scholarly journals Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures

2016 ◽  
Vol 82 (10) ◽  
pp. 2959-2965 ◽  
Author(s):  
Isabella Marchesi ◽  
Greta Ferranti ◽  
Antonella Mansi ◽  
Anna M. Marcelloni ◽  
Anna R. Proietto ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Legionella Pneumophila ◽  
Water Networks ◽  
Promising Alternative ◽  
Content Type ◽  
Hydrogen Peroxide Treatment ◽  
Temperature Levels ◽  
Physical And Chemical ◽  
Chemical Disinfection

ABSTRACTPhysical and chemical disinfection methods have been proposed with the aim of controllingLegionellawater contamination. To date, the most effective procedures for reducing bacterial contamination have not yet been defined. The aim of this study was to assess the long-term effectiveness of various disinfection procedures in order to reduce both culturable and nonculturable (NC) legionellae in different hospital water networks treated with heat, chlorine dioxide, monochloramine, and hydrogen peroxide. The temperature levels and biocide concentrations that proved to give reliable results were analyzed. In order to study the possible effects on the water pipes, we verified the extent of corrosion on experimental coupons after applying each method for 6 months. The percentage of positive points was at its lowest after treatment with monochloramine, followed by chlorine dioxide, hydrogen peroxide, and hyperthermia. Different selections ofLegionellaspp. were observed, as networks treated with chlorine-based disinfectants were contaminated mainly byLegionella pneumophilaserogroup 1, hyperthermia was associated with serogroups 2 to 14, and hydrogen peroxide treatment was associated mainly with non-pneumophilaspecies. NC cells were detected only in heat-treated waters, and also when the temperature was approximately 60°C. The corrosion rates of the coupons were within a satisfactory limit for water networks, but the morphologies differed. We confirm here that chemical disinfection controlsLegionellacolonization more effectively than hyperthermia does. Monochloramine was the most effective treatment, while hydrogen peroxide may be a promising alternative to chlorine-based disinfectants due to its ability to select for other, less virulent or nonpathogenic species.

scholarly journals Low-Temperature Decontamination with Hydrogen Peroxide or Chlorine Dioxide for Space Applications

2012 ◽  
Vol 78 (12) ◽  
pp. 4169-4174 ◽  
Author(s):  
T. Pottage ◽  
S. Macken ◽  
K. Giri ◽  
J. T. Walker ◽  
A. M. Bennett
Keyword(s):  
Hydrogen Peroxide ◽  
Low Temperature ◽  
Chlorine Dioxide ◽  
Exposure Period ◽  
Microbial Reduction ◽  
Space Applications ◽  
Content Type ◽  
Chlorine Dioxide Gas ◽  
Dry Heat ◽  
D Values

ABSTRACTThe currently used microbial decontamination method for spacecraft and components uses dry-heat microbial reduction at temperatures of >110°C for extended periods to prevent the contamination of extraplanetary destinations. This process is effective and reproducible, but it is also long and costly and precludes the use of heat-labile materials. The need for an alternative to dry-heat microbial reduction has been identified by space agencies. Investigations assessing the biological efficacy of two gaseous decontamination technologies, vapor hydrogen peroxide (Steris) and chlorine dioxide (ClorDiSys), were undertaken in a 20-m3exposure chamber. Five spore-formingBacillusspp. were exposed on stainless steel coupons to vaporized hydrogen peroxide and chlorine dioxide gas. Exposure for 20 min to vapor hydrogen peroxide resulted in 6- and 5-log reductions in the recovery ofBacillus atrophaeusandGeobacillus stearothermophilus, respectively. However, in comparison, chlorine dioxide required an exposure period of 60 min to reduce bothB. atrophaeusandG. stearothermophilusby 5 logs. Of the three otherBacillusspp. tested,Bacillus thuringiensisproved the most resistant to hydrogen peroxide and chlorine dioxide with D values of 175.4 s and 6.6 h, respectively. Both low-temperature decontamination technologies proved effective at reducing theBacillusspp. tested within the exposure ranges by over 5 logs, with the exception ofB. thuringiensis, which was more resistant to both technologies. These results indicate that a review of the indicator organism choice and loading could provide a more appropriate and realistic challenge for the sterilization procedures used in the space industry.

scholarly journals Antimicrobial Activity of Solithromycin against Clinical Isolates of Legionella pneumophila Serogroup 1

