摘要
      泰国正在迅速加强畜牧业生产，小型自给农场和中型商业农场并存。在中型农场，抗生素由兽医开具处方，而在小型农场，抗生素的使用基本上没有监督。这些差异以及其他农业实践对抗微生物耐药性基因（ARGs）的出现和组成的影响在很大程度上仍然未知。我们分析了363个产超广谱内酰胺酶（ESBL）和/或产AmpC大肠杆菌的基因组，这些大肠杆菌是在泰国孔敬省的中小型农场从人和猪身上回收的。我们测试了全基因组关联，以确定ARGs、宿主和农场规模之间的联系。来自小型养殖场的猪分离株分别与对粘菌素和氟喹诺酮产生耐药性的mcr和qnr基因相关。相反，来自培养基农场的猪分离株与ARGs有关，ARGs对培养基农场常用的药物（即链霉素）产生耐药性。与中型农场的质粒相比，来自小型农场的ESBL质粒共同携带ARG，使其更频繁地对至关重要的抗菌药物产生耐药性。频繁的ARG组合包括blaCTX-M-55 + qnrS1（中小型农场分别为29.8%和17.5%），blaCTX-M-55 + qnrS1型 + mcr-3.19（5%对0%），blaCTX-M-14 + qnrS1（9.3%对6.2%）和blaCTX-M-14 + qnrS1型 + mcr-1.1（3.1%对0%）。根据世界卫生组织的定义，ARGs在质粒上的共定位使其对至关重要的抗菌药物产生耐药性，这令人担忧，迫切需要采取行动遏制其传播。关于限制抗菌药物销售的立法以及更好地告知农民和兽医适当使用抗菌药物和农场生物安全的举措，有助于减少农场的抗菌药物使用。
Abstract
Thailand is undergoing rapid intensification of livestock production where small subsistence farms and medium sized commercial farms coexist. In medium farms, antimicrobials are prescribed by a veterinarian, whereas in small farms antimicrobial use remains largely unsupervised. The impact of these differences as well as other farming practices on the emergence and composition of antimicrobial resistance genes (ARGs) remains largely unknown. We analyzed 363 genomes of extended-spectrum ß-lactamase producing (ESBL) and/or AmpC producing Escherichia coli recovered from humans and pigs at small and medium farms from the Khon Kaen province, Thailand. We tested for genome-wide associations to identify links between ARGs, host, and farm size. Pig isolates from small farms were associated with mcr and qnr genes conferring resistance to colistin and fluoroquinolones, respectively. In contrast, pig isolates from medium farms were associated with ARGs conferring resistance to drugs commonly used on medium farms (i.e., streptomycin). ESBL plasmids from small farms co-carried ARGs conferring resistance to critically important antimicrobials more frequently compared to plasmid from medium farms. Frequent ARG combinations included blaCTX-M-55 + qnrS1 (29.8% vs 17.5% in small and medium farms, respectively), blaCTX-M-55 + qnrS1 + mcr-3.19 (5% vs 0%), blaCTX-M-14 + qnrS1 (9.3% vs 6.2%), and blaCTX-M-14 + qnrS1 + mcr-1.1 (3.1% vs 0%). The co-location on plasmids of ARGs conferring resistance to critically important antimicrobials as defined by the World Health Organization is concerning, and actions to curb their spread are urgently needed. Legislation on limiting antimicrobial sales and initiatives to better inform farmers and veterinarians on appropriate antimicrobial usage and farm biosecurity could help reduce antimicrobial use on farms.

https://link.springer.com/article/10.1186/s12866-022-02646-3