INFECTION control measures were beefed up by Glasgow health bosses in the months before two premature infants died, amid concerns that the region's hospitals were experiencing higher than average rates of the bug which killed them.

An investigation has been launched after two "extremely premature" babies died after contracting the bloodstream infection, Staphylococcus aureus, at the Princess Royal Maternity Hospital.

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NHS Greater Glasgow and Clyde said the infection was "one of a number of contributing causes" in both deaths. A third premature baby also required treatment but is now stable.

Figures reveal that the health board has recorded rates of Staphylococcus aureus above the national Scottish average over the past two years - 15 per cent higher in 2018 and 10% higher in 2017.

Between April and June last year, when hospital-based incidence peaked at 23% higher than average, NHS GGC began dispatching infection control doctors and microbiologists to carry out routine ward rounds to monitor levels of the bug in a bid to drive down incidence.

Board papers stated that the issue was a "a priority" for the health board.

Professor Hugh Pennington, said it was likely that poor infection control had led to NHS GGC's rate of Staphylococcus aureus running above average.

He said: "It's hard to say definitively without knowing more details about the patients, but on the face of it possible problems with infection control would be at the top of my list."

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By July to September last year, the most recent period for which data is available, the health board's intervention appeared to have reaped some success with rates dipping slightly below the national average.

Across Scotland, a total of 253 cases of patients infected with Staphylococcus aureus that they had picked up while in hospital were reported to Health Protection Scotland between July and September last year, including 67 cases in NHS GGC.

Of those, 28 were recorded at the Glasgow Royal Infirmary and Princess Royal Maternity Hospital, which are counted as one site.

In its most recent report on Staphylococcus aureus, the health board said nearly half (43%) of the hospital infections had entered the patient via an intravenous access device (IVAD) - such as a needle or a drip.

In December, NHS GGC staff were advised to remove intravenous devices "as soon as possible", rather than trying to maintain them, and the number of daily infection checks were doubled from one to two.

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A spokeswoman for NHS GGC said: "All Boards experience fluctuation in these rates from quarter to quarter but in NHSGGC these remain well within normal, expected levels.

These are monitored by Health Protection Scotland and NHSGGC has never been outwith these normal boundaries."

Staphylococcus aureus is a bacterium that is commonly found on the skin and in the nasal passage. In most people it is harmless, but can cause a problem if it enters the bloodstream in someone with low immunity.

An incident management team was set up on January 24 after it was detected in the neonatal unit, but Dr Alan Mathers, the chief of medicine, women's and children's services at NHS GGC, said they had not yet determined the source of the infection.

He added: "It may be that we don't ever get to the root of the problem. The issue is that everyone carries bacteria in their skin and are colonised by these things - that is very different from an infection.

"The premature baby has lots of systems that are just not ready for the world, including its immune system, and any breach in the fragility of these babies can lead to bacteria that would otherwise not bother us."

A former infection control consultant at NHS GGC told the Herald that some premature babies could be so vulnerable that the infection could enter their bloodstream through skin-to-skin contact alone.

She said: "In theory it could be a sign of poor infection control, but it can still happen in a reasonable environment."

Dr Tom Turner, a consultant paediatrician and neonatal expert who retired from NSHS GGC in 2008, said the infection was "very hard to stop" in premature babies, especially if they had other illnesses.

He said: "I wouldn't say [infection is] inevitable, but I wouldn't say it 'shouldn't happen' either.

"You constantly try to prevent infection, but you also have to take risks - because if you don't take risks by putting them on ventilators, putting catheters in, touching their skin, then they will die from their prematurity.

"So on the one side you've got all these risks inherent in the baby, and on the other you've got all the risks outside the baby, in the environment.

"It's a balance. It's easy to say infection 'shouldn't happen', but that is really naive."

The Princess Royal Maternity Hospital was at the centre of a previous infection outbreak in 2011 when one baby died and 11 others fell ill with Serratia marcescens, a normally harmless bacteria traced to the water supply.

The latest crisis comes as prosecutors investigate the deaths of a 10-year-old boy with cancer and a woman, 73, at the Queen Elizabeth University Hospital in Glasgow.

Both had tested positive for Cryptococcus, a fungus believed to have spread through the ventilation system from pigeon droppings.

A third QEUH patient is also seriously ill with a separate fungal infection, Mucormycosis, possibly linked to a water leak.