2013 ◽  
Vol 58 (2) ◽  
pp. 909-915 ◽  
Author(s):  
Julia Mallegol ◽  
Prabhavathi Fernandes ◽  
Roberto G. Melano ◽  
Cyril Guyard
Keyword(s):  
Legionella Pneumophila ◽  
Lung Epithelial Cells ◽  
Clinical Isolates ◽  
Protein Synthesis Inhibitor ◽  
Respiratory Pathogens ◽  
Synthesis Inhibitor ◽  
Promising Alternative ◽  
Content Type ◽  
Broth Microdilution Method

ABSTRACTThe activity of solithromycin was evaluated against clinicalLegionella pneumophilaserogroup 1 (Lp1) isolates (n= 196) collected in Ontario, Canada, from 1980 to 2011. Itsin vitroactivity was compared to that of azithromycin (AZM) using the broth microdilution method. Solithromycin had a MIC50of ≤0.015 μg/ml and a MIC90of 0.031 μg/ml, making its activity at least 8-fold to 32-fold higher than that of AZM (MIC50and MIC90, 0.125 μg/ml and 1 μg/ml, respectively). Ninety-nine percent of the isolates had MICs for solithromycin ranging from ≤0.015 μg/ml to 0.031 μg/ml, whereas 83.6% of the isolates showed MICs for AZM ranging from 0.062 μg/ml to 0.25 μg/ml. Interestingly, 96.7% (30 out of 31 clinical isolates) identified with higher AZM MICs (0.5 μg/ml to 2 μg/ml) belonged to the clinically prevalent sequence type 1. To investigate the intracellular activity of solithromycin,in vitroinvasion assays were also performed against a subset of representative Lp1 isolates internalized within human lung epithelial cells. Solithromycin and AZM both inhibited growth of all intracellular Lp1 isolates at 1× or 8× MICs, displaying bacteriostatic effects, as would be expected with protein synthesis inhibitor rather than bactericidal activity. Solithromycin demonstrated the highestin vitroand intracellular potency against all Lp1 isolates compared to AZM. Given the rapid spread of resistance mechanisms among respiratory pathogens and the reported treatment failures in legionellosis, the development of this new fluoroketolide, already in phase 3 oral clinical studies, constitutes a promising alternative option for the treatment of legionellosis.

scholarly journals Evaluation of Legionella pneumophila Decrease in Hot Water Network of Four Hospital Buildings after Installation of Electron Time Flow Taps

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 210 ◽  
Author(s):  
Michele Totaro ◽  
Tommaso Mariotti ◽  
Costanza Bisordi ◽  
Erica De Vita ◽  
Paola Valentini ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Cold Water ◽  
Control Measure ◽  
Critical Issue ◽  
Hot Water ◽  
Low Flow ◽  
Water Networks ◽  
Water Network ◽  
Time Flow ◽  
Chemical Disinfection

Legionella spp. control is a critical issue in hospital with old water networks. Chemical disinfection methods are applied as a control measure over prolonged time periods, but Legionella may be resistant to chemical agents in pipeworks with low flow and frequent water stagnation. We evaluated Legionella spp. colonization in the hot water network of Italian hospitals after the installation of time flow taps (TFTs). In the period between 2017 and 2019, TFTs were installed in four hospital water networks. They were programmed in order to obtain a hot water flow of 192 L/day from each TFTs. A continuous chlorination system (chlorine dioxide) and a cold water pre-filtration device were applied in all the buildings. Before and after TFT installation, Legionella spp. was investigated at scheduled times. Before TFT installation, Legionella pneumophila was detected in all the hospitals with counts ranging from 2 × 102 to 1.4 × 105 CFU/L. After TFT installation, a loss in Legionella pneumophila culturability was always achieved in the period between 24 h and 15 days. Total chlorine concentration (Cl2) was detected in the range between 0.23 and 0.36 mg/L while temperature values were from 44.8 to 53.2 °C. TFTs together with chemical disinfection represent a method which improve water quality and disinfectant efficacy, reducing Legionella colonization in dead-end sections.

