Antiseptics and disinfectants: activity, action, and resistance

VBNC induction and persistence of Listeria monocytogenes Scott A as a defence mechanism against free chlorine stress

Sodium hypochlorite (SH) belongs to the chlorine-releasing agents (CRAs) and is widely used as a disinfectant or a bleaching agent for sanitizing in the food processing environment and fresh-cut industry. In the present study, the potential induction of dormancy states, i.e. the VBNC state and persistence, in Listeria monocytogenes, Scott A strain, was evaluated after exposure to SH for 3 h at 20 °C. Our results showed that the concentration of free chlorine after cells (109.5 CFU/mL) resuspension into the working solution decreased down to 3.7 ppm (SD ± 0.4 ppm; pH 6.64 ± 0.1). To detect VBNC fractions we evaluated comparatively the results of plate counting with fluorescence microscopy, using 5(6)-carboxy-fluorescein diacetate (CFDA; metabolic activity) and propidium iodide (PI; death) staining. The resuscitation capacity of L. monocytogenes stressed single cells was monitored real-time on TSAYE at 37°C, using time-lapse microscopy. Thus, colony outgrowth kinetics were estimated and non-diving fractions were detected. Furthermore, variability in the division time per generation was examined. Our analyses showed that SH induces the VBNC state and persistence in L. monocytogenes. Phenotypic variants of "high" fitness, i.e. size colony variations (SCVs) were also detected in response to SH stress. L. monocytogenes cells presented a prolonged lag time after exposure to SH. This phenomenon is a defence mechanism that allows cells to tolerate stress and maximize population fitness. The investigation of the VBNC state is of high importance for the food industry, as the impacts of VBNC induction and single cell outgrowth heterogeneity can contribute to false-negative detection outcomes.

Improved pleiotropic antibacterial activity of Ag(I)-Thiolate coordination polymers via iodide encapsulation in multinuclear silver nano cages

Silver-based nanomaterials have attracted considerable attention due to their antimicrobial properties. In this study, two nano-AgI-cage-based coordination polymers, [Ag6(μ-StBu)6]n (University of South China Coordination Polymer USC-CP-2) and [Ag14(μ-StBu)12I2]n (USC-CP-3), were synthesized via the reaction of AgNO3 and 2-methyl-2-propanethiol (HStBu) with sodium ethylate as a non-toxic base in a water/ethanol mixed solvent, with and without iodide as a coligand. Structural analysis by single-crystal X-ray diffraction revealed that both polymers are one-dimensional Ag(I)-thiolate coordination polymers with distinct secondary building units: USC-CP-2 features Ag6 nano-cages stabilized by μ2-StBu ligands, while USC-CP-3 comprises nanochains formed by iodide-encapsulated Ag16-cages linked through edge-sharing. Antimicrobial studies against Escherichia coli demonstrated that USC-CP-3, featuring iodide-encapsulated Ag16-cages, exhibited superior antibacterial activity compared to the iodide-free Ag6-cages in USC-CP-2. Mechanistic studies, supported by ICP-MS, EPR, TEM, and SEM analyses, suggested that the synergistic bactericidal effects arise from the release of Ag(I) ions, hydroxyl radical generation, and the presence of iodide. This study highlights a rational design strategy for advanced antibacterial materials with potential applications in combating bacterial contamination.

Disinfectants and one health review: The role of reactive oxygen species in the bactericidal activity of chlorine against Salmonella

Salmonella are among the most common foodborne pathogens in humans, and they are associated with mild to severe diseases commonly referred to as salmonellosis. The genus resides in various animals' intestinal tracts, including humans. It is one of the most diverse genera of bacteria, including over 2500 serovars. Consumption of poultry products contaminated with Salmonella is a significant source of disease transmission in humans. Because of this food safety concern, the poultry industry and governments spend billions of dollars on Salmonella containment methods. However, a completely effective strategy is yet to be established. Chlorine has been commonly used as a disinfectant in the poultry industry. In humans, antibiotic therapy is the primary means for managing Salmonella infection. However, widespread use of both compounds at sub-inhibitory concentrations has allowed resistant strains to emerge and rapidly spread globally. Both antimicrobial compounds involve generating reactive oxygen species (ROS) as a bactericidal mechanism of action. However, ROS generation and its association with bacterial survival and growth inhibition have not been widely explored. Thus, a better understanding of ROS generation during antimicrobial treatments may help devise better Salmonella containment strategies.

DNA as a promising biomaterial for bone regeneration and potential mechanisms of action

DNA nanotechnology has created new possibilities for the use of DNA in tissue regeneration - an important advance for DNA use beyond its paradigmatic role as the hereditary biomacromolecule. Biomaterials containing synthetic or natural DNA have been proposed for several applications including drug and gene delivery, and more recently, as osteoconductive biomaterials. This review provides an in-depth discussion of studies that have used DNA-based materials for biomineralization and/or bone repair, with expansion on the topic of DNA hydrogels specifically, and the advantages they offer for advancing the field of bone regeneration. Four mechanisms of action for the osteoconductive capabilities of DNA-based materials are discussed, and a proposed model for degradation of these materials and its link to their osteoconductive properties is later presented. Finally, the review considers current limitations of DNA-based materials and summarizes important aspects that need to be addressed for future application of DNA nanotechnology in tissue repair. STATEMENT OF SIGNIFICANCE: Herein we summarize the developing field of DNA-based materials for biomineralization and bone repair, with a focus on DNA hydrogels. We first provide a comprehensive review of different forms of DNA-based materials described thus far which have been shown to enhance bone repair and mineralization (namely DNA coatings, DNA-containing pastes, DNA nanostructures and DNA hydrogels). Next, we describe four different mechanisms by which DNA-based materials could be exerting their osteogenic effect. Then, we propose a novel model that links DNA degradation and osteoconductivity. Lastly, we suggest possible research directions to enhance DNA-based materials for future clinical application. The suggested mechanisms and the proposed model can guide future research to better understand how DNA functions as a mineral- and bone-promoting molecule.

Emerging synergistic strategies for enhanced antibacterial sonodynamic therapy: Advances and prospects

Antibacterial therapy has been extensively applied in medical field to alleviate the severity and mortality of infection. However, it still exists some issues such as drug side effects, limited efficacy and bacterial resistance. Among the alternative therapies, antibacterial sonodynamic therapy (aSDT) has been explored as a promising approach to tackle those crises. It is meaningful to investigate superior strategy to augment the therapeutic efficacy of aSDT. This review summarizes the potential aSDT-based antibacterial mechanisms and comprehensively discusses the prevailing synergistic strategies, such as nanomaterials-based aSDT antibacterial strategy, aSDT + strategy with physical, chemical and biological methods. Moreover, we also reviewed the medical applications of aSDT strategies. Finally, the perspectives on the current challenges that need be resolved in aSDT are proposed. We expect that this review could provide robust support to expedite the clinical applications of aSDT.

Biocides as drivers of antibiotic resistance: A critical review of environmental implications and public health risks

The widespread and indiscriminate use of biocides poses significant threats to global health, socioeconomic development, and environmental sustainability by accelerating antibiotic resistance. Bacterial resistance development is highly complex and influenced significantly by environmental factors. Increased biocide usage in households, agriculture, livestock farming, industrial settings, and hospitals produces persistent chemical residues that pollute soil and aquatic environments. Such contaminants contribute to the selection and proliferation of resistant bacteria and antimicrobial resistance genes (ARGs), facilitating their dissemination among humans, animals, and ecosystems. In this review, we conduct a critical assessment of four significant issues pertaining to this topic. Specifically, (i) the role of biocides in exerting selective pressure within the environmental resistome, thereby promoting the proliferation of resistant microbial populations and contributing to the global spread of antimicrobial resistance genes (ARGs); (ii) the role of biocides in triggering transient phenotypic adaptations in bacteria, including efflux pump overexpression, membrane alterations, and reduced porin expression, which often result in cross-resistance to multiple antibiotics; (iii) the capacity of biocides to disrupt bacteria and make the genetic content accessible, releasing DNA into the environment that remains intact under certain conditions, facilitating horizontal gene transfer and the spread of resistance determinants; (iv) the capacity of biocides to disrupt bacterial cells, releasing intact DNA into the environment and enhancing horizontal gene transfer of resistance determinants; and (iv) the selective interactions between biocides and bacterial biofilms in the environment, strengthening biofilm cohesion, inducing resistance mechanisms, and creating reservoirs for resistant microorganisms and ARG dissemination. Collectively, this review highlights the critical environmental and public health implications of biocide use, emphasizing an urgent need for strategic interventions to mitigate their role in antibiotic resistance proliferation.

Impact of malodour on health-related quality of life of patients with chronic wounds due to volatile organic compounds

Chronic wounds significantly impact health-related quality of life (HRQoL). Unpleasant wound odour, caused by bacterial colonisation and necrotic processes, is a distressing symptom. Its exact composition is not well understood, but it could be the basis for a personalised odour avoidance strategy. Therefore, this feasibility study explored 92 wounds from 66 patients with the focus on wound odour, bacterial burden and their impact on health related-quality of life (HRQoL). Volatile organic compounds (VOCs) responsible for wound odours were detected at the molecular level, using gas chromatography-mass spectrometry and -ion mobility spectrometry and correlated to the HRQoL. In patients analysed (average age 69 ± 13 years, wound persistence 24.31 ± 70.8 months) 135 pathogens were identified by swabbing including 19% Staphylococcus aureus, 15% Pseudomonas aeruginosa and 35% Enterobacteria. The specific questionnaire 'Wound-QoL-14' showed a non-significant difference in HRQoL in patients with wound odour (2.1 ± 1.0 vs. 1.8 ± 1.0). The latter also had the highest number of VOC detections. The most frequently detected, relevant VOCs from prokaryotic sources were dimethyl-disulphide and diacetyl-(2,3-butanedione). Furthermore, potential biomarkers for specific pathogens were identified, including dimethyl-trisulphide for P. aeruginosa and indole for Escherichia coli. The most prevalent substance groups were ketones and alcohols. In conclusion, the malodour of chronic wounds is caused by a mixture of the intrinsic odour of bacterial products and necrosis. This exploratory study, which combines the analysis of decoded VOCs and the olfactory assessment of odour, could be a novel, targeted approach for identifying potential 'anti-wound odour therapies' that will significantly benefit the HRQoL of patients with malodourous tumour wounds, in particular.

