4株鸭源肠球菌的鉴定和致病性

对临床分离的4株鸭源肠球菌郑1株、郑2株、郑3株、北京株和1株粪肠球菌参考菌株进行了系统鉴定,并用SDS-PAGE和Western-blot技术对各菌株细胞壁蛋白图谱进行比较分析。结果5个菌株的形态、染色、生理生化特性均与粪肠球菌特性一致;它们均对青霉素、万古霉素和庆大霉素敏感而对四环素耐药;5个菌株人工感染雏鸭及小白鼠均有致病性,但各菌株间致病力存在差异,北京株最强,参考株最弱,其余3株介于北京株和参考株之间;各菌株的细胞壁蛋白经SDS-PAGE在相对分子质量33 370~131 690之间均显示数十条蛋白带,其中郑2株和北京株在相对分子质量66 840处均有1条染色较深的蛋白带,而用Western-blot分析显示抗北京株胞壁蛋白抗体只能检测到北京株相对分子质量为66 840的抗原蛋白。以上结果表明,这5个被检菌株为致病性粪肠球菌,且致病性以北京株最强。

Identification and virulence of four Enterococcus strains isolated from ducks

Four isolates obtained from dying ducks with Enterococcus in Beijing and Hubei province in 2000-2004 and one reference strain of E.faecalis were identified.Then the cell wall proteins profiles of these strains were compared by SDS-PAGE.Additionally,Western-blot analysis was performed on the cell wall proteins of these strains using sera of rabbits,experimentally infected with Beijing strain.The morphological,cultural and biochemistry characters indicated that the isolated bacteria belonged to genus E.faecalis.Sensitivity tests showed that all the five strains were sensitive to penicillin,vancomycin and gentamgcin,but resistant to tetracycline.Furthermore,experimental infections indicated that these strains were of differing virulence.Beijing strain was of the highliest virulence and the reference strain was of the lowest.The cell wall proteins of these strains exhibited complex array of more than 10 bands ranging from 33 370-131 690 by SDS-PAGE.However,the positive proteins were only observed in Beijing strain with a molecular mass 66 840.These findings may indicate that all the isolates obtained from ducks should be E.faecalis of different virulence.Beijing strain of highly virulence which has a antigen protein with a molecular mass 66 840.And this protein may be useful as additional virulence associated markers for E.faecalis.