Ability of chlorhexidine, octenidine, polyhexanide and chloroxylenol to inhibit metabolism of biofilm-forming clinical multidrug-resistant organisms

Still not sterile: viability-based assessment of the skin microbiome following pre-surgical application of a broad-spectrum antiseptic reveals transient pathogen enrichment and long-term recovery

Broad-spectrum antiseptics such as chlorhexidine gluconate (CHG) have widespread use as pre-surgical tools to lower skin microbial burden and reduce the risk of surgical site infection. However, the short- and long-term effects of CHG on healthy skin microbial communities remain undefined due to the confounding effects of CHG binding with persistent bacterial DNA on the skin surface. Here, we aim to accurately characterize the immediate and long-term impact of pre-surgical preparation with CHG-based antiseptics on the human skin microbiome. Twenty-eight patients undergoing elective surgeries were enrolled. Swabs of the surgical site and a control site skin microbiome were collected at multiple time points before and up to 2 weeks after surgery. A propidium monoazide (PMAxx)-based viability assay was optimized to selectively evaluate DNA from live microbes in complex skin microbial communities with viability-qPCR and viable 16S ribosomal RNA gene profiling. Pre-operative CHG induces a measurable reduction in the viable microbial bioburden at the surgical site. On the day of surgery, surgical sites displayed a significant increase in the relative abundance of several SSI-associated bacterial genera including Acinetobacter, Bacillus, Escherichia-Shigella, and Pseudomonas compared to baseline. Bacillus species isolated from subjects at baseline also demonstrate resistance to CHG with minimum inhibitory concentrations exceeding 1,000 µg/mL. Although there are major skin microbiome shifts upon exposure to CHG, we also find that these shifts are largely transient. For the majority of individuals, skin microbial bioburden and community structure recover to near baseline by post-surgical follow-up.IMPORTANCESurgical site infections continue to occur despite widespread adoption of surgical antiseptics. Before surgery, patients often wash their whole body multiple times with chlorhexidine gluconate (CHG)-based antiseptic soap and have CHG applied to the surgical site in the operating room. However, the effects of CHG antiseptics on the healthy skin microbiome are undefined due to CHG persisting and binding DNA from dead cells on the skin. We optimized a viability assay to selectively target DNA from live microbes on the skin before and after exposure to CHG. Our findings demonstrate that pre-surgical application of CHG significantly reduces the bioburden on skin; however, potentially pathogenic bacteria remain. Post-surgery, the skin microbiome eventually recovers to resemble its pre-CHG exposed state. Collectively, these findings identify tangible avenues for improving antiseptic formulations and further support that the skin microbiome is viable, stable, and resilient to chemical perturbation.

Effect of Bacterial Nanocellulose with Chemisorbed Antiseptics on Alveolar Bone Repair in Rats Undergoing Bisphosphonate Therapy

Objectives: This work investigated the effect of bacterial nanocellulose (BNC) alone or with chemisorbed chlorhexidine or povidone-iodine on post-tooth extraction repair in rats undergoing bisphosphonate therapy. Methods: Forty Wistar rats were treated with zoledronic acid, subjected to tooth extractions and allocated into groups according to the material inserted in the post-extraction socket: (1) BNC (n = 10); (2) BNC/Iodine (n = 10); (3) BNC/Chlorhex (n = 10); (4) Control (n = 10). Maxillae were dissected and macro- and microscopically analyzed. Results: Oral lesion frequency on macroscopic examination did not differ between the groups, whereas it was larger in the BNC/Iodine group compared to the BNC/Chlorhex and Control. BNC/Chlorhex had significantly more connective tissue than did BNC but did not differ from the BNC/Iodine and Control. Epithelium, vital bone, non-vital bone, tooth fragment and inflammatory infiltrate did not significantly differ between the groups. BNC/Iodine showed greater CD31 immunostaining compared to BNC and the Control. Myeloperoxidase staining did not differ between the groups, and scanning electron microscopy analysis showed similar characteristics in all groups. Conclusions: BNC with chemisorbed povidone-iodine is associated with increased vascularization in post-extraction wounds of rats undergoing bisphosphonate therapy, whereas BNC with chemisorbed chlorhexidine improves connective tissue formation. BNC works as an effective carrier for the antiseptics tested.

