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Ma X, Bibby K. Free chlorine and monochloramine inactivation kinetics of Aspergillus and Penicillium in drinking water. WATER RESEARCH 2017; 120:265-271. [PMID: 28501787 DOI: 10.1016/j.watres.2017.04.064] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 04/17/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
Fungi are near-ubiquitous in potable water distribution systems, but the disinfection kinetics of commonly identified fungi are poorly studied. In the present study, laboratory scale experiments were conducted to evaluate the inactivation kinetics of Aspergillus fumigatus, Aspergillus versicolor, and Penicillium purpurogenum by free chlorine and monochloramine. The observed inactivation data were then fit to a delayed Chick-Watson model. Based on the model parameter estimation, the Ct values (integrated product of disinfectant concentration C and contact time t over defined time intervals) for 99.9% inactivation of the tested fungal strains ranged from 48.99 mg min/L to 194.7 mg min/L for free chlorine and from 90.33 mg min/L to 531.3 mg min/L for monochloramine. Fungal isolates from a drinking water system (Aspergillus versicolor and Penicillium purpurogenum) were more disinfection resistant than Aspergillus fumigatus type and clinical isolates. The required 99.9% inactivation Ct values for the tested fungal strains are higher than E. coli, a commonly monitored indicator bacteria, and within a similar range for bacteria commonly identified within water distribution systems, such as Mycobacterium spp. and Legionella spp.
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Affiliation(s)
- Xiao Ma
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Kyle Bibby
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Computational and Systems Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA.
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Zhou B, Luo Y, Nou X, Lyu S, Wang Q. Inactivation dynamics of Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 in wash water during simulated chlorine depletion and replenishment processes. Food Microbiol 2015; 50:88-96. [PMID: 25998820 DOI: 10.1016/j.fm.2015.03.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/05/2015] [Accepted: 03/24/2015] [Indexed: 10/23/2022]
Abstract
Maintaining effective sanitizer concentration is of critical importance for preventing pathogen survival and transference during fresh-cut produce wash operation and for ensuring the safety of finished products. However, maintaining an adequate level of sanitizer in wash water can be challenging for processors due to the large organic load in the wash system. In this study, we investigated how the survival of human pathogens was affected by the dynamic changes in water quality during chlorine depletion and replenishment in simulated produce washing operations. Lettuce extract was added incrementally into water containing pre-set levels of free chlorine to simulate the chlorine depletion process, and sodium hypochlorite was added incrementally into water containing pre-set levels of lettuce extract to simulate chlorine replenishment. Key water quality parameters were closely monitored and the bactericidal activity of the wash water was evaluated using three-strain cocktails of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes. In both chlorine depletion and replenishment processes, no pathogen survival was observed when wash water free chlorine level was maintained above 3.66 mg/L, irrespective of the initial free chlorine levels (10, 50, 100 and 200 mg/L) or organic loading (chemical oxidation demand levels of 0, 532, 1013 and 1705 mg/L). At this free chlorine concentration, the measured ORP was 843 mV and pH was 5.12 for the chlorine depletion process; the measured ORP was 714 mV and pH was 6.97 for the chlorine replenishment process. This study provides quantitative data needed by the fresh-cut produce industry and the regulatory agencies to establish critical operational control parameters to prevent pathogen survival and cross-contamination during fresh produce washing.
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Affiliation(s)
- Bin Zhou
- U. S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Environmental Microbiology and Food Safety Laboratory, 10300 Baltimore Ave, Beltsville, MD 20705, USA; Department of Nutrition and Food Science, University of Maryland, 0112 Skinner Building, College Park, MD 20742, USA
| | - Yaguang Luo
- U. S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Environmental Microbiology and Food Safety Laboratory, 10300 Baltimore Ave, Beltsville, MD 20705, USA.
