Dilute Sodium Hypochlorite Solution Research Articles

Occurrence and Mitigation of Bacterial Regrowth in Stored Household Water in Eastern Coastal Madagascar

In communities where people lack on-demand, safely managed drinking water, stored household water often becomes contaminated by fecal bacteria, regardless of the source-water quality. The objectives of this paper are to assess and control bacterial contamination in stored household water in Toamasina, a rapidly urbanizing city in eastern coastal Madagascar. We collected samples of source water and stored household water from 10 representative households that use different water sources and different storage strategies, and we analyzed the samples for several fecal indicator bacteria. We also tested three methods that residents of Toamasina could realistically employ for cleaning their household water storage vessels, assessing the effect of the cleaning methods on measured bacterial levels in the water. Consistent with the previous literature, we found that concentrations of total coliforms in stored household water were significantly higher than in the corresponding source water (p < 0.05). In 100% of households that stored their water in 20 L polyethylene jerrycans (n = 4), biofilms on the walls of the jerrycan harbored total coliforms and Enterococcus. The use of a closed storage container was, on its own, not found to provide a meaningful protective effect against bacterial regrowth; to be protective, closed storage containers must be combined with high-quality source water and/or with adequate cleaning to prevent biofilm formation. A dilute solution of sodium hypochlorite, known locally as Sûr’Eau or Manadio Rano, was both the most effective and the least expensive method for cleaning household water storage containers. We conclude that regular and effective cleaning of storage containers is an essential component of safe water storage. Because household storage of collected water is common in many low- and middle-income countries, these results are important towards the worldwide achievement of the United Nations’ Sustainable Development Goal 6.

Evaluation of cleaning and disinfection protocols for commercial farm equipment following a foreign animal disease outbreak

AbstractThis study evaluated the microbiocidal efficacy of a cleaning and disinfection (C&D) treatment using stainless‐steel coupons applied to three common types of animal mortality transport vehicles when exposed to agricultural conditions. Metal test coupons, inoculated with bacteriophage MS2, were affixed to the undercarriage of three types of animal mortality transport vehicles at various locations. Coupons were grimed by maneuvering the test vehicles down a series of wet dirt roads. Coupons were attached and extracted at various points to evaluate C&D performance with and without grime. C&D efficacy using a water‐supplied pressure washing system and a dilute sodium hypochlorite (NaOCl) solution was determined by comparing the difference in recovered viable virus between positive control coupons and test coupons. The results demonstrated a relatively high surface decontamination efficacy, with all but one location showing >5 log reduction of MS2. Coupons located on the roll‐off truck's inside‐back bumper contained the highest level of grime and resulted in a 4 log reduction of MS2. There was no significant difference in C&D efficacy across vehicle types, but locations impacted by grime and lack of accessibility achieved lower efficacies on average. These findings suggest that common C&D protocols, when applied to farm mortality transport vehicles, are effective. Hard‐to‐access locations containing high levels of grime may be candidates for additional targeted treatment.

Stability of Free Available Chlorine Levels in Dilute Sodium Hypochlorite Solutions over a 6-Week Period.

Animal care and use programs commonly use chlorine and chlorine-based disinfectants to help prevent facility acquired infections in animals. The Department of Comparative Medicine (DCM) at Oregon Health and Science University (OHSU) follows the Centers for Disease Control and Prevention (CDC) disinfection guidelines for preparing and storing these disinfectants. DCM prepares bottles of dilute solutions of sodium hypochlorite (that is, commercial bleach) daily. In this study, we tested whether dilute bleach solutions, as prepared following the DCM protocol, remained stable under real-world practice conditions for up to 6 wk. We tested 4 groups of spray bottles filled with 0.5% bleach solutions in these experiments. Specifically, we sprayed 2 groups of bottles daily to mimic use while 2 other groups of bottles were not sprayed. We then measured free available chlorine (FAC) using 2 methods, spectrophotometry and colorimetric strips. All 4 test groups showed stable maintenance of FAC concentration for the length of the experiment. Mean FAC loss from baseline levels was not significantly different in the group of bottles not sprayed daily (6% for group 2 at week 5 compared with 7% for Group 4 at week 6). All bottles in Groups 1 and 3 measured by colorimetric strips showed concentrations at or near 5000 mg/L at all weekly time points throughout the experiment. This study shows that 0.5% sodium hypochlorite solutions stored and used in a standard rodent housing room and sprayed daily will maintain acceptable FAC concentrations for at least 5 to 6 wk, perhaps longer. In addition, we report that colorimetric strips may be a useful and accessible quality control tool for testing freshly prepared solutions at regular intervals. We conclude that sodium hypochlorite solutions can be prepared on a weekly, biweekly, or monthly basis with no loss in disinfection effectiveness.

