Legionella pneumophila found in windscreen washer fluid without added screenwash

Excerpt

A paper by Wallensten et al. [1] identified an epidemiological association between Legionnaires’ disease cases and the absence of screenwash in windscreen washer fluid and a follow up pilot study had identified Legionella species in one vehicle. The research extrapolated that as many as 20 % of sporadic community acquired cases may be attributed to this exposure and prevention by the use of screenwash could be readily achieved and could theoretically prevent 50 United Kingdom (UK) cases each year. However, Legionella pneumophila has never been grown from windscreen washer fluid and it is not known whether or not screenwash inhibits or prevents growth of Legionella. We undertook an open cross-sectional study aiming to investigate whether L. pneumophila can be detected in vehicle windscreen washer fluid reservoirs and to establish whether or not the addition of screenwash can inhibit the growth of L. pneumophila and at what concentration. 30 vehicles were sampled, six of which had no screenwash added and 24 used screenwash. L. pneumophila serogroup 1 was not detected in any of the cars with screenwash but was found in one of the other vehicles. The level of contamination was 6,000 colony forming units per litre (cfu/l). The positive vehicle was unusual in that it had never had screenwash added to it. Subsequently, a laboratory-based experimental study was also undertaken to see if screenwash had a bactericidal effect on Legionella. Standard screenwash was found to be effective against Legionella at very low concentrations (10 ppm). This is the first time that L. pneumophila has been identified in windscreen washer fluid and the first time that screenwash has been shown to be effective against its growth. …