Abstract
ObjectivesLegionella is a bacterial species able to cause influenza-like illness (Pontiac fever) or severe pneumonia (Legionnaires disease, LD). We assessed Legionella presence and concentration in composting facilities in The Netherlands. MethodsA total of 142 samples from 23 green waste composting facilities were screened for Legionella DNA using qPCR. ResultsOf 142 samples, Legionella spp. DNA was detected in 97 (68%), and the subspecies L. pneumophila and L. longbeachae in 33 (23%) and one (0.7%) samples, respectively. Legionella was observed in samples from all composting facilities. The concentration of Legionella spp. DNA ranged from 103 to 105 genomic units (GU)/gram. Compost temperature was negatively correlated with the presence (odds ratio 0.67, 95% CI 0.50–0.92 per 10 degrees increase) and concentration (geometric mean ratio 0.90, 95% CI 0.83–0.97 per 10 degrees) of Legionella spp. Average humidity in the week prior to sampling was negatively correlated with the L. pneumophila concentration (geometric mean ratio 0.73, 95% CI 0.56–0.96 per increase in 10% of humidity). DiscussionThis study suggests that composting facilities can be regarded as reservoirs of Legionella in The Netherlands, but additional studies should target if such facilities represent a human health risk.
Highlights
Legionellae are Gram-negative bacterial species able to cause influenza-like illness (Pontiac fever) or severe pneumonia (Legionnaire's disease, LD) in humans [1,2]
We aimed at assessing if green waste compost on Dutch composting facilities contains Legionella, to estimate the fraction composed of L. pneumophila and L. longbeachae, and to identify predictive factors for the presence of Legionella
Fresh waste samples were chopped in a Moulinex grinder prior to DNA extraction. qPCR was performed to detect generic Legionella spp. and L. pneumophila and L. longbeachae as previously described by Nasir et al, 2018 [7], applying the qPCRs described by Collins et al [6] and the genesig® L. longbeachae standard kit
Summary
Legionellae are Gram-negative bacterial species able to cause influenza-like illness (Pontiac fever) or severe pneumonia (Legionnaire's disease, LD) in humans [1,2]. By far the majority of the European LD cases with a known cause are due to L. pneumophila, whereas in Australia and New Zealand L. longbeachae has been observed to play a major role in LD incidence as well [3]. Green waste compost and potting soils can contain Legionellae [4]. Multiple clinical cases of potting soil- or compost-associated infection have been shown to be caused by L. longbeachae [3,5]. In The Netherlands, it is unclear if composting facilities may represent potential reservoirs of Legionella. We aimed at assessing if green waste compost on Dutch composting facilities contains Legionella, to estimate the fraction composed of L. pneumophila and L. longbeachae, and to identify predictive factors for the presence of Legionella
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