Scalable Production of Nanographene and Doping via Nondestructive Covalent Functionalization

A new method for top-down, one-pot, gram-scale production of high quality nanographene by incubating graphite in a dilute sodium hypochlorite solution at only 40 °C is reported here. The produced sheets have only 4 at% oxygen content, comparable with nanographene grown by chemical vapor deposition. The nanographene sheets are covalently functionalized using a nondestructive nitrene [2+1] cycloaddition reaction that preserves their π-conjugated system. Statistical analyses of Raman spectroscopy and X-ray photoelectron spectroscopy indicate a low number of sp3 carbon atoms on the order of 2% before and 4% after covalent functionalization. The nanographene sheets are significantly more conductive than conventionally prepared nanographene oxide, and conductivity further increases after covalent functionalization. The observed doping effects and theoretical studies suggest sp2 hybridization for the carbon atoms involved in the [2+1] cycloaddition reaction leading to preservation of the π-conjugated system and enhancing conductivity via n-type doping through the bridging N-atom. These methods are easily scalable, which opens the door to a mild and efficient process to produce high quality nanographenes and covalently functionalize them while retaining or improving their physicochemical properties.

Synthesis and application to cellulose of reactive dye precursor of anti‐bacterial N‐halamine

To achieve textile dyeing and functional finishing in one process, a bleach‐resistant reactive dye precursor to anti‐bacterial N‐halamine was synthesised by reacting a type of dichlorotriazine reactive dye with 4‐amino‐2,2,6,6‐tetramethylpiperidine. The synthesised compound, which can be transformed to an N‐halamine molecule by exposure to dilute bleach solution, was used to dye cotton fabrics. After exposure to a dilute sodium hypochlorite solution, dyed cotton fabrics showed excellent anti‐bacterial properties against Staphylococcus aureus and Escherichia coli O157:H7, facilitating a ca. 6‐log reduction in bacteria within a short period of contact. Compared with the dichlorotriazine reactive dye, the reactive dye precursor demonstrated comparable dyeing properties including exhaustion and fixation values. No differences in rub fastness, wash fastness or bleach fastness were detected between fabrics dyed with, respectively, dichlorotriazine reactive dye and the reactive dye precursor to N‐halamine.

Integrated antimicrobial and antifouling ultrafiltration membrane by surface grafting PEO and N-chloramine functional groups

Ultrafiltration membranes with integrated antimicrobial and antifouling properties were fabricated using an engineering thermoplastic (carboxylated cardopoly(aryl ether ketone, PEK-COOH). Different molecular weights of PEO (Mw: 120, 350, 550) were grafted to the PEK-COOH membrane surface via EDC/NHS methodology. N-chloramine modified membranes then were prepared by simple exposure to dilute sodium hypochlorite solution. The surface grafting processes were all performed in water (i.e. without organic solvent). With this surface modification, the hydrophilicity of membranes improved significantly and the pure water flux increased compared to the unmodified PEK-COOH membrane. Furthermore, the PEO and N-chloramine modified membranes were resistant not only to both protein adsorption and bacterial adhesion, but also to microbial proliferation. The results of this work suggest that PEO and N-chloramine modified membranes are promising as fouling-resistant membranes.

Preparation of antibacterial cellulose with s‐triazine‐based quaternarized N‐halamine

ABSTRACTTo reduce the neutral salt used in the textile finishing with s‐triazine derivatives, a novel s‐triazine‐based quaternarized N‐halamine precursor was synthesized by two simple steps and characterized by H‐NMR and FT‐IR. This compound can be effectively coated onto cellulose by nucleophilic substitution process without neutral salt. The treated cellulose was rendered with powerful biocidal efficacy after transferring to an N‐halamine structure by exposing to dilute sodium hypochlorite solution through the synergistic antimicrobial effect quaternary ammonium salt and N‐halamine. The chlorinated samples could inactivate 6‐logs of Staphylococcus aureus and Escherichia coli O157:H7 within 1 min and 5 min, respectively. In addition, about 50% of oxidant chlorine remained after 50 washing cycles and 30 days storage, and all of the lost active chlorines in the N‐halamine molecules recovered after exposing to bleach solution. With these advantages, the as‐prepared antimicrobial fabrics will have potential application, especially in the medical and healthcare textiles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44998.

