Sandoe Jonathan A T, Witherden Ian R, Cove Jonathan H, Heritage John, Wilcox Mark H
Department of Microbiology, The General Infirmary at Leeds1 and University of Leeds2, Leeds LS1 3EX, UK.
J Med Microbiol. 2003 Jul;52(Pt 7):547-550. doi: 10.1099/jmm.0.05201-0.
Hospital-acquired infections caused by enterococci have increased dramatically since the 1970s. Many nosocomial enterococcal bloodstream infections are associated with medical devices such as central venous catheters. The ability to form biofilm on medical devices is a potential virulence trait that may allow enterococci to cause infections in the expanding population of patients managed with such devices. In this study, the hypothesis that increased ability to form biofilm in vitro is associated with medical-device-related infection in vivo was tested. A microplate assay was employed to assess biofilm-forming characteristics of enterococci in 0.9 % (w/v) sodium chloride, an oligotrophic environment, and BHI, a nutrient-rich environment. Results were compared in isolates from different sources of infection. One hundred and nine enterococcal bloodstream isolates were assayed. Biofilm formation on microplates was demonstrated by all Enterococcus faecalis isolates and 16/38 (42 %) Enterococcus faecium isolates. E. faecalis isolates produced significantly more biofilm than E. faecium isolates in both media (P < 0.0001, Mann-Whitney U test). E. faecalis isolates from intravascular-catheter-related bloodstream infections (CRBSIs) produced significantly more biofilm than non-CRBSI isolates (P < 0.0001), or isolates of uncertain clinical significance (P < 0.0001). Biofilm formed by E. faecium isolates was not significantly affected by culture medium and did not differ between isolates from the different clinical categories. In conclusion, there was significantly more biofilm formed by E. faecalis isolates causing CRBSI compared with isolates from other types of infection or from isolates of uncertain clinical significance. The ability of E. faecalis isolates to form biofilm in vitro appears to be a marker of a virulence trait that enhances the ability of isolates to cause CRBSI.
自20世纪70年代以来，由肠球菌引起的医院获得性感染急剧增加。许多医院内肠球菌血流感染与诸如中心静脉导管等医疗设备有关。在医疗设备上形成生物膜的能力是一种潜在的毒力特性，这可能使肠球菌在使用此类设备治疗的患者群体不断扩大的情况下引发感染。在本研究中，对体外形成生物膜能力增强与体内医疗设备相关感染有关这一假设进行了检验。采用微孔板试验评估肠球菌在0.9%（w/v）氯化钠（一种贫营养环境）和脑心浸液（一种营养丰富的环境）中形成生物膜的特性。对来自不同感染源的分离株的结果进行了比较。对109株肠球菌血流分离株进行了检测。所有粪肠球菌分离株和16/38（42%）屎肠球菌分离株均在微孔板上形成了生物膜。在两种培养基中，粪肠球菌分离株产生的生物膜均明显多于屎肠球菌分离株（P<0.0001，曼-惠特尼U检验）。来自血管内导管相关血流感染（CRBSI）的粪肠球菌分离株产生的生物膜明显多于非CRBSI分离株（P<0.0001）或临床意义不确定的分离株（P<0.0001）。屎肠球菌分离株形成的生物膜不受培养基的显著影响，不同临床类别分离株之间也无差异。总之，与其他类型感染的分离株或临床意义不确定的分离株相比，引起CRBSI的粪肠球菌分离株形成的生物膜明显更多。粪肠球菌分离株在体外形成生物膜的能力似乎是一种毒力特性的标志，这种特性增强了分离株引起CRBSI的能力。
