Triclosan and Its Alternatives in Antibacterial Soaps

Triclosan and its alternatives, especially chlorhexidine, modulate macrophage immune response with distinct modes of action

Since European regulators restricted the use of bacteriocidic triclosan (TCS), alternatives for TCS are emerging. Recently, TCS has been shown to reprogram immune metabolism, trigger the NLRP3 inflammasome, and subsequently the release of IL-1β in human macrophages, but data on substitutes is scarce. Hence, we aimed to examine the effects of TCS compared to its alternatives at the molecular level in human macrophages. LPS-stimulated THP-1 macrophages were exposed to TCS or its substitutes, including benzalkonium chloride, benzethonium chloride, chloroxylenol, chlorhexidine (CHX) and cetylpyridinium chloride, with the inhibitory concentration (IC10-value) of cell viability to decipher their mode of action. TCS induced the release of the pro-inflammatory cytokine TNF and high level of IL-1β, suggesting the activation of the NLRP3-inflammasome, which was confirmed by non-apparent IL-1β under the NLRP3-inhibitor MCC950 treatment d. While IL-6 release was reduced in all treatments, the alternative CHX completely abolished the release of all investigated cytokines. To unravel the underlying molecular mechanisms, we used untargeted LC-MS/MS-based proteomics. TCS and CHX showed the strongest cellular response at the protein and signalling pathway level, whereby pathways related to metabolism, translation, cellular stress and migration were mainly affected but to different proposed modes of action. TCS inhibited mitochondrial electron transfer and affected phagocytosis. In contrast, in CHX-treated cells, the translation was arrested due to stress conditions, resulting in the formation of stress granules. Mitochondrial (e.g. ATP5F1D, ATP5PB, UQCRQ) and ribosomal (e.g. RPL10, RPL35, RPS23) proteins were revealed as putative key drivers. Furthermore, we have demonstrated the formation of podosomes by CHX, potentially involved in ECM degradation. Our results exhibit modulation of the immune response in macrophages by TCS and its substitutes and illuminated underlying molecular effects. These results illustrate critical processes involved in the modulation of macrophages' immune response by TCS and its alternatives, providing information essential for hazard assessment.

Antimicrobial Resistance in the COVID-19 Landscape: Is There an Opportunity for Anti-Infective Antibodies and Antimicrobial Peptides?

Although COVID-19 has captured most of the public health attention, antimicrobial resistance (AMR) has not disappeared. To prevent the escape of resistant microorganisms in animals or environmental reservoirs a "one health approach" is desirable. In this context of COVID-19, AMR has probably been affected by the inappropriate or over-use of antibiotics. The increased use of antimicrobials and biocides for disinfection may have enhanced the prevalence of AMR. Antibiotics have been used empirically in patients with COVID-19 to avoid or prevent bacterial coinfection or superinfections. On the other hand, the measures to prevent the transmission of COVID-19 could have reduced the risk of the emergence of multidrug-resistant microorganisms. Since we do not currently have a sterilizing vaccine against SARS-CoV-2, the virus may still multiply in the organism and new mutations may occur. As a consequence, there is a risk of the appearance of new variants. Nature-derived anti-infective agents, such as antibodies and antimicrobial peptides (AMPs), are very promising in the fight against infectious diseases, because they are less likely to develop resistance, even though further investigation is still required.

Indirect consequences of coronavirus disease 2019: Skin lesions caused by the frequent hand sanitation and use of personal protective equipment and strategies for their prevention

The coronavirus disease 2019 (COVID‐19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) enforced the use of hand sanitation and of personal protective equipment, such as masks and visors, especially by health‐care professionals, but also by the general public. However, frequent hand sanitation and the prolonged and continuous use of personal protective equipment are responsible for constant frictional and pressure forces on skin causing lesions, the most reported being acne, facial itching, dryness, and rash. Thus, it is important to find measures to prevent skin lesions, in order to improve the quality of life of health‐care professionals and of the general public. This article gathers the current information regarding measures to prevent human to human transmission of COVID‐19, reviews the most common skin lesions caused by the use of hand sanitizers and different types of personal protective equipment, and the possible preventive measures that can be used on a daily basis to minimize the risk of developing skin‐related pathologies. Daily skin care routines and the incorporation of a dressing between the skin and the personal protective equipment to serve as a protective barrier are some of the applied measures. Moisturizers and dressings improve the skin's ability to respond to constant aggressions. Lastly, the need for additional studies to evaluate the lubrication properties of different types of dressings is discussed. The understanding of what kind of dressing is more suitable to prevent pressure injuries is crucial to promote healthy skin and wellbeing during pandemic times.

Human exposure and health risk assessment of an increasingly used antibacterial alternative in personal care products: Chloroxylenol

The ban of some antibacterial ingredients, such as triclosan (TCS) and triclocarban (TCC), in personal care products (PCPs) in some countries (but not in China) has resulted in the increasing use of antibacterial alternatives, such as chloroxylenol (PCMX). However, the underlying human health risks and environmental impacts of PCMX exposure are largely unknown. Thus, the distribution characteristics of PCMX in PCPs and susceptible populations and the major routes and health risks of human exposure to PCMX were investigated. The PCMX, TCS, and TCC concentrations in PCPs, urine, drinking water, and surface water were determined using high-performance liquid chromatograph system equipped with diode array detector or triple quadrupole mass spectrometer. Results showed that PCMX is widely used in antibacterial hand sanitizers and household disinfectants in China. The addition of PCMX as an antibacterial ingredient in PCPs showed an increasing trend. The geomean concentrations of urinary PCMX in children and pregnant women were 21.6 and 31.9 μg·L^-1, respectively, which were much higher than TCS and TCC. A considerable concentration of PCMX ranging from 1.62 to 9.57 μg·L^-1 was observed in the aquatic environment, suggesting a potential massive-use of PCMX by humans. Human PCMX exposure via drinking was negligible because the PCMX concentrations in drinking water were less than 2.00 ng·L^-1. During human simulation experiment, we found that dermal contact was the dominant route of human PCMX exposure, accounting for 92.1% of the urinary PCMX concentration. The estimated daily intake of PCMX in 9.68% of children and 5.66% of pregnant women was higher than the reference dose. However, the urinary 8-hydroxy-2'-deoxyguanosine concentrations remained stable despite the elevated PCMX concentrations, thereby suggesting that daily PCMX exposure may not cause oxidative DNA damage in humans. Nevertheless, the potential ecotoxicity and health risks induced by chronic PCMX exposure cannot be ignored because of its increasing use.

Rapid start-up of partial nitrification process using benzethonium chloride-a novel nitrite oxidation inhibitor

Benzethonium chloride (BZC) is an antibacterial compound with extensive applications in various anti-infective products. However, the feasibility of attaining partial nitrification of municipal wastewater using BZC has not been reported. In this work, BZC was used for the first time to attain partial nitrification. Batch experiments indicated nitrite oxidizing bacteria (NOB) was more vulnerable to BZC than ammonia oxidizing bacteria (AOB). When activated sludge was treated only once with 0.023 g BZC·(g MLSS)^-1 for 18 h, partial nitrification was attained at the 29th cycle with NAR of 97.46% and sustained 91 cycles in stability tests. Complimentary DNA sequencing analysis revealed the suppression of Nitrospira was the reason for partial nitrification. Oligotyping analysis indicated AOB could likely resist to BZC by both the species shifts and development of tolerance, while most NOB species could not adapt to BZC. This study revealed the feasibility of BZC as a novel NOB inhibitor.