Legionella pneumophila in Municipal Shower Systems in Stavanger, Norway; A Longitudinal Surveillance Study Using Whole Genome Sequencing in Risk Management

Following an incidence of Legionnaires disease (LD) in 2007, where a municipal shower system was the likely source of infection, Stavanger municipality initiated a surveillance program for Legionella as part of establishing internal risk evaluation and prevention routines. More than 250 shower systems were examined for cultivatable Legionella pneumophila. The prevalence and diversity of serogroups (sg) and sequence types (STs) of L. pneumophila were mapped using available typing techniques over a period of more than 10 years (2010–2021). The surveillance showed an overall reduction in the L. pneumophila colonisation rate in municipal systems from 11 to 4.5% following prevention measures during the period, with the highest colonisation rate in complex systems (e.g., larger nursing homes and sports complexes). Further, an approximately even distribution between sg1 and 2–14 was seen. Whole genome sequencing (WGS) revealed that only a limited number of STs were detected, and they were consistent at specific locations over time. This study showed that environmental surveillance data in combination with available typing techniques and WGS can give the municipality a better tool for risk management and an overview of ST distributions that can be a valuable asset in future source investigations.publishedVersio

Long-read sequencing for reliably calling the mompS allele in Legionella pneumophila sequence-based typing

Sequence-based typing (SBT) of Legionella pneumophila is a valuable tool in epidemiological studies and outbreak investigations of Legionnaires’ disease. In the L. pneumophila SBT scheme, mompS2 is one of seven genes that determine the sequence type (ST). The Legionella genome typically contains two copies of mompS (mompS1 and mompS2). When they are non-identical it can be challenging to determine the mompS2 allele, and subsequently the ST, from Illumina short-reads. In our collection of 233 L. pneumophila genomes, there were 62 STs, 18 of which carried non-identical mompS copies. Using short-reads, the mompS2 allele was misassembled or untypeable in several STs. Genomes belonging to ST154 and ST574, which carried mompS1 allele 7 and mompS2 allele 15, were assigned an incorrect mompS2 allele and/or mompS gene copy number when short-read assembled. For other isolates, mainly those carrying non-identical mompS copies, short-read assemblers occasionally failed to resolve the structure of the mompS-region, also resulting in untypeability from the short-read data. In this study, we wanted to understand the challenges we observed with calling the mompS2 allele from short-reads, assess if other short-read methods were able to resolve the mompS-region, and investigate the possibility of using long-reads to obtain the mompS alleles, and thereby perform L. pneumophila SBT from long-reads only. We found that the choice of short-read assembler had a major impact on resolving the mompS-region and thus SBT from short-reads, but no method consistently solved the mompS2 allele. By using Oxford Nanopore Technology (ONT) sequencing together with Trycycler and Medaka for long-read assembly and polishing we were able to resolve the mompS copies and correctly identify the mompS2 allele, in accordance with Sanger sequencing/EQA results for all tested isolates (n=35). The remaining six genes of the SBT profile could also be determined from the ONT-only reads. The STs called from ONT-only assemblies were also consistent with hybrid-assemblies of Illumina and ONT reads. We therefore propose ONT sequencing as an alternative method to perform L. pneumophila SBT to overcome the mompS challenge observed with short-reads. To facilitate this, we have developed ONTmompS (https://github.com/marithetland/ONTmompS), an in silico approach to determine L. pneumophila ST from long-read or hybrid assemblies.publishedVersio

Necessity and effect of combating Legionella pneumophila in municipal shower systems.

The objective was to obtain research-based, holistic knowledge about necessity and effect of practiced measures against L. pneumophila in municipal shower systems in Stavanger, Norway. The effects of hot water treatment and membrane-filtering were investigated and compared to no intervention at all. The studies were done under real-world conditions. Additionally, a surveillance pilot study of municipal showers in Stavanger was performed. The validity of high total plate count (TPC) as an indication of L. pneumophila was evaluated. A simplified method, named "dripping method", for detection and quantification of L. pneumophila was developed. The sensitivity of the dripping method is 5 colony-forming units of L. pneumophila/ml. The transference of L. pneumophila from shower water to aerosols was studied. Interviews and observational studies among the stakeholders were done in order to identify patterns of communication and behavior in a Legionella risk perspective. No substantial effects of the measures against L. pneumophila were demonstrated, except for a distally placed membrane filter. No significant positive correlation between TPC and L. pneumophila concentrations were found. L. pneumophila serogroup 2-14 was demonstrated in 21% of the 29 buildings tested in the surveillance pilot. Relatively few cells of L. pneumophila were transferred from shower water to aerosols. Anxiety appeared as the major driving force in the risk governance of Legionella. In conclusion, the risk of acquiring Legionnaires' disease from municipal shower systems is evaluated as low and uncertain. By eliminating ineffective approaches, targeted Legionella risk governance can be practiced. Risk management by surveillance is evaluated as appropriate

Risk and Crisis Communication about Invisible Hazards

This article discusses differences between invisible and visible hazards, and how these differences can affect risk and crisis communication. Invisible hazards are risks that we cannot see, and often cannot touch, taste, nor smell. Examples are COVID-19, radon gas, mold spores, or asbestos fibers. Invisible hazards are often uncertain, complex, and ambiguous risk problems. Results from a Norwegian study show that authorities need to be aware of the possible differences in risk perception among authorities, stakeholders, and the general public. Involving citizens, creating trust, and being honest is important for all risk and crisis communication. However, the less we know about a hazard, the more we need to rely on others to make decisions, and consequently trust is particularly important when dealing with invisible hazards.publishedVersio

Correlation between TPC and <i>L. pneumophila</i> (<i>L. pn.</i>) concentration (cfu/ml) in the first water and system water under ordinary conditions and after hot water treatment, respectively.

