实验性金黄色葡萄球菌角膜炎期间家兔的年龄相关差异。

Age-related differences in rabbits during experimental Staphylococcus aureus keratitis.

作者信息

O'Callaghan Richard J, McCormick Clare C, Caballero Armando R, Marquart Mary E, Gatlin Hattie P, Fratkin Jonathan D

机构信息

Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216, USA.

出版信息

Invest Ophthalmol Vis Sci. 2007 Nov;48(11):5125-31. doi: 10.1167/iovs.07-0320.

DOI:10.1167/iovs.07-0320

PMID:17962465

Abstract

PURPOSE

To analyze age-related changes in susceptibility to experimental Staphylococcus aureus keratitis and purified alpha-toxin in rabbits.

METHODS

Intrastromal injection of S. aureus (100 colony-forming units [CFUs]) induced keratitis in young (6-8 weeks) and aged (approximately 30 months) New Zealand White rabbits. Bacteria and polymorphonuclear leukocytes (PMNs) per cornea were quantified. Purified alpha-toxin at 1, 10, 25, or 50 hemolytic units (HU) or heat-inactivated alpha-toxin was intrastromally injected into corneas, and pathologic changes were determined by slit lamp examination (SLE) and histopathologic analysis. alpha-Toxin hemolysis assays were performed using erythrocytes from young and aged rabbits.

RESULTS

S. aureus keratitis produced significantly higher SLE scores in young rabbits than in aged rabbits at 15, 20, and 25 hours postinfection (PI; P < or = 0.001); aged rabbits essentially recovered from S. aureus keratitis by 7 days PI. At 25 hours PI, numbers of CFUs and PMNs in corneas of young and aged rabbits were equivalent (P > or = 0.6); the bacterial burden in aged rabbits declined by 5 logs per cornea from day 1 to day 7 PI. Intrastromal injection of > or =10 HU alpha-toxin also produced significantly more disease in young than in aged rabbit corneas (P < or = 0.05), whereas 1 HU or heat-inactivated toxin yielded negligible pathologic changes in either group. Hemolysis assays of erythrocytes from young rabbits demonstrated greater susceptibility to alpha-toxin compared with those from aged rabbits.

CONCLUSIONS

Corneas and erythrocytes of young rabbits, relative to aged rabbits, are significantly more susceptible to S. aureus keratitis and to alpha-toxin.

摘要

目的

分析兔对实验性金黄色葡萄球菌角膜炎及纯化α毒素易感性的年龄相关变化。

方法

对年轻（6 - 8周）和老龄（约30个月）的新西兰白兔进行基质内注射金黄色葡萄球菌（100个菌落形成单位[CFU]）诱导角膜炎。对每只角膜中的细菌和多形核白细胞（PMN）进行定量。将1、10、25或50溶血单位（HU）的纯化α毒素或热灭活α毒素基质内注射到角膜中，通过裂隙灯检查（SLE）和组织病理学分析确定病理变化。使用年轻和老龄兔的红细胞进行α毒素溶血试验。

结果

感染后15、20和25小时，年轻兔的金黄色葡萄球菌角膜炎产生的SLE评分显著高于老龄兔（P≤0.001）；老龄兔在感染后7天基本从金黄色葡萄球菌角膜炎中恢复。在感染后25小时，年轻和老龄兔角膜中的CFU数量和PMN数量相当（P≥0.6）；从感染第1天到第7天，老龄兔角膜中的细菌载量每只角膜下降5个对数。基质内注射≥10 HU的α毒素在年轻兔角膜中产生的病变也明显多于老龄兔角膜（P≤0.05），而1 HU或热灭活毒素在两组中产生的病理变化可忽略不计。与老龄兔的红细胞相比，年轻兔的红细胞溶血试验显示对α毒素更敏感。