Impact of benzalkonium chloride, benzethonium chloride and chloroxylenol on bacterial antimicrobial resistance

This review examined 3,655 articles on benzalkonium chloride (BKC), benzethonium chloride (BZT) and chloroxylenol (CHO) aiming to understand their impact on antimicrobial resistance. Following the application of inclusion/exclusion criteria only 230 articles were retained for analysis; 212 concerned BKC, with only 18 for CHO and BZT. 78% of studies used MIC to measure BKC efficacy. Very few studies defined the term “resistance” and 85% studies defined “resistance” as < 10-fold increase (40% as low as 2-fold) in MIC. Only a few in vitro studies reported on formulated products and when they did, products performed better. In vitro studies looking at the impact of BKC exposure on bacterial resistance used either a stepwise training protocol or exposure to constant BKC concentrations. In these BKC exposure resulted in elevated MIC or/and MBC, often associated with efflux, and at time, a change in antibiotic susceptibility profile. The clinical relevance of these findings was however neither reported nor addressed. Of note, several studies reported that bacterial strains with an elevated MIC or MBC remained susceptible to the in-use BKC concentration. BKC exposure was shown to reduce in bacterial diversity in complex microbial microcosms, although the clinical significance of such a change has not been established. The impact of BKC exposure on the dissemination of resistant genes (notably efflux) remains speculative, although it is manifest that clinical, veterinary and food isolates with elevated BKC MIC carried multiple efflux pump genes. The correlation between BKC usage and gene carriage, maintenance and dissemination has also not been established. The lack of clinical interpretation and significance in these studies does not allow to establish with certainty the role of BKC on AMR in practice. The limited literature and BZT and CHO do not allow to conclude that these will impact negatively on emerging bacterial resistance in practice

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

Background In this study we assessed the propensity of biocide exposure in the development of antimicrobial resistance in bacteria. Methods 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. Results 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. Conclusions 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

Are amine-only-containing products sporicidal?

Clostridium difficile infection is linked to significant morbidity and mortality. C. difficile (endo)spores can survive on surfaces in healthcare settings for long periods of time, which makes the elimination of these spores from surfaces important. Bacterial spores are notoriously resistant to chemical and physical processes [1,2] and, not surprisingly, they are used as biological indicators for many sterilization processes. Their resistance is intrinsic and linked to their structure, dehydration and the presence of small acid-soluble proteins in their core protecting them from external chemical and physical damage [2]

Energies and widths of atomic core-levels in liquid mercury

High-resolution measurements of the photoinduced X-ray emission of liquid mercury were performed, using a transmission DuMond-type crystal spectrometer for transitions above 11 keV and a reflection von Hamos-type crystal spectrometer for transitions below 11 keV. The target X-ray fluorescence was produced by irradiating the sample with the Bremsstrahlung from X-ray tubes. The energies and natural linewidths of 6 K-shell, 26 L-shell and 2 M-shell X-ray transitions were determined. Using a least-squares-fit method to solve the two sets of equations derived from the observed transition energies and transition widths the binding energies of the subshells K to M₅ and O₁ and the level widths of the subshells K to N₅ and O₁ could also be determined

Impact of standard test protocols on sporicidal efficacy

Background There has been an increase in the availability of commercial sporicidal formulations. Any comparison of sporicidal data from the literature is hampered by the number of different standard tests available and the use of diverse test conditions including bacterial strains and endospore preparation. Aim To evaluate the effect of sporicidal standard tests on the apparent activity of eight biocides against Clostridium difficile and Bacillus subtilis. Methods The activity of eight biocidal formulations including two oxidizing agents, two aldehydes, three didecyldimethylammonium chloride (DDAC) and amine formulations, and sodium hypochlorite were evaluated using four standard sporicidal tests (BS EN 14347, BS EN13704, ASTM E2197-11, and AOAC MB-15-03) against B. subtilis (ACTC 19659) and C. difficile (NCTC 11209) spores. Findings C. difficile spores were more susceptible to the sporicides than were B. subtilis spores, regardless of the method used. There were differences in sporicidal activity between methods at 5 min but not at 60 min exposure. DDAC and amine-based products were not sporicidal when neutralized appropriately. Neutralization validation was confirmed for these biocides using the reporting format described in the BS EN standard tests, although the raw data appear to indicate that neutralization failed. Conclusion The different methods, whether based on suspension or carrier tests, produced similar sporicidal inactivation data. This study suggests that detailed neutralization validation data should be reported to ensure that neutralization of active spores is effective. Failure to do so may lead to erroneous sporicidal claims