Large-scale phenotypic and genomic analysis of Listeria monocytogenes reveals diversity in the sensitivity to quaternary ammonium compounds but not to peracetic acid

Listeria monocytogenes presents a significant concern for the food industry due to its ability to persist in the food processing environment. One of the factors contributing to its persistence is decreased sensitivity to disinfectants. Our objective was to assess the diversity of L. monocytogenes sensitivity to food industry disinfectants by testing the response of 1,671 L. monocytogenes isolates to quaternary ammonium compounds (QACs) and 414 isolates to peracetic acid (PAA) using broth microdilution and growth curve analysis assays, respectively, and to categorize the isolates into sensitive and tolerant. A high phenotype-genotype concordance (95%) regarding tolerance to QACs was obtained by screening the genomes for the presence of QAC tolerance-associated genes bcrABC, emrE, emrC, and qacH. Based on this high concordance, we assessed the QAC genes' dissemination among publicly available L. monocytogenes genomes (n = 39,196). Overall, QAC genes were found in 23% and 28% of the L. monocytogenes collection in this study and in the global data set, respectively. bcrABC and qacH were the most prevalent genes, with bcrABC being the most detected QAC gene in the USA, while qacH dominated in Europe. No significant differences (P > 0.05) in the PAA tolerance were detected among isolates belonging to different lineages, serogroups, clonal complexes, or isolation sources, highlighting limited variation in the L. monocytogenes sensitivity to this disinfectant. The present work represents the largest testing of L. monocytogenes sensitivity to important food industry disinfectants at the phenotypic and genomic level, revealing diversity in the tolerance to QACs while all isolates showed similar sensitivity to PAA.

IMPORTANCE

Contamination of Listeria monocytogenes within food processing environments is of great concern to the food industry due to challenges in eradicating the isolates once they become established and persistent in the environment. Genetic markers associated with increased tolerance to certain disinfectants have been identified, which alongside other biotic and abiotic factors can favor the persistence of L. monocytogenes in the food production environment. By employing a comprehensive large-scale phenotypic testing and genomic analysis, this study significantly enhances the understanding of the L. monocytogenes tolerance to quaternary ammonium compounds (QACs) and the genetic determinants associated with the increased tolerance. We provide a global overview of the QAC genes prevalence among public L. monocytogenes sequences and their distribution among clonal complexes, isolation sources, and geographical locations. Additionally, our comprehensive screening of the peracetic acid (PAA) sensitivity shows that this disinfectant can be used in the food industry as the lack of variation in sensitivity indicates reliable effect and no apparent possibility for the emergence of tolerance.

Immunomodulatory effects of alexidine dihydrochloride on mammalian macrophages through the modulation of the JNK pathway

A plethora of the cancer drugs with high therapeutic potential cannot pass the clinical trials because of their immunotoxic activities. In this study, we tested the immunomodulatory and immunostimulatory effects of the anticancer agent alexidine dihydrochloride on J774.2 macrophage cell lines in vitro. The production levels of the pro-inflammatory cytokines (TNF-α, IL-6, GM-CSF, IL-12p40) were measured and compared by ELISA method. The activated (phosphorylated) JNK protein levels were measured by flow cytometer and the possible related intracellular signaling pathway was examined in this way. According to our results, alexidine dihydrochloride has an anti-inflammatory effect on the LPS-stimulated macrophage cell lines, as evidenced by reduced cytokine production compared to controls. Furthermore, its intracellular mechanism of action was found to be mediated partially through JNK signaling pathways. These findings suggest that alexidine dihydrochloride, while being an effective anticancer agent, may also modulate immune responses by dampening excessive inflammation. In this study, determining the anti-inflammatory effect of alexidine dihydrochloride on the immune system will seriously shed light on the role of this anticancer agent in future clinical studies and will provide a serious basis. In summary, the effects of the most drug-active ingredients on the inflammatory response in immune system cells have not been fully tested, and this creates the problem of many drugs failing in clinical studies or lack of knowledge on their side effects. Our study aimed to determine the effect of alexidine dihydrochloride, used as an anticancer agent, on the inflammatory response in J774.2 macrophage cell lines. Future studies with more immune system cells and a wider analysis of the intracellular signaling pathways will be informative about the immunotoxicity of the drug molecule. Future research involving a broader range of immune cell types and a more comprehensive analysis of intracellular signaling pathways will help clarify the immunotoxicity profile of this anticancer agent.

Chemical Synthetic Lethality Screens Identify Selective Drug Combinations against Pseudomonas aeruginosa

The emergence of bacterial ESKAPE pathogens presents a formidable challenge to global health, necessitating the development of innovative strategies for antibiotic discovery. Here, we leverage chemical synthetic lethality to locate therapeutic combinations of small molecules against multidrug-resistant Pseudomonas aeruginosa. Using a transposon screen, we identify PyrD as a target for sensitizing P. aeruginosa to subinhibitory doses of ceftazidime. High-throughput inhibitor screens identify two PyrD inhibitors, nordihydroguaiaretic acid (NDGA) and chlorhexidine (CHX), each of which does not significantly affect growth in isolation but exhibits chemical synthetic lethality when combined with low-dose ceftazidime. Downstream biochemical studies elucidate the mechanism of inhibition by NDGA and CHX. Remarkably, this combination is toxic to P. aeruginosa but leaves commensal bacteria, which are more susceptible to antibiotics, unscathed. Aside from advancing drug combinations that may be explored further in the future, our results offer a new approach for devising potent and specific drug combinations against recalcitrant pathogens.

Degradation and Deactivation of Intracellular Bacterial Antibiotic Resistance Genes by Commonly Used Healthcare and Personal Care Disinfectants

This work investigated efficacies of commonly used healthcare and personal care disinfectants, including glutaraldehyde, chlorhexidine, ethanol, povidone-iodine, benzalkonium chloride, phenol, free chlorine, hydrogen peroxide (H2O2), and 254 nm UV light, in degrading (as measured by qPCR analyses of ∼1000 bp amplicon loss) and deactivating (as measured by transforming activity loss) bacterial antibiotic resistance genes (ARGs) during inactivation of antibiotic-resistant bacteria (ARB) on inanimate surfaces or in aqueous suspension. Intracellular ARGs (iARGs) blt, mecA, and ampC, within vegetative cells of Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa, respectively, were treated on PTFE and/or stainless-steel surfaces or in aqueous phosphate buffer (PB; H2O2 only), to simulate potential healthcare and personal care cleaning applications under representative disinfectant exposure conditions. No chemical disinfectant yielded more than limited (≤1.9log10) iARG degradation/deactivation under the conditions investigated, even when ARB cells were extensively inactivated (at levels from 3.1log10 to ≥6log10). In contrast, UV irradiation yielded up to ∼2.8-3.2log10 iARG degradation/deactivation at corresponding ARB inactivation levels up to ∼4log10 in the case of the blt gene within B. subtilis cells on PTFE surfaces, though levels of iARG degradation/deactivation and ARB inactivation were generally lower than expected based on prior aqueous-phase results, likely due to light-shielding effects at the typical ∼108-109 CFU/mL cell inoculum densities used for surface disinfection tests. During exposure to H2O2 in PB, iARG deactivation and ARB inactivation reached up to 1.7log10 and >3.5log10, respectively, while iARG degradation was minimal (≤0.2log10); this appears to be driven by DNA-strand fragmentation (as observed by pulsed-field gel electrophoresis analysis) likely resulting from reaction with endogenous HO• (or Fe(IV)) generated via intracellular iron-catalyzed H2O2 decomposition. While all investigated disinfectants were able to effectively inactivate ARB cells themselves, these results demonstrate that most are ineffective in simultaneously degrading and deactivating iARGs, highlighting the potential benefits of employing disinfectants such as 254 nm UV light, that selectively target bacterial DNA, to improve mitigation of antibiotic resistance dissemination.

Antifungal susceptibility and clinical efficacy of chlorhexidine combined with topical ophthalmic medications against Fusarium species isolated from corneal samples

Objective

This study investigated the susceptibility of various Fusarium fungi to five topical antifungal agents: natamycin, voriconazole, chlorhexidine, natamycin combined with chlorhexidine, and voriconazole combined with chlorhexidine. And to explore the clinical feasibility of combination therapy in the treatment of corneal infections caused by F. solani, with the goal of optimizing the treatment regimen for fungal keratitis.

Methods

A total of 194 strains of Fusarium were isolated from the corneas between 2013 and 2024 and identified to the species level using mass spectrometry. The MICs was determined using a commercial microdilution plate to assess the in vitro activity of the drugs used alone and in combination (natamycin/chlorhexidine, voriconazole/chlorhexidine). Additionally, the clinical efficacy was prospectively observed in 5 patients with corneal infections caused by F. solani. The treatment regimens included 5% natamycin combined with 0.04% chlorhexidine, chlorhexidine used alone, or natamycin used alone, with follow-up lasting up to 90 days.

Results

F. solani species complex (FSSC, 46.91%) and the F. fujikuroi species complex (FFSC, 45.88%) were the predominant isolates, with a geographical distribution concentrated in Northern China. The MICs for natamycin in FSSC and FFSC were both 2-8 μg /mL, respectively. The MICs for FSSC and FFSC respectively ranged from 0.25-16 and 1-8 μg/mL for voriconazole and 2 to > 16 μg/mL and 1 to > 16 μg/mL for chlorhexidine. The MICs of natamycin were not significantly different between FSSC and FFSC. However, voriconazole, chlorhexidine, natamycin combined with chlorhexidine, and voriconazole combined with chlorhexidine had significantly higher MICs for FSSC compared with FFSC. Compared with voriconazole, voriconazole combined with chlorhexidine exhibited enhancement of antifungal activity against 100% of tested Fusarium strains. Compared with natamycin, enhancement of antifungal activity of natamycin combined with chlorhexidine was 81.4% for all Fusarium spp., and the activity were significantly lower for F. solani (65.9%) than for non-F. solani species (93.6%). Among the 5 patients, 3 patients received treatment with natamycin combined with chlorhexidine, resulting in clinical cure in 2 patients (in 1-1.5 months), while 1 patient required a corneal transplant due to delayed treatment. One patient treated with natamycin alone and one treated with chlorhexidine alone both achieved clinical cure (in 2-3 months).

