粪链球菌引起的尿路感染，有临床诊断意义的最低菌落计数为( )

A．清洁中段尿培养，菌落计数为＜1000/ml
B．清洁中段尿培养，菌落计数为1000/ml
C．清洁中段尿培养，菌落计数为1万/ml
D．清洁中段尿培养，菌落计数为5万/ml
E．清洁中段尿培养，菌落计数为10万/ml