| | - Xiangwu Nou
- U. S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Environmental Microbiology and Food Safety Laboratory, 10300 Baltimore Ave, Beltsville, MD 20705, USA
| | - Shuxia Lyu
- College of Biological Sciences and Technology, Shenyang Agricultural University, Shenyang, PR China
| | - Qin Wang
- Department of Nutrition and Food Science, University of Maryland, 0112 Skinner Building, College Park, MD 20742, USA
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Efficacy of Colloidal Silver-Hydrogen Peroxide and 2-Bromo-2-nitroporopane-1,3-diol Compounds Against Different Serogroups of Legionella pneumophila Strains. Indian J Microbiol 2013; 52:54-9. [PMID: 23449761 DOI: 10.1007/s12088-011-0189-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 06/03/2011] [Indexed: 10/18/2022] Open
Abstract
Cooling towers are considered as amplifier and disseminator sources for Legionella spp. despite preventive treatments. Information which was obtained from biocidal tests could improve the effectiveness of treatments. Therefore, the choice of appropriate biocides and the applying of biocides in correct dosages and contact times are important. Various oxidizing and non-oxidizing biocides have been investigated in vitro for their effectiveness against legionellae. Colloidal silver-hydrogen peroxide (CSHP) and 2-bromo-2-nitroporopane-1,3-diol (BNPD) biocides were selected as an example for oxidizing and non-oxidizing agents, respectively, in view of bactericidal action against different serogroups of L. pneumophila strains [serogroup 1 (S1) and serogroup 2-14 (S2)] which are isolated different cooling towers in the vicinity of Istanbul, Turkey and reference strain. In the current study, oxidizing biocide was found more effective than non-oxidizing biocide in terms of contact times, log reductions and recommended dosages. At the recommended concentrations for cooling towers (100 ppm), while CSHP compound killed all strains in 3 h contact time, BNPD compound killed S2 and reference strain in the same contact time, S1 strain after 6 h contact time. The results of the present study showed that effective biocide applications can be achieved by pre-determining minimum inhibitory concentration (MIC) and minimum contact time of different biocides to kill target bacteria.
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Sanli-Yurudu NO, Kimiran-Erdem A, Cotuk A. Studies on the efficacy of Chloramine T trihydrate (N-chloro-p-toluene sulfonamide) against planktonic and sessile populations of different Legionella pneumophila strains. Int J Hyg Environ Health 2006; 210:147-53. [PMID: 16990048 DOI: 10.1016/j.ijheh.2006.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 07/25/2006] [Accepted: 08/08/2006] [Indexed: 10/24/2022]
Abstract
Effectiveness of Chloramine T trihydrate (N-chloro-p-toluene sulfonamide) on both planktonic and sessile populations of different Legionella pneumophila strains was assessed. Although Chloramine T is a recommended commercial formulation for disinfecting cooling towers, there is a lack of published data about the efficacy of this compound against both planktonic and sessile populations of L. pneumophila. Planktonic L. pneumophila strains were suspended in tap water and sessile L. pneumophila strains were grown on stainless steel which is used in the construction of cooling towers, followed by exposure to the biocide. The sensitivity of both planktonic and sessile populations of L. pneumophila strains was different. The biocide was found effective below recommended dosages (0.1-0.3%) against planktonic populations of L. pneumophila, whereas it was determined that higher dosages than those recommended were required for sessile populations of L. pneumophila. The results indicated that studying only the planktonic populations of L. pneumophila for biocide tests might not be sufficient to provide information about the optimum dosage and contact time. Therefore, efficacy has to be tested on both planktonic and sessile bacteria.
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Kim BR, Anderson JE, Mueller SA, Gaines WA, Kendall AM. Literature review--efficacy of various disinfectants against Legionella in water systems. WATER RESEARCH 2002; 36:4433-44. [PMID: 12418646 DOI: 10.1016/s0043-1354(02)00188-4] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
There have been reported outbreaks of Legionnaires' disease at hospitals and industrial facilities, which prompted the development of various preventive measures. For example, Ford has been developing and implementing such a measure at its facilities worldwide to provide technical guidance for controlling Legionella in water systems. One of the key issues for implementing the measure is the selection of a disinfectant(s) and optimum conditions for its use. Therefore, available publications on various disinfectants and disinfection processes used for the inactivation of Legionella bacteria were reviewed. Two disinfection methods were reviewed: chemical and thermal. For chemical methods, disinfectants used were metal ions (copper and silver), oxidizing agents (halogen containing compounds [chlorine, bromine, iodine, chlorine dioxide, chloramines, and halogenated hydantoins], ozone, and hydrogen peroxide), non-oxidizing agents (heterocyclic ketones, guanidines, thiocarbamates, aldehydes, amines, thiocyanates, organo-tin compounds, halogenated amides, and halogenated glycols), and UV light. In general, oxidizing disinfectants were found to be more effective than non-oxidizing ones. Among oxidizing agents, chlorine is known to be effective and widely used. Among non-oxidizing agents, 2,2-dibromo-3-nitropropionamide appears to be the most effective followed by glutaraldehyde. Isothiazolin (known as Kathon), polyhexamethylene biguanide, and 2-bromo-2-nitropropionamide (known as Bronopol) were found to be less effective than glutaraldehyde. Thermal disinfection is effective at > 60 degrees C (140 degrees F).
