The Food and Drug Administration never reviewed data from manufacturers regarding the procedures needed to clean the complex medical devices that recently infected seven patients with drug-resistant bacteria, an agency official acknowledged on Wednesday.

Now the F.D.A. has asked manufacturers to provide evidence that their recommended disinfection methods work, said Dr. Stephen Ostroff, the agency’s chief scientist.

“Institutions appear to have been doing the recommended procedures, and doing them extremely well,” said Dr. Ostroff, who will become acting commissioner when Dr. Margaret Hamburg departs. But the recent infections, at Ronald Reagan U.C.L.A. Medical Center, show that additional precautions may be needed, he said.

Duodenoscopes have been implicated in similar outbreaks at other hospitals. In 2013, 39 patients at Advocate Lutheran General Hospital in Park Ridge, Ill., were infected with carbapenem-resistant Enterobacteriaceae (CRE), also the cause of the infections in Los Angeles.