Legionella species and serogroups in Malaysian water cooling towers: identification by latex agglutination and PCR-DNA sequencing of isolates

Yong, Stacey F. Y.; Goh, Fen-Ning; Ngeow, Yun Fong

doi:10.2166/wh.2009.002

Cited by 5 publications

(3 citation statements)

References 19 publications

(14 reference statements)

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“…A similar proportion of Legionella culture-positive CTs has been reported from surveys conducted in Asia, Australia, and Europe [ 7 , 8 , 29 – 31 ]. Additionally, Lp has also been found to be the most highly recovered Legionella species in multiple studies outside of the US [ 7 , 8 , 30 – 32 ], underscoring the ubiquity of this pathogen within CTs across the globe. Similarity, cooling towers sampled as part of a recent large outbreak investigation in New York City also demonstrated similar detection levels of Lp1 DNA (38%) and isolates (25%) [ 33 ].…”

Section: Discussionmentioning

confidence: 99%

Distribution of Legionella and bacterial community composition among regionally diverse US cooling towers

et al. 2017

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Cooling towers (CTs) are a leading source of outbreaks of Legionnaires’ disease (LD), a severe form of pneumonia caused by inhalation of aerosols containing Legionella bacteria. Accordingly, proper maintenance of CTs is vital for the prevention of LD. The aim of this study was to determine the distribution of Legionella in a subset of regionally diverse US CTs and characterize the associated microbial communities. Between July and September of 2016, we obtained aliquots from water samples collected for routine Legionella testing from 196 CTs located in eight of the nine continental US climate regions. After screening for Legionella by PCR, positive samples were cultured and the resulting Legionella isolates were further characterized. Overall, 84% (164) were PCR-positive, including samples from every region studied. Of the PCR-positive samples, Legionella spp were isolated from 47% (78), L. pneumophila was isolated from 32% (53), and L. pneumophila serogroup 1 (Lp1) was isolated from 24% (40). Overall, 144 unique Legionella isolates were identified; 53% (76) of these were Legionella pneumophila. Of the 76 L. pneumophila isolates, 51% (39) were Lp1. Legionella were isolated from CTs in seven of the eight US regions examined. 16S rRNA amplicon sequencing was used to compare the bacterial communities of CT waters with and without detectable Legionella as well as the microbiomes of waters from different climate regions. Interestingly, the microbial communities were homogenous across climate regions. When a subset of seven CTs sampled in April and July were compared, there was no association with changes in corresponding CT microbiomes over time in the samples that became culture-positive for Legionella. Legionella species and Lp1 were detected frequently among the samples examined in this first large-scale study of Legionella in US CTs. Our findings highlight that, under the right conditions, there is the potential for CT-related LD outbreaks to occur throughout the US.

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Section: Discussionmentioning

confidence: 99%

Distribution of Legionella and bacterial community composition among regionally diverse US cooling towers

et al. 2017

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“…or species-specific (based on the mip gene, encoding the macrophage infectivity potentiator of L. pneumophila) detection (39). Other genome targets, such as the 5S rRNA gene (25), the 23S rRNA gene (34), or the rpoB gene (41), have also been used, but no qPCR method specific for the detection of high-risk isolates of L. pneumophila Sg1 is available yet, since no specific targets for Sg1 have been known.…”

mentioning

confidence: 99%

Specific Real-Time PCR for Simultaneous Detection and Identification of Legionella pneumophila Serogroup 1 in Water and Clinical Samples

Merault

Rusniok

Jarraud

et al. 2011

Appl Environ Microbiol

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Legionella pneumophila, a bacterium that replicates within aquatic amoebae and persists in the environment as a free-living microbe, is the causative agent of Legionnaires' disease. Among the many Legionella species described, L. pneumophila is associated with 90% of human disease, and within the 15 serogroups (Sg), L. pneumophila Sg1 causes more than 84% of Legionnaires' disease worldwide. Thus, rapid and specific identification of L. pneumophila Sg1 is of the utmost importance for evaluation of the contamination of collective water systems and the risk posed. Previously we had shown that about 20 kb of the 33-kb locus carrying the genes coding for the proteins involved in lipopolysaccharide biosynthesis (LPS gene cluster) by L. pneumophila was highly specific for Sg1 strains and that three genes (lpp0831, wzm, and wzt) may serve as genetic markers. Here we report the sequencing and comparative analyses of this specific region of the LPS gene cluster in L. pneumophila Sg6, -10, -12, -13, and -14. Indeed, the wzm and wzt genes were present only in the Sg1 LPS gene cluster, which showed a very specific gene content with respect to the other five serogroups investigated. Based on this observation, we designed primers and developed a classical and a real-time PCR method for the detection and simultaneous identification of L. pneumophila Sg1 in clinical and environmental isolates. Evaluation of the selected primers with 454 Legionella and 38 non-Legionella strains demonstrated 100% specificity. Sensitivity, specificity, and predictive values were further evaluated with 209 DNA extracts from water samples of hospital water supply systems and with 96 respiratory specimens. The results showed that the newly developed quantitative Sg1-specific PCR method is a highly specific and efficient tool for the surveillance and rapid detection of high-risk L. pneumophila Sg1 in water and clinical samples.Legionella pneumophila is ubiquitous in natural, aqueous environments, where it parasitizes aquatic protozoa (1). From these environments Legionella can contaminate artificial water circuits and then grow and proliferate to high numbers, in particular in hot water systems, including aerosol-producing devices such as air conditioning systems or cooling towers (18,19,37). Upon aerosol formation via man-made water systems, Legionella can enter the human lung and cause a severe form of pneumonia. Since transmission of Legionella from person to person has never been observed, prevention needs to concentrate on the elimination of this pathogen from water and aerosol-producing systems. Thus, rapid and precise detection of Legionella in water systems is of the utmost importance for risk prediction and the elimination of Legionella from possible infection sources.Water contamination by Legionella is currently monitored by culture-based methods approved by the International Organization for Standardization (29) and the French organization for standardization (2). The alert and action thresholds defined by the national authorities that obli...

