Common bugs linked to cot deaths

Post-mortems of hundreds of babies who had died suddenly revealed that many were harbouring potentially harmful bacteria.

High levels of two microbes, Staphylococcus aureus and Escherichia Coli, were obtained from infants who died for no apparent reason.

Both these bugs, categorised as "group 2 pathogens", can kill without showing any signs of damage to the body.

But scientists still do not know whether or not the bacteria are directly responsible for the unexplained deaths.

One possibility is that the toxins they release are proving fatal. Another is that other factors linked to cot death, such as overheating or passive smoking, might be promoting bacterial growth.

No cause is found for most cases of cot death or SUDI - sudden death of an infant - resulting in great anguish for the parents.

The new research, published in The Lancet medical journal, suggests that bacterial infection may be linked to these unexplained cases in previously unsuspected ways.

Scientists carried out a systematic review of infant post-mortems carried out at London's Great Ormond Street Hospital for Children between 1996 and 2005. They identified 546 infants between seven days and one year old who had died suddenly and unexpectedly. Swab and blood samples were taken from 470 of the dead babies, yielding a total of 2,871 separate bacterial cultures.

Of these deaths, 365 were unexplained, 53 were due to non-infectious causes such as heart defects, and 52 had signs of tissue damage suggesting a bacterial infection. Surprisingly, the samples revealed that around half the unexplained group carried bacteria which in life could trigger disease.