Szczuka Ewa, Jabłońska Lucyna, Kaznowski Adam
Department of Microbiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.
Microbiology (Reading). 2017 May;163(5):712-718. doi: 10.1099/mic.0.000453. Epub 2017 May 9.
Staphylococcus epidermidis is a leading cause of foreign body-associated infections. This is related to the bacterium's ability to form biofilms on synthetic materials. Bacteria within a biofilm may be exposed to subinhibitory concentrations (sub-MICs) of antibiotics because of an agent's limited penetration into the biofilm core. Here, we investigated the effect of sub-MICs of tigecycline and ciprofloxacin on the expression of biofilm-associated genes, i.e. icaA, altE and sigB, and the biofilm structure of five clinical isolates of S. epidermidis. For most tested isolates, the expression of these genes increased after exposure to 0.25 MIC and 0.5 MIC tigecycline. A slight decrease in icaAmRNA levels was observed only in two isolates in the presence of 0.25 MIC tigecycline. The effect of ciprofloxacin exposure was isolate-dependent. At 0.5 MIC, ciprofloxacin induced an increase of sigB and icaAmRNA levels in three of the five tested isolates. At the same time, expression of the altE gene increased in all isolates (from 1.3-fold to 42-fold, depending on the strain). Confocal laser scanning microscopy analysis indicated that sub-MIC ciprofloxacin decreased biofilm formation, whereas tigecycline stimulated this process. Our data suggest that sub-MIC tigecycline may have bearing on the outcome of infections.
表皮葡萄球菌是与异物相关感染的主要病因。这与该细菌在合成材料上形成生物膜的能力有关。由于药物对生物膜核心的渗透有限，生物膜内的细菌可能会接触到亚抑菌浓度（亚 MIC）的抗生素。在此，我们研究了替加环素和环丙沙星的亚 MIC 对表皮葡萄球菌五株临床分离株生物膜相关基因（即 icaA、altE 和 sigB）表达及生物膜结构的影响。对于大多数测试分离株，在接触 0.25 MIC 和 0.5 MIC 替加环素后，这些基因的表达增加。仅在两株分离株中，在存在 0.25 MIC 替加环素的情况下观察到 icaA mRNA 水平略有下降。环丙沙星暴露的影响因分离株而异。在 0.5 MIC 时，环丙沙星在五株测试分离株中的三株中诱导 sigB 和 icaA mRNA 水平增加。同时，altE 基因在所有分离株中的表达均增加（从 1.3 倍到 42 倍，取决于菌株）。共聚焦激光扫描显微镜分析表明，亚 MIC 环丙沙星可减少生物膜形成，而替加环素则刺激这一过程。我们的数据表明，亚 MIC 替加环素可能与感染结局有关。
