Cationic Biocides Research Articles

Cationic surfactant (CTAB) a multipurpose additive in polymer-based drilling fluids

Drilling fluids are designed to assist drilling by minimizing reservoir damage and increasing productivity of pay zone. Excess fluid loss due to degradation of additives of drilling fluids causes a major problem in real-time drilling. Usages of excess biocides are threat to the environment and cause handling problems. Effect of cetyltrimethylammoniumbromide, a cationic surfactant, on rheology, fluid loss and biocide has been studied in a polymer-based drilling fluid. Inhibitive polymer mud was formulated using XC polymer, shale inhibitors like KCl, K2SO4 and CaCO3 as bridging agent. Rheology and other properties were studied using Fann VG meter, API filter press, mud balance, roller oven apparatus. Dissolved oxygen meter was used to check the microbicidal property of cetyltrimethylammoniumbromide. Addition of cetyltrimethylammoniumbromide increased fluid retention capacity of the fluid even at very low concentration 0.1%(w/v) without affecting the mud properties. Also it is compatible with the commercially available fluid loss preventers like pre-gelatinized starch when used in combination. It also performed well in dissolved oxygen test, suggesting eliminating need of any other biocide to prevent degradation of bio-polymer-based drilling fluid. The dissolved oxygen test results are comparable with commercial available biocides. Thermal stability studies were carried out by using roller oven at different temperatures. It was found suitable for application in high-concentrated brine conditions and at high temperatures up to 120 °C without effecting the rheology and shear thinning property of the fluid. Bridging efficiency was investigated by analysing the mud cake using scanning electron microscope.

Direct Synthesis of Dextran-Based Antibacterial Hydrogels for Extended Release of Biocides and Eradication of Topical Biofilms.

Cationic small molecular biocides have been developed as promising antibiofilm agents because of their tunability in chemical structures and their ability to disrupt established biofilms. However, the impact of biocides in antibiofilm treatment is largely limited due to the lack of an effective delivery system that can ensure sustained release of biocides at the target site. Herein we report a biocide-encapsulated antibacterial and antibiofilm hydrogel that acts as an efficient delivery vehicle for the biocide and eradicates matured bacterial biofilm. The hydrogels are prepared using dextran methacrylate (Dex-MA), a biocompatible and photopolymerizable polymer, and a nontoxic cationic biocide with two cationic charges, two nonpeptidic amide bonds, and optimized amphiphilicity, which is capable of eradicating established bacterial biofilms. The gels, prepared via direct loading of the biocide and with highly controllable amounts, display 100% activity against both drug-sensitive and drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). Importantly, the gels are shown to release the biocide and kill bacteria for an extended period of time (until day 5). When being treated with the established bacterial biofilms, the released biocide from the gel is shown to completely eradicate establishedS. aureus, Escherichia coli, and MRSA biofilms, the most common biofilm forming bacteria that cause severe infections (e.g., skin infections, urinary tract infections, etc.) in humans. Moreover, the gels were shown to annihilate preformed MRSA biofilm with >99.99% bacterial reduction under in vitro and in vivo conditions in a superficial MRSA infection model in mice. Notably, when tested, excellent skin compatibility is observed for these materials in various animal models such as a rat model of acute dermal toxicity, guinea pig model of skin sensitization, and rabbit model of skin irritation. The biocompatible antibacterial and antibiofilm hydrogels developed herein thus might be useful in treating bacterial biofilm associated infections, especially topical infections.

Formulation of Biocides Increases Antimicrobial Potency and Mitigates the Enrichment of Nonsusceptible Bacteria in Multispecies Biofilms.

