Prevalance of Community-Acquired MRSA in Live Pigs and thier Human Handlers

描述（由申请人提供）：现在有越来越多的证据表明，牲畜可能参与社区相关耐甲氧西林金黄色葡萄球菌（CA-MRSA）的传播;最近来自欧洲和加拿大的研究报告了一种可能与养猪业相关的新菌株（ST 398）。本研究旨在确定和表征MRSA从猪的农场和饲养场在美国和他们的人类处理。它将确定是否存在猪源菌株，并探讨实施全国范围的农场筛查计划的必要性和可行性，作为监测工具，不仅对MRSA，但对其他新兴的人畜共患病，这将作为现有的监测系统的补充。该研究将检验以下两个零假设：（1）猪和农民携带MRSA的流行率和菌株之间没有关联;（2）与美国流行的菌株相比，猪农民中发现的MRSA菌株不存在遗传差异。这些将通过以下具体目的进行测试：目的1a：表征猪中的MRSA菌株，将这些菌株与从位于新英格兰南部（CT、MA、RI）、马里兰州、宾夕法尼亚州和怀俄明州东部/内布拉斯加州西部的养猪场和饲养场中生活或工作的人分离的菌株进行比较。这些数据将有助于确定MRSA在猪场和饲养场的基线流行率，并确定猪源的新菌株。为了实现这一目标，将从猪和它们的人类处理者身上采集鼻拭子，并进行特定的实验室分析以识别MRSA。目的1b：确定猪处理者MRSA感染的危险因素。这将通过对人类进行问卷调查来实现，以确定与MRSA定植相关的可能风险因素。如果存在这样的风险因素，这项研究将提供数据来开发系统，以测试并最终防止MRSA从猪传播到人类，从而减少新出现的菌株在人群中的传播。目的2：将目的1中鉴定的MRSA菌株与美国现有的流行菌株进行比较。将通过CDC的新兴感染项目的主动细菌核心监测（ABC）获得的从人类MRSA病例中分离的菌株数据与本研究中获得的菌株进行比较。这将能够解决新出现的菌株的负担和范围，如果它们存在的话。公共卫生相关性：随着MRSA流行病学的变化，需要关于其范围和负担程度的准确信息，以使公共卫生专业人员能够确定预防和控制的优先事项，特别是在职业暴露方面。它还将揭示猪中MRSA的公共卫生影响，因为养猪户或处理者可能是他们居住的社区其他人的感染源。

DESCRIPTION (provided by applicant): There is now growing evidence that livestock may be involved in spread of community-associated Methicillin Resistant Staphylococcus aureus (CA-MRSA); recent studies from Europe and Canada report a new strain (ST 398) that maybe associated with pig farming. This study seeks to identify and characterize MRSA from pigs on farms and in feedlots in the United States and from their human handlers. Lt will determine if a strain of swine origin exists, and also explore the necessity and feasibility of implementing a nation-wide farm screening scheme as a surveillance tool not only for MRSA but for other emerging zoonoses, which would serve as a complement to existing surveillance systems. The study will test the following two null hypotheses: (1) there is no association between MRSA carriage in pigs and farmers, in terms of prevalence rate and strain; (2) genetic difference do not exist in MRSA strains found in pig farmers compared to the strains circulating in the US. These will be tested by the following specific aims: Aim 1a: characterize MRSA strains in pigs, compare these to strains isolated from humans living or working on pig farms and feedlots located in southern New England (CT, MA, Rl,), Maryland, Pennsylvania and eastern Wyoming/western Nebraska. These data will help determine the baseline prevalence of MRSA on pig farms and feedlots and identify emerging strains of swine origin. To achieve this, nasal swabs will be taken from both pigs and their human handlers, and specific laboratory analysis will be done to identify MRSA. Aim 1b: determine risk factors for MRSA infection in pig handlers. This will be achieved by administrating a questionnaire to the humans to identify possible risk factors associated with MRSA colonization. If such risk factors exist, this study will provide data to develop systems to test for and eventually prevent transmission of MRSA from pigs to humans, thereby reducing the spread of an emerging strain within the human population. Aim 2: compare the MRSA strains identified in Aim 1 to existing strains circulating in the US. Data on strains isolated from human MRSA cases obtained through Active Bacterial Core surveillance (ABCs) by CDC's' Emerging Infections Program will be compared to the strains obtained in this study. This will be able to address the burden and scope of the emerging strains if they exist. PUBLIC HEALTH RELEVANCE: As the epidemiology of MRSA changes, accurate information on its scope and magnitude of the burden is needed to enable public health professionals to set priorities for prevention and control especially with regards to occupational exposure. Also it will reveal the public health implications of MRSA in pigs since pig farmers or handlers maybe a source of infection for the rest of the community they reside in.