In general, what do we know…
Most people have only heard about Legionella when there are news reports of outbreaks in hotels, hospitals, etc. The disease it causes involves respiratory problems, diarrhea, vomiting, headache, and muscle pain, which in some cases can be severe.
Precisely for this reason, epidemiological surveillance is necessary since the disease may be associated with devices and systems that use water at temperatures that allow its proliferation and produce aerosols during their operation.
This bacterium is capable of surviving between 20ºC and 50ºC and can be found in surface waters (rivers, lakes, ponds) and even in seawater.
From these natural reservoirs, the bacterium can colonize supply systems. Through the water distribution network, it can enter domestic water systems (cold or hot) or other systems such as cooling towers, for example.
Inadequate maintenance of these facilities can promote the accumulation of essential nutrients for Legionella, which could increase its presence and cause infections if, in addition, the facility has a mechanism that produces aerosols. Aerosols containing the bacterium can remain suspended in the air and therefore enter the respiratory system of people exposed to them.
For all these reasons, it was deemed necessary to establish coordinated and approved technical-health criteria by the Health Authorities at state, regional, and local levels.
Legislation and testing regulations
Swimming Pool Water
Royal Decree 742/2013(7) aims to establish the basic technical-health criteria for the quality of water and air in public swimming pools, except for natural pools and thermal or mineral-medicinal baths, in order to protect users’ health from possible physical, chemical, or microbiological risks arising from their use.
It establishes the need for accreditation according to UNE-EN ISO/IEC 17025 for laboratories analyzing samples; however, it does not include a reference to the analytical standards to be applied.
Treated Water
For this type of water, Royal Decree 1620/2007(8) also requires Legionella control, setting different limits depending on the intended use of the water.
It requires that analyses be carried out in testing laboratories with a quality control system according to UNE-EN ISO/IEC 17025. Accreditation is not explicitly required, but compliance with a quality system is.
In this case, reference is made to ISO 11731:1998, which is outdated compared to the new 2017 version. However, compliance could still be based on the 1998 version for this type of water.
It also states that alternative methods may be used, provided they are validated and yield results comparable to those obtained with the reference standard.
Water in facilities that use it in their operation, produce aerosols, whether indoors or outdoors, industrial facilities, or means of transport.
In 2001, Royal Decree 909/2001 of July 27(1) was approved, establishing hygienic-health criteria for the prevention and control of legionellosis. However, it mainly addresses maintenance aspects such as cleaning and disinfection of installations, without setting ranges or methodologies for the determination of Legionella.
In 2003, this Royal Decree was repealed by Royal Decree 865/2003 of July 4(2), which does establish a methodology for the detection and enumeration of Legionella, referencing ISO 11731:1998 as the standard. It applies to “installations that use water in their operation, produce aerosols, and are located inside or outside collective-use buildings, industrial facilities, or means of transport that may potentially become sources for the spread of the disease during operation, service tests, or maintenance.”
This Royal Decree 865/2003 includes compliance ranges for cooling towers and evaporative condensers, requiring corrective actions if exceeded, and mandates either laboratory accreditation for issuing results or the implementation of a Quality System.
In April 2017, the new version of UNE 100030:2017 “Guide for the prevention and control of the proliferation and dissemination of Legionella in installations” was published. This guide provides updated criteria and guidance for preventing and controlling the proliferation and spread of Legionella bacteria from certain installations and equipment. It is referenced in Royal Decree 865/2003 as a complementary standard, although in some aspects it conflicts with the Royal Decree, particularly regarding the classification of installations at risk of the presence and proliferation of the bacterium(3).
In December 2020, Directive (EU) 2020/2184(4) on the quality of water intended for human consumption was published. This Directive sets out a series of chemical and biological parameters to ensure the quality of such waters. An interesting aspect of this Directive is that, for Legionella determination, it includes not only ISO 11731 as the reference standard but also allows molecular methods, particularly PCR according to ISO 12869, as part of risk-based verification control and as a complement to culture methods.
