A study was conducted to compare the efficacy of
sulbactam:
ampicillin (
SAMP) (3.3:6.6 mg/kg
body weight (BW), IM, q24 h) to that of
ampicillin trihydrate (
AMP) (6 mg/kg BW, IM, q24 h) and
0.9% saline (SAL) (3 mL IM, q24 h) for the treatment of
diarrhea in calves induced by oral inoculation with Escherichia coli strain B44 (O9:K30:K99:H-). Treatment was initiated when severe
diarrhea was noted (T0) and continued for at least 3 d; or for 24 h after clinical signs resolved; or for a maximum duration of 7 d. Starting at T0, calves were examined twice daily: appetite; rectal temperature (TEMP); and fecal consistency (FECAL), mental status (ATTD), eye position (EYE), and skin elasticity (SKIN) scores were recorded. Feces collected at T0 were submitted for bacteriology, electron microscopy, and parasitology. A complete blood count was performed at T0 and T3 (24 h after third treatment). Severely dehydrated, depressed, and anorexic calves were euthanized and considered mortalities. Cause of death was determined by post mortem examination. A total of 30 calves were included in the study. Three calves were excluded from final analysis. E. coli strain B44 was cultured from feces of all calves at T0. At T2 (24 h after second treatment) mean TEMP of
SAMP calves was significantly higher (P < 0.05) than mean TEMP of SAL calves; EYE and SKIN scores of
SAMP calves were significantly lower (P < alpha beta = 0.025) than those of SAL and
AMP calves; and ATTD and FECAL scores of
SAMP calves were significantly lower (P < alpha beta = 0.025) than in SAL calves. At T3,
SAMP calves had significantly lower (P < 0.05) mean hematocrit than SAL calves and lower mean total
plasma protein concentration than
AMP and SAL calves. Mean
fibrinogen concentration in
SAMP calves at T3 was significantly lower (P < 0.05) than that of calves receiving either SAL or
AMP. The number of surviving
SAMP calves (10/10) was significantly higher (P < alpha beta = 0.025) than the number of surviving SAL calves (2/9), but not significantly different from the surviving
AMP calves (3/8).