Addressing the challenges in antisepsis: focus on povidone iodine

Antiseptics' Concentration, Combination, and Exposure Time on Bacterial and Fungal Biofilm Eradication

Background

This study aims to assess the activity of solutions containing povidone-iodine (PI) and hydrogen peroxide (H2O2) alone or combined on the biofilm of microbial species in the contest of periprosthetic joint infection (PJI).

Methods

Different antiseptic solutions were tested on 2-day-old biofilms of Gram-positive and Gram-negative bacteria and fungi at 1 and 3 minutes of exposure. The efficacy of these solutions was evaluated by measuring the biofilm metabolic activity by methoxynitrosulfophenyl-tetrazolium carboxanilide (XTT) reduction assay. The anti-biofilm effect of 5% PI and 0.3% PI + 0.5% H2O2 was tested on a 5-day-old biofilm using colony-forming unit counts and an XTT reduction assay.

Results

PI and H2O2 solutions showed concentration-dependent anti-biofilm activity except for E. faecalis. PI at 5% was the most active solution against the 2-day-old biofilm of all test microorganisms. The 0.3% PI + 0.5% H₂O₂ solution had a significant effect only at 3 minutes. The 5% PI and 0.3% PI + 0.5% H₂O₂ effect was evaluated on 5-day-old biofilms. PI at 5% produced a significant reduction in metabolic activity at both 1 and 3 minutes; 0.3% PI + 0.5% H₂O₂ caused a significant activity against all Gram-positive strains after 3 minutes, with a greater metabolic activity reduction than 5% PI.

Conclusions

In the case of PJI caused by Gram-positive bacteria, 0.3% PI + 0.5% H₂O₂ could be used for wound irrigation for 3 minutes of exposure. In the case of PJI with a different etiological agent or PJI with an unknown etiology, it is advisable to use 5% PI for 1 minute of exposure.

Silicone Bioadhesive with Shear-Stiffening Effect: Rate-Responsive Adhesion Behavior and Wound Dressing Application

Stimuli-responsive adhesives with on-demand adhesion capabilities are highly advantageous for facilitating wound healing. However, the triggering conditions of stimuli-responsive adhesives are cumbersome, even though some of them are detrimental to the adhesive and adjacent natural tissues. Herein, a novel stimuli-responsive adhesive called shear-stiffening adhesive (SSA) has been created by constructing a poly(diborosiloxane)-based silicone network for the first time, and SSA exhibits a rate-responsive adhesion behavior. Furthermore, we introduced bactericidal factors (PVP-I) into SSA and applied it as a wound dressing to promote the healing of infected wounds. Impressively, the wound dressing not only has excellent biocompatibility and long-term antibacterial properties but also performs well in accelerating wound healing. Therefore, this study provides a new strategy for the synthesis of intelligent adhesives with force rate response, which simplifies the triggering conditions by the force rate. Thus, SSA has great potential to be applied in wound management as an intelligent bioadhesive with on-demand adhesion performance.

Pathogens in FRI - Do bugs matter? - An analysis of FRI studies to assess your enemy

Fracture-related infection (FRI) is a devasting complication for both patients and their treating Orthopaedic surgeon that can lead to loss of limb function or even amputation. The unique and unpredictable features of FRI make its diagnosis and treatment a significant challenge. It has substantial morbidity and financial implications for patients, their families and healthcare providers. In this article, we perform an in-depth and comprehensive review of FRI through recent and seminal literature to highlight evolving definitions, diagnostic and treatment approaches, focusing on common pathogens such as Staphylococcus aureus, polymicrobial infections and multi-drug-resistant organisms (MDRO). Furthermore, multiple resistance mechanisms and adaptations for microbial survival are discussed, as well as modern evidence-based medical and surgical advancements in treatment strategies in combating FRI.

[Antiseptics in otorhinolaryngology-a substance overview]

For preoperative skin antisepsis, alcohol-containing iodine solutions and octenidine are suitable. For wound antisepsis, polyhexanide and hypochlorous acid (HOCL) are also available, but only PVP-iodine and HOCL can be applied to cartilage. Chlorhexidine should only be used as mouth- and bodywash for Staphylococcus aureus (MRSA) decolonization. For the many other throat antiseptics, evidence of clinical efficacy is lacking. For decolonization of the nares, polyhexanide and octenidine are available as nasal gels, but these are inferior to mupirocin for MRSA decolonization. PVP-iodine and HOCL are safe to use for nasal irrigation, but only HOCL has proven effective to improve symptoms of chronic rhinosinusitis. All antiseptics exhibit a certain ototoxicity. With an intact eardrum, acetic acid-containing eardrops can be used to prevent and treat external otitis and myringitis. When the eardrum is perforated, only alcohol-free PVP-iodine and HOCL may be used.

