2001 Volume 54 Issue 12 Pages 909-912
Studies to compare populations of acid-resistant Escherichia coli were conducted on 70 samples of rectal feces from neonatal and weaning piglets 20 to 40 days old from 7 farms. Fordetermination of total E. coli, samples were diluted by a volume of 10 times. Acid-resistant E. coli was estimated by viability in TSB media at pH 5, pH 4, pH 3, and pH 2. Total E. coli count in neonatal and weaning piglets was 7.09±1.63 (mean±S.D., log10/g). The pH 5-resistant E. coli count was 7.24±1.80; the pH 4 count was 7.06±1.75; the pH 3 count was 5.76±2.37; and the pH 2 count was 3.19±2.68. Acid-resistant E. coli counts were frequently higher in neonatal than in weaning piglets, and diarrheal feces generally contained more than normal feces. Although in neonatal piglets there was no significant difference in pH 2-resistant E. coli between diarrheal (3.35±2.31) and normal (4.15±2.45) feces, in weaning piglets the population was greater in diarrheal (4.64±2.45) than normal feces (1.51±2.25). Moreover, 23 of the 24 hemolytic acid-resistant strains isolated from the diarrheal feces of weaning piglets possessed the VT2 gene.
