Screening-level assays for potentially human-infectious environmental Legionella spp.

Buse, Helen Y.; Brehm, Abby; Domingo, Jorge W. Santo; Ashbolt, Nicholas J.

doi:10.1007/s12275-011-0233-z

Cited by 9 publications

(3 citation statements)

References 38 publications

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“…The THP-1 human macrophage-like monocyte cell line and A. castellanii were selected for the cytotoxicity assays due to their extensive use as models for Legionella virulence (18,29,30,54,55). Pore formation is a mechanism that contributes to destruction of alveolar epithelial cells and macrophages; thus, the strains' ability to cause pore formation using RBC (hemolytic activity) was assessed (17,21,22,47,56,57).…”

Section: Discussionmentioning

confidence: 99%

Virulence Traits of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

Sharaby

Rodríguez-Martínez

Pecellín

et al. 2018

Appl Environ Microbiol

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causes water-based infections resulting in severe pneumonia. Recently, we showed that different MLVA-8 (multilocus variable-number tandem-repeat analysis using 8 loci) genotypes dominated different sites of a drinking-water distribution system. Each genotype displayed a unique temperature-dependent growth behavior. Here we compared the pathogenicity potentials of different MLVA-8 genotypes of environmental and clinical strains. The virulence traits studied were hemolytic activity and cytotoxicity toward amoebae and macrophages. Clinical strains were significantly more hemolytic than environmental strains, while their cytotoxicity toward amoebae was significantly lower at 30°C. No significant differences were detected between clinical and environmental strains in cytotoxicity toward macrophages. Significant differences in virulence were observed between the environmental genotypes (Gt). Gt15 strains showed a significantly higher hemolytic activity. In contrast, Gt4 and Gt6 strains were more infective toward Moreover, Gt4 strains exhibited increased cytotoxicity toward macrophages and demonstrated a broader temperature range of amoebal lysis than Gt6 and Gt15 strains. Understanding the virulence traits of genotypes may improve the assessment of public health risks of in drinking water. is the causative agent of a severe form of pneumonia. Here we demonstrated that clinical strains were significantly more cytotoxic toward red blood cells than environmental strains, while their cytotoxicity toward macrophages was similar. Genotype 4 (Gt4) strains were highly cytotoxic toward amoebae and macrophages and lysed amoebae in a broader temperature range than to the other studied genotypes. The results can explain the relatively high success of Gt4 in the environment and in clinical samples; thus, Gt4 strains should be considered a main factor for the assessment of public health risks of in drinking water. Our findings shed light on the ecology, virulence, and pathogenicity potential of different genotypes, which can be a valuable parameter for future modeling and quantitative microbial risk assessment of in drinking-water systems.

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Section: Discussionmentioning

confidence: 99%

Virulence Traits of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

Sharaby

Rodríguez-Martínez

Pecellín

et al. 2018

Appl Environ Microbiol

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“…This finding is significant in that it demonstrates that the NSF International standards for Class-B POU secondary disinfection systems could be inadequate for removal of pathogenic L. pneumophila. Furthermore, culture-based detection would indicate no risk, as the bacteria are non-culturable directly following UV treatment, yet remain infectious and may regain culturability over time (potentially also with lung macrophages) [29].…”

Section: Resultsmentioning

confidence: 99%

Searching for Activity Markers that Approximate (VBNC) Legionella pneumophila Infectivity in Amoeba after Ultraviolet (UV) Irradiation

Grossi¹,

Dey²,

Ashbolt³

2018

Water

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Legionella pneumophila is an increasingly recognized threat to public health via aerosol exposures; with a variety of control measures including: water temperature/flow management and free chlorine used to reduce the risk of infection within healthcare centers. Despite these efforts, L. pneumophila often recolonizes plumbing systems after specific treatments, which prompted us to examine ultraviolet (UV) irradiation for a point-of-use, secondary control measure. Currently, there is no data on the efficacy of high (>254 nm) wavelength UV-C (100–280 nm) light inactivation of L. pneumophila with resuscitation of viable but non-culturable (VBNC) cells. We report for the first time L. pneumophila dose-responses for 268.6 nm and 288.6 nm UV-C, as compared to 256 nm, and demonstrate UV induced VBNC L. pneumophila remaining infectious to Acanthamoeba polyphaga during co-culture experiments. Findings were correlated to molecular-based activity assays to identify additional measures of L. pneumophila viability following UV disinfection compared to culture. A collection of viability markers may provide a more representative measure of risk compared to current culture-based detection, since UV-C irradiated L. pneumophila lose culturability, yet retain activity, increased ATP production, and the ability to be resuscitated by amoeba co-culture. This finding is significant as it identifies potential concern from VBNC cells following UV-C disinfection and the need for further research into the efficacy of UV inactivation as a point-of-use application for L. pneumophila control and management.

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“…L. pneumophila strain Lp02 was used in this study as previously described (24). Bacteria were grown on buffered charcoal yeast extract (BCYE) agar plates (BD Diagnostic Systems, Franklin Lakes, NJ) for 2 to 4 days at 37°C.…”

Section: Methodsmentioning

confidence: 99%

Legionella pneumophila Transcriptional Response following Exposure to CuO Nanoparticles

Struewing

Buse

et al. 2013

Appl Environ Microbiol

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eCopper ions are an effective antimicrobial agent used to control Legionnaires' disease and Pontiac fever arising from institutional drinking water systems. Here, we present data on an alternative bactericidal agent, copper oxide nanoparticles (CuONPs), and its efficacy on Legionella pneumophila. In broth cultures, the CuO-NPs caused growth inhibition, which appeared to be concentration and exposure time dependent. The transcriptomic response of L. pneumophila to CuO-NP exposure was investigated by using a whole-genome microarray. The expression of genes involved in metabolism, transcription, translation, DNA replication and repair, and unknown/hypothetical proteins was significantly affected by exposure to CuO-NPs. In addition, expression of 21 virulence genes was also affected by exposure to CuO-NP and further evaluated by quantitative reverse transcription-PCR (qRT-PCR). Some virulence gene responses occurred immediately and transiently after addition of CuO-NPs to the cells and faded rapidly (icmV, icmW, lepA), while expression of other genes increased within 6 h (ceg29, legLC8, legP, lem19, lem24, lpg1689, and rtxA), 12 h (cegC1, dotA, enhC, htpX, icmE, pvcA, and sidF), and 24 h (legP, lem19, and ceg19), but for most of the genes tested, expression was reduced after 24 h of exposure. Genes like ceg29 and rtxA appeared to be the most responsive to CuO-NP exposures and along with other genes identified in this study may prove useful to monitor and manage the impact of drinking water disinfection on L. pneumophila.

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Screening-level assays for potentially human-infectious environmental Legionella spp.

Cited by 9 publications

References 38 publications

Virulence Traits of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

Virulence Traits of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

Searching for Activity Markers that Approximate (VBNC) Legionella pneumophila Infectivity in Amoeba after Ultraviolet (UV) Irradiation

Legionella pneumophila Transcriptional Response following Exposure to CuO Nanoparticles

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