Selection Of Biocides Research Articles

Use of Hydrogen Peroxide Vapour for Microbiological Disinfection in Hospital Environments: A Review.

Disinfection of nosocomial pathogens in hospitals is crucial to combat healthcare-acquired infections, which can be acquired by patients, visitors and healthcare workers. However, the presence of a wide range of pathogens and biofilms, combined with the indiscriminate use of antibiotics, presents infection control teams in healthcare facilities with ongoing challenges in the selection of biocides and application methods. This necessitates the development of biocides and innovative disinfection methods that overcome the shortcomings of conventional methods. This comprehensive review finds the use of hydrogen peroxide vapour to be a superior alternative to conventional methods. Motivated by observations in previous studies, herein, we provide a comprehensive overview on the utilisation of hydrogen peroxide vapour as a superior high-level disinfection alternative in hospital settings. This review finds hydrogen peroxide vapour to be very close to an ideal disinfectant due to its proven efficacy against a wide range of microorganisms, safety to use, lack of toxicity concerns and good material compatibility. The superiority of hydrogen peroxide vapour was recently demonstrated in the case of decontamination of N95/FFP2 masks for reuse to address the critical shortage caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the COVID-19 pandemic. Despite the significant number of studies demonstrating antimicrobial activity, there remains a need to critically understand the mechanism of action by performing studies that simultaneously measure damage to all bacterial cell components and assess the correlation of this damage with a reduction in viable cell count. This can lead to improvement in antimicrobial efficacy and foster the development of superior approaches.

IMPROVING MICROBIAL CONTROL IN PRODUCED WATER FROM OIL FIELDS: A 5-STEP APPROACH

Microbial control in oil fields can be considered a complex subject, since microbiome diversity and physical-chemical characteristics of produced water (PW) originate a unique profile in oil fields. Standard biocides are used as chemical treatment, but the toxicity and the high volumes can cause elevated environmental impacts. Treatment effectiveness and, consequently, reduction of environmental impact may be improved through an adequate planning. The present study examines the bacterial resistance mechanisms to biocides and suggests a 5-step approach for the treatment planning: 1) determination of objectives; 2) bioaudit; 3) selection of biocide(s) in laboratory; 4) selection of representative Key Performance Indicators (KPI); and 5) monitoring of the treatment. Finally, this article demonstrates an optimization of a biocide treatment using the 5-step approach. The results show a reduction of approximately 50% in the dosage of the biocide, as well as reduction in frequency of dosage.

Biocide Susceptibility and Antimicrobial Resistance of Escherichia coli Isolated from Swine Feces, Pork Meat and Humans in Germany.

Phenotypic susceptibility testing of Escherichia (E.) coli is an essential tool to gain a better understanding of the potential impact of biocide selection pressure on antimicrobial resistance. We, therefore, determined the biocide and antimicrobial susceptibility of 216 extended-spectrum β-lactamase-producing (ESBL) and 177 non-ESBL E. coli isolated from swine feces, pork meat, voluntary donors and inpatients and evaluated associations between their susceptibilities. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of benzalkonium chloride, chlorhexidine digluconate (CHG), chlorocresol (PCMC), glutaraldehyde (GDA), isopropanol (IPA), octenidine dihydrochloride and sodium hypochlorite (NaOCl) showed unimodal distributions, indicating the absence of bacterial adaptation to biocides due to the acquisition of resistance mechanisms. Although MIC95 and MBC95 did not vary more than one doubling dilution step between isolates of porcine and human origin, significant differences in MIC and/or MBC distributions were identified for GDA, CHG, IPA, PCMC and NaOCl. Comparing non-ESBL and ESBL E. coli, significantly different MIC and/or MBC distributions were found for PCMC, CHG and GDA. Antimicrobial susceptibility testing revealed the highest frequency of resistant E. coli in the subpopulation isolated from inpatients. We observed significant but weakly positive correlations between biocide MICs and/or MBCs and antimicrobial MICs. In summary, our data indicate a rather moderate effect of biocide use on the susceptibility of E. coli to biocides and antimicrobials.

Exposure to Quaternary Ammonium Compounds Selects Resistance to Ciprofloxacin in Listeria monocytogenes.