The current investigation aimed to generate data to inform the development of risk assessments of biocide usage. Stabilized domestic drain biofilm microcosms were exposed daily over 6 months to increasing concentrations (0.01% to 1%) of the biocide benzalkonium chloride (BAC) in a simple aqueous solution (BAC-s) or in a complex formulation (BAC-f) representative of a domestic cleaning agent. Biofilms were analyzed by culture, differentiating by bacterial functional group and by BAC or antibiotic susceptibility. Bacterial isolates were identified by 16S rRNA sequencing, and changes in biofilm composition were assessed by high-throughput sequencing. Exposure to BAC-f resulted in significantly larger reductions in levels of viable bacteria than exposure to BAC-s, while bacterial diversity greatly decreased during exposure to both BAC-s and BAC-f, as evidenced by sequencing and viable counts. Increases in the abundance of bacteria exhibiting reduced antibiotic or BAC susceptibility following exposure to BAC at 0.1% were significantly greater for BAC-s than BAC-f. Bacteria with reduced BAC and antibiotic susceptibility were generally suppressed by higher BAC concentrations, and formulation significantly enhanced this effect. Significant decreases in the antimicrobial susceptibility of bacteria isolated from the systems before and after long-term BAC exposure were not detected. In summary, dose-dependent suppression of bacterial viability by BAC was enhanced by formulation. Biocide exposure decreased bacterial diversity and transiently enriched populations of organisms with lower antimicrobial susceptibility, and the effects were subsequently suppressed by exposure to 1% BAC-f, the concentration most closely reflecting deployment in formulated products.IMPORTANCE Assessment of the risks of biocide use has been based mainly on the exposure of axenic cultures of bacteria to biocides in simple aqueous solutions. The current investigation aimed to assess the effects of formulation on the outcome of biocide exposure in multispecies biofilms. Formulation of the cationic biocide BAC significantly increased antimicrobial potency. Bacteria with lower antimicrobial susceptibility whose populations were enriched after low-level biocide exposure were more effectively suppressed by the biocide at in-use concentrations (1% [wt/vol]) in a formulation than in a simple aqueous solution. These observations underline the importance of simulating normal deployment conditions in considering the risks and benefits of biocide use.

Promising silicones modified with cationic biocides for the development of antimicrobial medical devices

We have tested silicones containing 2% or 5% of the cationic biocides polyhexamethylene guanidine dodecylbenzenesulfonate (PHMG-DBS), 1-octyl-3-methylimidazolium tetrafluoroborate (OMIM-BF4) or 1-dodecyl-3-methylimidazolium tetrafluoroborate (DMIM-BF4) against the major relevant bacterial and yeast species in health care-associated infections (HCAI). Study conducted according to the international standard ISO 22196 revealed that silicones containing 2% or 5% DMIM-BF4 or 5% PHMG-DBS presented the highest antimicrobial activity, leading to a logarithmic growth reduction of 3.03 to 6.46 and 3.65 to 4.85 depending on the bacterial or fungal species. Heat-pretreated silicones containing 2% DMIM-BF4 kept a high activity, with at least a 3-log reduction in bacterial growth, except against P. aeruginosa where there was only a 1.1-log reduction. After 33days, the release ratio of cationic biocide from silicone films containing 5% of DMIM-BF4 was found to be 5.6% in pure water and 1.9% in physiological saline solution, respectively. No leaching of PHMG-DBS polymeric biocide was detected under the same conditions. These results demonstrate unambiguously that silicones containing 2% DMIM-BF4 or 5% PHMG-DBS present high antimicrobial activity, as well as high leaching resistance and therefore may be good candidates for the development of safer medical devices.

UV/chlorine as an advanced oxidation process for the degradation of benzalkonium chloride: Synergistic effect, transformation products and toxicity evaluation

