Baker Michelle, Hobman Jon L, Dodd Christine E R, Ramsden Stephen J, Stekel Dov J
School of Biosciences, University of Nottingham, Loughborough, LE12 5RD, UK.
School of Biosciences, University of Nottingham, Loughborough, LE12 5RD, UK
FEMS Microbiol Ecol. 2016 Apr;92(4):fiw040. doi: 10.1093/femsec/fiw040. Epub 2016 Feb 22.
Antimicrobial resistance is of global concern. Most antimicrobial use is in agriculture; manures and slurry are especially important because they contain a mix of bacteria, including potential pathogens, antimicrobial resistance genes and antimicrobials. In many countries, manures and slurry are stored, especially over winter, before spreading onto fields as organic fertilizer. Thus, these are a potential location for gene exchange and selection for resistance. We develop and analyse a mathematical model to quantify the spread of antimicrobial resistance in stored agricultural waste. We use parameters from a slurry tank on a UK dairy farm as an exemplar. We show that the spread of resistance depends in a subtle way on the rates of gene transfer and antibiotic inflow. If the gene transfer rate is high, then its reduction controls resistance, while cutting antibiotic inflow has little impact. If the gene transfer rate is low, then reducing antibiotic inflow controls resistance. Reducing length of storage can also control spread of resistance. Bacterial growth rate, fitness costs of carrying antimicrobial resistance and proportion of resistant bacteria in animal faeces have little impact on spread of resistance. Therefore, effective treatment strategies depend critically on knowledge of gene transfer rates.
抗菌药物耐药性是全球关注的问题。大部分抗菌药物用于农业；粪肥和泥浆尤为重要，因为它们含有多种细菌，包括潜在病原体、抗菌药物耐药基因和抗菌药物。在许多国家，粪肥和泥浆在作为有机肥料施用于农田之前会进行储存，尤其是在冬季。因此，这些地方是耐药基因交换和耐药性选择的潜在场所。我们开发并分析了一个数学模型，以量化储存的农业废弃物中抗菌药物耐药性的传播。我们以英国一家奶牛场的一个泥浆罐的参数作为示例。我们表明，耐药性的传播以一种微妙的方式取决于基因转移率和抗生素流入率。如果基因转移率很高，那么降低基因转移率可控制耐药性，而减少抗生素流入的影响很小。如果基因转移率很低，那么减少抗生素流入可控制耐药性。缩短储存时间也可控制耐药性的传播。细菌生长速率、携带抗菌药物耐药性的适应性代价以及动物粪便中耐药细菌的比例对耐药性传播的影响很小。因此，有效的治疗策略关键取决于对基因转移率的了解。