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Affiliation(s)
- B R Kim
- Ford Research Laboratory, Dearborn, MI 48121, USA.
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Bentham RH, Broadbent CR. Field trial of biocides for control of Legionella in cooling towers. Curr Microbiol 1995; 30:167-72. [PMID: 7765850 DOI: 10.1007/bf00296203] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Legionella and amebae populations in 16 cooling towers were challenged with three commercially available biocide formulations. The active agents were: a chlorinated phenolic thioether (CPTE), bromo-nitro-propane-diol (BNPD), and bromo-chloro-dimethylhydantoin (BCD, in briquette form). The towers were dosed with these biocides for approximately 4 weeks. BCD was effective against Legionella in each of nine challenge experiments, and CPTE in eight of nine challenges. BNPD was effective in only five of 11 challenges. None of the biocides had any significant effect in reducing planktonic amebae concentrations during the challenges.
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Affiliation(s)
- R H Bentham
- School of Biological Sciences, Flinders University of South Australia, Bedford Park
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Wright JB, Ruseska I, Costerton JW. Decreased biocide susceptibility of adherent Legionella pneumophila. THE JOURNAL OF APPLIED BACTERIOLOGY 1991; 71:531-8. [PMID: 1778846 DOI: 10.1111/j.1365-2672.1991.tb03828.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In a study of the in vitro effectiveness of biocides against Legionella pneumophila, some aspects of the cooling tower environment were replicated in the laboratory, paying particular attention to water hardness and pH. Pieces of Douglas fir and polyvinyl chloride were colonized in a recirculating system and the comparative efficacy of two biocides (Bronopol and Kathon) against the sessile and planktonic populations was examined. While the biocides were relatively effective against the planktonic L. pneumophila population over a short period of time (minimum 9-12 h), substantially longer periods of time (maximum greater than 48 h) were required to reduce the number of cultivable bacteria to below detectable levels in the adherent population. The results indicate that failure to monitor the sessile population of L. pneumophila in laboratory studies of biocides may result in the use of incorrect dosages and/or contact times in field trials with apparently reduced in situ efficacy.
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Affiliation(s)
- J B Wright
- Department of Biological Sciences, University of Calgary, Alberta, Canada
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Yamamoto H, Ezaki T, Ikedo M, Yabuuchi E. Effects of biocidal treatments to inhibit the growth of legionellae and other microorganisms in cooling towers. Microbiol Immunol 1991; 35:795-802. [PMID: 1808473 DOI: 10.1111/j.1348-0421.1991.tb01612.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects of biocidal treatments for cooling towers were examined through the use of chemicals and ultraviolet irradiation to inhibit the growth of legionellae and other microorganisms. In the water of cooling towers without continuous biocidal treatments, heterotrophic bacteria and bacterivorous protozoan first appeared, and then legionellae increased up to 10(4) CFU/100 ml. When a UV sterilizer was connected to the cooling tower, the legionellae count was 1/10 or 1/100 of that in the nontreated tower water. In the water of towers supplemented continuously with the biocidal chemicals, legionellae were not found during a 4-month period. The biocidal treatments tested were proved to suppress the increase of legionellae in cooling-tower water, and thus are useful in preventing the outbreak of legionellosis due to inhalation of contaminated aerosol from the cooling tower system.