Benzalkonium chlorides (BACs), as typical cationic surfactants and biocides widely applied in household and industrial products, have been frequently detected as micropollutants in many aquatic environments. In this study, the combination of UV irradiation and chlorine (UV/chlorine), a newly interested advanced oxidation process, was used to degrade dodecylbenzyldimethylammonium chloride (DDBAC). UV/chlorine showed synergistic effects on DDBAC degradation comparing to UV irradiation or chlorination alone. Radical quenching experiments indicated that degradation of DDBAC by UV/chlorine involved both UV photolysis and radical species oxidation, which accounted for 48.4% and 51.6%, respectively. Chlorine dosage and pH are essential parameters affecting the treatment efficiency of UV/chlorine. The pseudo first order rate constant (kobs, DDBAC) increased from 0.046 min−1 to 0.123 min−1 in response to chlorine dosage at 0–150 mg/L, and the degradation percentage of DDBAC within 12 min decreased from 81.4% to 56.6% at pH 3.6–9.5. Five main intermediates were identified and semi-quantified using HPLC-MS/MS and a possible degradation pathway was proposed. The degradation mechanisms of DDBAC by UV/chlorine included cleavage of the benzyl-nitrogen bond and hydrogen abstraction of the alkyl chain. Trichloromethane (TCM), chloral hydrate (CH), trichloropropanone (TCP), dichloropropanone (DCP) and dichloroacetonitrile (DCAN) were detected using GC-ECD. The formation of chlorinated products increased rapidly initially, then decreased (TCM, TCP, DCP and DCAN) or remained stable (CH) with extended treatment. The actual formation of TCM peaked at 30 min (50.3 μg/L), while other chlorinated products did not exceed 10 μg/L throughout the process. Based on the luminescent bacterial assay, DDBAC solution underwent almost complete detoxification subjected to UV/chlorine treatment for 120 min, which is more effective than UV irradiation or chlorination alone.

Poly(hexamethylene guanidine)-poly(ethylene glycol) solid blend for water microbial deactivation

Polyhexamethylene guanidine hydrochloride (PHMG) is a cationic polymeric biocide used in the treatment of contaminated drinking water. This article describes a PHMG controlled release system made from melt blend of PHMG and solid PEG rods. The polymeric blend system gradually dissolves upon contact with running water and release effective and safe doses of PHMG to the passing water. The PEG-PHMG rod units were installed in a water purifier system, and microbial inactivation efficiency was tested according to the WQA certification program against P231/EPA for 250 L, using 25 L of passing water per day with a flow rate of 8–10 min per liter. The released PHMG was analyzed by Raman spectroscopy, and the antimicrobial activity was determined against Escherichia coli and the virus surrogate, MS2. A constant release of 0.35–0.5 ppm PHMG along 250 L of passing water was achieved. Inactivation results exceeded the minimal requirement for bacterial removal of 4–5 log reduction throughout the entire 250L. The rod height correlated with amount of water eroding the rod from bottom surface. Thus, these PEG/PHMG rod unit systems can be used in water purification to provide microbial free drinking water and serve as an indicator for quantity of water passing through the filter.

Evolution of resistance to cationic biocides in Streptococcus mutans and Enterococcus faecalis

ObjectivesThe aim of this study was to investigate whether Streptococcus mutans and Enterococcus faecalis develop resistance to the cationic biocides chlorhexidine (CHX), cetylpyridinium chloride (CPC), and 12-methacryloyloxydodecylpyridinium bromide (MDPB). MethodsThe minimum inhibitory concentrations (MICs) of CHX, CPC, and MDPB were assessed after repeated exposure of S. mutans and E. faecalis to these biocides. Cell-surface hydrophobicity and protein expression profiles of bacterial cells were examined to elucidate possible resistance mechanisms. ResultsThe MIC of CHX against E. faecalis showed constant increases up to 10 passages. No changes in the MICs of CPC and MDPB against E. faecalis were observed. The MICs of CHX, CPC, and MDPB against S. mutans did not increase. The surface hydrophobicity of E. faecalis significantly increased with increasing exposure to CHX and CPC. However, changes in protein expression profiles were only found in CHX-adapted E. faecalis, as evidenced by the emergence of a novel, approximately 19-kDa band following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. ConclusionsWhile E. faecalis and S. mutans did not exhibit increased resistance to CPC or MDPB, repeated exposure of E. faecalis to CHX led to resistance. It is likely that the acquisition of resistance is related to an altered protein composition. Clinical SignificanceAlkyl pyridinium compounds, such as CPC and MDPB, could have a lower risk to cause adaptation of E. faecalis, which is advantageous compared with CHX.