Preparation and characterization of an antibacterial ultrafiltration membrane with N-chloramine functional groups

In this study, a cardo poly(aryl ether ketone) ultrafiltration membrane containing an N-chloramine functional group (PEK-N-Cl membrane) was easily obtained via exposure of a cardo poly(aryl ether ketone) ultrafiltration membrane (PEK-NH membrane) to dilute sodium hypochlorite solution. The chlorination process did not harm membrane performance. In addition, the PEK-N-Cl membrane was stable in both air and water. The PEK-N-Cl membrane exhibited excellent antimicrobial properties against both Gram-negative and Gram-positive bacteria (i.e. E. coli and Bacillus subtilis, respectively). The PEK-N-Cl membrane provided 94.2% and 100% reduction of E. coli and Bacillus subtilis, respectively, within 30min of contact times. Moreover, nearly 100% of the E. coli was killed after 2h during the filtration process for the PEK-N-Cl membrane. In addition, the water flux decreased by 42% for the PEK-N-Cl membrane compared to 77.6% for the PEK-NH membrane after filtration of the E. coli solution and incubation on LB nutrient agar plate, indicating that the PEK-N-Cl membrane enhibits antifouling. Furthermore, the PEK-N-Cl membrane is recyclable via subsequent exposure to a sodium hypochlorite solution.

Antimicrobial silica and sand particles functionalized with an N‐halamine acrylamidesiloxane copolymer

ABSTRACTThe monomer 2‐acrylamido‐2‐methyl‐1‐(5‐methylhydantoinyl)propane (HA) was copolymerized with 3‐(trimethoxysilyl)propyl methacrylate (SL) and covalently attached onto silica gel and sand particles. As a result HASL copolymer‐grafted silica gel and sand particles (HASL SGPs and SPs) were obtained. These two types of HASL SGPs and SPs provided excellent biocidal efficacy against Gram positive S. aureus and Gram negative E. coli O157:H7 bacteria when the copolymer‐grafted particles were exposed to dilute sodium hypochlorite (household bleach) solution. In a flowing water application, seven logs of bacteria were inactivated within 10 s of contact time with the particles packed into a column. The treated particles also exhibited good washing and storage stabilities. The chlorine loss during extensive flow could be recovered by further exposure to dilute bleach solution. The antimicrobial particles have potential application for use in inexpensive disinfecting water filters for slow water flows. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43413.

Biocidal Activity of N-Halamine Methylenebisacrylamide Grafted Cotton

Methylenebisacrylamide (MBA) was coated on cotton fabric via free radical polymerization with the aid of initiator. The surface of grafted fabric was characterized by FTIR and SEM, which confirmed that MBA was grafted onto cotton cellulose via covalent bonding. Exposure to dilute sodium hypochlorite solution was found to render the grafted fabric biocidal. The chlorinated cotton was found to inactivate 99.97% of Staphylococcus aureus and 99.99% of Escherichia coli O157:H7 within 30 min of contact time, respectively. The washing stability and UV irradiation recharge ability of coated fabric were also investigated. After 24 h exposure to UV light, over 92% of chlorine was recovered upon chlorination.

Antibacterial functionalization of cotton fabrics by electric‐beam irradiation

ABSTRACTAn N‐halamine precursor monomer, 2,2,6,6‐tetramethylpiperidinyl acrylate (TMPA), was synthesized and successfully grafted onto cotton fibers via an impregnation process (IP) and electron‐beam irradiation (EB). The grafted cotton fibers could provide antibacterial efficacy after chlorination through a dilute sodium hypochlorite solution. The antibacterial efficacy was challenged against Staphylococcus aureus and Escherichia coli. The cotton fibers grafted with TMPA and acrylic acid by EB inactivated all of the bacteria within 30 min of contact, whereas the samples grafted with TMPA via an IP could not completely kill the bacteria with 60 min. The breaking strength and UVA light stability also improved significantly. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42023.

Development and characterisation of antibacterial suture functionalised with N-halamines

Braided and biodegradable polyglycolide suture was antibacterially functionalised with N-halamines via layer-by-layer assembly technique. Multilayers of chitosan (polycation) and poly-sodium-p-styrenesulfonate (polyanion) were successfully coated via electrostatic assembly, followed by top layer of chitosan on polyglycolide suture. Upon chlorination of coated suture with dilute sodium hypochlorite solution, the amino groups of chitosan were transformed into N-halamine structures. The transformation was assessed by iodometric/thiosulfate titration, Fourier transform infrared spectroscopy and differential scanning calorimeter analysis. The surface morphology of coated suture was observed by scanning electron microscope and atomic force microscope. Chlorine loading, antibacterial efficacy and tensile strength of chlorinated sutures treated with two different molecular weights of chitosan were compared and evaluated. A general trend of linear increase in chlorine loadings of sutures with the increase in number of layers and solution concentration was found. The chlorinated suture with high molecular weight chitosan coating completely inactivated both Escherichia coli O157:H7 and Staphylococcus aureus bacteria within 15 min of contact time. The 3T3 mouse fibroblasts in vitro cell cytocompatibility studies demonstrated that antibacterial sutures have fairly good biocompatibility.

