The accused have the right to appeal to Libya's Supreme Court.
The medical workers, held for the past seven years, had previously been sentenced to death in May 2004, but the Supreme Court ordered a retrial following an appeal.
The case has provoked outrage abroad, and European governments have called for the medical workers' release.
Amnesty International has called on Libya not to carry out the death sentence which was "imposed after a grossly unfair trial."
The Finnish EU Presidency and Palestinian officials condemned the sentence and appealed for clemency.
The EU justice commissioner expressed shock at the decision, and Bulgaria's parliament speaker called on the Libyan authorities not to allow the executions.
Bulgarian officials and rights groups say the children were infected due to unhygienic practices at the hospital in Benghazi, and argue that the accused have been made scapegoats for the children's illnesses.