Use of a predictive protocol to measure the antimicrobial resistance risks associated with biocidal product usage

In this study we assessed the propensity of biocide exposure in the development of antimicrobial resistance in bacteria. Our protocol is based on reporting changes in established antimicrobial susceptibility profiles in biocides and antibiotics after during use exposure to a product. The during use exposure reflects worse conditions of product use during application. It differs from the term low concentration, which usually reflects a concentration below the minimal inhibitory concentration, but not necessarily a concentration that occurs in practice. Our results showed that exposure to triclosan (0.0004%) was associated with a high risk of developing resistance and cross-resistance in Staphylococcus aureus and Escherichia coli. This was not observed with exposure to chlorhexidine (0.00005%) or a hydrogen peroxide-based biocidal product (in during use conditions). Interestingly, exposure to a low concentration of hydrogen peroxide (0.001%) carried a risk of emerging resistance to antibiotics if the presence of the oxidizing agent was maintained. We observed a number of unstable clinical resistances to antibiotics after exposure to the cationic biocide and oxidizing agent, notably to tobramycin and ticarcillin-clavulanic acid. Using a decision tree based on the change in antimicrobial susceptibility test results, we were able to provide information on the effect of biocide exposure on the development of bacterial resistance to antimicrobials. Such information should address the call from the U.S. Food and Drug Administration and European Union Biocidal Products Regulation for manufacturers to provide information on antimicrobial resistance and cross-resistance in bacteria after the use of their product.

From broad-spectrum biocides to quorum sensing disruptors and mussel repellents: antifouling profile of alkyl triphenylphosphonium salts.

‘Onium’ compounds, including ammonium and phosphonium salts, have been employed as antiseptics and disinfectants. These cationic biocides have been incorporated into multiple materials, principally to avoid bacterial attachment. In this work, we selected 20 alkyl-triphenylphosphonium salts, differing mainly in the length and functionalization of their alkyl chains, in fulfilment of two main objectives: 1) to provide a comprehensive evaluation of the antifouling profile of these molecules with relevant marine fouling organisms; and 2) to shed new light on their potential applications, beyond their classic use as broad-spectrum biocides. In this regard, we demonstrate for the first time that these compounds are also able to act as non-toxic quorum sensing disruptors in two different bacterial models (Chromobacterium violaceum and Vibrio harveyi) as well as repellents in the mussel Mytilus galloprovincialis. In addition, their inhibitory activity on a fouling-relevant enzymatic model (tyrosinase) is characterized. An analysis of the structure-activity relationships of these compounds for antifouling purposes is provided, which may result useful in the design of targeted antifouling solutions with these molecules. Altogether, the findings reported herein provide a different perspective on the biological activities of phosphonium compounds that is particularly focused on, but, as the reader will realize, is not limited to their use as antifouling agents.

Microstructure and antibacterial performance of functionalized polyurethane based on polysiloxane tethered cationic biocides

The designed polyurethane containing polysiloxanes tethered quaternary ammonium salt groups exhibited special surface migrations, low surface free energy and excellent antibacterial activity towardsEscherichia coli.

New Derivatives of Pyridoxine Exhibit High Antibacterial Activity against Biofilm-EmbeddedStaphylococcusCells

