Long-Term Survival of Legionella pneumophila in the Viable But Nonculturable State After Monochloramine Treatment

Alleron, Laëtitia; Merlet, N.; Lacombe, Christian; Frère, Jacques

doi:10.1007/s00284-008-9275-9

Cited by 113 publications

(88 citation statements)

References 24 publications

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“…Two potential remedies for the low PPV with samples from environmental sources include reverse transcription-PCR, amplifying labile RNA targets present in metabolically active bacteria, and the use of a cell-impermeant chemical, such as ethidium monoazide (EMA) or propidium monoazide (PMA), to inhibit PCR amplification from nonviable cells or extracellular nucleic acids (385)(386)(387)(388)(389)(390). Notably, neither alternative protocol alone will discriminate VBNC legionellae; however, this cell population still poses a potential human health risk (391)(392)(393)(394).…”

Section: Nucleic Acid-based Molecular Diagnosticsmentioning

confidence: 99%

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

2015

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SUMMARY Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic “blind spot” for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.

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Section: Nucleic Acid-based Molecular Diagnosticsmentioning

confidence: 99%

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

2015

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“…It has been shown that unculturable L. pneumophila may resuscitate to a fully virulent form by passage through an amoebal host (30,33,34,36) and therefore provide a largely undetected source of infections. Unculturable Legionellae have been observed for example after prolonged incubation in laboratory tap water microcosms at different temperatures, including elevated temperature at 42°C (36), heat shock (50 -70°C) (37), following disinfection (31)(32)(33), and after treatment with heavy metals (38).…”

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confidence: 99%

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

Auraß

Gerlach

Becher

et al. 2016

Molecular & Cellular Proteomics

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Major differences in the transcriptional program underlying the phenotypic switch between exponential and post-exponential growth of Legionella pneumophila were formerly described characterizing important alterations in infection capacity. Additionally, a third state is known where the bacteria transform in a viable but nonculturable state under stress, such as starvation. We here describe phase-related proteomic changes in exponential phase (E), postexponential phase (PE) bacteria, and unculturable microcosms (UNC) containing viable but nonculturable state cells, and identify phasespecific proteins. We present data on different bacterial subproteomes of E and PE, such as soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins. In total, 1368 different proteins were identified, 922 were quantified and 397 showed differential abundance in E/PE. The quantified subproteomes of soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins; 841, 55, and 77 proteins, respectively, were visualized in Voronoi treemaps. 95 proteins were quantified exclusively in E, such as cell division proteins MreC, FtsN, FtsA, and ZipA; 33 exclusively in PE, such as motility-related proteins of flagellum biogenesis FlgE, FlgK, and FliA; and 9 exclusively in unculturable microcosms soluble whole cell proteins, such as hypothetical, as well as transport/binding-, and metabolism-related proteins. A high frequency of differentially abundant or phase-exclusive proteins was observed among the 91 quantified effectors of the major virulence-associated protein secretion system Dot/Icm (> 60%). 24 were E-exclusive, such as LepA/B, YlfA, MavG, Lpg2271, and 13 were PE-exclusive, such as RalF, VipD, Lem10. The growth phase-related specific abundance of a subset of Dot/Icm virulence effectors was confirmed by means of Western blotting. We therefore conclude that many effectors are predominantly abundant at either E or PE which suggests their phase specific function. The distinct temporal or spatial presence of such proteins might have important implications for functional assignments in the future or for use as lifestage specific markers for pathogen analysis. Molecular

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“…In fact, surfaceadherent microorganisms and bacteria living in protozoa are unrecognized by conventional methods (8). Alleron et al (2) have studied the effect of monochloramine on Legionella pneumophila and demonstrated that this bacterium can persist for long periods in biofilms in the VBNC state.…”

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confidence: 99%

Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

Farhat

Moletta-Denat

Frère

et al. 2012

Appl Environ Microbiol

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ABSTRACTLegionellaspecies are frequently detected in hot water systems, attached to the surface as a biofilm. In this work, the dynamics ofLegionellaspp. and diverse bacteria and eukarya associated together in the biofilm, coming from a pilot scale 1 system simulating a real hot water system, were investigated throughout 6 months after two successive heat shock treatments followed by three successive chemical treatments. Community structure was assessed by a fingerprint technique, single-strand conformation polymorphism (SSCP). In addition, the diversity and dynamics ofLegionellaand eukarya were investigated by small-subunit (SSU) ribosomal cloning and sequencing. Our results showed that pathogenicLegionellaspecies remained after the heat shock and chemical treatments (Legionella pneumophilaandLegionella anisa, respectively). The biofilm was not removed, and the bacterial community structure was transitorily affected by the treatments. Moreover, several amoebae had been detected in the biofilm before treatments (Thecamoebaesp.,Vannellasp., andHartmanella vermiformis) and after the first heat shock treatment, but onlyH. vermiformisremained. However, another protozoan affiliated with Alveolata, which is known as a host cell forLegionella, dominated the eukaryal species after the second heat shock and chemical treatment tests. Therefore, effectiveLegionelladisinfection may be dependent on the elimination of these important microbial components. We suggest that eradicatingLegionellain hot water networks requires better study of bacterial and eukaryal species associated withLegionellain biofilms.

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Long-Term Survival of Legionella pneumophila in the Viable But Nonculturable State After Monochloramine Treatment

Cited by 113 publications

References 24 publications

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

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