METHODS:It was treated by membrane filtration,we suspended the membrane in sterrilled normal saline and washed it by ultrasonics,then tested the microbial limit by regular method.

• 方法:经薄膜过滤法处理后，将滤膜置灭菌生理盐水中，超声洗菌，再按常规进行微生物限度检查。