Opportunistic bacteria Staphylococcus aureus and Staphylococcus epidermidis often form rigid biofilms on tissues and inorganic surfaces. In the biofilm bacterial cells are embedded in a self-produced polysaccharide matrix and thereby are inaccessible to biocides, antibiotics, or host immune system. Here we show the antibacterial activity of newly synthesized cationic biocides, the quaternary ammonium, and bisphosphonium salts of pyridoxine (vitamin B6) against biofilm-embedded Staphylococci. The derivatives of 6-hydroxymethylpyridoxine were ineffective against biofilm-embedded S. aureus and S. epidermidis at concentrations up to 64 μg/mL, although all compounds tested exhibited low MICs (2 μg/mL) against planktonic cells. In contrast, the quaternary ammonium salt of pyridoxine (N,N-dimethyl-N-((2,2,8-trimethyl-4H-[1,3]dioxino[4,5-c]pyridin-5-yl)methyl)octadecan-1-aminium chloride (3)) demonstrated high biocidal activity against both planktonic and biofilm-embedded bacteria. Thus, the complete death of biofilm-embedded S. aureus and S. epidermidis cells was obtained at concentrations of 64 and 16 μg/mL, respectively. We suggest that the quaternary ammonium salts of pyridoxine are perspective to design new synthetic antibiotics and disinfectants for external application against biofilm-embedded cells.

Comparative analysis of Salmonella susceptibility and tolerance to the biocide chlorhexidine identifies a complex cellular defense network.

Chlorhexidine is one of the most widely used biocides in health and agricultural settings as well as in the modern food industry. It is a cationic biocide of the biguanide class. Details of its mechanism of action are largely unknown. The frequent use of chlorhexidine has been questioned recently, amidst concerns that an overuse of this compound may select for bacteria displaying an altered susceptibility to antimicrobials, including clinically important anti-bacterial agents. We generated a Salmonella enterica serovar Typhimurium isolate (ST24CHX) that exhibited a high-level tolerant phenotype to chlorhexidine, following several rounds of in vitro selection, using sub-lethal concentrations of the biocide. This mutant showed altered suceptibility to a panel of clinically important antimicrobial compounds. Here we describe a genomic, transcriptomic, proteomic, and phenotypic analysis of the chlorhexidine tolerant S. Typhimurium compared with its isogenic sensitive progenitor. Results from this study describe a chlorhexidine defense network that functions in both the reference chlorhexidine sensitive isolate and the tolerant mutant. The defense network involved multiple cell targets including those associated with the synthesis and modification of the cell wall, the SOS response, virulence, and a shift in cellular metabolism toward anoxic pathways, some of which were regulated by CreB and Fur. In addition, results indicated that chlorhexidine tolerance was associated with more extensive modifications of the same cellular processes involved in this proposed network, as well as a divergent defense response involving the up-regulation of additional targets such as the flagellar apparatus and an altered cellular phosphate metabolism. These data show that sub-lethal concentrations of chlorhexidine induce distinct changes in exposed Salmonella, and our findings provide insights into the mechanisms of action and tolerance to this biocidal agent.

Computational study of bacterial membrane disruption by cationic biocides: structural basis for water pore formation.

The development of biocides as disinfectants that do not induce bacterial resistance is crucial to health care since hospital-acquired infections afflict millions of patients every year. Recent experimental studies of a class of cationic biocides based on the phenylene ethynylene backbone, known as OPEs, have revealed that their biocidal activity is accompanied by strong morphology changes to bacterial cell membranes. In vitro studies of bacterial membrane mimics have shown changes to the lipid phase that are dependent on the length and orientation of the cationic moieties on the backbone. This study uses classical molecular dynamics to conduct a comprehensive survey of how oligomers with different chemical structures interact with each other and with a bacterial cell membrane mimic. In particular, the ability of OPEs to disrupt membrane structure is studied as a function of the length of the biocides and the orientation of their cationic moieties along the backbone of the molecule. The simulation results show that the structure of OPEs radically affects their interactions with a lipid bilayer. Biocides with branched cationic groups form trans-membrane water pores regardless of their backbone length, while only 1-1.5 nm of membrane thinning is observed with biocides with cationic groups on their terminal ends. The molecular dynamics simulations provide mechanistic details at the molecular level of the interaction of these biocidal oligomers and the lipid bilayer and corroborate experimental findings regarding observed differences in membrane disruption by OPEs with different chemical structures.