Bleaching optimization at WestRock mill in Covington, Virginia

TAPPI Journal ◽  
2016 ◽  
Vol 15 (9) ◽  
pp. 581-586 ◽  
Author(s):  
RICARDO B. SANTOS ◽  
PETER W. HART ◽  
DOUGLAS C. PRYKE ◽  
JOHN VANDERHEIDE
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hydroxide ◽  
Chlorine Dioxide ◽  
Capital Expenditures ◽  
Equipment Repair ◽  
Optimization Program ◽  
Hardwood Pulp ◽  
Improved Performance

The WestRock mill in Covington, VA, USA, initiated a long term diagnostic and optimization program for all three of its bleaching lines. Benchmarking studies were used to help identify optimization opportunities. Capital expenditures for mixing improvement, filtrate changes, equipment repair, other equipment changes, and species changes were outside the scope of this work. This focus of this paper is the B line, producing southern hardwood pulp in a D(EP)DD sequence at 88% GE brightness. The benchmarking study and optimization work identified the following opportunities for improved performance: nonoptimal addition of caustic and hydrogen peroxide to the (EP) stage, carryover of D0 filtrate to the (EP) stage, and carryover of (EP) filtrate to the D1 stage. As a result of actions the mill undertook to address these opportunities, D0 kappa factor decreased about 5%, sodium hydroxide consumption in the (EP) stage decreased about 35%, chlorine dioxide consumption in the D1 stage decreased about 25%, and overall bleaching cost decreased about 15%.

An in vitro senescence model of gingival epithelial cell induced by hydrogen peroxide treatment

Odontology ◽  
2021 ◽  
Author(s):  
Sarita Giri ◽  
Ayuko Takada ◽  
Durga Paudel ◽  
Koki Yoshida ◽  
Masae Furukawa ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Epithelial Cell ◽  
Gingival Epithelial Cell ◽  
Hydrogen Peroxide Treatment

scholarly journals Human Lung Tissue Explants Reveal Novel Interactions during Legionella pneumophila Infections

2013 ◽  
Vol 82 (1) ◽  
pp. 275-285 ◽  
Author(s):  
Jens Jäger ◽  
Sebastian Marwitz ◽  
Jana Tiefenau ◽  
Janine Rasch ◽  
Olga Shevchuk ◽  
...  
Keyword(s):  
Lung Tissue ◽  
Legionella Pneumophila ◽  
Human Lung ◽  
Transcriptional Response ◽  
Human Infection ◽  
Bacterial Invasion ◽  
Human Lung Tissue ◽  
Content Type ◽  
Tissue Explants ◽  
Legionnaires Disease

ABSTRACTHistological and clinical investigations describe late stages of Legionnaires' disease but cannot characterize early events of human infection. Cellular or rodent infection models lack the complexity of tissue or have nonhuman backgrounds. Therefore, we developed and applied a novel model forLegionella pneumophilainfection comprising living human lung tissue. We stimulated lung explants withL. pneumophilastrains and outer membrane vesicles (OMVs) to analyze tissue damage, bacterial replication, and localization as well as the transcriptional response of infected tissue. Interestingly, we found that extracellular adhesion ofL. pneumophilato the entire alveolar lining precedes bacterial invasion and replication in recruited macrophages. In contrast, OMVs predominantly bound to alveolar macrophages. Specific damage to septa and epithelia increased over 48 h and was stronger in wild-type-infected and OMV-treated samples than in samples infected with the replication-deficient, type IVB secretion-deficient DotA−strain. Transcriptome analysis of lung tissue explants revealed a differential regulation of 2,499 genes after infection. The transcriptional response included the upregulation of uteroglobin and the downregulation of the macrophage receptor with collagenous structure (MARCO). Immunohistochemistry confirmed the downregulation of MARCO at sites of pathogen-induced tissue destruction. Neither host factor has ever been described in the context ofL. pneumophilainfections. This work demonstrates that the tissue explant model reproduces realistic features of Legionnaires' disease and reveals new functions for bacterial OMVs during infection. Our model allows us to characterize early steps of human infection which otherwise are not feasible for investigations.

scholarly journals Draft Genome Sequences of Four Clinical Legionella pneumophila Isolates from Ontario, Canada

2018 ◽  
Vol 6 (15) ◽  
pp. e00295-18
Author(s):  
Alexander Fortuna ◽  
Ricardo Ramnarine ◽  
Aimin Li ◽  
Nahuel Fittipaldi ◽  
Christine Frantz ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Genetic Relationships ◽  
Draft Genome ◽  
Genome Sequences ◽  
Content Type ◽  
Outbreak Investigations ◽  
Typing Methods

ABSTRACT Legionella pneumophila outbreak investigations require the development of reliable typing methods to better understand the genetic relationships of the isolates involved. Here, we report the draft genome sequences of four clinical Legionella pneumophila isolates obtained between 2000 and 2012 in Ontario, Canada.

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