Conclusion

Natamycin combined with chlorhexidine and voriconazole combined with chlorhexidine exhibited enhancement of antifungal activity against Fusarium spp. during in vitro sensitivity tests. The findings of this study provide valuable guidance for establishing the epidemiological cutoff and clinical MIC values for Fusarium spp. This study paves the way for future multicenter studies on the treatment of FK with natamycin and chlorhexidine.

Polyhexamethylene guanidine-phosphate enhances pro-coagulant activity of human erythrocytes and venous thrombosis in rats through phosphatidylserine externalization

Polyhexamethylene guanidine-phosphate (PHMG-p) is a main compound used as a humidifier disinfectant, but the systemic health effects of PHMG-p still need to be explored. The circulatory and blood system is the organ that comes into contact with compounds absorbed into the body after inhalation exposure, resulting in various health problems, including cardiovascular diseases. This study examined the impact of PHMG-p on erythrocytes (red blood cells; RBCs), which are essential for sustaining circulatory health and are directly associated with thrombotic risks. We demonstrated that PHMG-p could enhance the thrombotic risk by promoting pro-coagulant activity and reducing erythrocyte deformability. In PHMG-p-exposed erythrocytes, phosphatidylserine externalization in the outer membrane and microvesicle generation were significantly increased under sub-hemolytic conditions, along with the morphological alterations in the erythrocytes. Exposure to PHMG-p induced erythrocyte phosphatidylserine externalization, leading to enhanced pro-coagulant activity, which was characterized by increased adhesion to vascular endothelial cells, elevated thrombin generation, and decreased deformability. Notably, calcium chelation effectively inhibited PS externalization and thrombin generation, highlighting the pivotal role of calcium influx in PHMG-p-induced thrombogenic alterations. Moreover, intratracheal instillation of PHMG-p promoted phosphatidylserine externalization and thrombin generation in rat erythrocytes, leading to a significant increase in thrombus formation, thereby corroborating the link between in vitro findings and the increased thrombotic risk observed in vivo. These findings suggest that PHMG-p may increase pro-thrombotic risk by promoting RBC pro-coagulant activity through calcium influx-driven PS externalization.

Resorcinol-based Bolaamphiphilic Quaternary Ammonium Compounds

Quaternary ammonium compounds (QACs) play crucial disinfectant roles in healthcare, industry, and domestic settings. Most commercially utilized QACs like benzalkonium chloride have a common architectural theme, leading to a rise in bacterial resistance and urgent need for novel structural classes. Some potent QACs such as chlorhexidine (CHX) and octenidine (OCT) feature a bolaamphiphilic architecture, comprised of two cationic centers at the molecular periphery and a non-polar region connecting them; these compounds show promise to elude bacterial resistance mechanisms. Inspired by such structures, we synthesized a series of 43 biscationic amphiphilic compounds focused on a resorcinol core, featuring flexibility of linker lengths, alkyl tails, and relative substituent positioning, to study their structure activity relationships (SARs). Antibacterial activity evaluation against a panel of gram-positive and gram-negative strains, including ESKAPE pathogens (A. baumannii, P. aeruginosa), were encouraging, with minimum inhibitory concentrations (MICs) of 0.5-4 μM against all tested strains for select compounds. Ten prepared compounds bearing either 17 or 18 total side chain carbons demonstrated uniformly strong antibacterial activity against P. aeruginosa (MIC 4-16 μM) and 6 other strains (MIC ≤4 μM), irrespective of cationic spacing. These findings promise to further extend the application of bolaamphiphilic QACs as a novel class of disinfectants.

Antibacterial compounds against non-growing and intracellular bacteria

Slow- and non-growing bacterial populations, along with intracellular pathogens, often evade standard antibacterial treatments and are linked to persistent and recurrent infections. This necessitates the development of therapies specifically targeting nonproliferating bacteria. To identify compounds active against non-growing uropathogenic Escherichia coli (UPEC) we performed a drug-repurposing screen of 6454 approved drugs and drug candidates. Using dilution-regrowth assays, we identified 39 compounds that either kill non-growing UPEC or delay its regrowth post-treatment. The hits include fluoroquinolones, macrolides, rifamycins, biguanide disinfectants, a pleuromutilin, and anti-cancer agents. Twenty-nine of the hits have not previously been recognized as active against non-growing bacteria. The hits were further tested against non-growing Pseudomonas aeruginosa and Staphylococcus aureus. Ten compounds - solithromycin, rifabutin, mitomycin C, and seven fluoroquinolones-have strong bactericidal activity against non-growing P. aeruginosa, killing >4 log10 of bacteria at 2.5 µM. Solithromycin, valnemulin, evofosfamide, and satraplatin are unique in their ability to selectively target non-growing bacteria, exhibiting poor efficacy against growing bacteria. Finally, 31 hit compounds inhibit the growth of intracellular Shigella flexneri in a human enterocyte infection model, indicating their ability to permeate the cytoplasm of host cells. The identified compounds hold potential for treating persistent infections, warranting further comparative studies with current standard-of-care antibiotics.

In Situ-Gelling Antimicrobial Poly(oligoethylene glycol methacrylate)-Based Hydrogels Integrating Bound Quaternary Ammonia Compounds and Antibiotic Functionalities for Effective Infected Wound Healing

In situ-gelling antibacterial hydrogels are reported in which two antibacterial entities (quaternary ammonium (QA) groups and the antibiotic ciprofloxacin (CIP)) are tethered to a single precursor based on the anti-fouling polymer poly(oligoethylene glycol methacrylate) (POEGMA). Synergism between the QA and CIP tethers is demonstrated to enable broad-spectrum killing and/or disinfection of both gram-positive and gram-negative bacteria both in vitro and in vivo while also supporting improved functional recovery of uninjured skin morphology. Coupled with the suitable mechanics, swelling capacity, and stability of the gels, the multi-mechanism antibacterial properties of the hydrogels offer promise for treating or preventing infections of burn wounds.

In-Vitro Determination of Minimum Inhibitory Concentration (MIC) and Contact Time of Povidone-Iodine against Staphylococcus aureus and Klebsiella aerogenes Using Micro Suspension Test, Colorimetric Resazurin Microplate Assay, and Dey Engley Neutralizer Assay

Background and Objective

The human nasal passages host major human pathogens. Recent research suggests that the microbial communities inhabiting the epithelial surfaces of the nasal passages play a key factor in maintaining a healthy microenvironment by affecting both resistance to pathogens and immunological responses. Colonization of the nasal cavity by different pathogens such as Staphylococcus aureus and Klebsiella aerogenes, is associated with a higher postoperative infection morbidity. Povidone-iodine (PVP-I) as an antiseptic has been proven to display high antibacterial, antiviral, and antifungal properties even at low concentrations, and was shown to be effective in the control of infections to limit their impact and spread. It can be used as a topical antiseptic for skin decontamination and wound management, as a nasal spray, or as a gargle. There are different methods in testing the efficacy of potential antimicrobial suspensions. This study aimed to determine the concentration of PVP-I that is most effective in nasal decolonization using microsuspension test and colorimetric minimum inhibitory concentration (MIC) determination assays, resazurin microtiter assay (REMA), and Dey-Engley (D/E) neutralizer assay. The findings of this study will contribute to knowledge regarding the intended use of PVP-I in microbial control, particularly in bacterial infections.

Methods

Several dilutions (2.0%, 1.0%, 0.5%, 0.25%, 0.1% and 0.09%) of commercially bought 10% (10 mg per 100 ml) povidone-iodine were prepared and tested against a standardized inoculum (1x105) of Staphylococcus aureus and Klebsiella aerogenes at different contact times (5 seconds, 10 seconds, 30 seconds, 1 minute, and 5 minutes). Microdilution suspension test was performed to determine the log reduction per variable, while REMA and D/E neutralizer assay were used to determine the MIC. A value of greater than or equal to 5 log reduction was considered effective for microdilution suspension test. Estimates of agreement statistics were used to interpret the results of the assay in which the overall percent agreement (OPA), positive percent agreement (PPA), negative percent agreement (NPA), and Cohen's kappa statistics were calculated.

Results

Povidone-iodine concentration of 0.25% exhibited ≥5 log reduction against K. aerogenes at the minimum contact time of 5 seconds. On the other hand, a slightly higher PVP-I concentration was required to achieve ≥5 log reduction for S. aureus at 0.5% concentration and a minimum contact time of 1 minute. There was an observed concordance of the results of REMA and D/E neutralizer as MIC colorimetric indicators, which yielded an overall test percent agreement of 90.30% (95% CI: 84.73-94.36), and a strong level of agreement (Κ = 0.8, p<0.0001). A lower overall percent agreement for both REMA and D/E neutralizer versus the microsuspension test was observed at 79.17% (Κ = 0.57, p<0.0001) and 78.18% (Κ = 0.55, p<0.0001), respectively.

Conclusion

Low povidone-iodine concentrations (i.e., 0.5% against S. aureus and 0.25% against K. aerogenes) were observed to have bactericidal activity of at least 5 log reduction as rapid as the minimum contact time of 5 seconds. Furthermore, D/E and REMA, as colorimetric indicators, had comparable performance (OPA = 90.30%; Κ = 0.8, p<0.0001) suggesting that both REMA and D/E neutralizer assay may detect the same range of minimum inhibitory concentration for the organisms and disinfectant tested in this study.

Comparing In Vitro Virucidal Efficacy of Commercially Available Mouthwashes Against Native High-Risk Human Papillomavirus Types 16 and 18

The rising incidence of oropharyngeal cancer caused by high-risk Human Papillomavirus (HPV) type 16 and HPV18 in the U.S and other developed countries is an important public health issue. This has been attributed to changes in sexual behavior, including the practice of oral sex, which may expose individuals to increased risk of acquiring oral HPV infection. The incidence of oral HPV infections highlights the role of the oral cavity as an important anatomical site in the acquisition and transmission of high-risk HPVs. Generally, the use of mouthwash/oral rinses have focused on targeting the oral bacteriome, and could additionally be formulated for managing the oral virome. Here, we examined virucidal properties of common over-the-counter antibacterial mouthwash products against native HPV16 and HPV18 virion in vitro, and downstream modification of virus infectivity. We tested oral rinses containing essential oils/alcohol, hydrogen peroxide, and cetylpyridinium chloride. Our results demonstrated greater than 90% efficacy against HPV16 inactivation, but comparatively with less efficacy against HPV18. Overall, hydrogen peroxide containing oral rinses demonstrated the best efficacy against both high-risk types, albeit with lower efficacy against HPV18. Prophylactic virucidal oral rinses targeted towards high-risk HPVs could be beneficial in reducing incidental oral HPV load, prevalence, and persistent infections.

