Didecyldimethylammonium Research Articles

Borate and Quaternary Ammonia Dip Diffusion to Treat Fungal Pathogens of Metrosideros polymorpha Wood

Abstract Rapid Ohia Death is a major concern for the viability of ohia (Metrosideros polymorpha) in Hawaii and has led to restrictions on log movement. The potential for using disodium octaborate tetrahydrate (DOT) and didecyl dimethyl ammonium chloride (DDAC) dip diffusion treatments to control the two causal fungi (Ceratocystis lukuohia and Ceratocystis huliohia) was investigated. A 10 percent boric acid equivalent dip diffusion treatment killed the pathogens in 0.5-cm-thick disks obtained from 4.0- to 5.0-cm-diameter limbs of naturally colonized trees. DOT tended to diffuse more consistently in 50- to 60-cm-long bolts of small (4.0 to 9.0 cm) and large (9.1 to 17.0 cm) diameter healthy ohia compared with those bolts naturally infected by C. lukuohia. Diffusion periods longer than 6 weeks resulted in deeper penetration. Immersion (24 h) of logs (1.3 m long; 9 to 17 cm diameter) from C. lukuohia artificially inoculated trees in two forest locations in a 15 percent DOT/1 percent DDAC solution and storage for 10 weeks before evaluation resulted in incomplete elimination of the pathogen and lower boron concentrations in the inner sapwood than outer. Further investigations are needed to explore using either higher boron concentrations or longer diffusion periods to deliver fungicidal concentrations of boron deeper within the wood matrix.

Susceptibility patterns of bacteria isolated from the hospital environment towards disinfectants commonly used for surfaces and medical devices

This study aimed to evaluate the bactericidal activity of common disinfectants used for surfaces and medical devices. Sodium hypochlorite (D1), disinfectant (D2) composed of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, chloride de didecyldimethylammonium, and disinfectant (D3) composed of Didecyldimethylammonium chloride and Polyhexamethylene biguanide hydrochloride, were tested against 15 strains isolated from the hospital environment and four reference bacteria. The microdilution method was performed to assess antimicrobial activity. The susceptibility was evaluated by comparing the minimum inhibitory dilution with the dilution of disinfectant recommended by the manufacture. D1 and D2 were active against Staphylococcus epidermidis, Staphylococcus saprophyticus, Enterobacter cloacae, Escherichia coli, Pseudomonas fluorescens, Methicillin-resistant Staphylococcus aureus, Bacillus spp, Corynebacterium spp, Gram-positive bacillus, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 3366, and Pseudomonas aeruginosa ATCC 27853 strains but not active against Micrococcus spp, and Staphylococcus aureus ATCC 29213. D3 was ineffective against Micrococcus spp, Bacillus Gram Positive, Staphylococcus epidermidis, and Escherichia coli ATCC 25922. Therefore, D1 and D2 can eliminate most pathogenic bacteria in hospitals, in comparison to D3. It is necessary to monitor the antibacterial activity of disinfectants against reference strains but also against those usually present on surfaces. The obtained results could have promising applications in controlling the emergence of nosocomial infections.

Irrigation of wheat with select hydraulic fracturing chemicals: Evaluating plant uptake and growth impacts.

Oilfield flowback and produced water (FPW) is a waste stream that may offer an alternative source of water for multiple beneficial uses. One practice gaining interest in several semi-arid states is the reuse of FPW for agricultural irrigation. However, it is unknown if the reuse of FPW on edible crops could increase health risks from ingestion of exposed food, or impact crop growth. A greenhouse experiment was conducted using wheat (Triticum aestivum) to investigate the uptake potential of select hydraulic fracturing additives known to be associated with health risks. The selected chemicals included acrylamide, didecyldimethylammonium chloride (DDAC), diethanolamine, and tetramethylammonium chloride (TMAC). Mature wheat grain was extracted and analyzed by liquid chromatography-triple quadrupole mass spectrometry (LC-QQQ) to quantify chemical uptake. Plant development observations were also documented to evaluate impacts of the chemicals on crop yield. Analytical results indicated that TMAC and diethanolamine had significantly higher uptake into both wheat grain and stems than control plants which were not exposed to the four chemicals under investigation. Acrylamide was measured in statistically higher concentrations in the stems only, while DDAC was not detected in grain or stems. Growth impacts included lodging in treated wheat plants due to increased stem height and grain weight, potentially resulting from increased nitrogen application. While analytical results show that uptake of select hydraulic fracturing chemicals in wheat grain and stems is measurable, reuse of FPW for irrigation in real world scenarios would likely result in less uptake because water would be subject to natural degradation, and often treatment and dilution practices. Nonetheless, based on the outstanding data gaps associated with this research topic, chemical specific treatment and regulatory safeguards are still recommended.