Best practice in healthcare environment decontamination

There is now strong evidence that surface contamination is linked to healthcare-associated infections (HCAIs). Cleaning and disinfection should be sufficient to decrease the microbial bioburden from surfaces in healthcare settings, and, overall, help in decreasing infections. It is, however, not necessarily the case. Evidence suggests that there is a link between educational interventions and a reduction in infections. To improve the overall efficacy and appropriate usage of disinfectants, manufacturers need to engage with the end users in providing clear claim information and product usage instructions. This review provides a clear analysis of the scientific evidence supporting the role of surfaces in HCAIs and the role of education in decreasing such infections. It also examines the debate opposing the use of cleaning versus disinfection in healthcare settings

Candida auris dry surface biofilm (DSB) for disinfectant efficacy testing

Candida auris is an emerging pathogen that needs to be controlled effectively due to its association with a high mortality rate. The presence of biofilms on dry surfaces has been shown to be widespread in healthcare settings. We produced a C. auris dry surface biofilm (DSB) on stainless steel surfaces following sequential hydration and desiccation cycles for 12 days. The ASTM2967-15 was used to measure the reduction in viability of 12 commercially wipe-based disinfectants and sodium hypochlorite (1000 ppm) against C. auris DSB. We also evaluated C. auris transferability and biofilm regrowth post-treatment. A peracetic acid (3500 ppm) product and two chlorine-based products (1000 ppm available chlorine) were successful in reducing C. auris viability and delaying DSB regrowth. However, 50% of the products tested failed to decrease C. auris viability, 58% failed to prevent its transferability, and 75% did not delay biofilm regrowth. Using three different parameters to measure product efficacy provided a practical evaluation of product effectiveness against C. auris DSB. Although log10 reduction in viability is traditionally measured, transferability is an important factor to consider from an infection control and prevention point of view as it allows for determination of whether the surface is safe to touch by patients and hospital staff post-treatmen

Emerging contaminants affect the microbiome of water systems: strategies for their mitigation

The presence of emerging contaminants (ECs) in the environment has been consistently recognized as a worldwide concern. ECs may be defined as chemicals or materials found in the environment at trace concentrations with potential, perceived, or real risk to the One Health trilogy (environment, human, and animal health). The main concern regarding pharmaceuticals and in particular antibiotics is the widespread dissemination of antimicrobial resistance. Nevertheless, non-antimicrobials also interact with microorganisms in both bulk phase and in biofilms. In fact, drugs not developed for antimicrobial chemotherapy can exert an antimicrobial action and, therefore, a selective pressure on microorganisms. This review aims to provide answers to questions typically ignored in epidemiological and environmental monitoring studies with a focus on water systems, particularly drinking water (DW): Do ECs exposure changes the behavior of environmental microorganisms? May non-antibiotic ECs affect tolerance to antimicrobials? Do ECs interfere with biofilm function? Are ECs-induced changes in microbial behavior of public health concern? Nowadays, the answers to these questions are still very limited. However, this study demonstrates that some ECs have significant effects in microbial behavior. The most studied ECs are pharmaceuticals, particularly antibiotics, carbamazepine and diclofenac. The pressure caused by antibiotic and other antimicrobial agents on the acquisition and spread of antibiotic resistance seems to be unquestionable. However, regarding the effects of ECs on the development and behavior of biofilms, the conclusions of different studies are still controversial. The dissimilar findings propose that standardized tests are needed for an accurate assessment on the effects of ECs in the microbiome of water systems. The variability of experimental conditions, combined with the presence of mixtures of ECs as well as the lack of information about the effects of non-pharmaceutical ECs constitute the main challenge to be overcome in order to improve ECs prioritization.This work was financially supported by project UIDB/EQU/00511/2020—Laboratory for Process Engineering, Environment, Biotechnology and Energy—LEPABE funded by national funds through FCT/MCTES (PIDDAC); Projects PTDC/BII-BTI/30219/2017–POCI- 01-0145-FEDER-030219, PTDC/ASP-PES/28397/2017–POCI-01-0145-FEDER-028397 and POCI-01-0247-FEDER-035234 funded by FEDER funds through COMPETE2020— Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES.info:eu-repo/semantics/publishedVersio