Abstract

Diabetic foot ulcers (DFU) are exacerbated by bacterial colonisation. Here, a high prevalence of Enterococcus faecalis was observed in DFU patients from an Argentinean hospital. E. faecalis was frequently co-isolated with Escherichia coli, Morganella morganii, and Pseudomonas aeruginosa. The effect of interspecies interactions on bacterial growth was investigated in mixed-species macrocolony biofilms developed in Lubbock-Glc-agar. Similar cell counts were found for E. faecalis and M. morganii growing in mixed and single-species biofilms. An E. faecalis strain showed 1 Log higher cell counts in mixed biofilms with E. coli. Remarkably, E. faecalis strains showed 2 to 4 Log higher cell counts in mixed biofilms with P. aeruginosa. This effect was not observed in planktonic growth or biofilms developed in tryptic soy agar. The present findings reveal bacterial interactions that benefit E. faecalis in mixed-species biofilms, mainly with P. aeruginosa, in a medium that partially mimics the nutrients found in DFU.

摘要

细菌定植会加剧糖尿病足溃疡（DFU）。在阿根廷一家医院的 DFU 患者中观察到粪肠球菌的患病率很高。粪肠球菌经常与大肠杆菌、摩根氏菌和铜绿假单胞菌同时分离。在拉伯克-葡萄糖琼脂中形成的混合物种大菌落生物膜中研究了物种间相互作用对细菌生长的影响。在混合和单一物种生物膜中生长的粪肠球菌和莫氏分枝杆菌的细胞计数相似。粪肠球菌菌株在与大肠杆菌混合的生物膜中显示出高出 1 个对数的细胞计数。值得注意的是，粪肠球菌菌株在与铜绿假单胞菌的混合生物膜中显示出高出 2 至 4 Log 的细胞计数。在胰蛋白酶大豆琼脂中的浮游生长或生物膜中没有观察到这种效应。目前的研究结果表明，在部分模拟 DFU 中营养物质的培养基中，混合物种生物膜中的粪肠球菌（主要是与铜绿假单胞菌）之间的细菌相互作用有利于粪肠球菌。