Comparative study of Legiolert with ISO 11731-1998 standard method-conclusions from a Public Health Laboratory

Checa, Javier; Carbonell, Iago; Manero, Neus; Martí, Inés

doi:10.1016/j.mimet.2021.106242

Cited by 8 publications

(7 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…L. pneumophila was quantified using the Legiolert most probable number assay (IDEXX Laboratories, Inc., Westbrook, ME, USA) according to manufacturer protocols [IDEXX]. Legiolert is a liquid-based culture most probable number (MPN) method that correlates well with standard culture methods and has a low (3–4%) false positivity rate [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Section: Methodsmentioning

confidence: 99%

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

et al. 2022

View full text Add to dashboard Cite

When stay-at-home orders were issued to slow the spread of COVID-19, building occupancy (and water demand) was drastically decreased in many buildings. There was concern that widespread low water demand may cause unprecedented Legionella occurrence and Legionnaires’ disease incidence. In lieu of evidenced-based guidance, many people flushed their water systems as a preventative measure, using highly variable practices. Here, we present field-scale research from a building before, during, and after periods of low occupancy, and controlled stagnation experiments. We document no change, a > 4-log increase, and a > 1.5-log decrease of L. pneumophila during 3- to 7-week periods of low water demand. L. pneumophila increased by > 1-log after precautionary flushing prior to reoccupancy, which was repeated in controlled boiler flushing experiments. These results demonstrate that the impact of low water demand (colloquially called stagnation) is not as straight forward as is generally assumed, and that some flushing practices have potential unintended consequences. In particular, stagnation must be considered in context with other Legionella growth factors like temperature and flow profiles. Boiler flushing practices that dramatically increase the flow rate and rapidly deplete boiler temperature may mobilize Legionella present in biofilms and sediment.

show abstract

Section: Methodsmentioning

confidence: 99%

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

et al. 2022

View full text Add to dashboard Cite

show abstract

“…However, alternative methods such as the IDEXX Legiolert ® kit, a liquid culture method that yields results in most probable number (MPN) per volume, has become more widely used in recent years due to its ease of use and reported specificity for L. pneumophila. [34][35][36][37][38][39][40] DNA-based methods (e.g., quantitative polymerase chain reaction [qPCR] and droplet digital polymerase chain reaction [ddPCR]) have also become more common due to fast turnaround times, the possibility to detect cells in the viable but non-culturable (VBNC) state, and the potential for increased specificity. [41][42][43] However, comparison and interpretation of results obtained with different methods are generally lacking.…”

Section: Introductionmentioning

confidence: 99%

Legionella pneumophilaoccurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

Dowdell

Greenwald

Joshi

et al. 2022

Preprint

View full text Add to dashboard Cite

In spring 2020, reduced water demand was an unintended consequence of COVID-19 pandemic-related building closures. Concerns arose that contaminants associated with water stagnation, such as Legionella pneumophila, could become prevalent. To investigate this potential public health risk, samples from 26 reduced-occupancy buildings across 11 cities in the United States, Canada, and Switzerland were analyzed for L. pneumophila using liquid culture (Legiolert, n=258) and DNA-based methods (qPCR/ddPCR, n=138). L. pneumophila culture-positivity was largely associated with just five buildings, each of which had specific design or operational deficiencies commonly associated with L. pneumophila occurrence. Samples from free chlorine buildings had higher culture-positivity (37%) than chloramine buildings (1%), and 78% of culture-positive samples occurred when the residual was ≤0.1 mg/L Cl2. Although overall sample positivities using culture- and DNA-based methods were equivalent (34% vs. 35%), there was disagreement between the methods in 13% of paired samples. Few buildings reported any water management activities, and L. pneumophila concentrations in flushed samples were occasionally greater than in first-draw samples. This study provides insight into how building plumbing characteristics and management practices contribute to L. pneumophila occurrence during low water use periods and can inform targeted prevention and mitigation efforts.

show abstract

“…At present, culture analysis techniques are the only option that yields L. pneumophila concentrations, which may be compared against action levels. Legiolert ® has emerged as a viable analysis method that may be implemented at the utility level and with sensitivity consistent with action levels proposed in this study and in other protocols for responding to positive samples (Barrette, 2019;Boczek et al, 2021;Checa et al, 2021;Dowdell et al, 2022;Hirsh et al, 2021;Inoue et al, 2020;LeChevallier, 2019aLeChevallier, , 2019bMapili et al, 2020;Maqbool, 2019;McCuin et al, 2021;Niu et al, 2022;Omoregie et al, 2022;Petrisek & Hall, 2017;Rech et al, 2018;Sartory et al, 2017;Scaturro et al, 2020;Spies et al, 2018). Because most qPCR assays do not distinguish between genetic material from live and dead organisms, surveys with qPCR indicate very high occurrence (proportion positive samples) of Legionella, making the results less useful in diagnosing and controlling Legionella growth.…”

Section: Discussionmentioning

confidence: 59%

Protocol for responding to the detection of Legionella pneumophila in drinking water distribution systems

Bartrand,

LeChevallier,

Clancy

et al. 2024

AWWA Water Science

View full text Add to dashboard Cite

A protocol for responding to Legionella pneumophila detections in distribution system samples is presented and justified. The protocol was developed using existing protocols for building water systems, vetted in workshops, and provided to utilities participating in a research project. The protocol provides action levels and actions that utilities can take when L. pneumophila is detected in distribution system samples. Action levels are based on the best available science and expert judgment and are similar to those in protocols for assessing building water system monitoring results. Action levels should be reassessed as additional data and knowledge on the occurrence and growth potential of L. pneumophila in distribution systems become available. All positive detections trigger assessments that focus first on conditions local to the sample location and then extend further into the distribution system. Higher concentration or more frequent detections initiate more assertive responses and communication than lower concentration and frequency detections. The protocol provides a starting point for the development of protocols for purposes such as L. pneumophila operational surveillance or within an outbreak investigation.

show abstract

Comparative study of Legiolert with ISO 11731-1998 standard method-conclusions from a Public Health Laboratory

Cited by 8 publications

References 31 publications

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Legionella pneumophilaoccurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

Protocol for responding to the detection of Legionella pneumophila in drinking water distribution systems

Contact Info

Product

Resources

About