Patrick C C, Hetherington S V, Roberson P K, Henwick S, Sloas M M
Department of Infectious Diseases and Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105.
Pediatr Res. 1995 Jan;37(1):70-4. doi: 10.1203/00006450-199501000-00014.
Among coagulase-negative staphylococci, Staphylococcus epidermidis is the species most commonly implicated in catheter-related infections. Whether some staphylococcal organisms are inherently more virulent than others, or whether their ability to infect relates more to the sheer numbers of organisms at the catheter site, remains unclear. We therefore compared eight S. epidermidis isolates and two other coagulase-negative staphylococci using a murine model that allowed us to quantify catheter colonization and abscess formation in the same animal. The organisms were isolated from different clinically relevant settings and were classified according to their slime phenotype. The ability to evoke abscesses or colonize catheters in half of the animals (ID50) was assessed. ID50 inoculum titers (log10 data +/- SD) ranged widely, from 8.5 +/- 0.3 to 10.2 +/- 0.2 for abscess formation (p < 0.005) and from 7.5 +/- 0.5 to 10.3 +/- 1.0 for catheter colonization (p < 0.005). ID50 values by statistical criteria suggested variability among organisms in the ability to induce abscess formation. High slime production correlated with both parameters, but not with the clinical source of the isolate. Our findings demonstrate impressive heterogeneity in the ability of a representative group of S. epidermidis isolates to colonize catheters and to evoke abscess formation and implicate slime productivity as a major virulence factor. The murine model used permitted simultaneous analysis of multiple factors involved in pathogenesis and should be useful in establishing the basis of S. epidermidis pathogenicity.
在凝固酶阴性葡萄球菌中，表皮葡萄球菌是与导管相关感染最常牵连的菌种。一些葡萄球菌生物体是否天生比其他的更具毒性，或者它们的感染能力是否更多地与导管部位的生物体数量有关，仍不清楚。因此，我们使用一种小鼠模型比较了8株表皮葡萄球菌分离株和另外2株凝固酶阴性葡萄球菌，该模型使我们能够在同一只动物中量化导管定植和脓肿形成情况。这些生物体是从不同的临床相关环境中分离出来的，并根据其黏液表型进行分类。评估了在一半动物中诱发脓肿或使导管定植的能力（半数感染剂量[ID50]）。ID50接种滴度（对数10数据±标准差）范围广泛，脓肿形成的滴度为8.5±0.3至10.2±0.2（p<0.005），导管定植的滴度为7.5±0.5至10.3±1.0（p<0.005）。根据统计标准，ID50值表明生物体在诱导脓肿形成的能力方面存在差异。高黏液产生与这两个参数相关，但与分离株的临床来源无关。我们的研究结果表明，一组代表性的表皮葡萄球菌分离株在定植导管和诱发脓肿形成的能力方面存在显著异质性，并表明黏液产生能力是一个主要的毒力因子。所使用的小鼠模型允许同时分析发病机制中涉及的多个因素，并且应该有助于建立表皮葡萄球菌致病性的基础。