Current insights into the effects of cationic biocides exposure on Enterococcus spp

Cationic biocides (CBs), such as quaternary ammonium compounds and biguanides, are critical for controlling the spread of bacterial pathogens like Enterococcus spp., a leading cause of multidrug-resistant healthcare-associated infections. The widespread use of CBs in recent decades has prompted concerns about the potential emergence of Enterococcus spp. populations exhibiting resistance to both biocides and antibiotics. Such concerns arise from their frequent exposure to subinhibitory concentrations of CBs in clinical, food chain and diverse environmental settings. This comprehensive narrative review aimed to explore the complexity of the Enterococcus' response to CBs and of their possible evolution toward resistance. To that end, CBs' activity against diverse Enterococcus spp. collections, the prevalence and roles of genes associated with decreased susceptibility to CBs, and the potential for co- and cross-resistance between CBs and antibiotics are reviewed. Significant methodological and knowledge gaps are identified, highlighting areas that future studies should address to enhance our comprehension of the impact of exposure to CBs on Enterococcus spp. populations' epidemiology. This knowledge is essential for developing effective One Health strategies that ensure the continued efficacy of these critical agents in safeguarding Public Health.

The Effectiveness of Polyhexanide in Treating Wound Infections Due to Methicillin-Resistant Staphylococcus Aureus: A Prospective Analysis

Purpose

Polyhexanide is a safe and effective wound care antiseptic commonly used in clinics as wound rinsing solution and gel. However, the efficacy of Polyhexanide in treatment of wound infected with MRSA (methicillin-resistant Staphylococcus aureus) is unknown. The aim of this study is to assess the effectiveness of polyhexanide with povidone iodine in treating wound infected with MRSA.

Patients and Methods

A prospective analysis of 62 patients with wound infections, who were admitted to our department from 2016 to 2020, was conducted in order to assess the efficacy of different treatment approaches. The patients were divided into two groups: the experimental group and the control group. In the experimental group, 30 patients underwent treatment with a combination of diluted povidone iodine and polyhexanide immersion. Conversely, in the control group, 32 patients received treatment with diluted povidone iodine along with systemic antibiotic therapy. The time required for dressing changes, bacterial clearance rates, and the Bates-Jasen wound assessment tool (BWAT) scores were utilized as indicators to evaluate the effectiveness of the treatments.

Results

In our study, the findings indicated that the experimental group exhibited a lesser number of days for the bacteria culture to turn negative compared to the control group, with statistical significance (p<0.05). Furthermore, the decline in the BWAT score was significantly greater in the experimental group than in the control group (p<0.05). However, no significant differences were observed in terms of dressing times and wound coverage between the two groups (p>0.05).

Conclusion

Polyhexanide combined with povidone iodine can effectively remove MRSA infection in wounds and reduce antibiotic dosages.

[Multidrug-resistant bacterial colonisation in Ukrainian war injuries: a need for multimodal therapy]

This case report describes the interdisciplinary treatment of a complex shrapnel injury to the right femur of an 18-year-old Ukrainian soldier. This open multifragmentary fractur of the femur with a large bone defect, soft tissue damage and osteomyelitis was complicated by several multidrug-resistant bacteria, including Acinetobacter baumanii, which could not be eradicated by antibiotic treatment. Sterility was only achieved by multiple radical debridement and by negative pressure wound therapy with instillation (NPWTi) using hypochlorous acid. The femur was then reconstructed with a chimeric double-barrel fibula free flap. This report highlights the importance of multimodal antimicrobial wound treatments in an era of increasing antibiotic resistance to enable a successful und functional reconstruction of complex and infected fractures.

