Effectiveness of Disinfectants Used in Cooling Towers against &lt;i&gt;Legionella pneumophila&lt;/i&gt;

Garcı́a, Marı́a Teresa; Peláz, Carmen

doi:10.1159/000118662

Cited by 14 publications

(5 citation statements)

References 39 publications

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“…DDAC is a Quaternary Ammonium Compound (QAC) disinfectant often used in the industry to disinfect hard surfaces because of its relatively low toxicity, broad antimicrobial spectrum, non-volatility, and chemical stability [28]. In a previous study, the disinfectant DDAC showed the bactericidal activity against L. pneumophila at concentrations used in cooling tower treatments [29]. In addition, the DDAC is a membrane-active agent and causes membrane leakage of intracellular material [30].…”

Section: Discussionmentioning

confidence: 99%

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants

et al. 2020

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Francisella tularensis is a highly infectious, intracellular bacterium and it is the causative agent of tularemia. The bacterium has been isolated from more than 250 species, including protozoa. Previous studies have shown that the growth of Legionella pneumophila within the amoeba results in a dramatic increase in the resistance to disinfectants. Since Francisella persists in the environment for years, this study investigates whether Acanthamoeba castellanii-grown F. novicida exhibits an alteration in the resistance to disinfectants. The disinfectants used are didecyldimethylammonium chloride (DDAC) combined with isopropyl alcohol (D1), benzalkonium chloride combined with DDAC and formic acid (D2), and polyhexamethylene biguanide (PHMB, D3). The effect of disinfectants on the bacterial viability is determined by a colony-forming unit (CFU), by transmission electron microscopy (TEM), by fluorescence microscopy, and the damage of the bacterial membrane. Our data has shown that only a one-log10 loss in bacterial viability is exhibited upon treatment of agar-grown Francisella, while in amoeba-grown Francisella there was a three-log10 difference with D3. The D1 disinfectant sterilized the bacteria within 10 s. The treatment of agar-grown F. novicida with D2 reduces bacterial viability by seven-log10 within 10 s and 15 min, respectively. Surprisingly, the treatment of amoeba-grown F. novicida with D2 results in a total loss of bacterial viability. In conclusion, A. castellanii-grown F. novicida is more susceptible to many disinfectants.

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Section: Discussionmentioning

confidence: 99%

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants

et al. 2020

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“…Used appropriately, biocides offer an important means of reducing the transmission and growth of microorganisms (34)(35)(36). They have the potential, through disinfection and antisepsis, to reduce the incidence of infections and the burden on antibiotics (35,37) and to protect consumers through the preservation of liquid formulations (38).…”

Section: Discussionmentioning

confidence: 99%

Loss of Function in Escherichia coli Exposed to Environmentally Relevant Concentrations of Benzalkonium Chloride

Forbes

Morgan

Humphreys

et al. 2019

Appl Environ Microbiol

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Assessing the risk of resistance associated with biocide exposure commonly involves exposing microorganisms to biocides at concentrations close to the MIC. With the aim of representing exposure to environmental biocide residues, Escherichia coli MG1655 was grown for 20 passages in the presence or absence of benzalkonium chloride (BAC) at 100 ng/liter and 1,000 ng/liter (0.0002% and 0.002% of the MIC, respectively). BAC susceptibility, planktonic growth rates, motility, and biofilm formation were assessed, and differentially expressed genes were determined via transcriptome sequencing. Planktonic growth rate and biofilm formation were significantly reduced (P < 0.001) following BAC adaptation, while BAC minimum bactericidal concentration increased 2-fold. Transcriptomic analysis identified 289 upregulated and 391 downregulated genes after long-term BAC adaptation compared with the respective control organism passaged in BAC-free medium. When the BAC-adapted bacterium was grown in BAC-free medium, 1,052 genes were upregulated and 753 were downregulated. Repeated passage solely in biocide-free medium resulted in 460 upregulated and 476 downregulated genes compared with unexposed bacteria. Long-term exposure to environmentally relevant BAC concentrations increased the expression of genes associated with efflux and reduced the expression of genes associated with outer-membrane porins, motility, and chemotaxis. This was manifested phenotypically through the loss of function (motility). Repeated passage in a BAC-free environment resulted in the upregulation of multiple respiration-associated genes, which was reflected by increased growth rate. In summary, repeated exposure of E. coli to BAC residues resulted in significant alterations in global gene expression that were associated with minor decreases in biocide susceptibility, reductions in growth rate and biofilm formation, and loss of motility. IMPORTANCE Exposure to very low concentrations of biocides in the environment is a poorly understood risk factor for antimicrobial resistance. Repeated exposure to trace levels of the biocide benzalkonium chloride (BAC) resulted in loss of function (motility) and a general reduction in bacterial fitness but relatively minor decreases in susceptibility. These changes were accompanied by widespread changes in the Escherichia coli transcriptome. These results demonstrate the importance of including phenotypic characterization in studies designed to assess the risks of biocide exposure.