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.

Safety and effectiveness of an antiseptic wound cleansing and irrigation solution containing polyhexamethylene biguanide

OBJECTIVE

There is currently a wide range of cleansing and irrigation solutions available for wounds, many of which contain antimicrobial agents. The aim of this study was to assess the safety of HydroClean Solution (HARTMANN, Germany), a polyhexamethylene biguanide (PHMB)-containing irrigation solution, in a standard cytotoxicity assay, and to assess its effect in a three-dimensional (3D) full-thickness model of human skin.

METHOD

A number of commercially available wound cleansing and irrigation solutions, including the PHMB-containing irrigation solution, were tested in a cytotoxicity assay using L929 mouse fibroblasts (ISO 10993-5:2009). The PHMB-containing irrigation solution was then assessed in an in vitro human keratinocyte-fibroblast 3D full-thickness wounded skin model to determine its effect on wound healing over six days. The effect of the PHMB-containing irrigation solution on tissue viability was measured using a lactate dehydrogenase (LDH) assay, and proinflammatory effects were measured using an interleukin-6 (IL-6) production assay.

RESULTS

The PHMB-containing irrigation solution was shown to be equivalent to other commercially available cleansing and irrigation solutions when tested in the L929 fibroblast cytotoxicity assay. When assessed in the in vitro 3D human full-thickness wound healing model, the PHMB-containing irrigation solution treatment resulted in no difference in levels of LDH or IL-6 when compared with levels produced in control Dulbecco's phosphate-buffered saline cultures. There was, however, a pronounced tissue thickening of the skin model in the periwound region.

CONCLUSION

The experimental data presented in this study support the conclusion that the PHMB-containing irrigation solution has a safety profile similar to other commercially available cleansing and irrigation solutions. Evidence also suggests that the PHMB-containing irrigation solution does not affect tissue viability or proinflammatory cytokine production, as evidenced by LDH levels or the production of IL-6 in a 3D human full-thickness wound healing model. The PHMB-containing irrigation solution stimulated new tissue growth in the periwound region of the skin model.

Development, characterization, and evaluation of a simple polymicrobial colony biofilm model for testing of antimicrobial wound dressings

Chronic wound infections are generally of polymicrobial nature with aerobic and anaerobic bacteria, as well as fungi frequently observed in them. Wound treatment involves a series of steps, including debridement of the wound, flushing, and often the use of multiple wound dressings many of which are antimicrobial. Yet, many wound dressings are tested versus single species of planktonic microbes, which fails to mirror the real-life presence of biofilms.

AIMS

Simple biofilm models are the first step to testing of any antimicrobial and wound dressing; therefore, the aim of this study was to develop and validate a simple polymicrobial colony biofilm wound model comprised of Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans on RPMI-1640 agar. The model was then used to evaluate the topical disinfectant chlorohexidine and four commercially available wound dressings using the polymicrobial model. The model used was as a starting point to mimic debridement in clinical care of wounds and the effectiveness of wound dressings evaluated afterwards.

METHODS AND RESULTS

Planktonic assessment using AATCC100-2004 demonstrated that all antimicrobial wound dressings reduced the planktonic microbial burden below the limit of detection; however, when challenged with polymicrobial colony biofilms, silver wound dressings showed limited effectiveness (1-2 log CFU reductions). In contrast, a single iodine releasing wound dressing showed potent antibiofilm activity reducing all species CFUs below the limit of detection (>6-10 log) depending on the species. A disrupted biofilm model challenge was performed to represent the debridement of a wound and wound silver-based wound dressings were found to be marginally more effective than in whole colony biofilm challenges while the iodine containing wound dressing reduced microbial recovery below the limit of detection.

CONCLUSIONS

In this model, silver dressings were ineffective versus the whole colony biofilms but showed some recovery of activity versus the disrupted colony biofilm. The iodine wound dressing reduced the viability of all species below the level of detection. This suggests that mode of action of wound dressing should be considered for the type of biofilm challenge as should the clinical use, e.g. debridement.