Quality of lower limb preoperative skin preparation using colorless versus colored disinfectants-results of an experimental, randomized study in a close to reality setting

BACKGROUND

Appropriate preoperative skin cleansing is important to control surgical site infections. Both colored and colorless skin disinfectants are available, however certain types of skin preparation, such as octenidine-dihydrochloride with alcohol have a long residual antimicrobial effect but are available only in colorless form. We hypothesized that colorless skin disinfectants lead to more incomplete skin preparation of lower limbs compared to colored agents.

METHODS

We randomly assigned healthy volunteers to undergo a determined skin cleansing protocol for total hip arthroplasty in the supine position to either a colored or colorless skin cleansing protocol. The adequacy of skin preparation was compared between orthopedic consultants and residents. The colorless disinfectant was mixed with a fluorescent dye and missed skin areas were visualized using UV lamps. Both preparations were photo-documented following standardized protocols. The primary outcome of interest was the number of legs with an incomplete scrubbed area. The secondary outcome was the cumulative skin area not disinfected.

RESULTS

Fifty-two healthy volunteers (104 legs; 52 colored and 52 colorless) underwent surgical skin preparation. The number of legs incompletely disinfected was significantly higher in colorless compared to colored disinfectant group (38.5% (n = 20) vs. 13.5% (n = 7); p = 0.007). Regardless of the disinfectant, consultants performed better than the residents. When using colored disinfectant, residents incompletely prepared the site in 23.1% (n = 6) compared with 57.7% (n = 15) with a colorless disinfectant (p = 0.023). Conversely consultants using colored disinfectant incompletely prepared the site in 3.8% (n = 1) compared with 19.2% (n = 5) for colorless disinfectant (p = 0.191). The total amount of uncleansed skin was significantly higher using colorless skin disinfectant (mean ± standard deviation: 8.78 cm2± 35.07 vs. 0.65 cm2 ± 2.66, p = 0.002).

CONCLUSIONS

Application of colorless skin disinfectants for hip arthroplasty cleansing protocol led to decreased skin coverage among consultants and residents compared to colored preparations. Colored disinfectants remain the gold standard in hip surgery, however we should be aiming to develop newer colored disinfectants with long residual antimicrobial effects to enable visual control during the scrubbing process.

The Impact of Antiseptic-Loaded Bacterial Nanocellulose on Different Biofilms-An Effective Treatment for Chronic Wounds?

Introduction: Pathogenic biofilms are an important factor for impaired wound healing, subsequently leading to chronic wounds. Nonsurgical treatment of chronic wound infections is limited to the use of conventional systemic antibiotics and antiseptics. Wound dressings based on bacterial nanocellulose (BNC) are considered a promising approach as an effective carrier for antiseptics. The aim of the present study was to investigate the antimicrobial activity of antiseptic-loaded BNC against in vitro biofilms. Materials and Methods: BNC was loaded with the commercially available antiseptics Prontosan^® and Octenisept^®. The silver-based dressing Aquacel^®Ag Extra was used as a positive control. The biofilm efficacy of the loaded BNC sheets was tested against an in vitro 24-hour biofilm of Staphylococcus aureus and Candida albicans and a 48-hour biofilm of Pseudomonas aeruginosa. In vivo tests using a porcine excisional wound model was used to analyze the effect of a prolonged treatment with the antiseptics on the healing process. Results: We observed complete eradication of S. aureus biofilm in BNC loaded with Octenisept^® and C. albicans biofilm for BNC loaded with Octenisept^® or Prontosan^®. Treatment with unloaded BNC also resulted in a statistically significant reduction in bacterial cell density of S. aureus compared to untreated biofilm. No difference on the wound healing outcome was observed for the wounds treated for seven days using BNC alone in comparison to BNC combined with Prontosan^® or with Octenisept^®. Conclusions: Based on these results, antiseptic-loaded BNC represents a promising and effective approach for the treatment of biofilms. Additionally, the prolonged exposure to the antiseptics does not affect the healing outcome. Prevention and treatment of chronic wound infections may be feasible with this novel approach and may even be superior to existing modalities.