Liquid chromatography–mass spectrometry analysis of dyes formed by in situ oxidative methods then purified by absorption and extraction from hair wefts

The dye mixtures formed from three commercial hair colour formers were purified by absorption onto human hair wefts, washed and dried, extracted with dichloromethane:trifluoroacetic acid (75:25) and then analysed by liquid chromatography–mass spectrometry. Only 1–2 dyes were identified from each complex mixture of commercial aromatic amines along with a broad UV absorption mainly consisting of mixtures of quaternary ammonium salts from shampoos and some surfactants. Mecetronium ethyl sulfate and didecyldimethylammonium chloride were the main ammonium salts.

Effects of loblolly pine extract, primary and quaternary alkyl ammonium chlorides combined with burgundy oil from eastern red cedar against subterranean termites and wood-decay fungi

Burgundy oil (BO) from Eastern red cedar provides resistance against termites and wood-decay fungi and is enhanced when combined with an amylose inclusion complex (AIC) containing hexadecylammonium chloride (HAC). Indirect evidence also indicated that a methanol Loblolly pine extract (LPE) was inhibitory against termites. This study compared the effects of HAC and didecyldimethylammonium chloride (DDAC) combined with LPE and BO on termites and wood-decay fungi. Southern pine was treated by vacuum/pressure impregnation and resistance evaluated after exposure to termites and decay fungi. The combination of BO and either HAC/AIC or DDAC/AIC reduced wood mass losses by termites, increased termite mortality, and inhibited all wood-decay fungi. The HAC/AIC and DDAC/AIC resulted in equivalent mass losses by termites and termite mortalities. The DDAC was slightly more inhibitory than the HAC against wood-decay fungi. Given the slight advantage of DDAC over HAC and because DDAC is currently used to preserve wood, DDAC might be preferred over HAC. The LPE had a very minor effect on mass loss by termites, termite mortality, and only a slight inhibitory effect on G. trabeum and T. versicolor, while R. placenta and I. lacteus were unaffected. Higher concentrations of DDAC and/or LPE might improve protection against termites and wood-decay fungi.

Evaluation of Antibacterial Activity of Three Quaternary Ammonium Disinfectants on Different Germs Isolated from the Hospital Environment.

Background The microbiological risk of the hospital environment, including inert surfaces, medical devices, and equipment, represents a real problem. Objective This study is aimed at demonstrating and assessing the antibacterial activity of three synthetic disinfectants classified as quaternary ammoniums on different bacterial strains (Gram-negative and Gram-positive like Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus) isolated from the hospital environment. The reference strains included Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853 used as negative control strains. Method Three quaternary ammonium disinfectants were tested: DDN9® (0.5%) which contains didecylmethylpolyoxyethylammonium propionate as an active substance, spray (0.4%) containing quaternary ammonium compounds, and Phagosurf ND® (0.4%) with didecyldimethylammonium chloride. Their effect was evaluated using the disk diffusion technique and the broth dilution methods, allowing the Minimum Inhibitory Concentration (MIC) and then the Minimum Bactericidal Concentration (MBC). Result Only the growth of Gram-positive bacteria and some strains of Gram-negative bacteria were inhibited by the three synthetic disinfectants. NDD9® demonstrated an antibacterial effect only against the Gram-positive strains (S. aureus and S. aureus ATCC 29213) with a MIC of 0.25 mg/ml. The disinfectant spray showed effect against all four strains including E. coli (9), S. aureus, E. coli ATCC 25922, and P. aeruginosa ATCC 27853 with an inhibitory concentration of 4 mg/ml, while the growth of S. aureus ATCC 29213 was inhibited at 2 mg/ml. The third disinfectant, Phagosurf ND®, inhibited only the growth of S. aureus ATCC 29213 at a MIC of 4 mg/ml. Conclusion This study is the first here in Morocco to evaluate the bacterial activity of products intended for the control of the healthcare environment. The results obtained on the three disinfectants tested reveal an ineffectiveness against some isolated strains from the hospital environment.