N-halamine modified polyester fabrics: Preparation and biocidal functions

A cyclic N-halamine precursor, 1-glycidyl-s-triazine-2,4,6-trione (GTT), was synthesized and grafted onto polyester fibers. The tricarbimide rings could be transferred to N-halamine structure upon exposure to dilute sodium hypochlorite solution. Structural and surface characterizations of the polyester (PET) fabrics treated with GTT were accomplished using FT-IR, SEM, and DSC. The antimicrobial efficacy test showed that the N-halamine modified PET could inactivate 6-log of Staphylococcus aureus (Gram-positive) and E. coli O157:H7 (Gram-negative) within 10 min of contact time. The antimicrobial fabrics exhibited good durability and stability to washing and storage.

Randomized trial of drain antisepsis after mastectomy and immediate prosthetic breast reconstruction.

In this 2-site randomized trial, we investigated the effect of antiseptic drain care on bacterial colonization of surgical drains and infection after immediate prosthetic breast reconstruction. With IRB approval, we randomized patients undergoing bilateral mastectomy and reconstruction to drain antisepsis (treatment) for one side, with standard drain care (control) for the other. Antisepsis care included both: chlorhexidine disc dressing at drain exit site(s) and irrigation of drain bulbs twice daily with dilute sodium hypochlorite solution. Cultures were obtained from bulb fluid at 1 week and at drain removal, and from the subcutaneous drain tubing at removal. Positive cultures were defined as ≥1+ growth for fluid and >50 CFU for tubing. Cultures of drain bulb fluid at 1 week (the primary endpoint) were positive in 9.9 % of treatment sides (10 of 101) versus 20.8 % (21 of 101) of control sides (p = 0.02). Drain tubing cultures were positive in 0 treated drains versus 6.2 % (6 of 97) of control drains (p = 0.03). Surgical site infection occurred within 30 days in 0 antisepsis sides versus 3.8 % (4 of 104) of control sides (p = 0.13), and within 1 year in three of 104 (2.9 %) of antisepsis sides versus 6 of 104 (5.8 %) of control sides (p = 0.45). Clinical infection occurred within 1 year in 9.7 % (6 of 62) of colonized sides (tubing or fluid) versus 1.5 % (2 of 136) of noncolonized sides (p = 0.03). Simple and inexpensive local antiseptic interventions with a chlorhexidine disc and hypochlorite solution reduce bacterial colonization of drains, and reduced drain colonization was associated with fewer infections.

Efficacy of eight commercial disinfectants against Microsporum canis and Trichophyton spp. infective spores on an experimentally contaminated textile surface

An important part of treatment of dermatophytosis is the removal of infective material and decontamination of the environment. It is recognized that the role of disinfectants is to kill infective material not removed during the mechanical removal of debris and gross cleaning steps. A widely used disinfectant in the home is a dilute solution of sodium hypochlorite. To determine whether over-the-counter products, particularly ready-to-use formulations, with label claim as fungicidal are effective against Microsporum or Trichophyton spores isolated from cat hair. Eight commercial disinfectants were tested in vitro for fungicidal efficacy using three different trials and a 10 min contact time, as follows: a standard 1:10 spore dilution suspension test; 1 and 5 mL of disinfectant solution applied to contaminated gauze fabric; and, to simulate home use, one and five sprays of disinfectant applied to contaminated gauze. Good efficacy was defined as a product that completely inhibited growth. All products completely inhibited growth in the suspension test. Four of eight products showed complete inhibition of growth of both pathogens on the textile test after 1 mL or one spray; however, all eight products showed complete inhibition of pathogen growth after 5 mL or five sprays. Aggressive removal of contaminated material followed by thorough application of commercial ready-to-use disinfectants labelled as fungicidal against Trichophyton mentagrophytes are alternatives to dilute sodium hypochlorite.

Dakin’s Solution

Dakin's solution has been used for almost a century. It is a dilute solution of sodium hypochlorite, which is commonly known as household bleach. When properly applied, it can kill pathogenic microorganisms with minimum cytotoxicity. This article reviews its history and discusses how evolving technology might pave the way for a new role for this antiseptic.