Antiviral activity of contact lens care solutions and rub-and-rinse regimen against adenovirus

SIGNIFICANCE

Although human adenoviruses are the leading cause of acute viral conjunctivitis, there is a lack of data surrounding the efficacy of contact lens care products against these viruses.

PURPOSE

This study investigates the antiviral activity of several commercially available contact lens care solutions against human adenovirus type 5 (Ad5).

METHODS

Six contact lens care solutions (Biotrue, Boston Simplus, OPTI-FREE Puremoist, Clear Care, cleadew, and cleadew GP) were investigated. Quantitative suspensions tests were conducted on Ad5 solutions after interaction with the different contact lens care solutions for 4 or 6 hours. For the hydrogen peroxide solution (Clear Care), interaction times of 0, 2, 4, and 6 hours prior to neutralization were also investigated. Finally, the impact of rubbing and rinsing of Ad5 contaminated contact lenses with the solutions was studied.

RESULTS

Solutions based on povidone-iodine demonstrated a more than 3-log reduction in virus after 4 and 6 hours of incubation. In contrast, hydrogen peroxide only demonstrated a 0.52-log reduction after 6 hours of incubation. Increasing the contact time with hydrogen peroxide increased Ad5 inactivation, with a 2.18-log reduction after 6 hours of incubation with the solution prior to neutralization. Nonoxidative systems did not demonstrate a significant log reduction after 4 hours of incubation. However, rubbing and rinsing of contact lenses using the nonoxidative systems reduced the virus counts from contaminated contact lenses to below the limit of quantification.

CONCLUSIONS

Povidone-iodine solutions have a significant effect on reducing the viability of Ad5. Hydrogen peroxide care solutions are effective only if unneutralized contact time is increased. Nonoxidative systems can be effective in combating contaminated lenses only with the addition of a rub-and-rinse step.

Efficacy of 0.2% povidone-iodine and 0.1% polyhexamethylene biguanide as preoperative antiseptics in equine ophthalmic procedures

OBJECTIVE

This retrospective study evaluates the efficacy of povidone-iodine (PI) and polyhexamethylene biguanide (PHMB) as preoperative antiseptics in equine ophthalmic procedures.

ANIMALS STUDIED

Horses that underwent routine ophthalmic surgery and procedures.

PROCEDURES

Data were collected retrospectively from the medical records of equine patients undergoing ophthalmic procedures. Inclusion criteria were sampling for aerobic microbial culture at three different time points (T0: pre-irrigation, T1: post-irrigation, and T2: postoperatively) and T0 showing bacterial growth. Microbiological outcomes were assessed semi-quantitatively by creating a scoring system to describe the bacterial load. Furthermore, the species detected were evaluated. Poisson regression analysis was performed to evaluate the efficacy of the disinfectants.

RESULTS

Eighty eyes (75 horses) met the inclusion criteria, with 36 cases being aseptically prepared with PI and 44 with PHMB. Both antiseptics significantly reduced the bacterial load and number of bacterial species (p < .001) between time points T0 and T1, and T0 and T2. PHMB showed a reduction in the bacterial load by 64% (CI: 51%-73%) whereas PI reduced it by 48% (CI: 36%-58%) between time points T0 and T1. The reduction in the number of bacterial species between time points T0 to T1 was significantly greater in the PHMB group (85%, CI: 70%-93%), compared to PI (47%, CI: 26%-62%).

CONCLUSION

Both PHMB and PI reduced the bacterial load and number of species on the ocular surface and eyelids significantly, with 0.1% PHMB being superior to 0.2% PI. Therefore, PHMB can be considered as a good alternative in preoperative antisepsis in equine ophthalmic procedures.

Cytotoxicity and Antibacterial Activity of Protonated Diallylammonium Polymers: Influence of End Groups and Molecular Weight

A series of antimicrobial protonated diallylammonium polymers, poly(diallylammonium trifluoroacetate) (PDAATFA), were synthesized by classical polymerization, using an especially elaborated method for preparation of polymers with low molecular weight (MW), and by RAFT polymerization, with different end groups in a range of MW values of (8-43) × 103 g∙mol-1. Cytotoxicity relative to eukaryotic cells (epithelioid lines A-549 and MA-104) and bactericidal activity of the polymers (relative to Pseudomonas aeruginosa and Staphylococcus aureus) are investigated. The effect of the end groups and MW on toxicity and bactericidal activity is shown. Dependence of the activity and, most of all, cytotoxicity on MW is preserved even at a small difference in MW values in the MW range of (18-40) × 103 g·mol-1. A clear dependence of the studied properties on the nature of the terminal group is revealed. Sulfate -O-S(=O)2-O¯ end group has a noticeable effect on the bactericidal efficiency and smaller influence on toxicity, while dithiocarbonyl end group -S-C(=S)-O-CH2-CH3 has a significant effect on efficiency and especially toxicity, drastically increasing the latter. Overall, based on the results obtained, polymers PDAATFA of low MW are considered promising antimicrobial agents for the creation of new transdermal drugs.

Endotoxin-Retentive Filters for the Online Preparation of Ultrapure Dialysis Fluid and Non-Pyrogenic Substitution Fluid: A Critical Review and Reference Guide

Poor water treatments and concentrates to prepare dialysis fluids favor bacterial growth-producing pyrogens (e.g., endotoxins) that may cross hemodialysis, particularly high-flux, membranes. This puts hemodialysis patients at risk of acute bacteremia, pyrogenic reactions, long-term complications, loss of residual renal function, and poor nutritional status. Consequently, regulatory bodies worldwide recommend using ultrapure dialysis fluid for routine hemodialysis. Requests are also growing for the online production of sterile non-pyrogenic substitution fluid from ultrapure dialysis fluid. This way, large volumes of infusion solution may be safely and economically produced, enabling more end-stage kidney disease patients to benefit from the greater capacity of hemodiafiltration to remove toxins than purely diffusive hemodialysis treatment. Ultrapure dialysis and substitution fluids are often produced upstream from hemodialyzers by online filtration of standard dialysis fluid through cascades of bacteria- and endotoxin-retentive filters (ETRFs). Commercial ETRFs differ for membranes, operation, performance, duration and maintenance protocols, connection to a dialysis machine, disinfection procedures, and replacement schedule. Although suboptimal ETRF choice may increase treatment costs, the difficulty in gathering comparative information on commercial ETRFs complicates their selection. To aid dialysis centers in selecting the most convenient and suitable ETRF for their needs, herein, relevant characteristics of commercial ETRFs are reported and critically reviewed for a quick yet effective comparison.

Surgical Site Preparation Using Alcohol with Chlorhexidine Compared with Povidone Iodine with Chlorhexidine Results in Similar Rate of Infection After Primary Total Joint Arthroplasty

Background: Periprosthetic joint infection (PJI) is a devastating complication after total joint arthroplasty. A skin antiseptic solution is used to reduce the bacterial count and prevent PJI. There is no consensus in the literature on the application of antiseptic solutions. This study aims to compare the rate of infection between patients who received alcohol wash with Chloraprep to those who received povidone iodine wash with Chloraprep. Methods: A total of 607 patients who underwent total hip arthroplasty (THA) and total knee arthroplasty (TKA) at a single institution between January 2009 and July 2023 were reviewed. Perioperative variables were collected. The infection rate was used as a primary outcome. An odds ratio was calculated to compare infection and complication rates between the groups. Results: For patients who underwent THA, no difference in the rate of complications (alcohol wash: n = 6, 4.5%; povidone wash: n = 5, 3.6%; OR: 0.796; 95% CI: 0.237-2.673) or infection (alcohol wash: n = 1, 0.7%; povidone wash: n = 2, 1.4%; OR: 1.942; 95% CI: 0.174-21.667) was found. No difference in the rate of complications (alcohol wash: n = 3, 1.9%; povidone wash: n = 2, 1.2%; OR: 0.635; 95% CI: 0.105-3.849) or infection (alcohol wash: n = 0; povidone wash: n = 1, 0.6%; OR: 0.994; 95% CI: 0.983-1.006) was found in patients who underwent TKA. Conclusions: Surgical site preparation using alcohol wash with chlorhexidine offers similar short-term benefits in preventing postoperative infection to a povidone iodine wash with chlorhexidine in primary total joint arthroplasty. The use of alcohol wash and chlorhexidine is effective, while reducing the preparation time.

Photoinactivation of sulfate-reducing bacteria using 1,9-dimethyl-methylene blue - DMMB and laser light

Annually, the oil and gas industry faces equipment losses and product quality degradation due to the presence of sulfate-reducing bacteria (SRB). Given the negative impact of SRB, this study evaluates the use of photoinactivation (PI) with zinc chloride double salt of 1,9-Dimethyl-Methylene Blue (DMMB) as a photosensitizer (PS) in varying concentrations and combined with Laser light at different exposures in an SRB consortium. For culture growth, a modified Postgate C medium (without ferrous sulfate) was used, and cell quantification was performed on 100 μL aliquots of the consortium, read on a spectrophotometer (λ600 nm) in an oxygen- and light-free environment at room temperature. Statistical analyses included two-way ANOVA and ANOVA with interaction to separately and jointly evaluate the effects of PS and light in PI. Results indicated microbial activity in all groups, with an antimicrobial inhibition rate exceeding 50 % (p < 0.05) for concentrations above 1.5 μg/mL of DMMB. PI efficacy significantly depended on DMMB concentration and light density, achieving a 70.58 % (55.73-70.58, with a mean of 66.71 %) reduction (p < 0.05) with 1.5 μg/mL of DMMB and a 70.15 % (65-70.15, with a mean of 68.21 %) reduction with 2.0 μg/mL at an intensity of 21.6 J/cm2. In conclusion, PI presents a promising alternative to biocides in the oil and gas industry, offering easy application, avoiding bacterial resistance, being environmentally safe, and compatible with other SRB population control techniques.