Comparative Performance of Chemical and Biological-based Products in Management of Algal Leaf Spot on Magnolia

Magnolia trees (Magnolia sp.) are a popular choice for consumers when choosing flowering woody plants for landscapes. Magnolia species grow in a wide variety of both temperate and tropical locations. Southern magnolia (Magnolia grandiflora) is one of the more popular magnolias due to its pleasing aesthetics: large showy flowers in a range of colors and evergreen foliage. However, magnolias can be affected by algal leaf spot. Algal leaf spot is caused by Cephaleuros virescens, which is a widespread plant parasitic green alga. There has been little research on how to treat algal leaf spot on magnolia plants. This study focuses on identifying effective biological- and chemical-based fungicides for the management of algal leaf spot disease of magnolia plants. Two experiments were conducted in a randomized complete block design with six replications per treatment and a total of 12 treatments, including a nontreated control. The first experiment (Expt. 1) was conducted in a shade house (56% shade) at McMinnville, TN, using southern magnolia plants. The second experiment (Expt. 2) was conducted at a commercial nursery in McMinnvillle, TN, in a field plot planted with ‘Jane’ magnolia (Magnolia liliiflora ‘Nigra’ × Magnolia stellata ‘Rosea’). The algal leaf spot disease severity, disease progression, plant marketability and growth parameters were evaluated. In both experiments, all treatments reduced algal leaf spot disease severity and disease progress in comparison with the nontreated control. In Expt. 1, copper octanoate, copper oxychloride, chlorothalonil water-dispersible granules, chlorothalonil suspension concentrate, didecyl dimethyl ammonium chloride, azoxystrobin + benzovindiflupyr, hydrogen peroxide + peroxyacetic acid, and mono- and di-potassium salts of phosphorus acid + hydrogen peroxide reduced the disease severity and disease progress the most and were not statistically different from one another. In Expt. 2, azoxystrobin + benzovindiflupyr, didecyl dimethyl ammonium chloride, and copper oxychloride significantly reduced disease severity and disease progress (area under disease progress curve). Treatments had no deleterious effect on plant growth parameters such as height and width, and no phytotoxicity of applied treatments or defoliation was observed. Treated magnolia plants had better plant marketability compared with the nontreated control plants. The findings of this study will help growers to achieve better management of algal leaf spot disease on magnolia trees.

Design of Nanosystems for the Delivery of Quorum Sensing Inhibitors: A Preliminary Study.

Biofilm production is regulated by the Quorum Sensing system. Nowadays, Quorum Sensing represents an appealing target to design new compounds to increase antibiotics effects and avoid development of antibiotics multiresistance. In this research the use of liposomes to target two novel synthetic biofilm inhibitors is presented, focusing on a preformulation study to select a liposome composition for in vitro test. Five different liposome (LP) formulations, composed of phosphatidyl choline, cholesterol and charged surfactant (2:1:1, molar ratio) have been prepared by direct hydration and extrusion. As charged surfactants dicetyl phosphate didecyldimethylammonium chloride, di isobutyl phenoxy ethyl dimethyl benzyl ammonium chloride and stearylamine (SA) and have been used. Liposome charge, size and morphology were investigated by zeta potential, photon correlation spectroscopy, small angle x-ray spectroscopy and electron microscopy. LP-SA was selected for the loading of biofilm inhibitors and subjected to high performance liquid chromatography for entrapment capacity evaluation. LP-SA loaded inhibitors showed a higher diameter (223.6 nm) as compared to unloaded ones (205.7 nm) and a dose-dependent anti-biofilm effect mainly after 48 h of treatment, while free biofilm inhibitors loose activity. In conclusion, our data supported the use of liposomes as a strategy to enhance biofilm inhibitors effect.

Disinfectant and antimicrobial susceptibility studies of the foodborne pathogen Campylobacter jejuni isolated from the litter of broiler chicken houses