Durable antimicrobial cotton fabrics containing stable quaternarized N-halamine groups

A novel N-halamine precursor with tertiary amino group (5,5-dimethylhydantoinyl-3-ylethyl)-dimethylamine (DEADH), was synthesized and then covalently bonded onto cotton fabrics modified by 3-chloropropyltrimethoxysilane to form quaternarized N-halamine precursor grafted cotton fabrics which could be transferred to N-halamine structure upon exposure to dilute sodium hypochlorite solution. The grafted cotton fabrics were characterized by FT-IR, X-ray photoelectron spectroscopy, and field emission scanning electron microscope. The antimicrobial test showed that the cotton fabrics grafted with the quaternarized N-halamine were capable of 7-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 1 min of contact time. Very interestingly, it was found that the grafting process and following chlorination had almost no adverse effect on the tensile strength of cotton fabrics. Furthermore, the antimicrobial cotton fabrics exhibited good washing durability and stability.

Antimicrobial surface coatings for polypropylene nonwoven fabrics

Anionic and cationic N-halamine polyelectrolytes were synthesized, characterized and then immobilized onto melt-blown polypropylene fabrics having two different basis-weights. The coatings were rendered biocidal upon exposure to dilute sodium hypochlorite solution. The effect of single and multilayer deposition of the polyelectrolytes on the surfaces was investigated in terms of chlorine loadings, rechargeabilities, antimicrobial efficacies, and air permeabilities. It was found that all of the coatings provided remarkable biocidal efficacies with about six log reductions of bacteria within two min of contact time on filters having higher basis-weight, whereas slower inactivation was observed for lower-basis weight filters due to diminished surface areas and numbers of active halogen atoms. The antimicrobial coatings reduced the air permeabilities of the filters somewhat; however, the air permeabilities of the coated swatches were comparable to those of most protective textiles.

Randomized Controlled Trial to Reduce Bacterial Colonization of Surgical Drains After Breast and Axillary Operations

To determine whether bacterial colonization of drains can be reduced by local antiseptic interventions. Drains are a potential source of bacterial entry into surgical wounds and may contribute to surgical site infection after breast surgery. After institutional review board approval, patients undergoing total mastectomy and/or axillary lymph node dissection were randomized to standard drain care (control) or drain antisepsis (treated). Standard drain care comprised twice daily cleansing with alcohol swabs. Antisepsis drain care included (1) a chlorhexidine disc at the drain exit site and (2) irrigation of the drain bulb twice daily with dilute sodium hypochlorite (Dakin's) solution. Culture results of drain fluid and tubing were compared between control and antisepsis groups. Overall, 100 patients with 125 drains completed the study with 48 patients (58 drains) in the control group and 52 patients (67 drains) in the antisepsis group. Cultures of drain bulb fluid at 1 week were positive (1+ or greater growth) in 66% (38/58) of control drains compared with 21% (14/67) of antisepsis drains (P = 0.0001). Drain tubing cultures demonstrated more than 50 colony-forming units in 19% (8/43) of control drains versus 0% (0/53) of treated drains (P = 0.004). Surgical site infection was diagnosed in 6 patients (6%)--5 patients in the control group and 1 patient in the antisepsis group (P = 0.06). Simple and inexpensive local antiseptic interventions with a chlorhexidine disc and hypochlorite solution reduce bacterial colonization of drains. Based on these data, further study of drain antisepsis and its potential impact on surgical site infection rate is warranted (ClinicalTrials.gov Identifier: NCT01286168).

Synthesis of Novel N-Halamine Epoxide Based on Cyanuric Acid and Its Application for Antimicrobial Finishing

In this work, a novel N-halamine precursor, 1-glycidyl-s-triazine-2,4,6-trione (GTT), was synthesized through the reaction of cyanuric acid with epichlorohydrin in a facile condition. The pad–dry–cure technique was used to coat GTT onto cotton fabrics through the covalent surface modification of the cotton fibers. The GTT-coated cotton was characterized by FTIR spectroscopy and SEM. The N-halamine moieties attached to the cotton fibers could be rendered antimicrobial by treatment with a dilute sodium hypochlorite solution. The N-halamine-modified cotton fabrics demonstrated excellent antimicrobial efficacy against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli O157:H7) bacteria in brief contact times. Over 71% of the chlorine lost after the equivalent of 50 machine washes could be regained upon rechlorination. The chlorinated coated fabrics showed great rechargeability within one week under UVA light irradiation.