A narrative review of personal protective equipment gowns: lessons from COVID-19

This narrative review evaluates the evidence regarding the protection offered by isolation gowns, approaches to imparting antimicrobial activity to gowns, and the environmental impacts of gown use, particularly during the COVID-19 pandemic. We conducted a search of the Medline, PubMed, and Google Scholar databases for articles published between January 1, 2019 to February 20, 2024. We found that current standards pertaining to isolation gowns might be irrelevant to the protection of healthcare workers from pathogen transmission, as they focus primarily on fluid barrier resistance values that are not reflective of all transmission conditions in hospitals. Although most available isolation gowns are disposable, reusable gowns could offer greater barrier protection and are more environmentally sustainable. Several techniques have been studied for their ability to impart antimicrobial properties to isolation gowns, extending their lifespan and reducing environmental impacts. However, evidence of the effectiveness of such techniques in clinical settings is scarce. We advocate for standardised guidelines inclusive of common pathogen survival tests, comfort, and durability, which reflect the actual infection risks encountered by healthcare workers, to improve the safety and efficacy of isolation gowns in hospital settings. Further research into the clinical effectiveness of antimicrobial gowns and their long-term implications on the environment is also warranted.

Enhanced biocidal efficacy of alcohol based disinfectants with salt additives

Surfaces contaminated with pathogens pose a significant risk of disease transmission and infection. Alcohol-based disinfectants are widely utilized to decontaminate high-touch areas across various settings. However, their limited antimicrobial activity and the emergence of alcohol-tolerant strains necessitate the development of highly efficient disinfectant formulations. In this work we test the broad-spectrum antimicrobial activities of the salt-incorporated alcohol solution disinfectant against enveloped and non-enveloped viruses, spore-forming and non-spore-forming bacteria, and mold and yeast fungi. Specifically, the disinfection capability of the isopropanol (IPA) and ethanol (EtOH) solutions containing NaCl salts was evaluated by measuring (1) antibacterial activity against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli), and an alcohol-tolerant strain of E. coli; (2) sporicidal activity against Clostridioides difficile; (3) the antiviral activity against enveloped A/PR8/34 H1N1 influenza virus and non-enveloped adenovirus VR-5; and (4) the antifungal efficacy against Aspergillus niger and Cryptococcus neoformans from the time-dependent viability assays. Additionally, the biocidal activity of the disinfectant formulation was tested by spraying it on the biocontaminated surfaces, including plastics, stainless steel, and glass. Overall, the inclusion of salt in alcohol solutions significantly enhanced their disinfection activities, positioning these solutions as promising candidates for long-term disinfection and maintenance of hygienic environments. This method, which employs mild salt instead of toxic materials, offers a simpler, more cost-effective, and safer alternative to conventional alcohol-based disinfectants. This research is expected to significantly impact on disease prevention and contribute greatly to public health and safety.

Prospective, crossover, comparative study of two methods of chlorhexidine bathing

BACKGROUND

Bathing intensive care unit (ICU) patients with chlorhexidine gluconate (CHG) decreases healthcare-associated infections (HAIs). The optimal method of CHG bathing remains undefined.

METHODS

Prospective crossover study comparing CHG daily bathing with 2% CHG-impregnated cloths versus 4% CHG solution. In phase 1, from January 2020 through March 2020, 1 ICU utilized 2% cloths, while the other ICU utilized 4% solution. After an interruption caused by the coronavirus disease 2019 pandemic, in phase 2, from July 2020 through September 2020, the unit CHG bathing assignments were reversed. Swabs were performed 3 times weekly from patients' arms and legs to measure skin microbial colonization and CHG concentration. Other outcomes included HAIs, adverse reactions, and skin tolerability.

RESULTS

411 assessments occurred after baths with 2% cloth, and 425 assessments occurred after baths with 4% solution. Average microbial colonization was 691 (interquartile range 0, 30) colony-forming units per square centimeter (CFU/cm2) for patients bathed with 2% cloths, 1,627 (0, 265) CFUs/cm2 for 4% solution, and 8,519 (10, 1130) CFUs/cm2 for patients who did not have a CHG bath (P < .001). Average CHG skin concentration (parts per million) was 1300.4 (100, 2000) for 2% cloths, 307.2 (30, 200) for 4% solution, and 32.8 (0, 20) for patients without a recorded CHG bath. Both CHG bathing methods were well tolerated. Although underpowered, no difference in HAI was noted between groups.

CONCLUSIONS

Either CHG bathing method resulted in a significant decrease in microbial skin colonization with a greater CHG concentration and fewer organisms associated with 2% CHG cloths.

The Influence of the Temperature on Effectiveness of Selected Disinfectants Against African Swine Fever Virus (ASFV)

African swine fever (ASF) is one of the most economically significant diseases of pigs caused by African swine fever virus (ASFV). Due to the lack of effective and safe vaccines, one of the crucial measures to protect farms from the introduction of the ASFV is to apply a strict regime of biosecurity and disinfection. However, in field conditions, the activity of disinfectants may be influenced by temperature, resulting in reduced activity or biodegradation (i.e., freezing or evaporating). The aim of this study was to evaluate the effect of a wide range of temperatures on the virucidal activity of selected active substances commonly used against ASFV. Eight active substances were tested, namely: sodium hypochlorite (1.0%), glutaraldehyde (0.1%), potassium peroxysulfate (0.5%), caustic soda (1.0%), phenol (1.0%), acetic acid (3.0%), benzalkonium chloride (1.0%), and formaldehyde (0.4%). The virucidal activity of each compound was tested at different temperatures (21, -10, and -20 °C for 30 min) and compared to the initial virus titer under the same temperature conditions. Exposure to a range of temperatures did not significantly affect the virucidal efficacy of tested active substances against ASFV. Most of the evaluated substances had reduced virus titers ≥ 4 log10, regardless of the temperature. However, two of them (benzalkonium chloride and acetic acid) were sensitive to sub-zero temperatures, showing a lack of the required 4 log10 virus titer reduction. The conducted study showed that temperature could hamper the virucidal effect of selected substances (i.e., benzalkonium chloride and acetic acid), showing their moderate efficacy against ASFV -10 °C and -20 °C. The results suggest that extreme caution should be taken while applying these substances at sub-zero temperatures. The other substances had no significant sensitivity to the temperature range. Nevertheless, in the case of freezing the agent, insufficient penetration of the disinfected surface may occur, which may result in an ineffective disinfection process.

Effect of Chirality and Amphiphilicity on the Antimicrobial Activity of Tripodal Lysine-Based Peptides

A series of tripodal (three-arm) lysine-based peptides were designed and synthesized and their self-assembly properties in aqueous solution and antimicrobial activity were investigated. We compare the behaviors of homochiral tripodal peptides (KKY)3K and a homologue containing the bulky aromatic fluorenylmethoxycarbonyl (Fmoc) group Fmoc-(KKY)3K, and heterochiral analogues containing k (d-Lys), (kkY)3K and Fmoc-(kkY)3K. The molecular conformation and self-assembly in aqueous solutions were probed using various spectroscopic techniques, along with small-angle X-ray scattering (SAXS) and cryogenic-transmission electron microscopy (cryo-TEM). In cell viability assays using fibroblast cell lines, the tripodal peptides without Fmoc were observed to be noncytotoxic over the concentration range studied, and the Fmoc functionalized tripodal peptides were only cytotoxic at the highest concentrations (above the critical aggregation concentration of the lipopeptides). The molecules also show good hemocompatibility at sufficiently low concentration, and antimicrobial activity was assessed via MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) assays. These revealed that the Fmoc-functionalized tripodal peptides had significant activity against both Gram-negative and Gram-positive bacteria, and in the case of Gram-positive Staphylococcus aureus, the antimicrobial activity for Fmoc-(kkY)3K was improved compared to polymyxin B. The mechanism of the antimicrobial assay was found to involve rupture of the bacterial membrane as evident from fluorescence microscopy live/dead cell assays, and scanning electron microscopy images.

Role of the two-component system AmgRS in early resistance of Pseudomonas aeruginosa to cinnamaldehyde

Exposure of Pseudomonas aeruginosa to cinnamaldehyde (CNA), a natural electrophilic antimicrobial often used as self-medication to treat mild infections, triggers overproduction of the MexAB-OprM efflux system, leading to multidrug resistance. In this study, we demonstrate that CNA exposure induces expression of genes regulated by the two-component system AmgRS. AmgRS activates MexAB-OprM production, independent of repressors MexR and NalD. In addition to the essential role played by the NalC-ArmR pathway in this adaptive process, AmgRS is critical for the survival of P. aeruginosa challenged with CNA. Altogether, these data suggest that efflux-dependent and -independent mechanisms are activated in the early phase of CNA exposure, allowing for progressive enzymatic reduction of the biocide to non-toxic cinnamic alcohol.IMPORTANCEExposure of Pseudomonas aeruginosa to cinnamaldehyde (CNA), an antimicrobial used in self-medication, induces overproduction of the MexAB-OprM efflux system, leading to multidrug resistance. Our study demonstrates that the AmgRS two-component system aids in the survival of P. aeruginosa strain PA14 under CNA exposure through both MexAB-OprM-dependent and -independent mechanisms until the enzymatic reduction of CNA into the less toxic cinnamic alcohol. This discovery highlights the pivotal role of AmgRS in mediating defense against aldehyde biocides, emphasizing its significance in the persistence of P. aeruginosa, a pathogen associated with hospital-acquired infections and cystic fibrosis, and underscores the potential impact on clinical treatment strategies.

