Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA.
Vet Microbiol. 2012 Dec 7;160(3-4):539-43. doi: 10.1016/j.vetmic.2012.06.032. Epub 2012 Jun 30.
Animals on farms may be a potential reservoir and environmental source of methicillin-resistant Staphylococcus aureus (MRSA). Expanded surveillance methods for animal-associated MRSA are needed. To develop an environmental sampling method and to determine the correlation between animal and environmental MRSA positivity in the farm setting, we sampled horses, cattle, and their local environments at several farms in the mid-Atlantic United States. We obtained nasal swabs from 13 racehorses at first visit, and 11 racehorses at the same farm eight weeks later. We also sampled 26 pleasure horses and 26 beef cattle from two additional farm sites. Sterilized electrostatic cloths were used to collect dry dust samples from environmental surfaces in proximity to animals; cloths were cultured using a broth enrichment protocol. We described isolates by genotype and antimicrobial susceptibility phenotype. None of the samples (nasal or environmental) were positive from the pleasure horse farm or the cattle farm. On the racehorse farm, 8/13 (61%) nasal and 5/7 (71%) environmental samples were positive for MRSA at the first visit. Isolates found were indistinguishable by pulsed-field gel electrophoresis (PFGE) genotype. We observed significant positive correlation between nasal carriage of MRSA in animals and our ability to isolate MRSA from dry surface samples of their local environments. The methods presented here may aid in surveillance efforts for equine and other animal MRSA. This study successfully applies existing MRSA surveillance methods for indoor, high animal density settings to outdoor and low-density farms.
农场中的动物可能是耐甲氧西林金黄色葡萄球菌（MRSA）的潜在储主和环境来源。需要扩大针对动物相关 MRSA 的监测方法。为了开发一种环境采样方法，并确定农场环境中动物与环境 MRSA 阳性之间的相关性，我们在美国中大西洋地区的几个农场中对马、牛及其周围环境进行了采样。我们首次从 13 匹赛马中获得了鼻腔拭子，8 周后又从同一农场的 11 匹赛马中获得了鼻腔拭子。我们还从另外两个农场采集了 26 匹休闲马和 26 头肉牛。使用经消毒的静电布从靠近动物的环境表面收集干燥灰尘样本；使用肉汤富集方案对布进行培养。我们通过基因型和抗菌药物敏感性表型来描述分离株。从休闲马农场或肉牛农场的任何样本（鼻腔或环境）均未检测到 MRSA 阳性。在赛马农场，首次访问时，13 匹鼻腔样本中有 8 匹（61%）和 7 匹环境样本中有 5 匹（71%）MRSA 阳性。脉冲场凝胶电泳（PFGE）基因型未发现分离株存在差异。我们观察到动物鼻腔携带 MRSA 与我们从其周围环境的干燥表面样本中分离出 MRSA 的能力之间存在显著正相关。这里提出的方法可能有助于对马和其他动物的 MRSA 进行监测。本研究成功地将现有的室内、高动物密度环境下的 MRSA 监测方法应用于室外、低密度的农场。