Microbial community adaptation to quaternary ammonium biocides as revealed by metagenomics

Quaternary ammonium compounds (QACs) represent widely used cationic biocides that persist in natural environments. Although microbial degradation, sensitivity and resistance to QACs have been extensively documented, a quantitative understanding of how whole communities adapt to QAC exposure remain elusive. To gain insights into these issues, we exposed a microbial community from a contaminated river sediment to varied levels of benzalkonium chlorides (BACs, a family of QACs) for 3 years. Comparative metagenomic analysis showed that the BAC-fed communities were dramatically decreased in phylogenetic diversity compared with the control (no BAC exposure), resulting presumably from BAC toxicity, and dominated by Pseudomonas species (> 50% of the total). Time-course metagenomics revealed that community adaptation occurred primarily via selective enrichment of BAC-degrading Pseudomonas populations, particularly P. nitroreducens, and secondarily via amino acid substitutions and horizontal transfer of a few selected genes in the Pseudomonas populations, including a gene encoding a PAS/PAC sensor protein and ring-hydroxylating dioxygenase genes. P. nitroreducens isolates were reproducibly recoverable from communities after prolonged periods of no-BAC exposure, suggesting that they are robust BAC-degraders. Our study provides new insights into the mechanisms and tempo of microbial community adaptation to QAC exposure and has implications for treating QACs in biological engineered systems.

Assessment of the mode of action of polyhexamethylene biguanide against Listeria innocua by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis

Polyhexamethylene biguanide (PHMB) is a cationic biocide. The antibacterial mode of action of PHMB (at concentrations not exceeding its minimal inhibitory concentration) upon Listeria innocua LRGIA 01 was investigated by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis. Fourier transformed infrared spectra of bacteria treated with or without PHMB presented some differences in the lipids region: the CH(2)/CH(3) (2924 cm(-1)/2960 cm(-1)) band areas ratio significantly increased in the presence of PHMB. Since this ratio generally reflects membrane phospholipids and membrane microenvironment of the cells, these results suggest that PHMB molecules interact with membrane phospholipids and, thus, affect membrane fluidity and conformation. To assess the hypothesis of PHMB interaction with L. innocua membrane phospholipids and to clarify the PHMB mode of action, we performed fluorescence anisotropy experiments. Two probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and its derivative 1-[4-(trimethyl-amino)-phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), were used. DPH and TMA-DPH incorporate inside and at the surface of the cytoplasmic membrane, respectively. When PHMB was added, an increase of TMA-DPH fluorescence anisotropy was observed, but no changes of DPH fluorescence anisotropy occurred. These results are consistent with the hypothesis that PHMB molecules perturb L. innocua LRGIA 01 cytoplasmic membrane by interacting with the first layer of the membrane lipid bilayer.

Molecular Dynamics Simulation Study of the Interaction of Cationic Biocides with Lipid Bilayers: Aggregation Effects and Bilayer Damage

A novel class of phenylene ethynylene polyelectrolyte oligomers (OPEs) has been found to be effective biocidal agents against a variety of pathogens. The mechanism of attack is not yet fully understood. Recent studies have shown that OPEs cause catastrophic damage to large unilamellar vesicles. This study uses classical molecular dynamics (MD) simulations to understand how OPEs interact with model lipid bilayers. All-atom molecular dynamics simulations show that aggregates of OPEs inserted into the membrane cause significant structural damage and create a channel, or pore, that allows significant leakage of water through the membrane on the 0.1 μs time scale.