Chitosan‑iodine complexes: Preparation, characterization, and antibacterial activity

Bacterial infections have always been a major threat to public health, and the development of effective antibacterial substances from natural polymers is crucial. 2-Aminoisonicotinic acid (AN) was grafted onto chitosan by 1-ethyl-(3-dimethylaminopropyl)carbodiimide-mediated coupling reactions, and then modified chitosan‑iodine (CSAN-I) complexes were prepared by solvent-assisted grinding. The samples were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray diffraction, confirming that CSAN-I complexes had been successfully prepared. Thermogravimetric (TG) analysis indicated that the chemical modification of chitosan and iodine complexation reduced the thermal stability; X-ray photoelectron spectroscopy (XPS) analysis revealed that 81 % of the iodine in CSAN-I complex was in the form of triiodide ions. The iodine contents of three CSAN-I complexes (CSAN-I-1, CSAN-I-2 and CSAN-I-3) were 1.59 ± 0.22 %, 3.18 ± 0.26 %, and 5.56 ± 0.41 %, respectively. The antibacterial effects were evaluated in vitro, and the results indicated that CSAN-I complexes had strong antibacterial activities against both E. coli and S. aureus. In particular, CSAN-I-3 exhibited the best antibacterial effect. In addition, CSAN-I-3 was nontoxic to L929 cells with good cytocompatibility. Therefore, CSAN-I complexes can be considered as promising candidates for wound management in clinical applications.

Antiseptic, Hemostatic, and Wound Activity of Poly(vinylpyrrolidone)-Iodine Gel with Trimethyl Chitosan

Wound management practices have made significant advancements, yet the search for improved antiseptics persists. In our pursuit of solutions that not only prevent infections but also address broader aspects of wound care, we investigated the impact of integrating trimethyl chitosan (TMC) into a widely used poly(vinylpyrrolidone)-iodine gel (PVP-I gel). Our study assessed the antimicrobial efficacy of the PVP gel with TMC against Escherichia coli, Staphylococcus aureus, multidrug-resistant S. aureus MRSA, and Candida albicans. Additionally, we compared hemostatic effects using a liver puncture bleeding model and evaluated wound healing through histological sections from full-thickness dermal wounds in rats. The results indicate that incorporating TMC into the commercially available PVP-I gel did not compromise its antimicrobial activity. The incorporation of TMC into the PVP-I gel markedly improves its hemostatic activity. The regular application of the PVP-I gel with TMC resulted in an increased blood vessel count in the wound bed and facilitated the development of thicker fibrous tissue with a regenerated epidermal layer. These findings suggest that TMC contributes not only to antimicrobial activity but also to the intricate processes of tissue regeneration. In conclusion, incorporating TMC proves beneficial, making it a valuable additive to commercially available antiseptic agents.

Advances in Contact Lens Care Solutions: PVP-I Disinfectant and HAD Wetting Agents From Japan

ABSTRACT

Half of the individuals who wear contact lenses use reusable lenses that require proper care. Improper contact lens (CL) care and using inadequate disinfecting solutions can lead to lens contamination, CL-related microbial keratitis, and Acanthamoeba keratitis. Oxidative disinfecting solutions, such as hydrogen peroxide, show higher efficacy than multipurpose solutions. Povidone-iodine (PVP-I), an oxidative disinfectant used in ophthalmic surgery, has been proven to be safe and effective. The PVP-I system, a CL disinfecting solution developed in Japan, has demonstrated excellent antimicrobial and antiviral properties. Although CL discomfort does not have a risk of ocular disorders with poor visual prognosis, such as keratitis, CL discomfort can still lead to lens dropout and thus needs to be addressed. To mitigate CL discomfort, it is essential to use disinfecting solutions containing surfactants and wetting agents that improve wettability of the lens surface. A CL solution containing hyaluronic acid derivatives (HADs) as wetting agents that permanently adhere to the lens surface to improve wettability of the lens surface was developed in Japan. There is potential for HAD to be integrated into various solutions. This article reviews the efficacy of novel PVP-I-based disinfecting solution and HAD wetting agents.