Nosocomial Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus: Sensitivity to Chlorhexidine-Based Biocides and Prevalence of Efflux Pump Genes

The widespread use of disinfectants and antiseptics has led to the emergence of nosocomial pathogens that are less sensitive to these agents, which in combination with multidrug resistance (MDR) can pose a significant epidemiologic risk. We investigated the susceptibility of nosocomial Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus to a 0.05% chlorhexidine (CHX) solution and a biocidal S7 composite solution based on CHX (0.07%) and benzalkonium chloride (BAC, 0.055%). The prevalence of efflux pump genes associated with biocide resistance and their relationship to antibiotic resistance was also determined. Both biocides were more effective against Gram-positive S. aureus than Gram-negative bacteria. The most resistant strains were P. aeruginosa strains, which were mainly killed by 0.0016% CHX and by 0.0000084% (CHX)/0.0000066% (BAC) S7. The S7 bactericidal effect was observed on P. aeruginosa and S. aureus after 10 min, while the bactericidal effect of CHX was only observed after 30 min. qacEΔ1 and qacE efflux pump genes were prevalent among E. coli and K. pneumoniae, while mexB was more often detected in P. aeruginosa. norA, norB, mepA, mdeA, and sepA were prevalent in S. aureus. The observed prevalence of efflux pump genes highlights the potential problem whereby the sensitivity of bacteria to biocides could decline rapidly in the future.

Antiseptic efficacy and plasma chlorhexidine levels following two different methods of application of 1% aqueous chlorhexidine gluconate for skin disinfection in preterm newborns: a randomized controlled trial

OBJECTIVE

Many neonatal units have started using Chlorhexidine gluconate for neonatal skin antisepsis. However, there is in-vitro evidence of inhibition of neurite growth. The current study aimed to compare two methods of its local application, for the extent of systemic absorption and antiseptic efficacy.

STUDY DESIGN

Parallel group, blinded, randomised trial, at a Level III, neonatal intensive care unit. Between December 2020 to July 2022, neonates from 28 to 34 weeks gestation, were randomized to local skin antisepsis by either- (a) 1% aqueous chlorhexidine (CHG aq) followed by cleansing off the residual agent with sterile water swab (Cleansing group) or (b)1% CHG aq followed by air drying (No cleansing group). The outcome measures were the proportion of post antisepsis skin swabs with no/insignificant growth, and the plasma chlorhexidine levels.

RESULTS

Of the total of 457 enrollments (Cleansing: n = 230; No Cleansing: n = 227), 216 (93.91%) in "Cleansing" vs. 221 (97.36%) in "No cleansing" (risk difference -3.45%, 95% CI -7.2 to 0.28%; p = 0.072) had no/insignificant growth post-antisepsis. The lower bound of the confidence interval crossed the pre-specified non-inferiority limit of 5%. The median (IQR) plasma chlorhexidine levels were not significantly different between the two groups (7.9 (5.6, 17.9)) ng/mL in Cleansing vs. 6.5 (4.6, 17.7) in No cleansing groups (p = 0.437).

CONCLUSION

Cleansing with sterile water after application of chlorhexidine in preterm neonates was not shown to be non-inferior compared to no cleansing, for skin antisepsis efficacy. Systemic absorption occurred to a similar extent despite cleansing off the residual agent.

TRIAL REGISTRATION NUMBER

CTRI/2020/10/028719.

Comparative effectiveness of interventions for the treatment of denture stomatitis: A systematic review with network meta-analysis

STATEMENT OF PROBLEM

Symptomatic denture stomatitis (DS) is a painful oral mucosal disorder that can impair quality of life in denture wearers. A complete cure of DS is difficult to achieve, and the most efficacious regimen to treat DS has not yet been conclusively established.

PURPOSE

The purpose of this network meta-analysis was to assess the comparative efficacy of interventions used for the treatment of DS.

MATERIAL AND METHODS

A search was conducted for trials published in Medline, Scopus, PubMed, and Cochrane Central Register of Controlled Trials from inception until February 2022 (PROSPERO Reg no: CRD42021271366). Network meta-analysis was performed on data from randomized controlled trials that assessed the comparative efficacy of any form of intervention for the treatment of DS in denture wearers. Agents were ranked according to their effectiveness in the treatment of DS based on outcomes using surface under the cumulative ranking (SUCRA).

RESULTS

A total of 25 articles were included in the quantitative analysis. Topical antifungal agents (risk ratio [RR]=4.37[95% confidence interval [CI]: 2.15,8.90), topical antimicrobial agents used along with systemic antifungal agents (RR=4.25[95% CI: 1.79,10.33]), systemic antifungal agents (RR=4.25[95% CI: 1.79,10.10]), photodynamic therapy (RR=4.25[95% CI: 1.75,8.98]), and topical plant products (RR=3.40[95% CI: 1.59,7.26]) were found to effectively improve DS. Microwave disinfection concurrently administered with topical antifungal agents (RR=7.38(95% CI: 2.75,19.81), microwave disinfection 7.38[95% CI: 2.75,19.81]), topical antifungal agents (RR=4.88[95% CI: 1.92,12.42]), topical plant products (RR=4.49[95% CI: 1.70,11.82]), systemic antifungal agents together with topical antimicrobial agents (RR=3.85[95% CI: 1.33,11.10]), topical antimicrobial agents (RR=3.39[95% CI: 1.17,9.81]), systemic antifungal agents (RR=3.37[95% CI: 1.21,9.34]), and photodynamic therapy or photochemotherapy (PDT) (RR=2.93[95% CI: 1.01,8.47]) were found to effectively resolve mycological DS. Topical antifungals ranked highest in the SUCRA ranking for clinical improvement, whereas microwave disinfection concurrently administered with topical antifungal agents ranked highest for mycological resolution. None of the agents demonstrated significant side effects except for topical antimicrobial agents which demonstrated altered taste and staining of oral structures.

CONCLUSIONS

Available evidence suggests that topical antifungals, microwave, and systemic antifungals are effective in the treatment of DS, but confidence in these findings is low because of the limited number of studies and a high risk of bias. Additional clinical trials are needed on photodynamic therapy, topical plant products, and topical antimicrobials.

Dual action electrochemical bandage operated by a programmable multimodal wearable potentiostat

We have developed electrochemical bandage (e-bandage) prototypes that generate the reactive oxygen species hypochlorous acid (HOCl) or hydrogen peroxide (H2O2) for potential use to treat biofilm-infected wounds in humans. We have shown that both e-bandage-generated HOCl and H2O2 kill biofilms in vitro and in infected wounds on mice, with the former being more active in vitro. The H2O2-generating e-bandage, more so than the HOCl-generating e-bandage, was associated with improved healing of infected wounds. Here, a strategy in which H2O2 and HOCl are alternately generated-for dual action-was explored. The goal was to develop a programmable multimodal wearable potentiostat [PMWP] that can generate HOCl or H2O2, as needed. An ultralow-power microcontroller unit was developed to manage operation of the PMWP. The system was operated with a 260-mAh capacity coin battery and weighed 4.6 g, making it suitable for future small animal experiments (and ultimately, potential evaluation in humans). As assessed using electrochemical parameters, the device functioned comparably to a commercial benchtop potentiostat. To confirm antimicrobial activity, PMWP-controlled e-bandages were tested in vitro against clinical isolates of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecium, and Candida auris. When programmed to deliver HOCl followed by H2O2, PMWP-controlled e-bandages exhibited activity against biofilms of all study isolates tested. Finally, we demonstrated the PMWP's usability in a murine wound infection model.

Antimicrobial efficacy of modified gutta-percha for obturation - A systematic review

Gutta Percha (GP) cones are made in an aseptic environment, a number of investigations have shown the presence of bacteria in recently opened boxes and this contamination rises with incorrect handling, storage and aerosol application. Numerous physicochemical techniques have been documented aiming to boost the antibacterial activity of GP cones while ensuring its obturation requirements. This systematic review aimed to critically evaluate the efficacy of antibacterial activity of GP modified with various antibacterial agents. The protocol for this systematic review has been registered with the PROSPERO International prospective register of systematic reviews, registry No. CRD42024573067. The search was carried out across reputable databases, including PubMed/Medline, Web of Science, Scopus and it was specifically designed to include articles published until March 2024. The search queries in the database were formulated with the basis of PICO questions in combination with various Boolean operators such as AND, OR. MeSH terms used for the search included GP, antibacterial agents, nanoparticles, root canal treatment, medicated GP. The extraction of the information was done by two independent authors. The evaluation of the methodological quality of the included studies was assessed using QUIN TOOL. This systematic review was reported following the Preferred Reporting Items for Systematic Reviews (PRISMA 2020) guidelines. Initial search yielded 51 studies from database search. Out of 51, 9 articles ultimately satisfied the requirements and were therefore discussed in the current systematic review. The included studies were assessed and data were extracted and tabulated. Based on the results of the current systematic review, modified GP with various antimicrobial agents showed significantly increased antibacterial effectiveness than standard GP.

The Hygienic Significance of Microbiota and Probiotics for Human Wellbeing

The human body can be viewed as a combination of ecological niches inhabited by trillions of bacteria, viruses, fungi, and parasites, all united by the microbiota concept. Human health largely depends on the nature of these relationships and how they are built and maintained. However, personal hygiene practices have historically been focused on the wholesale elimination of pathogens and "hygiene-challenging microorganisms" without considering the collateral damage to beneficial and commensal species. The microbiota can vary significantly in terms of the qualitative and quantitative composition both between different people and within one person during life, and the influence of various environmental factors, including age, nutrition, bad habits, genetic factors, physical activity, medication, and hygienic practices, facilitates these changes. Disturbance of the microbiota is a predisposing factor for the development of diseases and also greatly influences the course and severity of potential complications. Therefore, studying the composition of the microbiota of the different body systems and its appropriate correction is an urgent problem in the modern world. The application of personal hygiene products or probiotics must not compromise health through disruption of the healthy microbiota. Where changes in the composition or metabolic functions of the microbiome may occur, they must be carefully evaluated to ensure that essential biological functions are unaffected. As such, the purpose of this review is to consider the microbiota of each of the "ecological niches" of the human body and highlight the importance of the microbiota in maintaining a healthy body as well as the possibility of its modulation through the use of probiotics for the prevention and treatment of certain human diseases.

Inhibition of biofilm formation and preformed biofilm in Acinetobacter baumannii by resveratrol, chlorhexidine and benzalkonium: modulation of efflux pump activity

Introduction

The persistence of Acinetobacter baumannii in the contaminated environment is sustained by tolerance to biocides and ability to growth as biofilm. The aim of the study was to analyze the susceptibility of A. baumannii biofilms to chlorhexidine (CHX) and benzalkonium (BZK) biocides and the ability of natural monomeric stilbenoid resveratrol (RV) to modulate the phenomenon.

