Antibiotic resistance in Escherichia coli isolates from rectal swab of Holstein cows and calves

• Published in: Science Bulletin of the College of Agriculture - University of the Ryukyus (Japan) no. 50
• Main Authors: Iwasaki, K. (Ryukyu Univ., Nishihara, Okinawa (Japan). Coll. of Agriculture), Samejima, Y, Shimojoh, N, Higoshi, H
• Format: Journal Article
• Language: Japanese
• Published: 01.12.2003
• Subjects: ANTIBIOTICS; CALVES; COWS; ESCHERICHIA COLI; FAECES; INTESTINES; RESISTANCE TO CHEMICALS
• ISSN: 0370-4246

A total of 252 Escherichia coli isolates were recovered from rectal swabs of two Holstein cows (designated cow A and B) on postpartum days I and 7 and the female calf of each (designated calf A and B, respectively) on postnatal days 1-7. Each isolate was tested for susceptibility to 7 antibiotics [ampicillin (ABPC), chloramphenicol (CP) , chlortetraeycline (CTC ) , kanamycin (KM) , streptomycin (SM), nalidixic acid (NA) , and sulfadimethoxine (SA)] and for prevalence of conjugative R-plasmids. The results of these studies are: 1. Resistance to at least one of antibiotics tested was found in 69% (173/252) of the E,coli isolates. The mean frequency of resistant isolates was: cow A, 20%; calf A, 61%; cow B, 80%; and calf B, 90%. These results show that calves are readily infected with resistant bacteria: on postnatal day 1, 47% of the E.coli isolates from calf A and 93% from calf B were antibiotic-resistant. Furthermore, the fraction of isolates that were antibiotic-resistant increased after postnatal day 3. 2. On postpartum day 7, isolates with resistance to only 4 of the antibiotics tested (ABPC, CTC, SM, and SA) were obtained from cow A and to only to 5 of the antibiotics (CP, CTC. SM, NA, and SA) from cow B. On postnatal day l, both calves already had isolates with the same-antibiotic resistances as the corresponding cow. By postnatal day 2, isolates from calf A were also resistant to the other 3 antibiotics (CP, KM, and NA) . Isolates resistant to one of the other antibiotics (ABPO were found in calf B by postnatal day 5, but no isolate to the remaining antibiotic (KM) was found in calf B by postnatal day 7. 3. A number of antibiotic resistance patterns were found, ranging from isolates resistant to a single antibiotic to isolates resistant to multiple (i.e., 2-7) antibiotics. Isolates from calves had more resistance patterns than those from cows, and no isolates from cows were resistant to more than 4 antibiotics. On postnatal day 1, isolates from both calves already had different resistance patterns than those from the corresponding cow. Isolates with resistance to a single antibiotic were predominant during postnatal day 1-3. However, after postnatal day 3, isolates with resistance to multiple antibiotics were predominant. 4. The prevalence of a conjugative R-plasmid was investigated in 76 of the antibiotic-resistant isolates; 6 from cow A, 28 from calf A, 11 from cow B, and 31 from calf B. Conjugative R plasmid transfer was found in 4 of these isolates: a day 4 postnatal isolate from calf A with resistance to I antibiotic (ABPC), a day 6 postnatal isolate from calf A with resistance to I antibiotic (ABPC), a day 4 postutal isolate from calf A with resistance to 3 antibiotics (ABPC-CP-CTC), and a day 3 postnatal isolate from calf B with resistance to 2 antibiotics (CTC-SA) .