Fibrous matrices facilitate pleurocidin killing of wound associated bacterial pathogens

Conventional wound infection treatments neither actively promote wound healing nor address the growing problem of antibacterial resistance. Antimicrobial peptides (AMPs) are natural defense molecules, released from host cells, which may be rapidly bactericidal, modulate host-immune responses, and/or act as endogenous mediators for wound healing. However, their routine clinical use has hitherto been hindered due to their instability in the wound environment. Here we describe an electrospun carrier system for topical application of pleurocidin, demonstrating sufficient AMP release from matrices to kill wound-associated pathogens including Acinetobacter baumannii and Pseudomonas aeruginosa. Pleurocidin can be incorporated into polyvinyl alcohol (PVA) fiber matrices, using coaxial electrospinning, without major drug loss with a peptide content of 0.7% w/w predicted sufficient to kill most wound associated species. Pleurocidin retains its activity on release from the electrospun fiber matrix and completely inhibits growth of two strains of A. baumannii (AYE; ATCC 17978) and other ESKAPE pathogens. Inhibition of P. aeruginosa strains (PAO1; NCTC 13437) is, however, matrix weight per volume dependent, with only larger/thicker matrices maintaining complete inhibition. The resulting estimation of pleurocidin release from the matrix reveals high efficiency, facilitating a greater AMP potency. Wound matrices are often applied in parallel or sequentially with the use of standard wound care with biocides, therefore the presence and effect of biocides on pleurocidin potency was tested. It was revealed that combinations displayed additive or modestly synergistic effects depending on the biocide and pathogens which should be considered during the therapy. Taken together, we show that electrospun, pleurocidin-loaded wound matrices have potential to be investigated for wound infection treatment.

Evaluation of dermal toxicity and toxicokinetics of povidone‑iodine in Göttingen minipigs

BACKGROUND

Povidone‑iodine (PVP-I) is an effective and commonly used broad-spectrum antiseptic; limited information exists around its long-term safety and impact on endocrine disruption. We assessed the dermal toxicity and toxicokinetics following a once-daily application of 7.5% (w/v) and 10% (w/v) PVP-I in Göttingen Minipigs® for up to 39 weeks.

METHODS

An in vivo study was conducted in male (n = 27) and female (n = 27) minipigs. Animals were randomized into untreated control, 7.5% and 10% PVP-I, and matching vehicle treatment groups. Animals were assessed for general in-life measurements, including skin irritation and organ weights. Serum samples were analyzed for PVP, total iodine, triiodothyronine [T3], thyroxine [T4], thyroid stimulating hormone [TSH], and toxicokinetic parameters.

RESULTS

Neither 7.5% nor 10% PVP-I affected general in-life measurements. Increased mean thyroid gland absolute weights were noted with 7.5% and 10% PVP-I. Serum levels of PVP, T3, T4, and TSH in the 7.5% and 10% PVP-I treatment group animals were similar to those in vehicle treatment group animals. Mean total serum iodine concentration was 52- and 13-fold higher with 7.5% and 10% PVP-I, respectively, vs respective vehicle treatments. There was no dose-dependent increase in mean maximum serum concentration and area under the curve from 0 to 24 h for PVP, T3, T4, and TSH, nor accumulation of PVP, T3, T4, or TSH in the study.

CONCLUSION

Once-daily dermal application of 7.5% and 10% PVP-I for up to 39 weeks was safe and well tolerated in Göttingen Minipigs® and was not associated with skin irritation, thyroid dysfunction, or endocrine disruption. As the anatomy and physiology of the minipig skin closely resembles that of human skin, the findings of this study suggest that 7.5% and 10% PVP-I may be translated into antimicrobial benefits for humans without the risk of endocrine disruption.

Iodine-doped TiO2 nanotube coatings: a technique for enhancing the antimicrobial properties of titanium surfaces against Staphylococcus aureus

BACKGROUND

Implant-related infections are a challenging complication of orthopedic surgery, primarily due to the formation of bacterial biofilms on the implant surface. An antibacterial coating for titanium implants was developed to provide novel insights into the prevention and treatment of implant-related infections.

METHODS

Titanium plates were coated with TiO2 nanotubes by anodization, and iodine was doped onto the coating via electrophoretic deposition. The obtained plates were characterized using a range of analytical techniques. Subsequently, Staphylococcus aureus was inoculated onto the surfaces of untreated titanium plates (control group), TiO2-nanocoated titanium plates (TiO2 group), and iodine-doped TiO2-nanocoated titanium plates (I-TiO2 group) to compare their antibacterial properties.

