Charges have been brought against doctors, anesthetists, suppliers, technicians and local health officials in the 2007 alleged pipe-fitting mistake that may have led to the deaths, ANSA reported Monday.
The defendants will stand trial July 2 on charges including manslaughter, negligence, supplying incorrect materials and administrative violations, ANSA said.
Among those charged are staff and executives of Ossitalia, a company specializing in the installation of medical gas equipment.
The deaths at Castellaneta hospital in southern Italy initially didn't arouse suspicion, officials said, because the patients, all of whom had heart ailments, were elderly and frail.
The victims' families have joined the case as civil plaintiffs along with the regional government and the local health board, ANSA said.
Public confidence in Italy's health system has been hit by a series of errors and allegedly avoidable deaths in the past years, ANSA reported.