In this contribution, the antimicrobial susceptibility toward 11 antibiotics and four biocides of a panel of 205 Listeria monocytogenes (Lm) strains isolated from different ecological niches (i.e., food, animals and natural environment) was evaluated. The impact of exposure to biocides on the antibiotic susceptibilities of Lm was also investigated. Lm strains isolated from food exhibited overall a lower susceptibility (higher minimal inhibitory concentrations, MIC) for ammonium quaternary compounds (QACs) and peracetic acid (PAC) than strains isolated from animals and natural environments. Conversely, the ecological origins of Lm strains did not significantly affect their susceptibilities towards antibiotics. Interestingly, repeated exposure to QACs recurrently led to a decrease in susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human medicine. Moreover, these lower levels of susceptibility to CIP remained stable in most Lm strains even after subcultures without biocide selection pressure, suggesting an adaptation involving modifications at the genetic level. Results underlined the ability of Lm to adapt to biocides, especially QACs, and the potential link between this adaptation and the selection of resistance toward critical antibiotics such as ciprofloxacin. These data support a potential role of the extensive use of QACs from “farm to fork” in the selection of biocide and antibiotic resistance in pathogenic bacteria such as Lm.

Research on the selection of biocides for the ‘disinfection’ of statues and masonry at the National Trust (UK)

In order to refresh guidance on garden statuary maintenance conservation, 16 biocides available on the British and European markets were selected for testing in situ at 11 properties of the National Trust (NT) located in England and Wales. For the testing, a range of decorative items, statues and architectural features were chosen, made of various types of stone, including limestone, sandstone, marble, slate and granite, as well as cast concrete, terracotta and brick. Tests were preceded by evaluation of the local microclimate and visual examination of the condition of the objects, including assessment of the presence of any micro-organisms and salt efflorescence. The history of previous conservation works and their materials was also reviewed. Microbiological analysis was carried out in many cases, which identified various algae, lichens and mosses. The effectiveness of the biocides and any potential side effects were evaluated periodically for 24 months after application. Three of the most effective biocides were selected for further assessment. An adenosine triphosphate (ATP) luminometer was used to measure whether biological growth had recurred on the stone at 7 and 12 months after application. Observed side effects included an occasional brown discolouration of Carrara marble after application of three of the biocides tested. An important outcome of the project was not only to recommend which biocides to use where treatment was necessary but also to determine when their use would not be advisable.

Biocidal Activity of Selected Preparations for Leather Protection

This research work involved the selection of biocides for the antimicrobial treatment of leathers. The scope of the research work covered microbiological tests of leather samples tanned utilising the same technology, with microbiological treatment made using 9 different preparations, as well as a test of leather without biostabilisation. Commercial biocides taken for inwestigation were as follows: NS 500 – an aqueous solution of nanosilver 500 ppm, ODH – tea tree oil, and OP – orange oil. Preparations prepared by diluting the purchased products were as follows: S27-22 – an aqueous solution containing silver chloride and titanium dioxide, SH 22-27 – an aqueous solution containing zinc pyrithione, ST 99-19 – an aqueous solution containing dimethyltetradecyl [3-(trimethoxysilyl)propyl]ammonium chloride, SU – an aqueous solution containing polyhexamethylene biguanide, and SGP – a saturated solution of aluminum potassium sulfate. Also a preparation was made by combining NS 500 M250 – 500 ppm nanosilver solution and a 250 ppm copper colloid. Evaluation of the effectiveness of biostabilisation of the leather samples and antimicrobial activity of the preparations used was carried out. Staphylococcus aureus and Escherichia coli bacteria and Candida albicans, Aspergillus brasiliensis and Trichophyton mentagrophytes fungi were used in the study. The assessment of microbial growth on samples was carried out according to Polish standards. Assessment of the resistance to bacteria and C. albicans yeast was made according to the PN-EN ISO 20645: 2006 standard – a method of diffusion on an agar plate. Assessment of the resistance to A. brasiliensis and T. mentagrophytes fungi was made according to the PN-EN ISO 14119: 2005 standard. Among the tested preparations to protect leathers against the effects of microorganisms, overall efficacy was obtained for SH 22-27, NS 500 M 250, SU and ODH.

Biocide-Tolerant Listeria monocytogenes Isolates from German Food Production Plants Do Not Show Cross-Resistance to Clinically Relevant Antibiotics.

