Jayarao B M, Schilling E E, Oliver S P
Department of Animal Science, University of Tennessee, Knoxville 37901-1071.
J Dairy Sci. 1993 Feb;76(2):468-74. doi: 10.3168/jds.S0022-0302(93)77367-1.
Fifty plasmid-free strains of Streptococcus uberis, including 40 strains isolated from cows in two dairy herds in Tennessee with subclinical and clinical mastitis, 9 strains isolated from cows in the US, and 1 strain from Great Britain were examined for genomic DNA restriction fragment length polymorphisms. The 50 strains belonged to 35 DNA fingerprint patterns. Within a herd, fingerprint patterns from isolates obtained from cows with subclinical mastitis at different periods of the lactation cycle and from episodes of clinical mastitis were similar. Restriction fragment length polymorphism analysis revealed the presence of DNA fragments > or = 21 kb in all 12 strains of S. uberis isolated from episodes of clinical mastitis and in only 8 of the 38 (21%) remaining strains. Cluster analysis placed the 50 strains into eight distinct clusters. Most strains from the northeastern US were confined to one cluster, whereas most of the isolates from episodes of clinical mastitis belonged to two different clusters. These data suggest that clonal diversity exists among strains of S. uberis isolated from bovine mammary secretions.
对50株无质粒的乳房链球菌进行了基因组DNA限制性片段长度多态性检测，其中包括从田纳西州两个奶牛场患有亚临床和临床乳腺炎的奶牛中分离出的40株、从美国奶牛中分离出的9株以及从英国分离出的1株。这50株菌株属于35种DNA指纹图谱类型。在一个牛群中，从处于泌乳周期不同阶段的患有亚临床乳腺炎的奶牛以及临床乳腺炎发病期分离出的菌株的指纹图谱相似。限制性片段长度多态性分析显示，从临床乳腺炎发病期分离出的所有12株乳房链球菌中均存在≥21 kb的DNA片段，而在其余38株（21%）菌株中只有8株存在。聚类分析将这50株菌株分为8个不同的簇。美国东北部的大多数菌株局限于一个簇，而临床乳腺炎发病期分离出的大多数菌株属于两个不同的簇。这些数据表明，从牛乳腺分泌物中分离出的乳房链球菌菌株之间存在克隆多样性。
