per piglet (10.4 mg/kg) twice a day for 4 days completely prevented both diarrhea and mortality, whereas nonmedicated piglets had 100% diarrhea and all died. When eight doses of cephamycin C were given therapeutically starting at 6 h post-inoculation, mortality was reduced from 79 to 23% (P < 0.02), and diarrhea was eliminated in the surviving medicated piglets by 4 days post-inoculation. In infected suckling piglets, cephamycin C administered therapeutically by gavage at 12.5 mg per piglet twice a day for 3 days starting at 6 h post-inoculation, diarrhea and mortality were reduced (P < 0.05): infected, nonmedicated piglets had 87% diarrhea and 75% mortality, whereas infected, medicated piglets had 25% diarrhea and 31% mortality. All surviving medicated piglets had solid feces by 2 days post-inoculation. Thus, cephamycin C was highly effective in restoring the calves and piglets to good health by eliminating diarrhea and reducing mortality.