In vitro study of the ecotoxicological risk of methylisothiazolinone and chloroxylenol towards soil bacteria

Methylisothiazolinone (MIT) and chloroxylenol (PCMX) are popular disinfectants often used in personal care products (PCPs). The unregulated discharge of these micropollutants into the environment, as well as the use of sewage sludge as fertilizer and reclaimed water in agriculture, poses a serious threat to ecosystems. However, research into their ecotoxicity towards nontarget organisms is very limited. In the present study, for the first time, the ecotoxicity of biocides to Pseudomonas putida, Pseudomonas moorei, Sphingomonas mali, and Bacillus subtilis was examined. The toxicity of MIT and PCMX was evaluated using the microdilution method, and their influence on the viability of bacterial cells was investigated by the AlamarBlue® test. The ability of the tested bacteria to form biofilms was examined by a microtiter plate assay. Intracellular reactive oxygen species (ROS) production was measured with CM-H2DCFDA. The effect of MIT and PCMX on phytohormone indole-3-acetic acid (IAA) production was determined by spectrophotometry and LC‒MS/MS techniques. The permeability of bacterial cell membranes was studied using the SYTOX Green assay. Changes in the phospholipid profile were analysed using LC‒MS/MS. The minimal inhibitory concentrations (MICs) values ranged from 3.907 to 15.625 mg L^-1 for MIT and 62.5 to 250 mg L^-1 for PCMX, indicating that MIT was more toxic. With increasing concentrations of MIT and PCMX, the cell viability, biofilm formation ability and phytohormone synthesis were maximally inhibited. Moreover, the growth of bacterial cell membrane permeability and a significantly increased content of ROS were observed, indicating that the exposure caused serious oxidative stress and homeostasis disorders. Additionally, modifications in the phospholipid profile were observed in response to the presence of sublethal concentrations of the chemicals. These results prove that the environmental threat posed by MIT and PCMX must be carefully monitored, especially as their use in PCPs is still growing.

In vitro evaluation of the antimicrobial activity of antiseptics against clinical Acinetobacter baumannii strains isolated from combat wounds

Healthcare-associated infections (HCAIs) are among the most prominent medical problems worldwide. In the context of increasing antibiotic resistance globally, the use of antiseptics as the main active agent and potentiator of antibiotics for the treatment of purulent-inflammatory complications of traumatic wounds, burns, and surgical wounds can be considered to tackle opportunistic infections and their prevention during war. This study presents a comparative investigation of the antimicrobial efficacy of antiseptics used for surgical antisepsis and antiseptic treatment of skin, mucous membranes, and wounds against multidrug-resistant clinical isolates of Acinetobacter baumannii as a wound pathogen of critical priority (according to the WHO). It was found that strains of A. baumannii, which have natural and acquired resistance to antimicrobial drugs, remain susceptible to modern antiseptics. Antiseptic drugs based on decamethoxine, chlorhexidine, octenidine, polyhexanide, and povidone-iodine 10% and 2% provide effective bactericidal activity against A. baumannii within the working concentrations of these drugs. Chlorhexidine and decamethoxine can inhibit biofilm formation by A. baumannii cells. In terms of bactericidal properties and biofilm formation inhibition, chlorhexidine and decamethoxine are the most effective of all tested antiseptics.