Contamination of food during processing is recognized as a main transmission route of Listeria monocytogenes To prevent microbial contamination, biocides are widely applied as disinfectants in food processing plants. However, there are concerns about the development of antimicrobial resistance in foodborne pathogens due to widespread biocide usage. In our study, 93 L. monocytogenes isolates from German food production facilities were (i) tested for biocide and antibiotic susceptibility using broth microdilution assays, (ii) analyzed for links between reduced biocide susceptibility and antibiotic resistance, and (iii) characterized by whole-genome sequencing, including the detection of genes coding for biocide tolerance, antibiotic resistance, and other virulence factors. Fifteen L. monocytogenes isolates were tolerant to benzalkonium chloride (BAC), and genes conferring BAC tolerance were found in 13 of them. Antibiotic resistance was not associated with biocide tolerance. BAC-tolerant isolates were assigned to 6 multilocus sequence type (MLST) clonal complexes, and most of them harbored internalin A pseudogenes with premature stop codons or deletions (n = 9). Our study demonstrated a high genetic diversity among the investigated isolates including genotypes that are frequently involved in human infections. Although in vitro adaptation studies to biocides have raised concerns about increasing cross-resistance to antibiotics, our results do not provide evidence for this phenomenon in field isolates.IMPORTANCE Foodborne pathogens such as L. monocytogenes can persist in food production environments for a long time, causing perennial outbreaks. Hence, bacterial pathogens are able to survive cleaning and disinfection procedures. Accordingly, they may be repeatedly exposed to sublethal concentrations of disinfectants, which might result in bacterial adaptation to these biocides. Furthermore, antibiotic coresistance and cross-resistance are known to evolve under biocide selection pressure in vitro Hence, antimicrobial tolerance seems to play a crucial role in the resilience and persistence of foodborne pathogens in the food chain and might reduce therapeutic options in infectious diseases.

Continuing Impacts of Selective Inhibition on Bacterial and Fungal Communities in an Agricultural Soil.

Selective inhibition (SI) has been routinely used to differentiate the contributions of bacteria and fungi to soil ecological processes. SI experiments typically measured rapid responses within hours since the addition of inhibitor, but the long-term effects of selective biocides on microbial community composition and function were largely unknown. In this study, a microcosm experiment was performed with an agricultural soil to explore the effectiveness of two bactericides (bronopol, streptomycin) and two fungicides (cycloheximide, captan), which were applied at two different concentrations (2 and 10mgg-1). The microcosms were incubated for 6weeks. A radiolabeled substrate, [1,2,3,4,4a,9a-14C] anthracene, was spiked to all microcosms, and the derived CO2 was monitored during the incubation. The abundance and composition of bacteria and fungi were assessed by qPCR and Miseq sequencing of ribosomal rRNA genes. It was demonstrated that only 2mgg-1 bronopol and cycloheximide significantly changed the bacteria to fungi ratio without apparent non-target inhibition on the abundances; however, community shifts were observed in all treatments after 6weeks incubation. The enrichment of specific taxa implicated a selection of resistant or adapted microbes by these biocides. Mineralization of anthracene was continuingly suppressed in all SI microcosms, which may result in biased estimate of bacterial and fungal contributions to pollutant degradation. These findings highlight the risks of long-term application of selective inhibition, and a preliminary assessment of biocide selection and concentration is highly recommended.

Effect of selected biocides on microbiologically influenced corrosion caused by Desulfovibrio ferrophilus IS5

The marine bacterial strain Desulfovibrio ferrophilus IS5, known for its lithotrophic growth ability to use metallic iron as a sole electron donor and for causing corrosion of steel, was used in the current study. Four commonly used biocides in the oil and gas industry, namely tetrakis(hydroxymethyl) phosphonium sulfate (THPS), glutaraldehyde (GLUT), benzalkonium chloride (BAC), and GLUT/BAC were selected to study their efficacy in controlling carbon steel corrosion in the presence of this strain. Incubations containing strain IS5 and low carbon steel coupons were prepared in the presence and absence of the four biocides, and these were monitored using both electrochemical methods (electrochemical impedance spectroscopy, linear polarization resistance and potentiodynamic polarization) and surface analyses (scanning electron microscopy, confocal measurements, optical microscopy, and profilometry) to assess the biofilm/metal interactions. When THPS, BAC, and GLUT/BAC treatments were applied, minimal corrosion was measured by all methods. In contrast, severe pitting was observed in the presence of 50 ppm GLUT, similar to what was observed when D. ferrophilus IS5 was incubated in the absence of biocide, suggesting that GLUT alone may not be effective in controlling MIC in marine environments. This study also showed that the use of non-destructive electrochemical methods is effective for screening for real time biocide selection and monitoring of the impact of chemicals post-dosage in oil and gas operations.

Investigation of fungicidal activity of biocides by method of direct contact with test cultures

The article substantiates the possibility of using the method of direct contact with test cultures as an express method for assessing the quality of biocidal substances. This technique allows to test soluble biocidal preparations, while reducing the time of biocide selection, which eliminates the need for large-scale full-scale testing of structures under real operating conditions, providing cost savings.