<p>Correlation between TPC and <i>L. pneumophila</i> (<i>L. pn.</i>) concentration (cfu/ml) in the first water and system water under ordinary conditions and after hot water treatment, respectively.</p

Effect of hot water-treatment on TPC.

<p>A) TPC as a function of time before, just after (0), and days after hot water treatment of shower systems (4 different shower system, 6–9 showers per system). The data is presented as an average of all treated shower systems and the error bars represent the standard deviation. B) Comparison of TPC at the three nursing homes NH 1, NH 2 and NH 3. The included showers (N = 8) at NH 1 had not been hot water-treated, while the ones at NH 2 (N = 16) and 3 (N = 14) had been at least monthly treated for years. The TPC was measured one week after thermal treatment. Additionally, at NH 3 the shower armature were systematically treated with a product aimed at eliminating lime depositing. * The difference between NH 1 and NH 2 was significant (P<0.05, non-parametrical).</p

Biogass/biorestproduksjon som bærekraftig gjødselhåndteringsstrategi på Jæren

Hovedmålet med dette kvalifiseringsprosjektet har vært å vurdere om separering av husdyrgjødsel fra storfe og gris i en våt og en tørr fraksjon før behandling i biogassanlegg, vil kunne bidra til å løse noen av landbrukets utfordringer i forhold til klima og miljø regionalt og bondens utfordringer lokalt. Vi har spesielt sett på om separering av husdyrgjødsel fra storfe og svin i en våt og en tørr fraksjon før videre håndtering av tørr fraksjon i et sentralisert biogassanlegg (hub) kan være en mulig måte for gårdene å møte de foreslåtte skjerpede krav til tillatt spredning av fosfor. Resultatene fra prosjektet viser at separering av husdyrgjødsel kan være en del av løsningen for en bærekraftig gjødselhåndtering. Separering vil kunne øke mengden husdyrgjødsel som prosesseres i et biogassanlegg samtidig som volumet som må transporteres reduseres. I tillegg vil metoden gi en bedre fordeling av næringsstoffer, siden den våte fraksjonen inneholder mer nitrogen, mens fosforet i større grad følger den tørre fraksjonen. Ved å separere husdyrgjødsel og transportere fosfor ut av gården vil de fleste gårdene (ca. 90%) ha nok eget spredeareal til å kunne oppfylle fremtidige skjerpede krav. En større sentralisert hub vil sannsynligvis kunne dekke det samlede behovet for hele regionen. Biogassproduksjon fra husdyrgjødsel kan spille en viktig rolle som klimatiltak i landbruket. Klimagevinsten ved behandling av husdyrgjødsel er i stor grad knyttet til reduserte utslipp fra lagring på grunn av kortere lagringstid. Beregningene av klimagassutslipp viser derfor at jo mer husdyrgjødsel som går til biogassproduksjon, dess større reduksjoner av klimagasser kan man oppnå. Samtidig er det foreløpig lite kunnskap om hvordan separering påvirker utslippene fra våt og tørr fraksjon. Det er i dette prosjektet antatt at utslippene per tonn tørrstoff er upåvirket av separeringsprosessen. Bedriftsøkonomiske analyser fra bondens perspektiv viser at separering av husdyrgjødsel og levering av den tørre fraksjonen til et sentralt biogassanlegg vil kunne være lønnsomt for gårder som i dag har kostnader knyttet til transport av husdyrgjødsel til nærliggende spredningsareal. Dette resultatet vil kunne påvirkes negativt dersom gårdene må bygge nye lagre for den våte eller den tørre fraksjonen etter separering. Det økonomiske resultatet for den enkelte bonde vil også avhenge av økonomien til den sentraliserte biogass-huben og avtalene med hver enkelt gård. Resultatet påvirkes positivt dersom huben kan betale for mottak; resultatet påvirkes negativt dersom bøndene må betale huben for leveransene. Prosjektet har ikke sett på forretningsmodell for huben og heller ikke hvordan huben skal få avsetning for bioresten. For å få framdrift i gjødselhåndteringen i regionen vil et naturlig steg videre være etablering av et demoanlegg for å teste ut teknologi og kartlegge aktuelle «stakeholders» i biogass-verdikjeden

Transfer of <i>L. pneumophila (L. pn.)</i> and TPC from shower water to aerosol.

<p>Transfer of <i>L. pneumophila (L. pn.)</i> and TPC from shower water to aerosol.</p

Correlation between <i>L. pneumophila</i> sg 2–14 and TPC in the shower system of School 1 over a period of 1 year.

<p>The arrows indicate time points for hot water treatment and the star represents a one-time chlorination treatment (Concentrate of di-n-decyl dimethylammonium chloride (<2%), quaternary ammonium combinations, benzyl-C8-18-alkyldimetyl, chlorides (<2%) and hexamethylene biguanide hydrochloride (<1%) (Barrier Tech Concentrate)) of the system.</p

Risiko- og krisekommunikasjon om usynlige farer

Denne rapporten formidler funn fra prosjektet «Risiko- og krisekommunikasjon om usynlige farer i norske kommuner», gjennomført av en tverrfaglig prosjektgruppe ved NORCE fra august 2017 til mai 2020. Prosjektet ble gjennomført i samarbeid med fire norske kommuner; Fjell, Stavanger, Øygarden og Lindås, og Direktoratet for strålevern og atomsikkerhet (DSA). Prosjektet er finansiert av Regionale Forskningsfond Vestlandet (RFFVEST)