The influence of nonconjugative Escherichia coli plasmids on biofilm formation and resistance

This work describes the effects of the presence of nonconjugative plasmids in Escherichia coli cells forming biofilms on a flow cell system under turbulent conditions. The pET28 and pUC8 plasmids were separately used to transform E. coli JM109(DE3). Biofilm formation, removal and antimicrobial susceptibility to the cationic biocide benzyldimethyldodecylammonium chloride (BDMDAC) were assessed. Transformed cells formed thicker biofilms with higher cell densities, and the metabolic activity was higher whereas nontransformed cells had higher viabilities. Biocide treatment was not efficient for biofilm removal but was effective for cell killing. Biofilms formed by nontransformed cells were less affected by the treatment. Cell transformation with the tested plasmids has significant impacts on biofilm formation, cell viability, metabolic activity and resistance to biocide treatment. Our results show that in biofilm studies involving deletion/complementation experiments, a control with the strain carrying a plasmid devoid of the gene under investigation must be included so that the real effects of the genetic manipulation are not biased by the presence of the plasmid backbone. This is the first report where the presence of nonconjugative plasmids is assessed in flow conditions analysing biofilm formation, removal and antimicrobial susceptibility of high cell-density biofilms.

Antimicrobial finishing of wool using an oxidative pretreatment to enhance the exhaustion of quaternary ammonium compounds

AbstractAntimicrobial treatments of textiles confer multiple benefits to the textiles and the wearers. We previously demonstrated that a pretreatment of wool with peroxymonosulfate and sulfite uniquely enabled the wool to exhaust large quantities of the cationic biocide poly(hexamethylene biguanide). In this study, we extended our previous work to quaternary ammonium compounds (QACs), using cetylpyridinium chloride (CPC) as an example. QACs are cationic biocides widely used in household and industrial disinfectants. It was found that the pretreatment enabled the otherwise unreceptive wool to exhaust up to 10% of CPC on the weight of wool. The presence of CPC on the wool was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. The exhaustion proceeded rapidly and efficiently at room temperature and could be slightly enhanced at 40–60°C but was not affected by pH over a broad range. Dyeing with reactive dye had little effect on the exhaustion, but acid dye, premetalized dye, and chrome dye decreased CPC exhaustion by 25–50%. Wool fabrics finished with CPC exhibited a strong antimicrobial ability, deactivating 99.9% of Escherichia coli inoculated into the fabrics. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polyhexamethylene Biguanide Dressing – Another Promising Tool to Reduce Catheter-related Bloodstream Infection

PurposeThis article provides a description of polyhexamethylene biguanide (PHMB), its current uses and clinical outcomes, and potential uses. Review of Relevant LiteraturePHMB is an antiseptic agent from the cationic biocide family, which also includes chlorhexidine. In vitro testing has found it to be effective against gram-positive and gram-negative bacteria including methicillin-resistant staphylococcus aureus, fungi and viruses. Its action is directed toward disruption of the cell wall, a mechanism not known for developing resistance. PHMB is currently used for many other products and industries for more than 50 years. Dressings impregnated with PHMB are now successfully being used to prevent surgical site infections. DiscussionElimination of catheter-related bloodstream infection (CR-BSI) is now the achievable goal for all healthcare settings. The use of PHMB provides another engineering tool targeting the skin as the source of these infections. Successful use with prevention of surgical site infections is now being reported. These wounds can become infected with the same organisms as those found in CRBSI. Implications for Clinical PracticeThis agent should be considered for clinical studies to determine the rates of CRBSI reduction resulting from its use.

Screening for Potential Antimicrobial Activities of Some Cationic Uracil Biocides Against Wide‐Spreading Bacterial Strains

AbstractEight novel uracil‐based cationic surfactants containing Schiff base species were synthesized and characterized using elemental analysis, FTIR, 1H‐NMR and 13C‐NMR spectroscopy. The surface activities of the synthesized Schiff bases and their cationic derivatives were determined based on interfacial tension measurements and partition coefficient values in water/octanol system. The synthesized Schiff bases and their cationic derivatives were evaluated as novel biocides against different bacteria and fungi strains. The results showed that the biocidal activity of the synthesized Schiff bases was considerably increased by quaternization. The influence of the cationic surfactants as biocides was increased by increasing the hydrophobic chain length and the presence of the methoxy groups. The biocidal activity was also increased by increasing the partition coefficient in water/octanol system. The structure and surface activity/biocidal activity of the different compounds were discussed.