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“…Legionella are not completely eliminated from drinking water by standard water treatment practices. For example, Legionella are comparatively more resistant to chlorine than Escherichia coli ( Garcia and Pelaz 2008 ; Hosein et al 2005 ; Kim et al 2002 ; Zhang et al 2007 ). Legionella are also known to be sheltered within encysted amoebae; indeed, after phagocytosis by amoebae, whose cells are relatively chlorine-resistant, Legionella can survive up to 50 ppm chlorine ( Kilvington and Price 1990 ).…”

Section: Legionella Ecologymentioning

confidence: 99%

Epidemiology and Ecology of Opportunistic Premise Plumbing Pathogens: Legionella pneumophila , Mycobacterium avium , and Pseudomonas aeruginosa

Falkinham

Hilborn

Arduino

et al. 2015

Environ Health Perspect

227

187

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BackgroundLegionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa are opportunistic premise plumbing pathogens (OPPPs) that persist and grow in household plumbing, habitats they share with humans. Infections caused by these OPPPs involve individuals with preexisting risk factors and frequently require hospitalization.ObjectivesThe objectives of this report are to alert professionals of the impact of OPPPs, the fact that 30% of the population may be exposed to OPPPs, and the need to develop means to reduce OPPP exposure. We herein present a review of the epidemiology and ecology of these three bacterial OPPPs, specifically to identify common and unique features.MethodsA Water Research Foundation–sponsored workshop gathered experts from across the United States to review the characteristics of OPPPs, identify problems, and develop a list of research priorities to address critical knowledge gaps with respect to increasing OPPP-associated disease.DiscussionOPPPs share the common characteristics of disinfectant resistance and growth in biofilms in water distribution systems or premise plumbing. Thus, they share a number of habitats with humans (e.g., showers) that can lead to exposure and infection. The frequency of OPPP-infected individuals is rising and will likely continue to rise as the number of at-risk individuals is increasing. Improved reporting of OPPP disease and increased understanding of the genetic, physiologic, and structural characteristics governing the persistence and growth of OPPPs in drinking water distribution systems and premise plumbing is needed.ConclusionsBecause broadly effective community-level engineering interventions for the control of OPPPs have yet to be identified, and because the number of at-risk individuals will continue to rise, it is likely that OPPP-related infections will continue to increase. However, it is possible that individuals can take measures (e.g., raise hot water heater temperatures and filter water) to reduce home exposures.CitationFalkinham JO III, Hilborn ED, Arduino MJ, Pruden A, Edwards MA. 2015. Epidemiology and ecology of opportunistic premise plumbing pathogens: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. Environ Health Perspect 123:749–758; http://dx.doi.org/10.1289/ehp.1408692

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Effectiveness of Disinfectants Used in Cooling Towers against <i>Legionella pneumophila</i>

Cited by 14 publications

References 39 publications

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants

Loss of Function in Escherichia coli Exposed to Environmentally Relevant Concentrations of Benzalkonium Chloride

Epidemiology and Ecology of Opportunistic Premise Plumbing Pathogens: Legionella pneumophila , Mycobacterium avium , and Pseudomonas aeruginosa

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