Foodborne illness is an ongoing problem worldwide and is caused by bacteria that invade the food chain from the farm, slaughter house, restaurant or grocery, or in the home and can be controlled by strategies using biocides (antiseptics and disinfectants). Susceptibility profiles were determined for 96 Campylobacter jejuni strains obtained in 2011–2012 from broiler chicken house environments to antimicrobials and disinfectants as per the methods of the Clinical and Laboratory Standards Institute and TREK Diagnostics using CAMPY AST Campylobacter plates. Low prevalence of antimicrobial resistance was observed in C. jejuni strains to tetracycline (TET; 21.9%), ciprofloxacin (CIP; 13.5%), and nalidixic acid (NAL; 12.5%). The resistance profiles had a maximum of 3 antimicrobials, CIP-NAL-TET, with TET being the main profile observed. No cross-resistance was observed between antimicrobials and disinfectants. The C. jejuni strains (99%) were resistant to triclosan, 32% were resistant to chlorhexidine, and they all were susceptible to benzalkonium chloride. The strains had low-level minimum inhibitory concentrations (MICs) to the disinfectants P-128, Food Service Sanitizer, F-25 Sanitizer, Final Step 512 Sanitizer, OdoBan, dioctyldimethylammmonium chloride, didecyldimethylammonium chloride (C10AC), benzyldimethyldodecylammonium chloride (C12BAC), and benzyldimethyltetradecylammonium chloride (C14BAC). Intermediate MICs against DC&R, cetylpyridinium bromide hydrate, hexadecylpyridinium chloride, ethylhexadecyldimethylammonium bromide, and hexadecyltrimethylammonium bromide with elevated intermediate MICs against Tek-Trol, benzyldimethylhexadecylammonium chloride, tris(hydroxylmethyl)nitromethane (THN), and formaldehyde. The highest MIC were obtained for povidone-iodine. The components THN and the benzylammonium chlorides C12BAC and C14BAC were responsible for the inhibition by DC&R. The components C10AC and C12BAC may act synergistically causing inhibition of C. jejuni by the disinfectant P-128. The formaldehyde component in DC&R was not effective against C. jejuni compared with the ammonium chloride components. Its use in disinfectants may result in additional unnecessary chemicals in the environment. Didecyldimethylammonium chloride is the most effective ammonium chloride component against C. jejuni.

How to improve the chemical disinfection of contaminated surfaces by viruses, bacteria and fungus?

In response to the current pandemic situation, we present the development of an effective virucidal and biocidal solution to prevent from the spread of infectious diseases through contact with contaminated surfaces. The disinfectants, based on equimolar mixtures of didecyldimethylammonium chloride ([DiC10][Cl]), dodecyloctaglycol (C12E8), and cyclodextrin (CD), show synergistic effects against enveloped viruses (RSV, HSV-1, VACV) and fungi (C. albicans), and additive responses against bacteria (P. aeruginosa). These synergistic mixtures could then be highly helpful for prevention of respiratory illnesses, since a boosted activity allows: (i) a faster eradication of pathogens, (ii) a shorter contact time, and (iii) a complete and broad-spectrum eradication to avoid spread of resistant strains (including bacteria and fungi).

Mechanism of Inversion of Montmorillonite Sorption Properties by Cationic Surfactant

Organo-mineral derivatives of montmorillonite modified by salts of quaternary ammonium compounds are promising adsorbents for wastewater purification from heavy metal anions, as well as anionic dyes and pesticides. The understanding of the mechanism of anion adsorption by the example of montmorillonite modified by didecyldimethylammonium chloride cationic surfactant is expanded. The high rate of chromium anion adsorption, the appearance of adsorption capacity only during charge exchange of the surface, and the pH dependence of adsorption, including for pH-independent nitrate anions, indicate that a significant contribution to adsorption of anions is made by silanol and aluminol groups on the edge surface of the aluminosilicate layers of the mineral. The redistribution of access to various types of adsorption centers of the surface for adsorptive is the mechanism of inversion of the adsorption properties for montmorillonite. The inner negatively charged surface is screened by the double layer of the surfactant molecules that block the interlayer space. The surfactant molecules are not hydrated, which impedes delamination of the mineral in aqueous medium.

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants.

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.

Disinvasive action of aldehyde and chlorine disinfectants on the test-culture of Toxocara canis eggs

