Filippitzi Maria Eleni, Chantziaras Ilias, Devreese Mathias, Dewulf Jeroen
a Veterinary Epidemiology Unit, Faculty of Veterinary Medicine , Ghent University , Ghent , Belgium.
b Porcine Health Management Unit, Faculty of Veterinary Medicine , Ghent University , Ghent , Belgium.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2018 Jul;35(7):1266-1277. doi: 10.1080/19440049.2018.1461257. Epub 2018 May 30.
The cross-contamination of non-medicated feed with residues of anti-microbials (AM) causes a public and animal health concern associated with the potential for selection and dissemination of resistance. To analyse the associated risks, a probabilistic model was built using @Risk® (Palisade Corporation®) to show the potential extent of the effect of cross-contaminated pig feed on resistance selection. The results of the model include estimations of the proportion of pigs per production stage with residues of doxycycline, chlortetracycline, sulfadiazine and trimethoprim in their intestinal contents, as a result of exposure to cross-contaminated feed with different carry-over levels, in Belgium. By using a semi-quantitative approach, these estimations were combined with experimental data on AM concentrations associated with potential for resistance-selection pressure. Based on this model, it is estimated that 7.76% (min = 1.67; max = 36.94) of sows, 4.23% (min = 1.01%; max = 18.78%) of piglets and 2.8% (min = 0.51%; max = 14.9%) of fatteners in Belgium have residues of doxycycline in their intestinal tract due to consumption of feed with at least 1% carry-over. These values were estimated to be almost triple for sulfadiazine, but substantially lower for chlortetracycline and trimethoprim. Doxycycline concentrations as low as 1 mg/L (corresponding to consumed feed with at least 1% carry-over) can select for resistant porcine commensal Escherichia coli in vitro and in vivo. Conclusions on this risk could not be drawn for other AM at this stage, due to the lack of data on concentrations associated with resistance development. However, since the possibility of resistance mechanisms (e.g. co-selection) occurring cannot be excluded, the results of this model highlight that the use of AM medicated feed should be minimised where possible. In case of medicated feed production, good practice should be followed thoroughly at all levels of production, distribution, storage and administration, with a special focus on the feed distributed to piglets and sows.
非药用饲料与抗菌药物（AM）残留的交叉污染引发了公众和动物健康方面的担忧，这与耐药性的产生和传播可能性相关。为分析相关风险，使用@Risk®（Palisade Corporation®）构建了一个概率模型，以展示交叉污染的猪饲料对耐药性产生影响的潜在程度。该模型的结果包括对比利时不同生产阶段的猪，因接触具有不同残留水平的交叉污染饲料，其肠道内容物中含有强力霉素、金霉素、磺胺嘧啶和甲氧苄啶残留的猪的比例的估计。通过使用半定量方法，这些估计值与关于与耐药性选择压力可能性相关的抗菌药物浓度的实验数据相结合。基于该模型，估计比利时7.76%（最小值 = 1.67；最大值 = 36.94）的母猪、4.23%（最小值 = 1.01%；最大值 = 18.78%）的仔猪和2.8%（最小值 = 0.51%；最大值 = 14.9%）的育肥猪因食用残留量至少为1%的饲料而在肠道中有强力霉素残留。据估计，磺胺嘧啶的这些值几乎是强力霉素的三倍，但金霉素和甲氧苄啶的值则低得多。低至1毫克/升的强力霉素浓度（对应于食用残留量至少为1%的饲料）在体外和体内均可筛选出耐药的猪源共生大肠杆菌。由于缺乏与耐药性发展相关的浓度数据，现阶段无法就其他抗菌药物得出关于此风险的结论。然而，由于不能排除耐药机制（如共选择）发生的可能性，该模型的结果突出表明，应尽可能减少抗菌药物药用饲料的使用。在生产药用饲料时，应在生产、分销、储存和给药的各个层面严格遵循良好规范，尤其要关注供应给仔猪和母猪的饲料。