RESULTS

Twenty-four hour in vitro antimicrobial activity test of the I-TiO2 group against Staphylococcus aureus was superior to those of the other groups, and this difference was statistically significant (P < 0.05).

CONCLUSIONS

This coating technology provides a new theoretical basis for the development of anti-infective implants against Staphylococcus aureus in orthopedics.

Decamethoxin and chlorhexidine bigluconate effect on the adhesive and biofilm-forming properties of Streptococcus mitis

The aim of the study

Was to investigate the effect of antiseptics on the adhesive and biofilm-forming properties of clinical S.mitis isolates isolated from the oral cavity of patients with an infectious and inflammatory post-extraction complication.

Materials and methods

Twenty four clinical isolates of S.mitis isolated from patients were studied. The studied antiseptics included 0.02% aqueous solution of decamethoxin and 0.05% solution of chlorhexidine bigluconate. Adhesion of clinical isolates under the action of decamethoxin and chlorhexidine bigluconate was determined by the method of V.I. Brillis. The biofilm-forming properties of clinical isolates were studied using the "microtiter plate test" according to G.D. Christensen.

Results

The studied clinical isolates of S.mitis are classified as highly adherent microorganisms. Action of decamethoxin on clinical isolates decreases the adhesion index of the studied isolates in comparison with the adhesion index of the control culture. Action of chlorhexidine bigluconate on S.mitis isolates increases of adhession of the studied clinical isolates in comparison with the control. After the effect of decamethoxin, the optical density of clinical isolates decreased considering the optical density results of the control. The clinical isolates left an average film-forming capacity even after chlorhexidine bigluconate action.

Conclusions

Clinical isolates of S.mitis are highly adherent microorganisms. The antiseptic decamethoxin decreases the adhesion index of these bacteria, while chlorhexidine bigluconate increases the adhesion index of clinical S.mitis isolates. Clinical S. mitis isolates have an average biofilm formation capacity index. The antiseptic decamethoxin inhibits the biofilm formation capacity of S.mitis from medium to low.

Investigating the effect of eye drops based on iodine nanoparticles in the treatment of corneal ulcers in rabbit eyes

BACKGROUND

Various organisms, such as bacteria, viruses, and fungi, can cause corneal ulcers. One of the leading causes of vision loss and disability worldwide is corneal ulceration. Practical, accessible, and affordable treatment for this disease seems essential.

MATERIALS AND METHODS

Fifteen New Zealand rabbits infected with Staphylococcus aureus (ATCC 25923) corneal ulcers were randomly divided into three groups of five for the present study. (I, II, and III). Group I was used as the control group (without treatment). The second group received an iodine solution (1.25%) without a nanoparticle structure (betadine). The third group received an iodine solution with a nanoparticle structure used as eye drops. Drops in the corneal ulcer group were used five times daily for 14 days. Microbial counts and disease severity scores were measured on the first, second, fifth, and fourteenth days and compared between groups separately for each disease.

RESULTS

The results showed that the changes in microbial load were significant in the group that received betadine and nanoparticles. The microbial load was further reduced when using iodine nanoparticles than betadine. The betadine and nano-iodine groups significantly reduced the severity of the disease in rabbits with corneal ulcers (p < 0.05). The average changes in disease severity score were 4.8 ± 1.3, -2.6 ± 0.89, and -2.22 ± 1.22 in the untreated, nano iodine, and betadine groups, respectively. However, a significant increase in disease severity was observed in the untreated group (p = 0.001). It shows a significant difference (p < 0.001) between the nano iodine, betadine, and untreated groups. However, the difference in disease severity changes between nano iodine and non-nano iodine groups was insignificant.

CONCLUSION

Nanoparticle iodine is more effective than non-nanoparticle iodine in reducing bacterial load. In reducing the severity of the disease, both types of iodine were superior to no treatment. But there was no apparent difference between the two groups treated with iodine.