Methods

Biofilm formation and preformed biofilm were tested by Crystal violet and tetrazolium salt reduction assay, respectively. Analysis of efflux pump (EP) expression during biofilm growth was performed by Real-time RT-PCR assays.

Results

CHX and BZK at ¼ and ½ MICs alone or in combination inhibited biofilm growth of A. baumannii ATCC 19606, 4190, and 3909 strains. RV at 32 mg/L and CHX and BZK at ¼ or ½ MICs showed a synergistic effect and completely inhibited biofilm formation in all A. baumannii strains. Similarly, RV at 32 mg/L and CHX and BZK at ½ MIC significantly inhibited air-liquid biofilm formation of A. baumannii ATCC 19606, 4190 and 3909 strains. The inactivation of AdeB and AdeJ RND EPs in A. baumannii ATCC19606 increased the susceptibility to CHX and BZK alone or in the presence of 32 mg/L RV. Concordantly, carbonyl cyanide m-chlorophenylhydrazine (CCCP) increased the susceptibility to CHX, BZK and RV and dose-dependently inhibited biofilm formation in A. baumannii ATCC 19606, 4190 and 3909 strains. RV at 32 mg/L inhibited basal and CHX-induced EP genes expression, while increased EP gene expression in the presence of BZK during A. baumannii ATCC19606 biofilm growth. In addition, CHX and BZK alone or in combination dose-dependently reduced preformed biofilm of all A. baumannii strains. The combination of RV with CHX and BZK additively decreased minimal biofilm eradicating concentrations in A. baumannii strains.

Conclusion

These results demonstrate that: (i) CHX and BZK alone or in the presence of RV inhibit biofilm growth and preformed biofilm in A. baumannii; (ii) tolerance to CHX and BZK during biofilm growth is dependent on the activation of AdeB and AdeJ EPs; and (iii) the inhibitory effect of RV on biofilm growth is mediated by the inhibition of EP genes expression in A. baumannii.

Clinical and In Vitro Safety of Heyndrickxia coagulans AO 1167B: A Double-Blind, Placebo-Controlled Trial

(1) Background: Heyndrickxia coagulans, a lactic acid-producing bacterium, displays characteristics of both Lactobacillus and Bacillus genera. Clinical evidence suggests its potential health benefits. This study evaluated the safety of H. coagulans AO1167B as a candidate probiotic supplement. (2) Methods: Strain identification was confirmed through morphological, cultural, and genomic analyses, including 16S RNA and whole genome sequencing to assess antimicrobial resistance and virulence factors. Phenotypic tests, such as disk diffusion for antimicrobial resistance, and safety assays for cytotoxicity and hemolytic activity, were conducted. In a phase I, double-blind, placebo-controlled clinical trial, healthy adults were randomized into H. coagulans AO1167B and placebo groups for 60 days. Daily capsule consumption was monitored through clinical and hematological evaluations, adverse event tracking, and health surveys. (3) Results: The genome of H. coagulans AO1167B revealed no concerning features. Disk diffusion tests showed no antimicrobial resistance. The strain exhibited no cytotoxic or hemolytic activity, indicating in vitro safety. No significant differences in clinical or hematological parameters were observed between groups. The most common adverse event, gas, diminished over time. (4) Conclusions: H. coagulans AO1167B demonstrates a suitable safety profile, genetic stability, and probiotic potential for gastrointestinal health, justifying further clinical research.

Plants and their uses in dermatological recipes of the Receptarium of Burkhard III von Hallwyl from 16th century Switzerland - Data mining a historical text and preliminary in vitro screening

ETHNOPHARMACOLOGICAL RELEVANCE

Historical texts on materia medica can be an attractive source of ethnopharmacological information. Various research groups have investigated corresponding resources from Europe and the Mediterranean region, pursuing different objectives. Regardless of the method used, the indexing of textual information and its conversion into data sets useful for further investigations represents a significant challenge.

AIM OF THE STUDY

First, this study aims to systematically catalogue pharmaco-botanical information in the Receptarium of Burkhard von Hallwyl (RBH) in order to identify candidate plants in a targeted manner. Secondly, the potential of RBH as a resource for pharmacological investigations will be assessed by means of a preliminary in vitro screening.

MATERIALS AND METHODS

We developed a relational database for the systematic recording of parameters composing the medical recipes contained in the historical text. Focusing on dermatological recipes, we explored the mentioned plants and their uses by drawing on specific literature. The botanical identities (candidate species) suggested in the literature for the historical plant names were rated based on their plausibility of being the correct attribution. The historical uses were interpreted by consulting medical-historical and modern clinical literature. For the subsequent in vitro screening, we selected candidate species used in recipes directed at the treatment of inflammatory or infectious skin disorders and wounds. Plants were collected in Switzerland and their hydroethanolic crude extracts tested for possible cytotoxic effects and for their potential to modulate the release of IL-6 and TNF in PS-stimulated whole blood and PBMCs.

RESULTS

The historical text analysis points up the challenges associated with the assessment of historical plant names. Often two or more plant species are available as candidates for each of the 161 historical plant names counted in the 200 dermatological recipes in RBH. On the other hand, our method enabled to draw conclusions about the diseases underlying the 56 medical applications mentioned in the text. On this basis, 11 candidate species were selected for in vitro screening, four of which were used in RBH in herbal simple recipes and seven in a herbal compound formulation. None of the extracts tested showed a noteworthy effect on cell viability except for the sample of Sanicula europaea L. Extracts were tested at 50 μg/mL in the whole blood assay, where especially Vincetoxicum hirundinaria Medik. or Solanum nigrum L. showed inhibitory or stimulatory activities. In the PBMC assay, the root of Vincetoxicum hirundinaria revealed a distinct inhibitory effect on IL-6 release (IC50 of 3.6 μg/mL).

CONCLUSIONS

Using the example of RBH, this study illustrates a possible ethnopharmacological path from unlocking the historical text and its subsequent analysis, through the selection and collection of plant candidates to their in vitro investigation. Fully documenting our approach to the analysis of historical texts, we hope to contribute to the discussion on solutions for the digital indexing of premodern information on the use of plants or other natural products.

Hydroaminoalkylation for Amine Functionalization of Vinyl-Terminated Polyethylene Enables Direct Access to Responsive Functional Materials

While functionalized polyethylenes (PEs) exhibit valuable characteristics, the constraints of existing synthetic approaches limit the variety of readily incorporated functionality. New methods to generate functionalized PEs are required to afford new applications of this common material. We report 100 % atom economic tantalum-catalyzed hydroaminoalkylation of vinyl-terminated polyethylene (VTPE) as a method to produce amine-terminated PE. VTPEs with molecular weights between 2200-16800 g/mol are successfully aminated using solvent-free conditions. Our catalytic system is efficient for the installation of both aromatic and aliphatic amines, and can be carried out on multigram scale. The associating amine functional groups afford modified material properties, as measured by water contact angle, differential scanning calorimetry (DSC) and polymer rheology. The basic amine functionality offers the opportunity to convert inert PE into stimuli-responsive materials, such that the protonation of aminated PE affords the generation of functional antibacterial PE films.

The mobilome landscape of biocide-resistance in Brazilian ESKAPE isolates

The increasing frequency of antibiotic-resistant bacteria is a constant threat to global human health. Therefore, the pathogens of the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Enterobacter spp.) are among the most relevant causes of hospital infections responsible for millions of deaths every year. However, little has been explored about the danger of microorganisms resistant to biocides such as antiseptics and disinfectants. Widely used in domestic, industrial, and hospital environments, these substances reach the environment and can cause selective pressure for resistance genes and induce cross-resistance to antibiotics, further aggravating the problem. Therefore, it is necessary to use innovative and efficient strategies to monitor the spread of genes related to resistance to biocides. Whole genome sequencing and bioinformatics analysis aiming to search for sequences encoding resistance mechanisms are essential to help monitor and combat these pathogens. Thus, this work describes the construction of a bioinformatics tool that integrates different databases to identify gene sequences that may confer some resistance advantage about biocides. Furthermore, the tool analyzed all the genomes of Brazilian ESKAPE isolates deposited at NCBI and found a series of different genes related to resistance to benzalkonium chloride, chlorhexidine, and triclosan, which were the focus of this work. As a result, the presence of resistance genes was identified in different types of biological samples, environments, and hosts. Regarding mobile genetic elements (MGEs), around 52% of isolates containing genes related to resistance to these compounds had their genes identified in plasmids, and 48.7% in prophages. These data show that resistance to biocides can be a silent, underestimated danger spreading across different environments and, therefore, requires greater attention.

Adaptations to cationic biocide exposure differentially influence virulence factors and pathogenicity in Pseudomonas aeruginosa

Cationic biocides (CBs), which include quaternary ammonium compounds (QACs), are employed to mitigate the spread of infectious bacteria, but resistance to such surface disinfectants is rising. CB exposure can have profound phenotypic implications that extend beyond allowing microorganisms to persist on surfaces. Pseudomonas aeruginosa is a deadly bacterial pathogen that is intrinsically tolerant to a wide variety of antimicrobials and is commonly spread in healthcare settings. In this study, we pursued resistance selection assays to the QAC benzalkonium chloride and quaternary phosphonium compound P6P-10,10 to assess the phenotypic effects of CB exposure in P. aeruginosa PAO1 and four genetically diverse, drug-resistant clinical isolates. In particular, we sought to examine how CB exposure affects defensive strategies and the virulence-associated "offensive" strategies in P. aeruginosa. We demonstrated that development of resistance to BAC is associated with increased production of virulence-associated pigments and alginate as well as pellicle formation. In an in vivo infection model, CB-resistant PAO1 exhibited a decreased level of virulence compared to wild type, potentially due to an observed fitness cost in these strains. Taken together, these results illustrate the significant consequence CB resistance exerts on the virulence-associated phenotypes of P. aeruginosa.