Assessment of efficacy of biocides in different soil types for use in sorption studies of low molecular weight organic compounds

The abiotic protection of low molecular weight organic compounds (LMWOC) in soils may be an important regulator of C cycling. The study of the protection of LMWOC through sorption typically employs soils shaken in solution, which may be compromised by biological activity. We used 14C-labelled glucose as a LMWOC in batch assays of four different soils with contrasting physico-chemical properties (Arenosol, Luvisol, Ferralsol and Andisol). The commonly used biocides NaN3 and HgCl2 were employed alone or in concert across a range of concentrations to assess their efficacy in inhibiting microbial degradation. For short (<1 day) sorption experiments, low NaN3 concentrations (50 µM) were sufficient to inhibit microbial activity, whereas for longer (2 week) equilibrium assays, only high HgCl2 concentrations (10 mM) were effective in all soils tested. All combinations of biocide were most effective in inhibiting microbial activity in the Arenosol and least effective in the Andisol. Thus, in some soils, particular care is required with biocide selection for complete inhibition of biological activity. The findings presented here are of relevance for the design of studies investigating sorption of labile organic compounds in soils.

Flow cytometry as a tool for oilfield biocide efficacy testing and monitoring

Currently, oilfield biocide performance testing relies on classical microbiological culture techniques and culture-independent based methods such as ATP measurement. Although each method has its merits, there are significant drawbacks for each. For example, results from culturing require a two to four week incubation, which delays optimization of the biocide application. It also assumes that the microbes are able to grow in oilfield culture media. ATP photometry has reduced the time necessary for system optimization to one day, but there can be challenges with quantification of stressed and dying – yet intact – microbes. Flow cytometry is a technique that allows a real-time, absolute measurement of individual cells and gives insight into microbial kill mechanisms by distinguishing physiologic states other than alive or dead. Based on these advantages we show that flow cytometry may be a better alternative for biocide selection compared to culture- and ATP-based methods. Here we show that kill studies done with flow cytometry can give more meaningful and significant results compared to culture-based methods and commercially available ATP kits on pure-culture preparations and oilfield water samples.

The microbiology of Lascaux Cave

Lascaux Cave (Montignac, France) contains paintings from the Upper Paleolithic period. Shortly after its discovery in 1940, the cave was seriously disturbed by major destructive interventions. In 1963, the cave was closed due to algal growth on the walls. In 2001, the ceiling, walls and sediments were colonized by the fungus Fusarium solani. Later, black stains, probably of fungal origin, appeared on the walls. Biocide treatments, including quaternary ammonium derivatives, were extensively applied for a few years, and have been in use again since January 2008. The microbial communities in Lascaux Cave were shown to be composed of human-pathogenic bacteria and entomopathogenic fungi, the former as a result of the biocide selection. The data show that fungi play an important role in the cave, and arthropods contribute to the dispersion of conidia. A careful study on the fungal ecology is needed in order to complete the cave food web and to control the black stains threatening the Paleolithic paintings.

Biofilms and hygiene on dairy farms and in the dairy industry: sanitation chemical products and their effectiveness on biofilms - a review

Microbial biofilms which form on all types of surfaces of technological systems in the dairy industry and on dairy farms adversely affect the quality and safety of final products, i.e. both foodstuffs and raw materials used for their production. The fact that a number of microorganisms are alimentary pathogens, e.g. <I>Staphylococcus aureus</I> or <I>Listeria monocytogenes,</I> makes a serious problem directly affecting human health. Biofilms are usually formed by various species of microorganism, which protect each other against the effects of biocidal (antibacterial) agents and are resistant to these agents. The colonisation of surfaces of the open and closed piping systems, floors, waste, walls and ceilings of the production halls becomes a major problem in the selection of effective sanitation agents for their control. Based on the existing model studies, practical methods for testing the effectiveness of sanitation procedures should be evaluated, including the selection of biocides and comparison of the physical parameters of the sanitation procedures. Testing the effectiveness of the sanitation agents should be performed with the use of standardised tests, which consider microbial, structural, and chemical characteristics of the living microbial communities on specific contact surfaces in the food-processing industry.

Predicting dermal permeability of biocides in commercial cutting fluids using a LSER approach

The aim of this study is to predict dermal permeability of four phenolic biocides in four different formulations using a linear solvation energy relationship (LSER) approach, with a calibrated flow through diffusion cell system. Mathematical descriptors were determined in the laboratory, by mathematical computations, and by statistical methods. Infinite doses of 4 biocides and 25 probe chemicals in water, 17% methanol and 2 commercial metalworking fluids namely Astrocut–C ® and Tapfree 2 ® were applied to porcine skin flow through diffusion cells. The strength coefficients for the 25 probe compounds for each system were determined from multiple linear regression analysis and plugged into the Abraham's LSER equation to predict permeability values for biocides. Biocide permeability significantly decreased in methanol, Astrocut–C ® and Tapfree 2 ® when compared to water. The strength coefficients revealed that hydrophobicity played an important role in explaining the reduced permeability in vehicles compared to water. This finding is important for selection of biocides and cutting fluids formulation. The R 2 between experimental and predicted log Kp of probe solutes for water, methanol, Astrocut–C ® and Tapfree 2 ® were 0.70, 0.78, 0.89 and 0.84, respectively. In conclusion, the LSER approach adequately predicted the dermal permeability of four biocides in commercial cutting fluids and also shed light on the chemical interactions resulting in reduced permeability.

