Linhares Leticia L, Yang My, Sreevatsan Srinand, Munoz-Zanzi Claudia A, Torremorell Montserrat, Davies Peter R
Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN (Linhares, Yang, Sreevatsan, Torremorell, Davies)Division of Epidemiology & Community Health, School of Public Health, University of Minnesota, Minneapolis, MN (Munoz-Zanzi).
Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN (Linhares, Yang, Sreevatsan, Torremorell, Davies)Division of Epidemiology & Community Health, School of Public Health, University of Minnesota, Minneapolis, MN (Munoz-Zanzi)
J Vet Diagn Invest. 2015 Jan;27(1):55-60. doi: 10.1177/1040638714559598.
Despite active research into methicillin-resistant Staphylococcus aureus (MRSA) in pigs since 2004, the ecology of the susceptible ancestral organism has been neglected. A longitudinal study of pigs in 2 intensive production systems was conducted to investigate the effects of age and anatomical site on detection of S. aureus. Sampling was replicated in 2 cohorts per farm, with swabs collected from the nares, tonsils, skin (axilla), and rectum in lactating sows, suckling, weaned, and market-age pigs, plus the vagina of sows. No MRSA were isolated, but S. aureus was detected in a least 1 site in 175 (91.1%) out of 192 pigs. Pig-level prevalence did not differ among the age groups, but the proportion of positive samples (all sites) was higher in market-age pigs (75.2%) and nursery-age pigs (63.2%) than in sows (40.7%) and suckling piglets (38%). Prevalence did not differ among nasal (67.9%), skin (62.3%), and tonsil (61.7%) swabs, but was lower in rectal (42%) and vaginal swabs (39.6%). Multiple multilocus sequence typing (MLST) and spa types were found in both production systems, but all isolates were of ST398, ST9, or ST5. These MLST lineages have been variably predominant among reports of MRSA in pigs on 3 continents, and the presence of methicillin-sensitive variants in several countries raises the likelihood that MRSA in pigs has likely resulted from independent acquisition of the mecA gene by multiple S. aureus lineages that have been adapted to swine over the long term, rather than recent introduction of novel clones into swine populations.
尽管自2004年以来一直在积极研究猪体内的耐甲氧西林金黄色葡萄球菌（MRSA），但对该易感祖先菌株的生态学研究却被忽视了。对两个集约化生产系统中的猪进行了一项纵向研究，以调查年龄和解剖部位对金黄色葡萄球菌检测的影响。每个农场的两个队列进行了重复采样，从泌乳母猪、哺乳仔猪、断奶仔猪、育肥猪的鼻腔、扁桃体、皮肤（腋窝）和直肠以及母猪的阴道采集拭子。未分离出MRSA，但在192头猪中的175头（91.1%）至少一个部位检测到了金黄色葡萄球菌。猪群水平的患病率在各年龄组之间没有差异，但育肥猪（75.2%）和保育猪（63.2%）的阳性样本（所有部位）比例高于母猪（40.7%）和哺乳仔猪（38%）。鼻腔拭子（67.9%）、皮肤拭子（62.3%）和扁桃体拭子（61.7%）的患病率没有差异，但直肠拭子（42%）和阴道拭子（39.6%）的患病率较低。在两个生产系统中都发现了多种多位点序列分型（MLST）和spa型，但所有分离株均为ST398、ST9或ST5。在三大洲关于猪MRSA的报告中，这些MLST谱系的优势各不相同，并且在几个国家存在甲氧西林敏感变体，这增加了猪体内的MRSA可能是由多个长期适应猪的金黄色葡萄球菌谱系独立获得mecA基因所致，而不是近期将新克隆引入猪群的可能性。
