The coliforms die from starvation, from inhibition, and lack of space. Thus, the life in the worm bin is critical for maintaining the beneficial nature of the material. If the soil foodweb is not healthy, coliforms can grow in any compost. Those organisms sooner or later get rubbed off as the worm continues to travel. All worms leave behind a mix of smaller organisms, as long as those organisms were present to get a ride on or in the worm to begin with.
Worms are great taxicabs and mixers.
But within the material that the worms are actively consuming and living in, which happens to be where bacterial and fungal growth is most rapid, most active, the worms are selecting for bacterial growth. Thus, vermicompost in which worms are active will be bacterial-dominated. But, as fresh layers of food are added and the worms consume most of the rapidly growing bacteria. Of course, more bacteria grow, but huge numbers of protozoa and bacterial-feeding nematodes consume the bacteria as well as the worms. As worm numbers increase, the older worms which move less rapidly than the baby worms, or perhaps that require fungi for reproduction to proceed, stay in the older compost material.