Investigation of antibiotic resistance genes in staphylococcal isolates from bovine milk

现代医学和兽医实践依赖于有效的抗生素来预防和治疗人类和动物的感染。细菌耐药性的流行是21世纪世纪公共卫生领域最棘手的挑战之一。大约80%的抗生素消耗量用于食用动物。因此，更好地了解农场使用的抗生素的影响将为公共政策提供更强大的平台。奶牛场使用抗生素最常见的原因是治疗和预防乳腺炎。乳腺炎是一种具有重大经济意义的疾病（加拿大乳制品行业每年损失约3.5亿美元）。乳腺炎可由革兰氏阳性菌和革兰氏阴性菌引起。乳腺炎的大多数抗菌治疗针对革兰氏阳性菌。牛乳腺中最常见的革兰氏阳性菌是葡萄球菌，包括金黄色葡萄球菌和凝固酶阴性球菌（CNS）。大多数牛奶S。金黄色葡萄球菌和CNS分离株具有多重耐药性。葡萄球菌中的一种特殊类型的抗微生物耐药性，即甲氧西林耐药性（MR），最近一直是乳腺炎研究人员关注的焦点，因为β-内酰胺类抗生素是奶牛场最常用的药物。

Modern medical and veterinary practice relies on effective antibiotics to prevent and treat infections in humans and animals. The prevalence of antibiotic resistance in bacteria is one of the most intractable challenges in 21st century public health. Approximately 80% of the total antibiotic consumption are used in food animals. Thus, a better understanding of the impacts of antibiotics used on farms would produce a more robust platform for public policy. The most common reason for antibiotic use on dairy farms is to treat and prevent mastitis. Mastitis is a disease of major economic importance (approximately $350 million loss per year for the Canadian dairy industry). Mastitis can be caused by both Gram-positive and Gram-negative bacteria. Most antimicrobial therapies for mastitis have been targeted against Gram-positive bacteria. The most common Gram-positive bacteria from bovine mammary glands are staphylococci, including Staphylococcus aureus and coagulase-negative staphylococcus (CNS). Most milk S. aureus and CNS isolates are multi-drug resistant. A particular type of antimicrobial resistance among staphylococci, methicillin resistance (MR), has been a recent focus of mastitis researchers, since members of the β-lactam class of antibiotics are the most commonly used drugs on dairy farms.