Leung J W, Liu Y L, Desta T, Libby E, Inciardi J F, Lam K
Division of Gastroenterology and C. W. Law Biofilm Research Center, University of California, Davis Medical Center, Sacramento 95817, USA.
Gastrointest Endosc. 1998 Sep;48(3):250-7. doi: 10.1016/s0016-5107(98)70186-5.
Biliary sludge which forms as a result of bacterial adherence and biofilm formation in the biliary system is a recognized cause of blockage of plastic stents. Bacteriological cultures of sludge have revealed a mixed infection with gram-positive and gram-negative bacteria. Animal studies have shown that prophylactic ciprofloxacin, which selectively suppress gram-negative bacteria, results in prolonged stent patency despite colonization of the stents by gram-positive bacteria.
We tested a possible synergistic effect between gram-negative and gram-positive bacteria in adherence and biofilm formation on plastic stents. Clinical isolates of Escherichia coli and Enterococcus were cultured in separate chemostats to achieve a steady growth. Adherence of the two bacteria on plastic stent surface were tested separately by perfusing infected bile with the respective bacteria through different modified Robbins devices containing 10F polyethylene stent pieces up to 4 days. In a second experiment, Enterococcus was perfused through stent pieces precolonized with E. coli for 24 hours. The stent pieces were then removed daily and analyzed by bacteriologic culture and scanning electron microscopy for bacterial adherence and biofilm formation.
Gram-negative E. coli were more adherent than gram-positive Enterococcus. Precolonization with E. coli facilitates subsequent attachment of Enterococcus.
We concluded that there is a synergistic effect between gram-positive and gram-negative bacteria in adherence and biofilm formation.
胆道系统中由于细菌黏附和生物膜形成而产生的胆泥是塑料支架堵塞的一个公认原因。胆泥的细菌培养显示存在革兰氏阳性菌和革兰氏阴性菌的混合感染。动物研究表明，选择性抑制革兰氏阴性菌的预防性环丙沙星可使支架通畅时间延长，尽管支架被革兰氏阳性菌定植。
我们测试了革兰氏阴性菌和革兰氏阳性菌在塑料支架黏附和生物膜形成方面可能存在的协同作用。将大肠杆菌和肠球菌的临床分离株分别在恒化器中培养以实现稳定生长。通过将含有各自细菌的感染胆汁灌注通过不同的改良Robbins装置（包含10F聚乙烯支架片段）长达4天，分别测试这两种细菌在塑料支架表面的黏附情况。在第二个实验中，将肠球菌灌注通过预先被大肠杆菌定植24小时的支架片段。然后每天取出支架片段，通过细菌培养和扫描电子显微镜分析细菌黏附和生物膜形成情况。
革兰氏阴性的大肠杆菌比革兰氏阳性的肠球菌更具黏附性。大肠杆菌的预先定植促进了肠球菌随后的附着。
我们得出结论，革兰氏阳性菌和革兰氏阴性菌在黏附和生物膜形成方面存在协同作用。
