Akridge Heather D, Rankin Shelley C, Griffeth Gregory C, Boston Raymond C, Callori Nancy E, Morris Daniel O
Department of Clinical Studies - Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA, 19104, USA.
Vet Dermatol. 2013 Oct;24(5):525-e124. doi: 10.1111/vde.12061. Epub 2013 Sep 2.
Meticillin-resistant Staphylococcus aureus (MRSA) strain USA 500 predominately colonizes horses and people working with them. Previous studies demonstrate that some Staphylococcus species exhibit higher affinity for corneocytes of specific mammalian species.
HYPOTHESIS/OBJECTIVES: The objective was to determine the relative affinities of various MRSA strains, meticillin-susceptible S. aureus (MSSA) strains and a meticillin-susceptible Staphylococcus pseudintermedius (MSSP) for equine corneocytes. We hypothesized that MRSA strain USA 500 would exhibit greater adhesion than other staphylococcal strains tested.
Epidemic MRSA strains (USA 100, USA 300, USA 500 and USA 800), two MSSA control strains and an MSSP field strain were tested on corneocytes from 15 client-owned horses. Isolates were incubated with corneocytes in conditions (bacterial concentration of 10(8) colony-forming units/mL for 45 min) recently shown to maximize adherence of S. aureus without competitive interference. A validated image-analysis system was used to quantify the cell surface density of bacterial adhesion.
The MSSP strain adhered with significantly higher affinity (P < 0.0015) to corneocytes than did MSSA strains. All MRSA strains other than USA 500 had significantly higher affinity than MSSA strains (P range <0.03 to <0.0015). There were no statistical differences in adhesion between strain USA 500 and the other MRSA strains tested.
Meticillin-resistant S. aureus strain USA 500 did not adhere more robustly than other strains of Staphylococcus; therefore, its affinity to colonize horses may not be solely attributed to corneocyte adhesion. Additional studies are required to explain the epidemiological role of this strain as the predominant cause of colonization and infections of horses in North America.
耐甲氧西林金黄色葡萄球菌（MRSA）美国500型主要定植于马匹及与马匹接触的人员。先前的研究表明，某些葡萄球菌物种对特定哺乳动物物种的角质形成细胞具有更高的亲和力。
假设/目的：目的是确定各种MRSA菌株、甲氧西林敏感金黄色葡萄球菌（MSSA）菌株和一株甲氧西林敏感中间葡萄球菌（MSSP）对马角质形成细胞的相对亲和力。我们假设MRSA美国500型菌株的黏附力会高于所测试的其他葡萄球菌菌株。
对流行的MRSA菌株（美国100型、美国300型、美国500型和美国800型）、两株MSSA对照菌株和一株MSSP野外菌株在15匹客户拥有的马的角质形成细胞上进行测试。将分离菌株与角质形成细胞在最近显示能使金黄色葡萄球菌黏附最大化且无竞争干扰的条件下（细菌浓度为10⁸ 菌落形成单位/毫升，孵育45分钟）孵育。使用经过验证的图像分析系统来量化细菌黏附的细胞表面密度。
MSSP菌株对角质形成细胞的黏附亲和力显著高于MSSA菌株（P < 0.0015）。除美国500型菌株外的所有MRSA菌株的亲和力均显著高于MSSA菌株（P值范围为<0.03至<0.0015）。美国500型菌株与所测试的其他MRSA菌株之间的黏附无统计学差异。
耐甲氧西林金黄色葡萄球菌美国500型菌株的黏附力并不比其他葡萄球菌菌株更强；因此，其在马匹中定植的亲和力可能并非完全归因于对角质形成细胞的黏附。需要进一步研究来解释该菌株作为北美马匹定植和感染的主要原因所起的流行病学作用。
