U.S. Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Division of Animal and Food Microbiology, Laurel, Maryland, 20708, USA.
U.S. Food and Drug Administration, Center for Veterinary Medicine, Office of Surveillance and Compliance, Division of Animal Feeds, Rockville, Maryland, 20855, USA.
Sci Rep. 2017 Sep 8;7(1):11017. doi: 10.1038/s41598-017-09593-4.
Distillers grains are co-products of the corn ethanol industry widely used in animal feed. We examined the effects of erythromycin, penicillin, and virginiamycin at low concentrations reflective of those detected in distillers grains on bacterial resistance selection. At 0.1 µg/ml erythromycin, macrolide-resistant mutants were induced in one Campylobacter coli and one Enterococcus faecium strain, while these strains plus three additional C. coli, one additional E. faecium, and one C. jejuni also developed resistance when exposed to 0.25 µg/ml erythromycin. At 0.5 µg/ml erythromycin, a total of eight strains (four Campylobacter and four Enterococcus) obtained macrolide-resistant mutants, including two strains from each genus that were not selected at lower erythromycin concentrations. For penicillin, three of five E. faecium strains but none of five Enterococcus faecalis strains consistently developed resistance at all three selection concentrations. Virginiamycin at two M:S ratios did not induce resistance development in four out of five E. faecium strains; however, increased resistance was observed in the fifth one under 0.25 and 0.5 µg/ml virginiamycin selections. Although not yet tested in vivo, these findings suggest a potential risk of stimulating bacterial resistance development in the animal gut when distillers grains containing certain antibiotic residues are used in animal feed.
酒糟是玉米乙醇工业的副产物，广泛用于动物饲料。我们研究了低浓度的红霉素、青霉素和维吉尼亚霉素对细菌耐药性选择的影响，这些浓度反映了在酒糟中检测到的浓度。在 0.1μg/ml 的红霉素作用下，一种弯曲杆菌和一种屎肠球菌菌株诱导产生了大环内酯类耐药突变体，而这两种菌株加上另外三种弯曲杆菌、一种屎肠球菌和一种空肠弯曲杆菌在暴露于 0.25μg/ml 的红霉素时也产生了耐药性。在 0.5μg/ml 的红霉素作用下，共有 8 株（4 株弯曲杆菌和 4 株肠球菌）获得了大环内酯类耐药突变体，包括两种在较低红霉素浓度下未被选择的属内菌株。对于青霉素，5 株屎肠球菌中有 3 株但 5 株粪肠球菌无一株在所有 3 个选择浓度下都能持续产生耐药性。在五种屎肠球菌菌株中，有四种在两种 M:S 比例的维吉尼亚霉素作用下没有诱导耐药性的产生，但在 0.25 和 0.5μg/ml 的维吉尼亚霉素选择下，第五种菌株的耐药性增加。尽管尚未在体内进行测试，但这些发现表明，当含有某些抗生素残留的酒糟在动物饲料中使用时，可能会刺激动物肠道中的细菌耐药性发展。
