The cause of deaths of the four newborns at Ewha Womans University Hospital was Citrobacter sepsis, police said Friday.
“Combining the results of the epidemiological investigation by the Korea Centers for Disease Control and Prevention and those of the autopsies by the National Forensic Service, we have concluded that the four newborns died of sepsis, caused by an infection with Citrobacter freundii,” the Seoul Metropolitan Police Agency said.
According to police, the NFS autopsies found the bacteria in all of the blood samples of the four dead newborns.
“It was rare that the newborns infected with the bacteria died almost at the same time,” the NFS said. “Considering that all the babies showed a drastic change in heartbeats and bloated bellies, it is likely that they were infected at around the same time and showed similar developments.”
As for the transmission route, the NFS said the injections of nutritional supplements were either contaminated initially or became so while being handled to be injected into intravenous tubes.
“There is a possibility that either lipid-based nutritional supplements in a vial were contaminated or the contamination occurred while the vial was open and the supplements were injected,” the police also said.
However, the police said they could not confirm the possibility of contamination of the nutritional supplements because they were still waiting for the test results from the Ministry of Food and Drug Safety.
The NFS said it was unlikely that the premature babies died of infections with Rotavirus or necrotizing enterocolitis, although it detected Rotavirus from the bodies of the newborns.
Autopsies showed that Rotavirus was detected only inside the small and large intestines, and there were other surviving babies also infected with Rotavirus at the time, the NFS said.
The police said they would book five medical staffs on charges of involuntary manslaughter. The two nurses allegedly infringed on the duty of infection control while handling the injection of nutrient supplements. A chief nurse, a specialist, and an attending physician reportedly breached the duty of guide and supervision of the two nurses.
The police also said they would summon Professor Cho Su-jin, chief of the intensive care unit, as a suspect Tuesday.
The KCDC said it would work closely with the police if there is a need for finding an additional epidemiological cause. “If necessary, we will carry out communication with related agencies swiftly, accurately, and transparently,” it said.