Chlorine Inactivation of Escherichia coli O157:H7 in Water

Zhao, Tong; Doyle, Michael P.; Zhao, Ping; Blake, Paul A.; Wu, Fone-Mao

doi:10.4315/0362-028x-64.10.1607

Cited by 54 publications

(35 citation statements)

References 16 publications

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“…In other words, after 30 seconds of treatment no E. coli cells formed colonies on a solid medium. This observation of cultivability loss is in agreement with what has been previously reported for Helicobacter pylori [23] and E. coli [24]. At the same time, only a 0.42-log reduction after 1 hour (0.2 mg/L Cl2) of treatment was observed for a metabolic activity.…”

Section: A Chlorinationsupporting

confidence: 81%

The Effect of Chlorination on Escherichia Coli Viability in Drinking Water

Denisova

Mežule

Juhna

2014

Material Science and Applied Chemistry

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-The assessment of drinking water disinfection efficiency traditionally involves the estimation of faecal indicator inactivation rates in the form of reduction of cultivable counts. Widely described, viable but noncultivable (VBNC) state as a form of bacterial survival strategy in oligotrophic conditions is not considered in these estimations. The aim of the present research is to assess the effect of free chlorine disinfection on faecal indicator Escherichia coli in order to study the succession of cellular alterations in response to chlorine exposure. To determine the inactivation rates, cell ability to form colonies, ability to divide as such and metabolic activity have studied. 0.064 mg/L min -1 free chlorine has been needed to obtain 99 % inactivation of cultivable counts; however, 5 till 200 times higher disinfectant dose x contact time has been required to reduce cell ability to divide and metabolic activity, respectively. The results have shown that to determine correct drinking water disinfectant doses multiple cell viability parameters should be analyzed.

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Section: A Chlorinationsupporting

confidence: 81%

The Effect of Chlorination on Escherichia Coli Viability in Drinking Water

Denisova

Mežule

Juhna

2014

Material Science and Applied Chemistry

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“…However, the efficacy of chlorine in killing E. coli O157:H7 is dependent on the purity of the water, and its bactericidal activity is reduced or eliminated in the presence of high levels of organic material, such as soil and feces (15,39). Our studies determined that the addition of rumen content to water with 5 ppm chlorine reduced or eliminated the bactericidal effect of chlorine.…”

Section: Discussionmentioning

confidence: 77%

“…Standard chlorine solutions obtained from HACH Company (Loveland, CO) were freshly diluted for each experiment in deionized water to the required concentration according to a method described previously (39). The free-chlorine concentrations in the diluted chlorine solutions were determined with a Digital Titrator (HACH Co.).…”

mentioning

confidence: 99%

Inactivation of Enterohemorrhagic Escherichia coli in Rumen Content- or Feces-Contaminated Drinking Water for Cattle

Zhao

West

et al. 2006

Appl Environ Microbiol

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Cattle drinking water is a source of on-farm Escherichia coli O157:H7 transmission. The antimicrobial activities of disinfectants to control E. coli O157:H7 in on-farm drinking water are frequently neutralized by the presence of rumen content and manure that generally contaminate the drinking water. Different chemical treatments, including lactic acid, acidic calcium sulfate, chlorine, chlorine dioxide, hydrogen peroxide, caprylic acid, ozone, butyric acid, sodium benzoate, and competing E. coli, were tested individually or in combination for inactivation of E. coli O157:H7 in the presence of rumen content. Chlorine (5 ppm), ozone (22 to 24 ppm at 5°C), and competing E. coli treatment of water had minimal effects (<1 log CFU/ml reduction) on killing E. coli O157:H7 in the presence of rumen content at water-to-rumen content ratios of 50:1 (vol/wt) and lower. Four chemical-treatment combinations, including (i) 0.1% lactic acid, 0.9% acidic calcium sulfate, and 0.05% caprylic acid (treatment A); (ii) 0.1% lactic acid, 0.9% acidic calcium sulfate, and 0.1% sodium benzoate (treatment B); (iii) 0.1% lactic acid, 0.9% acidic calcium sulfate, and 0.5% butyric acid (treatment C); and (iv) 0.1% lactic acid, 0.9% acidic calcium sulfate, and 100 ppm chlorine dioxide (treatment D); were highly effective (>3 log CFU/ml reduction) at 21°C in killing E. coli O157:H7, O26:H11, and O111:NM in water heavily contaminated with rumen content (10:1 water/rumen content ratio [vol/wt]) or feces (20:1 water/feces ratio [vol/wt]). Among them, treatments A, B, and C killed >5 log CFU E. coli O157:H7, O26:H11, and O111:NM/ml within 30 min in water containing rumen content or feces, whereas treatment D inactivated approximately 3 to 4 log CFU/ml under the same conditions. Cattle given water containing treatment A or C or untreated water (control) ad libitum for two 7-day periods drank 15.2, 13.8, and 30.3 liters/day, respectively, and cattle given water containing 0.1% lactic acid plus 0.9% acidic calcium sulfate (pH 2.1) drank 18.6 liters/day. The amounts of water consumed for all water treatments were significantly different from that for the control, but there were no significant differences among the water treatments. Such treatments may best be applied periodically to drinking water troughs and then flushed, rather than being added continuously, to avoid reduced water consumption by cattle.Escherichia coli O157:H7 has emerged in the last 10 years as an important food-borne pathogen (12,15,22,30,32,36), with an estimated 73,000 cases of E. coli O157 infection annually in the United States (23). Cattle are a major reservoir of E. coli O157:H7 (2, 4, 5, 7), and cattle water troughs are important sources of the pathogen on farms (2,4,5,7,17,20,21,27,28,37). Studies have further revealed that when present in cattle drinking water, the pathogen was disseminated to other cattle consuming the contaminated water (19,29).Genomic subtyping by pulsed-field gel electrophoresis of E. coli O157:H7 isolates from farms revealed that a single O157:H7 str...

