Ramadhan A A, Hegedus E
School of Biomedical Sciences, Faculty of Health, Sciences, Cumberland Campus, PO Box 170, Lidcombe, NSW 1825, Australia.
J Clin Pathol. 2005 Jul;58(7):685-6. doi: 10.1136/jcp.2004.024109.
To investigate biofilm production and esp carriage in enterococci.
Biofilm production in vancomycin resistant enterococci (VRE) and vancomycin susceptible enterococci (VSE) was tested on a microtitre plate method, using both brain heart infusion (BHI) broth and human serum as media. Isolates were screened for the esp gene, which has been reported to be essential for biofilm formation in enterococci, by means of the polymerase chain reaction.
None of seven VRE and nine of 28 VSE tested formed a biofilm. One initially negative VRE Enterococcus faecium isolate produced a strong biofilm after 21 weeks of dry starvation on a cotton swab. By Fisher's exact test, there was no significant difference in biofilm formation between VRE and VSE, E faecalis and E faecium, or isolates from different sites. Biofilm formation was independent of possession of the esp gene. One isolate produced a strong biofilm in human serum but only a weak biofilm in BHI, whereas another produced a moderate biofilm in human serum but a weak biofilm in BHI.
The acquisition of vancomycin resistance may result in a lower ability to form biofilms, but a larger study using clinical isolates is needed to test this hypothesis. That one initially negative VRE isolate produced a strong biofilm after prolonged dry starvation suggests that biofilm formation may be an adaptive response. The esp gene does not appear to be necessary or sufficient for production of biofilms in enterococci.
研究肠球菌生物膜的形成及肠球菌表面蛋白（esp）的携带情况。
采用微量滴定板法，以脑心浸液（BHI）肉汤和人血清为培养基，检测耐万古霉素肠球菌（VRE）和万古霉素敏感肠球菌（VSE）生物膜的形成情况。通过聚合酶链反应筛选分离株中与肠球菌生物膜形成密切相关的esp基因。
所检测的7株VRE中无一形成生物膜，28株VSE中有9株形成生物膜。一株最初呈阴性的VRE粪肠球菌分离株在棉拭子上干燥饥饿21周后形成了较强的生物膜。经Fisher精确检验，VRE与VSE之间、粪肠球菌与屎肠球菌之间或不同部位分离株的生物膜形成无显著差异。生物膜的形成与esp基因的携带无关。一株分离株在人血清中形成较强的生物膜，但在BHI中仅形成较弱的生物膜；而另一株在人血清中形成中等强度的生物膜，但在BHI中形成较弱的生物膜。
获得万古霉素耐药性可能导致生物膜形成能力降低，但需要进行更大规模的临床分离株研究来验证这一假设。一株最初呈阴性的VRE分离株在长期干燥饥饿后形成较强的生物膜，提示生物膜形成可能是一种适应性反应。在肠球菌中，esp基因似乎并非生物膜形成所必需或充分条件。
