Indeed worker bees have a barbed sting which stays in the body of stung mammals. They will then loose the sting and the poison sack, which will continue to pump into the victim. The ejected sting system also has a gland which emits an odor to signal other bees where the enemy is. This is a great strategy for a social insect which needed a collective defense against large animals.
The sting will however not stay in other insects so that worker bees can sting several times in that case. Wasps and hornets do not have a barbed sting and routinely sting several times in a row. The sting of the queen honeybee is also not barbed.