Research finds Legionella bacteria in compost products

The Department of Civil & Environmental Engineering led the UK's first substantial analysis of Legionella in UK composts - discovering the bacteria exists in a significant number of commercial products.

The research

The study conducted at Strathclyde is the first of its kind in the UK and found that Legionella bacteria are a common part of the microflora found within the composts tested.

It is widely recognised that Legionella bacteria are commonly present in the environment and the researchers found that compost could be a potential source of infection.

Twenty two different brands of compost, commercially available in the UK, were examined for the presence of Legionella bacteria – 14 of those tested contained a variety of Legionella species.

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Dr Tara K. Beattie, who led the research, said:

Disease causing micro-organisms are widespread in the environment, and therefore it is not too surprising that species of Legionella that can cause human disease are present in compost.

Any environment where you have pathogenic bacteria could be a source of infection, and we already know that compost has been linked to human Legionella infection in countries such as Australia and New Zealand.

Within the UK and across Europe composts have traditionally been composed of peat, whereas sawdust and bark are more often used to produce compost in Australia and New Zealand where Legionellosis associated with compost is more common.

It may be that the change in composition of composts in the UK, moving away from peat based products, could be resulting in species such as Legionella longbeachae being present in compost and therefore more cases of infection could occur.

´╗┐The study was conducted by Dr Beattie, fellow academic Dr Charles Knapp, Strathclyde PhD student Sandra Currie and Dr Diane Lindsay of the Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory.