Schinasi Leah, Wing Steve, Augustino Kerri L, Ramsey Keith M, Nobles Delores L, Richardson David B, Price Lance B, Aziz Maliha, MacDonald Pia D M, Stewart Jill R
Department of Epidemiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Environ Health. 2014 Jun 23;13(1):54. doi: 10.1186/1476-069X-13-54.
Distinct strains of methicillin resistant Staphylococcus aureus (MRSA) have been identified on livestock and livestock workers. Industrial food animal production may be an important environmental reservoir for human carriage of these pathogenic bacteria. The objective of this study was to investigate environmental and occupational exposures associated with nasal carriage of MRSA in patients hospitalized at Vidant Medical Center, a tertiary hospital serving a region with intensive livestock production in eastern North Carolina.
MRSA nasal carriage was identified via nasal swabs collected within 24 hours of hospital admission. MRSA carriers (cases) were gender and age matched to non-carriers (controls). Participants were interviewed about recent environmental and occupational exposures. Home addresses were geocoded and publicly available data were used to estimate the density of swine in residential census block groups of residence. Conditional logistic regression models were used to derive odds ratio (OR) estimates and 95% confidence intervals (CI). Presence of the scn gene in MRSA isolates was assessed. In addition, multi locus sequence typing (MLST) of the MRSA isolates was performed, and the Diversilab® system was used to match the isolates to USA pulsed field gel electrophoresis types.
From July - December 2011, 117 cases and 119 controls were enrolled. A higher proportion of controls than cases were current workforce members (41.2% vs. 31.6%) Cases had a higher odds of living in census block groups with medium densities of swine (OR: 4.76, 95% CI: 1.36-16.69) and of reporting the ability to smell odor from a farm with animals when they were home (OR: 1.51, 95% CI: 0.80-2.86). Of 49 culture positive MRSA isolates, all were scn positive. Twenty-two isolates belonged to clonal complex 5.
Absence of livestock workers in this study precluded evaluation of occupational exposures. Higher odds of MRSA in medium swine density areas could reflect environmental exposure to swine or poultry.
已在牲畜及畜牧工人身上发现了不同菌株的耐甲氧西林金黄色葡萄球菌（MRSA）。工业化食用动物生产可能是人类携带这些病原菌的一个重要环境储存库。本研究的目的是调查在维丹特医疗中心住院的患者中，与MRSA鼻腔携带相关的环境和职业暴露情况。维丹特医疗中心是一家为北卡罗来纳州东部集约化牲畜生产地区服务的三级医院。
通过在入院24小时内采集的鼻拭子来确定MRSA鼻腔携带情况。MRSA携带者（病例）在性别和年龄上与非携带者（对照）相匹配。对参与者进行了关于近期环境和职业暴露的访谈。对家庭住址进行了地理编码，并使用公开可用数据来估计居住普查街区组中猪的密度。使用条件逻辑回归模型得出比值比（OR）估计值和95%置信区间（CI）。评估了MRSA分离株中scn基因的存在情况。此外，对MRSA分离株进行了多位点序列分型（MLST），并使用Diversilab®系统将分离株与美国脉冲场凝胶电泳类型进行匹配。
2011年7月至12月，共纳入117例病例和119例对照。对照中当前在职人员的比例高于病例（41.2%对31.6%）。病例居住在猪密度中等的普查街区组中的几率更高（OR：4.76，95%CI：1.36 - 16.69），且报告在家时能闻到来自有动物农场的气味的几率也更高（OR：1.51，95%CI：0.80 - 2.86）。在49株培养阳性的MRSA分离株中，所有分离株scn均为阳性。22株分离株属于克隆复合体5。
本研究中没有畜牧工人，因此无法评估职业暴露情况。在猪密度中等的地区，MRSA感染几率较高可能反映了对猪或家禽的环境暴露。