Approaches for the Inactivation of Yersinia pestis

Introduction

Yersinia pestis is the gram-negative, facultative intracellular bacterium that causes the disease known as plague. Due to the risk for aerosol transmission, a low infectious dose, and the acute and lethal nature of pneumonic plague, research activities with Y. pestis require Biosafety Level 3 (BSL-3) facilities to provide the appropriate safeguards to minimize accidental exposures and environmental release. However, many experimental assays cannot be performed in BSL-3 due to equipment availability, and thus require removal of samples from the BSL-3 laboratory to be completed.

Objectives

To remove samples from BSL-3 containment and safely handle them at lower containment requires effective inactivation of any viable organisms from the samples prior to removal. While commonly used inactivation methods have been published for various select agents, there is an absence in the literature of a single source providing detailed examples for inactivation methods for Y. pestis. Our objective here is to provide examples of dose-dependent kill curves for commonly used inactivation approaches against Y. pestis.

Methods

Time- and dose-dependent kill curves using heat, methanol, and formaldehyde inactivation methods, and common nucleic acid extraction procedures.

Results/Conclusions

We show data demonstrating the complete inactivation of Y. pestis using these methods. While not all-inclusive, this study provides data and examples that can be used by other researchers to develop their own in-house validated inactivation protocols for Y. pestis.

Improving Recovery of Diatoms Bio-Silica Using Chemical Treatment with VAUSTM

High-temperature baking is a typical method to remove organic matter from diatoms, but it is not suitable for bio-silica because of the high crystallinity. This study provides a method using the VAUSTM to remove organic matter from diatoms more quickly and biocompatibly. The optimal frequency for organic matter removal was investigated for domestically produced M. nummuloides. The removal efficiency of TOC/TN was calculated and analyzed. The C and Si elements were analyzed in EDS, and organic matter removal was analyzed by XRD. TOC RE% at a frequency of 35 kHz exhibited the highest value, indicating a statistically significant difference. XRD analysis demonstrated that the organic matter was nearly entirely removed using NaOCl compared to high-temperature-baked M. nummuloides. In the EDS analysis, there were significant differences in the C and Si elements with respect to frequency. This is very similar to the values from the positive control group, high-temperature-baked M. nummuloides. Ultrasonic treatment and frequency adjustments were found to significantly impact the chemical removal of organic matter from M. nummuloides. Although vacuum application was initially considered, it did not demonstrate a statistically significant effect according to TOC analysis.

Multifunctional Temporary Dental Nanofillers Enhanced with Synergistically Active Chlorine-Containing Molecules against Streptococcus mutans and Its Effects on Oral Epithelial Cells

Temporary dental fillers are critical for safeguarding teeth during the period between caries removal and permanent restoration. However, conventional fillers often lack sufficient antimicrobial properties to prevent bacterial colonization. To address this issue, the study researches on the development of antimicrobial Temporary Dental Nano-Fillers (TDNF) capable of targeting multiple cariogenic pathogens, including Streptococcus mutans, Lactobacillus casei, Candida albicans, and mixed-species planktonic cells/biofilms, which play a significant role in the progression of dental caries. The TDNF was formulated using a combination of Chloramine-T (CRT) and Cetylpyridinium Chloride (CPC), both known for their antimicrobial efficacy, and embedded in a nanoparticle matrix of hydroxyapatite (HAP) and silicon dioxide (SiO2). The synergistic antimicrobial effect of CRT and CPC, with MIC90 values of 12.5 and 6.25 ppm, respectively, displayed potent activity against S. mutans. Proteomic analysis, including gene ontology and protein-protein interaction network evaluations, further confirmed significant disruptions in S. mutans metabolic and stress response pathways, highlighting the bactericidal effectiveness of the formulation against S. mutans. Additionally, the formulation demonstrated sustained antimicrobial efficacy against other cariogenic pathogens such as L. casei, C. albicans and mixed-species planktonic cells and biofilms over a 16-day period. The TDNF (HAP+SiO2+CRT+CPC matrix) exhibited superior mechanical properties with a compressive strength of 237.7 MPa, flexural strength of 124.3 MPa, and shear bond strength of 52 MPa. Biocompatibility tests conducted on human oral squamous carcinoma cells (OECM-1) indicated over 95% cell viability, affirming its safety for preclinical or clinical applications. The multifunctional TDNF developed in this study successfully combines mechanical reinforcement with broad-spectrum antimicrobial efficacy, offering a promising interim solution in dental restorations. Its ability to protect against microbial colonization, while maintaining structural stability, positions it as an effective temporary material that enhances patient outcomes during the period before permanent restoration.

Efficacy and safety of three antiseptics for neonatal skin disinfection: a cohort study

BACKGROUND

The choice of the ideal antiseptic is not only based on its efficacy but also on safety and skin-friendliness. There are no standard recommendations regarding ideal skin preparation in neonates.

METHODS

This was a prospective cohort study to evaluate the efficacy of 3 antiseptics[10% Povidone Iodine(PI), 70% isopropyl alcohol(AL), 2% chlorhexidine in 70% alcohol(CHG-IPA)] in disinfecting the skin before venipuncture in term neonates as assessed by logarithmic reduction in skin bacterial colony counts post-application. Secondary objectives were to assess the changes in skin condition. Measurements were done pre-, post-antiseptic and 6-24 h (for residual effect) later. Fifty neonates were enrolled in each group.

RESULTS

All three antiseptics caused a significant reduction in bacterial load post-application, but maximal efficacy [2.6(2.2-2.8)log reduction] and, maximal residual effect at 6-24 h was seen with CHG-IPA [2.4(2.2-2.6)log reduction]. The logarithmic reduction in colony counts from pre-intervention to 6-24 h later remained significant for all three groups [(PI, p-0.039; CHG-IPA, p-0.00; AL, p - 0.01)]. After an initial alteration in hydration, and skin condition score, there was a return to baseline after 6-24 h.

CONCLUSION(S)

2% CHG-IPA had better efficacy than AL or PI for skin antisepsis in term neonates. There was no significant change in skin integrity in all three groups.

IMPACT

All three antiseptics [2% chlorhexidine gluconate in 70% isopropyl alcohol(CHG + IPA), 10% Povidone Iodine(PI), and 70% isopropyl alcohol(AL)] cause significant reduction in bacterial colony counts. CHG + IPA has the maximum efficacy as assessed by log reduction of bacterial colony counts with optimal residual effect favouring its usage in term neonates. The least efficacy is seen with 70% isopropyl alcohol. All three antiseptics are skin-friendly and do not affect the skin integrity. Future studies addressing the clinical outcomes and safety in preterm populations with these commonly used antiseptics should be done.

Antibiotic concentrations induce morphological changes and increase biofilm formation in multi-antibiotic and heavy metal resistant Kluyvera cryocrescens and Serratia fonticola

Water pollution is the biggest challenge that has rendered existing water resources unusable due to contamination with antibiotics and heavy metals. Antibiotics are often used to treat bacterial diseases. Heavy metals, on the other hand, are micro-pollutants that pose a threat to aquatic systems, especially when they accumulate in nature. Increasing pollution and the uncontrolled use of antibiotics have exposed bacteria to non-lethal concentrations (sub-MIC), potentially leading to resistance. In this study, Kluyvera cryocrescens and Serratia fonticola were isolated from a freshwater source and characterised. The resistance profiles of the isolates to 16 antibiotics and 8 heavy metals were determined, revealing that they are multidrug-resistant. The effects of sub-MICs (MIC/2 and MIC/4) of antibiotics on biofilm formation, siderophore production, and cell morphology of bacteria were analysed. It was found that at some sub-MIC values of kanamycin, tetracycline, meropenem, erythromycin, and clarithromycin, biofilm formation by K. cryocrescens increased. An increase in biofilm production was also observed in S. fonticola at sub-MIC values of imipenem, meropenem, ceftazidime, ciprofloxacin, and clarithromycin. Moreover, significant morphological changes were observed in both isolates following treatment with meropenem, ciprofloxacin, and ceftazidime. After treatment with meropenem, the typical rod-shaped (bacillary) morphology of the isolates shifted to a round (coccoid) form. In contrast, the bacteria developed into long filaments after treatment with ciprofloxacin and ceftazidime. These changes in the bacteria may favour the development of resistance and pose challenges for the prevention and treatment of diseases. Therefore, it is crucial to understand how sub-MIC levels of antimicrobial agents alter the virulence properties of bacteria.

The Ocular Microbiome: Micro-Steps Towards Macro-Shift in Targeted Treatment? A Comprehensive Review

A healthy ocular surface is inhabited by microorganisms that constitute the ocular microbiome. The core of the ocular microbiome is still a subject of debate. Numerous culture-dependent and gene sequencing studies have revealed the composition of the ocular microbiome. There was a confirmed correlation between the ocular microbiome and ocular surface homeostasis as well as between ocular dysbiosis and pathologies such as blepharitis, microbial keratitis, and conjunctivitis. However, the role of the ocular microbiome in the pathogenesis and treatment of ocular surface diseases remains unclear. This article reviews available data on the ocular microbiome and microbiota, their role in maintaining ocular homeostasis, and the impact of dysbiosis on several ophthalmic disorders. Moreover, we aimed to discuss potential treatment targets within the ocular microbiota.

Healthcare waste management and antimicrobial resistance: a critical review

The rapid growth of populations and urbanization has led to a significant increase in healthcare waste, posing serious health risks. A search on Google Scholar identified seven relevant articles from Ethiopia that examine the relationship between improper waste management in healthcare facilities (HCFs) and the rise of antimicrobial resistance (AMR) genes. This review aims to highlight key concepts, evidence sources, and knowledge gaps specific to the Ethiopian context. The unsafe disposal of antibiotics through leaks and solid waste has contributed to what some are calling a 'silent pandemic,' raising concerns about emerging infectious diseases. Studies have revealed alarming rates of infectious agents and AMR in healthcare wastewater. Isolates of C. jejuni, Escherichia coli, Enterococcus faecalis, and Enterococcus faecium from various healthcare waste sites in Ethiopia demonstrate high levels of AMR genes. Additionally, research indicates that HCFs produce significant amounts of waste, with high per-person daily waste production rates. Leachate from landfills containing this waste can negatively affect soil health, biological activity, water quality, agriculture, animal health, and human well-being. To mitigate these risks, effective waste management practices and the promotion of alternative antimicrobial use are essential strategies for reducing the emergence of pandemic diseases in developing countries.