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“…The samples were placed in the Techne Thermal Cycler device for the first-step PCR run. The conditions used to run the first step PCR were: 1 cycle of initial denaturation at 95 °C for 90 sec; 30 cycles composed of denaturation for 10 sec at 95 °C, annealing at 64 °C for a min and extension at 72 °C for a min; final extension at 72 °C for 5 min (Yong et al, 2010). PCR products were run on a 1% agarose gel at 110 V for 30 min and visualized with SYBR Green in a UV transilluminator (Kodak GL 1500).…”

Section: First-step Pcrmentioning

confidence: 99%

Detection methods for Legionella pneumophila in diverse environmental conditions: A comparative study of FISH, seminested PCR and conventional culture

Alver, I. A.,

Kimiran, A.

2024

MJM

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Aims: Legionella bacteria cause Legionnaires' disease and Pontiac fever. It is commonly found in natural water resources and manmade water systems. Environmental conditions such as nutrient deficiency, temperature, pH, disinfectant and the presence of other bacteria can cause Legionella bacteria to pass into the viable but not-culturable (VBNC) phase. This study was aimed to determine appropriate methods to detect Legionella pneumophila bacteria living in water systems with wide temperature and pH ranges threatening human health. Methodology and results: In this study, water samples containing L. pneumophila at a concentration of 10 8 cell/L were exposed to different temperatures (5 °C, 50 °C, 55 °C and 60 °C) and pH (2.2, 5.8, 7.0 and 8.2) values. Conventional culture, FISH and seminested PCR methods were used to detect L. pneumophila. A comparison was made between the methods used in the study to determine the most appropriate method for detecting L. pneumophila bacteria. The results showed that the highest detection rates of L. pneumophila were at 5 °C for 24 h (100%) and at pH 2.2 for 0 th min (100%) by using FISH method. All the samples could be determined by the seminested PCR method. The results of our study showed that the highest detection rates of L. pneumophila were at 5 °C for 24 h (100%) and at pH 2.2 for 0 min (100%) by FISH method. All of the samples could be determined by the seminested PCR method. It was determined that the detection rate was the lowest in the FISH method at 3 min at 60 °C and the highest was 24 h at 5 °C. The lowest detection rate was also observed by using FISH method in the samples exposed to 60 °C for 3 min. Results show that the FISH and seminested PCR methods are the most suitable for detecting L. pneumophila bacteria from water systems exposed to different environmental conditions. Conclusion, significance and impact of study: Different methods (conventional culture, FISH, seminested PCR) used to detect L. pneumophila bacteria were compared in this study. It was concluded that Legionella bacteria passed into the VBNC phase, and compared to molecular methods, the conventional culture method provides a low detection rate of these bacteria. Research findings suggest that it is insufficient to use the conventional culture method alone for the detection of Legionella bacteria from man-made water systems or human samples. This study is important as it is decisive for the determination of the most appropriate method for detecting the human pathogen L. pneumophila bacteria from water samples and the choice for a fast and effective method for the elimination of the infectious agent.

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Legionella species and serogroups in Malaysian water cooling towers: identification by latex agglutination and PCR-DNA sequencing of isolates

Cited by 5 publications

References 19 publications

Distribution of Legionella and bacterial community composition among regionally diverse US cooling towers

Distribution of Legionella and bacterial community composition among regionally diverse US cooling towers

Specific Real-Time PCR for Simultaneous Detection and Identification of Legionella pneumophila Serogroup 1 in Water and Clinical Samples

Detection methods for Legionella pneumophila in diverse environmental conditions: A comparative study of FISH, seminested PCR and conventional culture

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