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Affiliation(s)
- H Yamamoto
- Department of Microbiology, Gifu University School of Medicine, Japan
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Williams DE, Swango LJ, Wilt GR, Worley SD. Effect of organic N-halamines on selected membrane functions in intact Staphylococcus aureus cells. Appl Environ Microbiol 1991; 57:1121-7. [PMID: 2059036 PMCID: PMC182855 DOI: 10.1128/aem.57.4.1121-1127.1991] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Two N-halamine compounds, 3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone, were compared with free chlorine as to their effects on selected membrane functions of intact Staphylococcus aureus cells. Free chlorine was found to cause a loss of permeability control, as measured by the efflux of potassium from the cells and a dramatic increase in hydrogen ion permeability, and to affect cell respiration in a nonreversible fashion, as measured by oxygen uptake. The two N-halamines were found to have very little effect on permeability to either potassium or hydrogen ions but were both found to dramatically inhibit respiration in a reversible manner. It is proposed that the first step in the disinfection process by these N-halamines is an inhibition of respiratory enzymes that, if not reversed, ultimately leads to a loss of cell viability.
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Affiliation(s)
- D E Williams
- Department of Chemistry, College of Sciences and Mathematics, Auburn University, Alabama 36849
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Williams DE, Smith MS, Worley SD. Combined halogen disinfectants in poultry processing. Poult Sci 1990; 69:2248-51. [PMID: 2084684 DOI: 10.3382/ps.0692248] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Three organic N-halamine compounds (combined halogen disinfectants) were compared with free chlorine (as calcium hypochlorite) as bactericides against Salmonella typhimurium and unidentified normal poultry bacterial flora under controlled conditions of pH, temperature, and halogen demand similar to those encountered in poultry processing. Two of the compounds (3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone) at a concentration of 50 mg/L were found to cause a 99.9999% decline in viable organisms in less than 1 min at 48 C, whereas a third compound (1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone) was found to be less suitable (5.6 min to 99.9999% decline under the same conditions).
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Affiliation(s)
- D E Williams
- Department of Chemistry, Auburn University, Alabama 36849
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Smith MS, Williams DE, Worley SD. Potential uses of combined halogen disinfectants in poultry processing. Poult Sci 1990; 69:1590-4. [PMID: 2247422 DOI: 10.3382/ps.0691590] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Five organic N-halamine compounds (combined halogen disinfectants) were compared for their bactericidal activities against Salmonella typhimurium under controlled pH and temperature. All five compounds were effective as bactericides in demand-free buffers ranging from pH 5.0 to 9.0 and treatment temperatures from 4 to 48 C. The range of contact times necessary for a 99.9999% inactivation of viable cells was from .22 to 29 min, depending on the halogen concentration, temperature, and pH of the demand-free buffer. Two of the compounds (3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone) were found to have considerable promise in high-temperature applications, and a third compound (1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone) was more suitable for low-temperature treatments.
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Affiliation(s)
- M S Smith
- Department of Chemistry, Auburn University, Alabama 36849
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Kong LI, Swango LJ, Blagburn BL, Hendrix CM, Williams DE, Worley SD. Inactivation of Giardia lamblia and Giardia canis cysts by combined and free chlorine. Appl Environ Microbiol 1988; 54:2580-2. [PMID: 3202635 PMCID: PMC204322 DOI: 10.1128/aem.54.10.2580-2582.1988] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Free chlorine and a combined organic N-chloramine (3-chloro-4,4-dimethyl-2-oxazolidinone, compound 1) were compared for efficacy as disinfectants against an admixture of cysts of Giardia lamblia and Giardia canis in water solution under a variety of test conditions; variables were pH, temperature, and water quality. In general, compound 1 was found to reduce the giardial excystation in the solutions at lower concentration or shorter contact time at a given total chlorine concentration than did free chlorine.
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Affiliation(s)
- L I Kong
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama 36849-5312
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Abstract
The principle of Le Chatelier was used in demonstrating that 3-chloro-4,4-dimethyl-2-oxazolidinone (compound 1) itself kills Staphylococcus aureus rather than the very small amount of free chlorine in hydrolysis equilibrium with compound 1. On the other hand, when the N-bromo analog of compound 1 (compound 1B) was used as the disinfectant, the mixture of combined compound 1B and free bromine formed in the hydrolysis equilibrium provided disinfection. When the hydrolysis equilibrium for 1B was suppressed to the level at which a negligible amount of free bromine remained in solution, combined compound 1B was much more efficacious than combined compound 1 at killing S. aureus.
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Affiliation(s)
- D E Williams
- Department of Chemistry, College of Sciences and Mathematics, Auburn University, Alabama 36849
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