Leuck Anne-Marie, Johnson James R, Dunny Gary M
Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America.
Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America; VA Health Care System, Minneapolis, Minnesota, United States of America.
PLoS One. 2014 Sep 25;9(9):e107282. doi: 10.1371/journal.pone.0107282. eCollection 2014.
Biofilm formation may play an important role in the pathogenesis of infections caused by Enterococcus faecalis, including endocarditis. Most biofilm studies use a polystyrene dish assay to quantify biofilm biomass. However, recent studies of E. faecalis strains in tissue and animal models suggest that polystyrene dish results need to be interpreted with caution. We evaluated 158 clinical E. faecalis isolates using a polystyrene dish assay and found variation in biofilm formation, with many isolates forming little biofilm even when different types of media were used. However, all tested clinical isolates were able to form biofilms on porcine heart valve explants. Dextrose-enhanced biofilm formation in the polystyrene dish assay was found in 6/12 (50%) of clinical isolates tested and may explain some, but not all of the differences between the polystyrene dish assay and the heart valve assay. These findings suggest that in studies assessing the clinical relevance of enterococcal biofilm-forming ability, ex vivo biofilm formation on a relevant tissue surface may be warranted to validate results of in vitro assays.
生物膜形成可能在粪肠球菌引起的感染（包括心内膜炎）发病机制中起重要作用。大多数生物膜研究使用聚苯乙烯培养皿试验来量化生物膜生物量。然而，最近对组织和动物模型中的粪肠球菌菌株研究表明，聚苯乙烯培养皿试验结果需谨慎解读。我们使用聚苯乙烯培养皿试验评估了158株临床粪肠球菌分离株，发现生物膜形成存在差异，即使使用不同类型的培养基，许多分离株形成的生物膜也很少。然而，所有测试的临床分离株都能够在猪心脏瓣膜外植体上形成生物膜。在测试的12株临床分离株中有6株（50%）在聚苯乙烯培养皿试验中出现葡萄糖增强的生物膜形成，这可能解释了聚苯乙烯培养皿试验和心脏瓣膜试验之间的部分而非全部差异。这些发现表明，在评估肠球菌生物膜形成能力的临床相关性的研究中，可能需要在相关组织表面进行体外生物膜形成试验，以验证体外试验结果。