Disinfection of environmental objects with highly effective disinfectants is a reliable and effective means of preventing the occurrence of outbreaks of infectious and parasitic diseases. The purpose of our work was to determine the disinfection properties of modern disinfectants based on the test culture of Toxocara canis helminths and to establish the optimal modes of their use. It has been proven that an aldehyde disinfectant containing didecyldimethylammonium chloride (2.25%), benzalkonium chloride (8.0%), glutaraldehyde (15.0%), phosphoric acid, nonionic surfactants, water exhibits disinvasive activity against test cultures of Toxocara canis eggs at a concentration of 2.0-4.0% at a temperature of 20±0.5°C and an exposure of 3-24 hours, and the ovocidal efficiency is from 90.60% to 99.70%. Aldehyde disinfectant can be used for disinfection of soil (black earth, sandy loam, loamy) contaminated with Toxocara canis eggs, at a concentration of 4.0% at 6:00 exposure and a consumption rate of 3000 cm3/m2. Chlorine agent, contains dichlorantin, dimethylhydantoin (12.4-16.4%), dispersant (9.0-12%), nonionic surfactants, corrosion inhibitor, filler exhibits disinvasive activity against Toxocara canis test culture in a concentration of 3.0-4.0% with an exposure of 3-24 hours, and the ovocidal efficiency in this case ranges from 97.40% to 98.82%. The chlorine agent is effective for soil disinfection only at a depth of up to 2 cm at a concentration of 4.0% at a consumption rate of 1000 cm3/m2 and an exposure time of 24 hours.

Formation of lamellar body-like structure may be an initiator of didecyldimethylammonium chloride-induced toxic response

Due to the pandemic of coronavirus disease 2019, the use of disinfectants is rapidly increasing worldwide. Didecyldimethylammonium chloride (DDAC) is an EPA-registered disinfectant, it was also a component in humidifier disinfectants that had caused idiopathic pulmonary diseases in Korea. In this study, we identified the possible pulmonary toxic response and mechanism using human bronchial epithelial (BEAS-2B) cells and mice. First, cell viability decreased sharply at a 4 μg/mL of concentration. The volume of intracellular organelles and the ROS level reduced, leading to the formation of apoptotic bodies and an increase of the LDH release. Secretion of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and matrix metalloproteinase-1 also significantly increased. More importantly, lamellar body-like structures were formed in both the cells and mice exposed to DDAC, and the expression of both the indicator proteins for lamellar body (ABCA3 and Rab11a) and surfactant proteins (A, B, and D) was clearly enhanced. In addition, chronic fibrotic pulmonary lesions were notably observed in mice instilled twice (weekly) with DDAC (500 μg), ultimately resulting in death. Taken together, we suggest that disruption of pulmonary surfactant homeostasis may contribute to DDAC-induced cell death and subsequent pathophysiology and that the formation of lamellar body-like structures may play a role as the trigger. In addition, we propose that the cause of sudden death of mice exposed to DDAC should be clearly elucidated for the safe application of DDAC.

Prior Exposure to Ortho-Phthalaldehyde Augments IgE-Mediated Immune Responses to Didecyldimethylammonium Chloride: Potential for 2 Commonly Used Antimicrobials to Synergistically Enhance Allergic Disease.

Health-care workers have an increased incidence of allergic disease compared with the general public and are exposed to a variety of high-level disinfectants. Although exposure to these agents has been associated with allergic disease, findings between epidemiology and animal studies often conflict respecting immunological mechanisms. Therefore, we hypothesized that previous exposure to a representative IgE-mediated sensitizer (ortho-phthalaldehyde [OPA]) alters immune responses to a representative T-cell-mediated sensitizer (didecyldimethlyammonium chloride [DDAC]). Here, BALB/c mice were topically exposed to OPA (0.5%) for 3 days, rested, then topically exposed to DDAC (0.0625%, 0.125%, and 0.25%) for 14 days. Coexposure resulted in phenotypic changes in draining lymph node (dLN) cells, including a decreased frequency of CD8+ T cells and increased frequency and number of B cells compared with DDAC-only treated mice. The coexposed mice also had enhanced Th2 responses, including significant alterations in: dLN Il4 (increased), B-cell activation (increased), CD8+ T-cell activation (decreased), and local and systemic IgE production (increased). These changes were not observed if mice were exposed to DDAC prior to OPA. Exposure to OPA alone shows Th2 skewing, indicated by increased activation of skin type 2 innate lymphoid cells, increased frequency and activation of draining lymph node B cells, and increased levels of type 2 cytokines. These findings suggest that the OPA-induced immune environment may alter the response to DDAC, resulting in increased IgE-mediated immune responses. This data may partially explain the discordance between epidemiological and laboratory studies regarding disinfectants and provide insight into the potential immunological implications of mixed chemical exposures.

