Comparison of two culture methods for the enumeration of <i>Legionella pneumophila</i> from potable water samples

Boczek, Laura A.; Tang, Min; Formal, Casey; Lytle, Darren A.; Ryu, Hodon

doi:10.2166/wh.2021.051

Cited by 17 publications

(22 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This may be why the MPN method produces a small number of false positive samples, which has also been observed in other studies [ 34 , 42 ]. In this study, it was found that the elimination of residual chlorine could effectively improve the detection ability of L. pneumophila by the MPN method, which was consistent with the opinion of a reported article [ 35 ], because chlorine residues decrease the culturability of L. pneumophila .…”

Section: Discussionsupporting

confidence: 91%

“…Studies in recent years have indicated that the MPN method is equivalent or better than the plate culture method when used for the determination and evaluation of L. pneumophila in potable water and non-potable water [ 32 ]. Additionally, many studies have disclosed that the MPN method has a higher sensitivity and specificity compared with the plate culture method [ 33 , 34 , 35 , 36 ]. The MPN method has been included in the UK’s Standing Committee of Analysts’ recent update on determining the presence of Legionella , which demonstrates that the MPN method is at least as effective as the plate culture method in detecting and enumerating L. pneumophila in water samples [ 37 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of a Most Probable Number Method for Detection and Quantification of Legionella pneumophila

Niu

Zhang

2022

Pathogens

View full text Add to dashboard Cite

The detection and enumeration of Legionella pneumophila (L. pneumophila) in water is crucial for water quality management, human health and has been a research hotspot worldwide. Due to the time-consuming and complicated operation of the plate culture method, it is necessary to adopt a fast and effective method for application. The present study aimed to comprehensively evaluate the performance and applicability of the MPN method by comparing its qualitative and quantitative results with the GB/T 18204.5-2013 and ISO methods, respectively. The qualitative results showed that 372 samples (53%) were negative for both methods; 315 samples (45%) were positively determined by the MPN method, compared with 211 samples (30%) using GB/T 18204.5-2013. The difference in the detection rate between the two methods was statistically significant. In addition, the quantitative results showed that the concentration of L. pneumophila by the MPN method was greater than ISO 11731 and the difference was statistically significant. However, the two methods were different but highly correlated (r = 0.965, p < 0.001). The specificity and sensitivity of the MPN method were 89.85% and 95.73%, respectively. Overall, the results demonstrated that the MPN method has higher sensitivity, a simple operation process and good application prospects in the routine monitoring of L. pneumophila from water samples.

show abstract

Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Evaluation of a Most Probable Number Method for Detection and Quantification of Legionella pneumophila

Niu

Zhang

2022

Pathogens

View full text Add to dashboard Cite

show abstract

“…Stenotrophomonas maltophilia and unidentified organisms were recovered from the false‐positive samples. Several studies indicate that Legiolert and the ISO methods produce comparable results, with Legiolert at times proving to be slightly more sensitive (Boczek et al, 2021; McCuin et al, 2021; Scaturro et al, 2020; Spies et al, 2018). In this study, the counts were close to the limit of detection for both methods, and with such few positives, determining whether one method truly offered an advantage in sensitivity of detection was not possible in this study.…”

Section: Resultsmentioning

confidence: 99%

Legionella monitoring in the New York City water distribution system 2017 to 2019

Omoregie

Szczerba²,

Novak

et al. 2022

AWWA Water Science

View full text Add to dashboard Cite

This study investigated prevalence of Legionella in the New York City (NYC) water distribution system using International Organization for Standardization 11731:2017 and Legiolert (IDEXX, USA) culture-based methods and polymerase chain reaction. All water samples met applicable Environmental Protection Agency and New York State water quality guidelines. Eighty-five percent (448/528) of water samples were positive for Legionella DNA. Despite this, Legionella bacteria were detected in only 2.8% (15/544) of water samples using culture methods. All Legionella pneumophila culture-positive samples were recovered from a single distribution site, which was undergoing a street reconstruction project. The site had conditions indicative of stagnation, and an adjacent building's service line was periodically backflowing. These factors indicate that L. pneumophila may have been introduced from an external source. The lack of culturable Legionella in samples with detectable Legionella DNA suggests that NYC practices are sufficient to protect against culturable Legionella in NYC's water distribution system.

show abstract

“…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

Comparison of two culture methods for the enumeration of Legionella pneumophila from potable water samples

Cited by 17 publications

References 33 publications

Evaluation of a Most Probable Number Method for Detection and Quantification of Legionella pneumophila

Evaluation of a Most Probable Number Method for Detection and Quantification of Legionella pneumophila

Legionella monitoring in the New York City water distribution system 2017 to 2019

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Contact Info

Product

Resources

About