TESTS exposed widespread bacterial contamination of the water supply at Glasgow's superhospital even before it opened, a new report has revealed.

The contractor responsible for building the Queen Elizabeth University Hospital (QEUH) and Royal Hospital for Children (RHC) was forced to sanitise the entire system before handing it over to the health board after sampling detected "hygiene issues with the water supply" and signs of unusually high microbial contamination.

Read more: Prosecutors investigating death of boy, 10, who died after contracting pigeon infection at QEUH

In spite of efforts to cleanse the hospitals' water supply, Health Protection Scotland said that "there are a number of reports which indicate that there may still have been a number of areas with higher than normally acceptable levels of [microbes]."

The new hospitals opened in May 2015, but just a few months later - in February 2016 - a child with cancer developed a bloodstream infection caused by Cupriavidus pauculus, a rare water-borne bacteria.

The patient was being treated in Ward 2A at the children's hospital and subsequent tests traced the source to a tap from a wash-hand basin in the pharmacy department where artificial nutrition was prepared.

The sink was subsequently removed.

A second paediatric cancer patient fell ill with the same bug in September 2017, but the source was found to be a different wash-hand basin.

Then, between January 29 and September 20 2018, a further 21 children in wards 2A and 2 B - known as the Schiehallion unit - developed a range of blood infections caused by 12 separate types of bacteria and fungi.

These included Serratia marascens, which was previously the cause of an outbreak at the Princess Royal Maternity Hospital in 2011 which saw one infant die and 11 others sickened.

Read more: NHS Glasgow had battled higher than average infection rate in months before babies died 

Stenotrophomonas maltophilia - recently implicated in the death of a patient at the Royal Alexandra Hospital in Paisley - was also detected, and there were seven cases of infection with Enterobacter cloacae, a bacteria that is particularly dangerous due to its resistance to many antibiotics.

None of the infections were fatal, however.

The Health Protection Scotland report into the crisis reveals that all cases were linked to the water supply or drains.

It also reveals that tests as far back as March 2018 highlighted risks of infection at the adjacent adult hospital.

At the time, plans were underway to transfer bone-marrow transplant patients from the Beatson Oncology Unit to ward 4B of the QEUH.

However, water sampling undertaken as a precautionary measure revealed the presence of Cupriavidus pauculus - the same bacteria first detected at the children's hospital.

Read more: Young cancer patients hit again by water-borne infections at children's hospital 

This was "the initial suggestion that there may be widespread contamination of the water system that serves both QEUH and RHC", said Health Protection Scotland.

It adds: "Further testing provided confirmation of this, with positive samples being identified in a number of areas across both sites".

Meanwhile, staff within the Schiehallion unit also reported seeing "black effluent" around the rim of the drain in some hand-washing basins. This was later confirmed in laboratory testing to be biofilm - a build up of microbes - well in excess of expected levels.

The HPS report adds: "Sampling identified significant contamination of the drains with microorganisms and fungi.

"Drain contamination is not unexpected, however the level of biofilm evident was not in keeping with a water system of less than four years old."

It noted that taps with flow regulators of the type installed at the QEUH and RHC were no longer recommended following changes to technical guidance in 2015 as they "potentially create ideal conditions for the development of biofilm".

HPS said it will now carry out a national review of the water systems at all healthcare facilities in Scotland built since 2013.

NHS Greater Glasgow and Clyde apologised that children had contracted bugs, but stressed that there have been no cases of infection associated with water at the site since September 2018, when wards 2A and 2B were closed and patients transferred to the adult hospital for treatment.

However, the report comes as prosecutors investigate the deaths of a 10-year-old boy and a woman, 73, who had both contracted infections caused by a fungus, Cryptococcus, linked to pigeon droppings.

The bug is believed to have been spread through the £900 million QEUH's ventilation system.

A 63-year-old grandmother, Mito Kaur, is also fighting for her life at the hospital after developing mucormycosis, a rare fungal infection caused by mould found in soil, plants, manure, and decaying fruits and vegetables.

Meanwhile, NHS Greater Glasgow and Clyde has also confirmed that three premature babies who died at the Princess Royal Maternity Hospital in January had tested positive for an "extremely rare strain" of the bacteria Staphylococcus aureus, never previously detected in Scotland.

In a statement responding to the HPS report, NHS GGC said: "There have been no cases of infection associated with water since September 2018.

"Our engineering teams have installed a water treatment system within the RHC and are working on the new system for the adult hospital. This will be completed in March.

"In the meantime, filters remain in place and we continue to monitor the quality of water with very encouraging results.

"Over the past few months, whilst our investigations continued, our overriding priority has always been the safety of our patients.

"We are sorry that a number of young patients in our care suffered an infection and also apologise for the inconvenience and worry that the families in wards 2A and B in particular will have experienced.

"Since the report, written in December 2018, the Cabinet Secretary for Health and Sport has announced a review into the design, commissioning and construction of the Queen Elizabeth University Hospital and the Royal Hospital for Children.

"Earlier this week our Board also approved a further three reviews into the hospital to provide assurance to the public and address recent concerns.

"Our teams will be supported in these reviews by national experts including Health Protection Scotland and Healthcare Facilities Scotland."