EFFECTS OF THE bap AND eno GENES ON THE EFFECTIVENESS OF DISINFECTANTS AGAINST COAGULASE-NEGATIVE STAPHYLOCOCCI

This study sought to determine the minimum bactericidal concentrations (MBCs) of didecyldimethylammonium chloride (DDAC), povidone iodine (PI), and chlorhexidine and the differences in these values among coagulase-negative staphylococci (CNSs) that harbor or do not harbor biofilm-related genes (eno, bap, and ica). Using the limiting dilution technique, the MBCs against three different disinfectants were estimated and compared using statistical methods. The results showed that the biofilm-gene-positive CNS isolates exhibited higher tolerance ([Formula: see text], upper-tailed test) to 2[Formula: see text]mg[Formula: see text]L[Formula: see text] DDAC and 10[Formula: see text]mg[Formula: see text]L[Formula: see text] povidone iodine ([Formula: see text], upper-tailed test). Different resistance capacities were found among these three biofilm formation-related genes. The isolates that contained the bap gene exhibited a higher tolerance level. This observation was confirmed by logistic regression models, which revealed that the bap (odds ratio [Formula: see text]) and eno (odds ratio [Formula: see text]) genes significantly affected the survival capacity. This study demonstrated that biofilm-gene-positive CNS isolates exhibited increased survival in the presence of higher concentrations of all three disinfectants and that both the bap and eno genes could affect the survival capacity. Among the three genes, the bap gene had the strongest effect on the survival capacity of CNSs in the presence of all three disinfectants. The appropriate use of disinfectants can control these biofilm-gene embedded CNSs more efficiently.

Effectiveness of commonly used high level disinfectants on bacteria responsible for hospital acquired infections in Sri Jayewardenepura General Hospital, Sri Lanka

Introduction: Hospital-acquired infections (HAIs) cause high morbidity and mortality in patients throughout the world. Nosocomial pathogens can be transmitted through contaminated instruments and surfaces. Disinfectants play a crucial role in preventing HAIs. This study focuses on two high level disinfectants designated ‘disinfectant 1’ which contains primarily peracetic acid and ‘disinfectant 2’ which contains primarily didecyldimethylammonium chloride. Objective: To determine the effectiveness of commonly used high level disinfectants on bacteria responsible for causing HAIs in Sri Jayewardenepura General Hospital, Sri Lanka (SJGH), on different surfaces. Method: Data of the Infection Prevention and Control (IPC) unit of SJGH was traced back to identify bacteria causing HAIs from 1st January to 31st July 2018. This experimental study was conducted for disinfectant 1 and 2 according to the quantitative carrier test (European Standard EN 14561:2006). Disinfectants were tested at three different concentrations on glass, stainless steel and rexine surfaces against the commonest three bacteria responsible for causing HAIs in SJGH. Results: Coliforms, Acinetobacter species and Staphylococcus aureus were the three most common bacteria responsible for causing HAIs in SGJH. Surgical site infections were the predominant type of HAI and Intensive Care Units (ICUs) were identified as having the highest prevalence of HAIs. Both high level disinfectants achieved a Microbicidal Effect (ME) value of 5 as per ‘clean disinfectants’ in manufacturer recommended dilutions and passed the test against Escherichia coli, Acinetobacter spp. and S. aureus under both clean and dirty condition on all three tested surfaces. However, bacterial colonies of all 3 test organisms were detected after both disinfectant 1 and 2 use . Effect of disinfectant 1 was poor in manufacturer recommended concentrations on glass, stainless steel and rexine surfaces. ME of disinfectant 2 was considerably higher when compared to disinfectant 1. Conclusion: Although the manufacturer stated test standard was achieved for both disinfectants, the presence of residual bacteria after high level disinfectant use on different surfaces is not acceptable.

The role of disinfectological investigations in the management of the complex of preventive activities

