A baby has died and six others were in isolation last night after an infection broke out in a hospital's neonatal unit.

The baby, who was born prematurely at Heartlands Hospital in Birmingham almost two weeks ago, was one of two infants to become infected with Serratia bacteria.

Staff at the Bordesley Green hospital are hopeful the second baby infected with the bug will go home "in the next few weeks", a spokeswoman said.

Five other babies, who tested positive for Serratia on their skin, are in a six-cot isolation unit as a "precaution".

The hospital director, Lisa Dunn, said when the bacteria was found on the infants, "measures were immediately implemented and remain in place".

"Two extremely pre-term babies were infected with the bacteria. Very sadly, one baby died. The second baby is doing very well," she said.

The intensive care room was closed to admissions and other babies were being cared for in a separate room.

"These measures have been very successful in preventing the bacteria spreading and the intensive care facility is expected to reopen to new admissions this week," Ms Dunn said.

Serratia, which causes infections in the blood and respiratory tracts, can be deadly if it attacks under-developed lungs. A hospital spokeswoman said the five babies who had tested positive to the bacteria on their skin were not "infected" because the bug had not entered their bodies.

Figures from the Health Protection Agency show there were 1,196 reported cases of Serratia in England, Wales and Northern Ireland in 2007.