Infection spread in hospitals

With up to 9% of all patients in the UK contracting a Healthcare Acquired Infections and an associated annual cost to tax payers estimated at £1 billion, the control and reduction of the spread of infection in hospitals is a top priority for the NHS. Researchers at PRoBE have identified the sanitary plumbing and sewerage system as a potentially significant, yet often forgotten, source of infection spread within hospital buildings.

The sanitary plumbing and sewerage system is one of only a few engineered systems that interconnect all parts of a building, and it is the only one that acts a collection network for human waste. In a hospital building, this waste has a high potential for pathogenic contamination, making the sanitary plumbing and sewer system a potentially rich reservoir for pathogenic microorganisms. Failures within the system, such as empty U-bends at appliances or wastewater backup due blockages, can contribute to the spread of pathogens from the sanitary plumbing and sewerage system into the hospital building – considerably adding to the risk of infection spread.

Research carried out by PRoBE in hospital buildings using polymerase chain reaction (PCR) tests on waste water samples confirmed that the sanitary plumbing and sewerage system is contaminated by pathogens released directly to the system by infected patients. In one example, the sanitary plumbing and sewerage system tested positive to Norovirus GII over a number of weeks during an outbreak within the hospital building.

Furthermore, measurement of the conditions within the hospital sanitary plumbing and sewerage system showed average temperatures of just over 24°C and an average humidity of almost 97%. The warm and humid conditions that exist within the system not only aides pathogen survival, it also facilitates the airborne transmission of aerosolised pathogens around the system, and potentially into the hospital building, through air movement and buoyancy effects.