TIANJIN -- The death toll of newborns contracting infection in a hospital of north China's Tianjin Municipality rose to five as one more infant was confirmed dead Sunday, local authorities said.

The mishap happened at Jixian County Maternal and Child Care Service Center, where six newborns developed respiratory problems from March 18.Five of them had been dead as of 2 p.m. Sunday after they were transferred to the Beijing Children's Hospital, said the Tianjin Health Department spokesman.

The other one is still under treatment, the spokesman said.

Initial investigation showed the deaths were caused by hospital-acquired infection of enterobacter cloacae, a clinically significant Gram-negative bacterium.

Medical experts have taken measure to prevent other infants at the Center from contracting the infection, and no new case were found yet, the spokesman said.