Glasgow & West Scotland

Legionella 'common' in compost brands, Strathclyde University study finds

Gardener holds a plant
Image caption The study found Legionella species in 14 out of 22 compost brands tested

Legionella bacteria appears to be "common" in many compost brands sold in the UK, a study has found.

A team from Strathclyde University in Glasgow tested 22 different brands of compost and found that 14 contained a variety of Legionella species.

It says a larger survey is needed to determine the extent of the issue.

The study, "Legionella spp. in UK composts - a potential public health issue", is published by Clinical Microbiology and Infection.

Dr Beattie, one of those who conducted the study, 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."

Hygiene warnings

Dr Beattie said European produced composts have traditionally been composed of peat, whereas those from Australia and New Zealand had more often used sawdust and bark.

"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," she said.

Dr Beattie wants a larger scale survey, covering a wider range of compost products, to be carried out to see if Legionella bacteria are as widespread in composts as her study suggests.

She added: "It should be emphasised though, that although Legionella seem to be common in compost, human infection is very rare, especially if you consider the volume of compost sold and used.

"But with any potential source of infection precautions should always be taken.

"The occurrence of these bacteria in composts in Australia and New Zealand, and the cases of infection that have been traced to compost has resulted in hygiene warnings on compost packaging in these countries, and this is something manufacturers in the UK may wish to consider."

The study was conducted by Dr Tara 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.

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