Topical Antibiofilm Agents With Potential Utility in the Treatment of Chronic Rhinosinusitis: A Narrative Review

The role of bacterial biofilms in chronic and recalcitrant diseases is widely appreciated, and the treatment of biofilm infection is an increasingly important area of research. Chronic rhinosinusitis (CRS) is a complex disease associated with sinonasal dysbiosis and the presence of bacterial biofilms. While most biofilm-related diseases are associated with highly persistent but relatively less severe inflammation, the presence of biofilms in CRS is associated with greater severity of inflammation and recalcitrance despite appropriate treatment. Oral antibiotics are commonly used to treat CRS but they are often ineffective, due to poor penetration of the sinonasal mucosa and the inherently antibiotic resistant nature of bacteria in biofilms. Topical non-antibiotic antibiofilm agents may prove more effective, but few such agents are available for sinonasal application. We review compounds with antibiofilm activity that may be useful for treating biofilm-associated CRS, including halogen-based compounds, quaternary ammonium compounds and derivatives, biguanides, antimicrobial peptides, chelating agents and natural products. These include preparations that are currently available and those still in development. For each compound, antibiofilm efficacy, mechanism of action, and toxicity as it relates to sinonasal application are summarised. We highlight the antibiofilm agents that we believe hold the greatest promise for the treatment of biofilm-associated CRS in order to inform future research on the management of this difficult condition.

Effectiveness of implementing a preventive urinary catheter care bundle in hip fracture patients

Background

Urinary catheter (UC)–associated infections are one of the most common preventable healthcare-associated infections (HAIs) and they frequently occur in older, frail populations.

Aim

The study aim was to describe the incidence of UC-associated infection in elderly patients undergoing hip fracture surgery after implementing a preventive care bundle.

Methods

A longitudinal prospective study using a before-and-after design. The bundle was theory driven and involved the co-creation of a standard operational procedure, education and practical training sessions. Prospectively collected registry data were analysed. Univariable statistics and multivariable logistic regressions were used for analyses.

Results

2,408 patients with an acute hip fracture were included into the study. There was an overall reduction in UC catheter associated-associated urinary tract infections, from 18.5% (n = 75/406) over time to 4.2% (n = 27/647). When adjusting for all identified confounders, patients in phase 4 were 74% less likely to contract an UC-associated infection (OR, 0.26; 95% CI, 0.15–0.45, p < 0.0001).

Discussion

Bundled interventions can reduce UC-associated infections substantially, even in elderly frail patients. Partnership and co-creation as implementation strategies appear to be promising in the fight against HAI.

Silver distribution in chronic wounds and the healing dynamics of chronic wounds treated with dressings containing silver and octenidine

Although silver is an efficient antimicrobial and is a widely used antiseptic in wound healing, previous studies have reported the cytotoxic in vitro effects of silver dressings. Moreover, few studies have addressed the distribution of silver in chronic wounds. The study compares the healing of chronic wounds treated with a standard-of-care silver dressing (Ag-CMC) and a dressing containing antiseptic octenidine (OCT-HA). Biopsies were taken from two wound areas before the commencement of treatment (baseline), after 2 weeks and after 6 weeks (the end of the study). We analyzed the histopathologic wound-healing score, silver distribution, and expression of selected genes. The wound-healing score improved significantly in the wounded area treated with OCT-HA after 2 weeks compared to the baseline and the Ag-CMC. The Ag-CMC wound areas improved after 6 weeks compared to the baseline. Moreover, collagen maturation and decreases in the granulocyte and macrophage counts were faster in the OCT-HA parts. Treatment with OCT-HA resulted in less wound slough. The silver, visualized via autometallography, penetrated approximately 2 mm into the wound tissue and associated around capillaries and ECM fibers, and was detected in phagocytes. The metallothionein gene expression was elevated in the Ag-CMC wound parts. This exploratory study determined the penetration of silver into human chronic wounds and changes in the distribution thereof during treatment. We observed that silver directly affects the cells in the wound and elevates the metallothionein gene expression. Octenidine and hyaluronan dressings provide a suitable alternative to silver and carboxymethyl cellulose dressings without supplying silver to the wound.