A FOURTH person tested positive for a bacterial infection that contributed to the death of a patient at the Royal Alexandra Hospital, it has emerged.

Earlier this month the health board confirmed a patient who was seriously ill due to an underlying condition had died after being treated for the Stenotrophomonas Maltophilia bacterium.

The board said at the time that two other patients had been affected by the infection, that is rare and considered difficult to treat. It has now emerged a fourth patient was identified on February 8.

READ MORE: Patient dies after contracting bacterial infection at Royal Alexandra Hospital

NHS Greater Glasgow and Clyde said tests had not yet concluded to identify if there is a link to the other cases.

The board said no additional cases were identified as of February 11.

Five patients have died in recent weeks following a series of infections at the Queen Elizabeth University Hospital, the Princess Royal Maternity hospital and the RAH. The source of four separate infections have not yet been identified. 

READ MORE: Call for more support for Royal Alexandra Hospital staff after hygiene failures in report

NHS Greater Glasgow and Clyde announced on Tuesday it is carrying out its own inquiry into the QEUH, independent of the Scottish Governmentinvestigation.