Although this Directive does not explicitly require accreditation for issuing analytical results, its Annex III states that testing laboratories or entities must comply with quality management practices in accordance with UNE-EN ISO/IEC 17025.
The draft Royal Decree(5), February 2021, also includes hygienic-health criteria for the prevention and control of legionellosis and, like previous legislation, considers preventive and risk analysis aspects.
Noteworthy aspects include resolving discrepancies between the current Royal Decree and UNE 100030:2017(6):
- The establishment of Legionella Safety Plans or, failing that, Legionella Prevention and Control Plans (PPCL) for all types of facilities susceptible to the proliferation and dissemination of the bacterium, not only those previously identified as high risk.
- The definition of minimum contents to be included in PPCLs.
- The requirement for accredited sample collection for Legionella control.
- The introduction, under certain circumstances and as a complement to the reference method, of alternative methods to culture for Legionella.
The “certain circumstances” relate to public health risk investigations, outbreak investigations, or when deemed necessary by the health authority. Outside these circumstances, the reference standard must be applied.
It also states that these alternative methods must meet minimum requirements, with nationally or internationally recognized validation.
Unlike the Directive, it does not mention a specific molecular method as a reference standard.
This draft Royal Decree explicitly requires laboratories to be accredited under UNE-EN ISO/IEC 17025 for both testing and sample collection, and specifies a sample volume of 1L, whereas the current reference standard allows the laboratory to process the volume it deems appropriate.
In summary…
As already mentioned, there is a requirement for accreditation or compliance with a Quality System, since even among Member States, it is understood that such compliance provides guarantees for the analytical results obtained by laboratories or entities performing the tests.
In this sense, and focusing on Legionella determination, the method to be accredited would be ISO 11731:2017, which is a technique for counting Legionella spp., although it also includes complementary tests for species and serotype identification.
Each Member State previously legislated this parameter unilaterally, but by including it in the EU Water Directive, it has now been harmonized among Member States.
These complementary tests, which relate to drinking water matrices, although mentioned in the Water Directive with reference to the analytical standard to be followed, are less specifically detailed in this draft Royal Decree. Thus, provided they are validated by recognized entities or regulations, any commercial alternative method could be used, which could benefit laboratories by allowing them to choose the method best suited to their circumstances.
On the other hand, the fact that these are not the reference methods required by the Legionella Safety or Prevention Plans means that, by following the systematic procedure according to the reference standard, the time needed to issue analytical results is longer than, for example, when using a PCR technique validated by an independent entity such as AFNOR, which is also accredited by COFRAC.
It should be noted that if PCR testing is carried out, with results expressed in Genomic Units (GU), there is no direct correlation between these GUs and CFUs, which could complicate the interpretation of the results.
In outbreak cases, speed is crucial, and the quick release of analyzed sample results can be a decisive factor in preventing the spread of this microorganism.
References
(1) https://www.boe.es/boe/dias/2001/07/28/pdfs/A27750-27759.pdf
(2) https://www.boe.es/boe/dias/2003/07/18/pdfs/A28055-28069.pdf
(3) https://higieneambiental.com/aire-agua-y-legionella/a-consulta-publica-el-proyecto-de-rd-sobre-criterios-sanitarios-para-la-prevencion-y-el-control-de-la-legionelosis
(4) https://www.boe.es/doue/2020/435/L00001-00062.pdf
(5) https://www.mscbs.gob.es/normativa/audiencia/docs/RD_CONTROL_LEGIONELOSIS.pdf
(6) https://www.mscbs.gob.es/normativa/docs/Ficha_Audiencia_publica_previa_Legionella.pdf
(7) https://www.boe.es/buscar/act.php?id=BOE-A-2013-10580
(8) https://www.boe.es/buscar/pdf/2007/BOE-A-2007-21092-consolidado.pdf
