Are pathogenic Legionella non-pneumophila a common bacteria in Water Distribution Networks?

The present study analyzes at the national level, the presence of circulating Legionella in the artificial aquatic systems of different facilities of all of them state-owned centers throughout Spain for 12 months. 1754 water samples from various state-owned centers were collected from January to December 2014. Samples were collected from the cooling towers and evaporative condensers (CTC), and water distribution networks such as domestic hot water (DHW), cold water for human consumption (CW), sprinkler irrigation systems (SIS), fire sprinkler systems (FSS), and water from decorative fountains (DF). All these facilities are considered, according to current regulations, as potential amplifying systems for bacteria and possible sources of infection by the generation of droplets and aerosols. The isolation and counting of Legionella in water samples was carried out using microbiological culture following the international normative UNE-EN-ISO 11,731:2007 (ISO 11,731:1998) and UNE-EN ISO 8199:2008 (ISO 8199:2005).The quantification of Legionella colonization, the annual distribution, and the geographical distribution of the Legionella isolates recovered in the water were analyzed. Besides, molecular techniques were used for the characterization of the Legionella non-pneumophila isolates. Legionella was recovered from 15.79% of the analyzed water samples. High colonization was more frequently detected in water samples from CTC, DHW, CW, and DF. Regarding the geographic distribution, positive samples of Legionella were obtained in 14 of the 18 Spanish locations analyzed. Legionella non-pneumophila was the most prevalent and was isolated from water samples from 13 different geographical locations (72%). Legionella anisa and Legionella jordanis were the most frequently non-pneumophila species isolated. Legionella donaldsonii was isolated for the first time in the water distribution networks in Spain. Legionella pneumophila sg 2-14 was detected in 13 locations and Legionella pneumophila sg 1 in 11 locations. Therefore, our study concludes that the presence of Legionella pneumophila and Legionella non-pneumophila species in these systems can be a potential threat to public health and should be examined thoroughly with complementary techniques, such as molecular techniques as a screen for routine diagnosis.

Legionella risk in evaporative cooling systems and underlying causes of associated breaches in health and safety compliance

Legionella bacteria can colonise and proliferate in water systems in the built environment and can be spread by aerosol generation. If inhaled by a susceptible individual, this can lead to respiratory infections such as Legionnaires' Disease (LD), or the generally milder Pontiac fever. Evaporative cooling systems (ECS), including cooling towers, used in industrial processes to dissipate excessive heat are prone to contamination by Legionella. From these systems it is possible for contaminated aerosols to be dispersed over a wide area, potentially exposing workers on site, neighbouring workplaces or nearby members of the public. Analysis of reported data on outbreaks of LD in Great Britain, collated for a ten year period, identified 44 separate legionellosis outbreaks of which seven were attributed to ECS and were responsible for 229 infections and 10 fatalities. This prompted an examination of health and safety inspection records which revealed, over a five year period, 321 enforcement actions taken against failings in Legionella control, of which 31% were attributed to cooling towers. Based on this evidence, an intervention programme was undertaken by health and safety inspectors in which 1,906 sites with ECS were inspected. During these inspections, sites were rated against four topics that are used to demonstrate compliance with statutory requirements for Legionella control: Risk Assessment; Written Control Scheme; Implementation of Control Scheme; and Record Keeping. While there was compliance at the majority of sites, breaches of the legislation were found at 625 sites (33% of those inspected), leading to 409 Improvement Notices (compelling dutyholders to make improvements to health and safety breaches of law in a given timeframe) and 12 Prohibition Notices (compelling dutyholders to stop work until they have remedied breaches in health and safety law) being served at 229 sites (12.0% of those inspected). Data from the intervention programme was analysed to identify root causes of these breaches of legislation on Legionella control. The majority of Improvement Notices (53%) were issued for the 'lack of effective implementation of a Written Control Scheme', with 'Risk Assessment' and 'Written Control Scheme' both accounting for 23%. More detailed examination showed major problems to be lack of training; failure to maintain the cleanliness of cooling towers and the water within them; risk assessments either being absent or not up to date, i.e., no longer representing the risks present; and Written Control Schemes being absent or insufficiently detailed. This provides a valuable data resource for dutyholders, so that they can understand where they need to focus to achieve significant improvement in legal compliance and therefore reduce the risk of LD for employees and members of the public affected by their workplace, and valuable data for regulators to target future interventions aimed at improving dutyholder compliance leading to better protection of workers and members of the public.