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“…Factors such as ionic strength, pH, turbidity and chlorine demand, biofilm growth, and the physiological state of the cells can alter disinfection efficacy (6,16,18,22,31). The contact concentration and time values (Ct) (mg ⅐ min/liter) required to achieve disinfection have been observed to vary between strains of the same organism (23,36). Additionally, stressrelated phenotypic changes in Vibrio species have been linked to increased tolerance to chlorine (20,24,34).…”

mentioning

confidence: 99%

Variability of Burkholderia pseudomallei Strain Sensitivities to Chlorine Disinfection

O’Connell

Rose

Shams

et al. 2009

Appl Environ Microbiol

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Burkholderia pseudomallei is a select agent and the causative agent of melioidosis. Variations in previously reported chlorine and monochloramine concentration time (Ct) values for disinfection of this organism make decisions regarding the appropriate levels of chlorine in water treatment systems difficult. This study identified the variation in Ct values for 2-, 3-, and 4-log 10 reductions of eight environmental and clinical isolates of B. pseudomallei in phosphate-buffered water. The greatest calculated Ct values for a 4-log 10 inactivation were 7.8 mg ⅐ min/liter for free available chlorine (FAC) at pH 8 and 5°C and 550 mg ⅐ min/liter for monochloramine at pH 8 and 5°C. Ionic strength of test solutions, culture hold times in water, and cell washing were ruled out as sources of the differences in prior observations. Tolerance to FAC was correlated with the relative amount of extracellular material produced by each isolate. Solid-phase cytometry analysis using an esterase-cleaved fluorochrome assay detected a 2-log 10 -higher level of organisms based upon metabolic activity than did culture, which in some cases increased Ct values by fivefold. Despite strain-to-strain variations in Ct values of 17-fold for FAC and 2.5-fold for monochloramine, standard FAC disinfection practices utilized in the United States should disinfect planktonic populations of these B. pseudomallei strains by 4 orders of magnitude in less than 10 min at the tested temperatures and pH levels.Burkholderia pseudomallei, a gram-negative soil saprophyte, is endemic to Southeast Asia (30) and northern Australia and has been linked to waterborne illness in these areas (9, 15). B. pseudomallei has been identified by the Centers for Disease Control and Prevention (CDC) as a select agent. The organism can tolerate a wide variety of soil and temperature conditions (33), which enables it to exist in soil and water in subtropical zones (10,19,32,35). Information on survival of B. pseudomallei in drinking water containing disinfectants is necessary to ensure that the end users of water distribution systems are sufficiently protected from exposure to this organism.Free available chlorine (FAC) and monochloramine are the most commonly used drinking water disinfectants (1, 2, 28). Factors such as ionic strength, pH, turbidity and chlorine demand, biofilm growth, and the physiological state of the cells can alter disinfection efficacy (6,16,18,22,31). The contact concentration and time values (Ct) (mg ⅐ min/liter) required to achieve disinfection have been observed to vary between strains of the same organism (23, 36). Additionally, stressrelated phenotypic changes in Vibrio species have been linked to increased tolerance to chlorine (20,24,34).Several strains of B. pseudomallei endemic to northern Australia were found by Howard and Inglis (13) to be more chlorine and monochloramine tolerant than other strains via techniques such as plate culture, a most-probable-number (MPN) recovery method, and flow cytometry using a membrane integrity stain. Disinfectio...

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Chlorine Inactivation of Escherichia coli O157:H7 in Water

Cited by 54 publications

References 16 publications

The Effect of Chlorination on Escherichia Coli Viability in Drinking Water

The Effect of Chlorination on Escherichia Coli Viability in Drinking Water

Inactivation of Enterohemorrhagic Escherichia coli in Rumen Content- or Feces-Contaminated Drinking Water for Cattle

Variability of Burkholderia pseudomallei Strain Sensitivities to Chlorine Disinfection

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