Health officials are investigating a third death linked to a contaminated drip given as a nutritional supplement to a number of premature babies. The baby was being treated at Addenbrooke's Hospital in Cambridge.
Officials said that preliminary inquiries have shown that the equipment used to treat the youngster contained a bacteria thought to have come from a batch of fluid called parental nutrition, which is supposed to deliver a variety of nutrients intravenously when a baby is unable to eat on its own.
The premature baby was given fluid from the suspected contaminated batch on May 27 but was not identified to have developed blood poisoning straight away afterwards, as seen in other cases.
The child's death has been referred to the coroner, a spokeswoman said.
Experts at Public Health England and the Medicines and Healthcare Regulatory Agency are now looking into a total of 23 cases of babies thought to be infected with the bacillus cereus bacteria after being given the feed, including three deaths.
A spokesman for Cambridge University Hospitals NHS Foundation Trust, where the youngster died, said: "Our thoughts are with the family and we are supporting them during this very difficult and emotional time.
"A consultant neonatologist has spoken to all of the families on the unit.
Officials are investigating 19 confirmed cases and four probable cases at 11 NHS organisations in England.
Three were confirmed at Addenbrooke's Hospital in Cambridgeshire. Experts are also looking into three cases in Essex, including one possible and one confirmed case at Southend University Hospital and a possible case at Basildon University Hospital.
They are also looking into further confirmed cases including two at Luton and Dunstable University Hospital, one at Peterborough City Hospital and another at Stoke Mandeville Hospital in Buckinghamshire.
A Public Health England spokeswoman said investigators are in the "final stages" of their inquiries.
Experts have so far found that the strain of the bacteria identified in the 19 confirmed cases has been identified in "environmental samples" located within a particular "sterile" area at ITH Pharma where the feed was manufactured.
They said they have found "sufficient evidence" to confirm that the contamination was introduced to the specific supplies of total parental nutrition (TPN) during manufacture on May 27.
Some unopened supplies of the feed manufactured on he date of manufacture have also been found to have the same strain of bacteria, the spokeswoman said.
"There are still some elements of our investigation that need finalising but the main findings have all pointed towards there being a single incident that occurred on one day and was associated with the illness seen in the babies," said PHE's incident director Professor Mike Catchpole.
"We are reassured that this was a very rare occurrence as we have not seen this particular strain of bacteria in any product made since that day and there has been no further illness."