Introduction. Among infectious agents associated with provision of medical care, resistant ones to disinfectants from various chemical groups are more often met. In this regard, disinfection measures carried out in a medical facility are not always effective enough. Material and methods. 9 strains of microorganisms were selected for research (Klebsiella pneumoniae -2 pcs., Enterococcus faecalis, Staphylococcus warneri, Serratia rubidaea, Staphylococcus sciuri, Enterobacter cloacae, Acinetobacter baumannii, Enterococcus faecium - per 1 pcs.), isolated from the objects of hospital environment in operating unit, intensive care and trauma units, as well as 5 samples of disinfectants from different chemical groups (on the basis of quaternary ammonium salt, tertiary amine and polyhexamethyleneguanidine; on the basis of sodium percarbonate with activator; on the basis of hydrogen peroxide and didecyldimethylammonium chloride; in the form of tablets on the basis of sodium salt sodium dichloroisocyanurate acid), used in the specified divisions of medical facities. The studies were performed in accordance with the methodology set out in methodology instructions MU 3.5.1.3439-17 “Assessment of sensitivity to disinfectants of microorganisms circulating in medical organizations.” Results. When conducting chemical-analytical studies of samples of disinfectants 4 samples out of 5 were found to have inconsistencies in one or another quality indices. The analysis of instructions on application of disinfectants 4 means from 5 were showed to have unreasonably underestimated modes of application. According to the results of the evaluation of the sensitivity of microorganisms to disinfectants, the majority of isolated microorganisms was found to have resistance to the studied disinfectants Conclusion. Based on the results of the study of sensitivity of microorganisms to disinfectants, a new tactic for improving disinfection measures is proposed for medical facilities: rotation of disinfectants and an enhanced system of microbiological monitoring of the sensitivity of microorganisms to disinfectants

THE ROLE OF DISINFECTOLOGICAL INVESTIGATIONS IN THE MANAGEMENT OF THE COMPLEX OF PREVENTIVE ACTIVITIES

Introduction. Among infectious agents associated with provision of medical care, resistant ones to disinfectants from various chemical groups are more often met. In this regard, disinfection measures carried out in a medical facility are not always effective enough. Material and methods. 9 strains of microorganisms were selected for research (Klebsiella pneumoniae -2 pcs., Enterococcus faecalis, Staphylococcus warneri, Serratia rubidaea, Staphylococcus sciuri, Enterobacter cloacae, Acinetobacter baumannii, Enterococcus faecium - per 1 pcs.), isolated from the objects of hospital environment in operating unit, intensive care and trauma units, as well as 5 samples of disinfectants from different chemical groups (on the basis of quaternary ammonium salt, tertiary amine and polyhexamethyleneguanidine; on the basis of sodium percarbonate with activator; on the basis of hydrogen peroxide and didecyldimethylammonium chloride; in the form of tablets on the basis of sodium salt sodium dichloroisocyanurate acid), used in the specified divisions of medical facities. The studies were performed in accordance with the methodology set out in methodology instructions MU 3.5.1.3439-17 “Assessment of sensitivity to disinfectants of microorganisms circulating in medical organizations.” Results. When conducting chemical-analytical studies of samples of disinfectants 4 samples out of 5 were found to have inconsistencies in one or another quality indices. The analysis of instructions on application of disinfectants 4 means from 5 were showed to have unreasonably underestimated modes of application. According to the results of the evaluation of the sensitivity of microorganisms to disinfectants, the majority of isolated microorganisms was found to have resistance to the studied disinfectants Conclusion. Based on the results of the study of sensitivity of microorganisms to disinfectants, a new tactic for improving disinfection measures is proposed for medical facilities: rotation of disinfectants and an enhanced system of microbiological monitoring of the sensitivity of microorganisms to disinfectants

Binding isotherms of surfactants used in detergent formulations to bovine serum albumin

Protein-surfactant interactions are the focus of extensive research due to their many applications in food technology and detergent industry. In this work, we investigate the interaction between bovine serum albumin (BSA) and five relevant surfactants to the cleaning industry, which differ in head group charge, namely: sodium alkyl ether sulphate (C12-C14 AE3S), Cocoamidopropyl amine-oxide (CapAO), alkyl dimethyl amine oxide (C12C14AO), octaethylene glycol monodecyl ether (C10EO8) and didecyldimethylammonium chloride (DDAC). The results collected with fluorescence emission spectroscopy highlight zwitterionic and nonionic surfactants have the lowest affinity for the protein, as their interaction does not result in protein denaturation. Instead, higher and mutually close binding constants are found for AE3S (anionic) and DDAC (cationic) due to the presence of electrostatic interactions between the surfactant heads and the charged residues of BSA. AE3S leads to irreversible protein unfolding. The case of DDAC is more complex and has been studied through a combination of fluorescence, DLS, PGSE-NMR and zeta-potential measurements. At low concentration DDAC binding neutralizes negatively charged residues present in BSA, causing a reversible flocculation of BSA after the isoelectric point (23 DDAC molecules per protein). Further DDAC adsorption, at 70 DDAC molecules per protein, leads to an excess of positive charge on the protein which restores electrostatic repulsions between BSA-surfactant complexes.