Edrington T S, Callaway T R, Bischoff K M, Genovese K J, Elder R O, Anderson R C, Nisbet D J
Food and Feed Safety Research Unit, Southern Plains Agricultural Research Center, USDA, ARS, College Station, TX 77845, USA.
J Anim Sci. 2003 Feb;81(2):553-60. doi: 10.2527/2003.812553x.
Escherichia coli O157:H7 and Salmonella are widely recognized as important agents of foodborne disease with worldwide distribution. The use of ionophores in feeding growing ruminants is widespread in the United States and has attracted recent interest due to the apparent temporal relationship between initial ionophore use and the increase in human E. coli O157:H7 cases. Two experiments were conducted to evaluate the effects of short-term feeding of ionophores on fecal shedding, intestinal concentrations, and antimicrobial susceptibility of E. coli O157:H7 and S. typhimurium in growing lambs. Sixteen lambs were used in each experiment, four lambs per treatment group: monensin, laidlomycin propionate, bambermycin, and a control treatment. Lambs were fed a grain and hay (50:50) diet with their respective ionophore for 12 d before experimental inoculation with E. coli O157:H7 or S. typhimurium. Animals were maintained on their respective diets an additional 12 d, and fecal shedding of inoculated pathogens was monitored daily. Lambs were killed and tissues and contents were sampled from the rumen, cecum, and rectum. No differences (P > 0.05) in fecal shedding of Salmonella or E. coli O157:H7 were observed due to treatment. Occurrence of Salmonella or E. coli in luminal contents and tissue samples from the rumen, cecum, and rectum did not differ (P > 0.05) among treatments. Feeding monensin decreased (P < 0.05) the incidence of scours in sheep infected with Salmonella compared with the other treatments. No differences in antimicrobial susceptibility were found in any of Salmonella or E. coli O157:H7 isolates. Results from these studies indicate that short-term ionophore feeding had very limited effects on E. coli and Salmonella shedding or on antimicrobial susceptibility in experimentally infected lambs.
大肠杆菌O157:H7和沙门氏菌被广泛认为是食源性疾病的重要病原体，在全球范围内均有分布。在美国，在生长中的反刍动物饲料中使用离子载体的情况很普遍，并且由于最初使用离子载体与人类大肠杆菌O157:H7病例增加之间明显的时间关系，最近引起了人们的关注。进行了两项实验，以评估短期饲喂离子载体对生长羔羊粪便排出、肠道浓度以及大肠杆菌O157:H7和鼠伤寒沙门氏菌抗菌药敏性的影响。每项实验使用16只羔羊，每个处理组4只羔羊：莫能菌素、丙酸盐拉沙洛西菌素、杆菌肽锌，以及一个对照处理组。在实验性接种大肠杆菌O157:H7或鼠伤寒沙门氏菌之前，羔羊用谷物和干草（50:50）日粮与其各自的离子载体一起饲喂12天。动物在其各自的日粮上再维持12天，并每天监测接种病原体的粪便排出情况。宰杀羔羊，并从瘤胃、盲肠和直肠采集组织和内容物。由于处理方式不同，未观察到沙门氏菌或大肠杆菌O157:H7粪便排出量的差异（P>0.05）。瘤胃、盲肠和直肠的管腔内容物和组织样本中沙门氏菌或大肠杆菌的出现情况在各处理组之间没有差异（P>0.05）。与其他处理相比，饲喂莫能菌素降低了（P<0.05）感染沙门氏菌的绵羊腹泻的发生率。在任何沙门氏菌或大肠杆菌O157:H7分离株中均未发现抗菌药敏性的差异。这些研究结果表明，短期饲喂离子载体对实验感染羔羊的大肠杆菌和沙门氏菌排出或抗菌药敏性的影响非常有限。