Efflux-mediated antimicrobial resistance

Antibiotic resistance continues to plague antimicrobial chemotherapy of infectious disease. And while true biocide resistance is as yet unrealized, in vitro and in vivo episodes of reduced biocide susceptibility are common and the history of antibiotic resistance should not be ignored in the development and use of biocidal agents. Efflux mechanisms of resistance, both drug specific and multidrug, are important determinants of intrinsic and/or acquired resistance to these antimicrobials, with some accommodating both antibiotics and biocides. This latter raises the spectre (as yet generally unrealized) of biocide selection of multiple antibiotic-resistant organisms. Multidrug efflux mechanisms are broadly conserved in bacteria, are almost invariably chromosome-encoded and their expression in many instances results from mutations in regulatory genes. In contrast, drug-specific efflux mechanisms are generally encoded by plasmids and/or other mobile genetic elements (transposons, integrons) that carry additional resistance genes, and so their ready acquisition is compounded by their association with multidrug resistance. While there is some support for the latter efflux systems arising from efflux determinants of self-protection in antibiotic-producing Streptomyces spp. and, thus, intended as drug exporters, increasingly, chromosomal multidrug efflux determinants, at least in Gram-negative bacteria, appear not to be intended as drug exporters but as exporters with, perhaps, a variety of other roles in bacterial cells. Still, given the clinical significance of multidrug (and drug-specific) exporters, efflux must be considered in formulating strategies/approaches to treating drug-resistant infections, both in the development of new agents, for example, less impacted by efflux and in targeting efflux directly with efflux inhibitors.

Selection of biocides for use in floral preservatives

The effects of concentrations of various biocides, in a solution containing 0.2 g l−1 citric acid and 10 g l−1 glucose, were tested on cut roses (Rosa hybrida L., ‘Classy’), Alstroemeria pelegrina L. and carnations (Dianthus caryophyllus L.). Compounds were evaluated for their effects on flower life (time to decline in fresh weight), maximum gain in fresh weight, solution uptake from 4 to 6 days, resistance to water flow in the stem, stem respiration and solution absorbance. Longer flower life and higher gain in fresh weight of roses were observed with a concentration of 0.05 g l−1 than with higher concentrations of most biocides. At this concentration, bromopropanediol, Dantogard and thiabendazole did not prevent a rise in stem resistance to water flow, or solution absorbance. Aluminium sulphate up to 0.8 g l−1 was also ineffective in these respects. Stem respiration was inhibited by sodium benzoate, hydroxyquinoline citrate (HQC), Isocil and Physan-20. Principal component analysis on the rose data indicated that the best treatments were 0.05 g l−1 benzoate, cetylpyridinium chloride, Isocil and Physan-20, 0.05 and 0.2 g l−1 dichloroisocyanuric acid, and 0.2 and 0.8 g l−1 HQC. Tests with carnation and Alstroemeria indicated that HQC, Isocil and Physan most consistently promoted fresh weight increase and maintenance.

Biodeterioration of Stone in Tropical Environments: An Overview

Part 1 General aspects of biodegeneration in tropical regions: characteristics of tropical regions ecological aspects of biodeterioration identification of biodeteriogens and their activity phenomenology of biological alterations. Part 2 Biodeteriogens - characteristics and biodeterioration mechanisms: bacteria and bacterial biodeterioration fungi and fungal biodeterioration algae and algal biodeterioration lichens and lichenic biodeterioration biodeterioration by mosses and liverworts biodeterioration by higher plants. Part 3 Preventive and remedial methods: preventive methods remedial methods. Part 4 Selection of chemical treatments: some considerations in biocide selection biocide application - procedures and precautions chemical treatments used to control biodeteriogens. Part 5 Current research status and areas for further investigation: current research status areas for further investigation.

5206151 Rapid selection of biocide using a reduction oxidation indicator system: Linda Robertson assigned to Nalco Chemical Company

5206151 Rapid selection of biocide using a reduction oxidation indicator system: Linda Robertson assigned to Nalco Chemical Company