Anti-influenza Activity of Povidone-Iodine-Integrated Materials

Personal protective equipment (PPE), including medical masks, should be worn for preventing the transmission of respiratory pathogens via infective droplets and aerosols. In medical masks, the key layer is the filter layer, and the melt-blown nonwoven fabric (NWF) is the most used fabric. However, the NWF filter layer cannot kill or inactivate the pathogens spread via droplets and aerosols. Povidone-iodine (PVP-I) has been used as an antiseptic solution given its potent broad-spectrum activity against pathogens. To develop PPE (e.g., medical masks) with anti-pathogenic activity, we integrated PVP-I into nylon-66 NWF. We then evaluated its antiviral activity against influenza A viruses by examining the viability of Madin-Darby canine kidney (MDCK) cells after inoculation with the virus strains exposed to the PVP-I-integrated nylon-66 NWF. The PVP-I nylon-66 NWF protected the MDCK cells from viral infection in a PVP-I concentration-dependent manner. Subsequently, we found to integrate PVP-I into nylon-66 and polyurethane materials among various materials. These PVP-I materials were also effective against influenza virus infection, and treatment with PVP-I nylon-66 NWF showed the highest cell survival among all the tested materials. PVP-I showed anti-influenza A virus activity when used in conjunction with PPE materials. Moreover, nylon-66 NWF integrated with PVP-I was found to be the best material to ensure anti-influenza activity. Therefore, PVP-I-integrated masks could have the potential to inhibit respiratory virus infection. Our results provide new information for developing multi-functional PPEs with anti-viral activity by integrating them with PVP-I to prevent the potential transmission of respiratory viruses.

Assessment of SARS-CoV-2 (COVID-19) Clinical Mouthwash Protocol and Prevalence of the Oral Pathogen Scardovia wiggsiae: A Pilot Study of Antibacterial Effects

One protocol in healthcare facilities and dental offices due to the COVID-19 pandemic for reducing the amount of detectable oral SARS-CoV-2 has been gargling with mouthwash for 60 s. This protocol lasts longer than the daily routine for most patients and may have unexpected benefits in reducing oral microbes as a result. This project evaluated the prevalence of the newly identified oral pathogen Scardovia wiggsiae before and after this procedure to determine any measurable effects. Using an approved protocol, n = 36 pre-mouthwash patient samples, n = 36 matched post-mouthwash samples, and n = 36 matched recall samples were identified (total sample number n = 108). DNA was isolated from each sample (pre-, post-mouthwash, and recall). Screening using qPCR and validated primers revealed n = 10/36 or 27.8% tested positive for Scardovia among the pre-mouthwash (Sample A) isolates with n = 3/36 or 8.3% testing positive among the post-mouthwash (Sample B) isolates. Screening of the recall (Sample C) samples has revealed n = 10/36, or 27.8% once again tested positive for Scardovia, demonstrating that this pathogen was found among a significant proportion of pediatric patient samples. Moreover, the COVID-19-related procedure of requiring sustained mouth washing prior to clinical treatment appears to reduce the levels of detectable Scardovia, at least initially. However, this study found no long-term effects using this isolated protocol.

Phenotypic Modulation of Adipose-Derived Stem Cells and Fibroblasts Treated with Povidone-Iodine and Chlorhexidine in Mono and Coculture Models

Topical antiseptics are essential in wound treatment, and adipose-derived stem cells (ADSCs) have recently been proven to facilitate healing. However, the impact of antiseptics on ADSCs has not been fully elucidated, especially in relation to other relevant cell types present in the wound microenvironment, e.g., fibroblasts. This study evaluated the effects of chlorhexidine and povidone-iodine on four cellular constructs in 2D and 3D in vitro culture systems. Cell constructs were treated with two concentrations of each antiseptic, after which cell migration activity, α-SMA, and Ki67 marker expressions were assessed and compared. Both tested concentrations of povidone-iodine impaired migration and sprouting compared to chlorhexidine, which had minimal effects when used in low concentrations. The gap in the wound healing assay did not close after 24 h of povidone-iodine treatment, although, at the lower concentration, cells started to migrate in a single-cell movement pattern. Similarly, in 3D culture systems, sprouting with reduced spike formation was observed at high povidone-iodine concentrations. Both antiseptics modulated α-SMA and Ki67 marker expressions at 5 days following treatment. Although both antiseptics had cytotoxic effects dependent on drug concentration and cell type, povidone-iodine contributed more substantially to the healing process than chlorhexidine, acting especially on fibroblasts.

Evaluation of the role of povidone‑iodine in the prevention of surgical site infections

Background

The occurrence of surgical site infections (SSIs) is associated with increased risk of mortality, development of other infections, and the need for reintervention, posing a significant health burden. The aim of this review was to examine the current data and guidelines around the use of antiseptic povidone‑iodine (PVP-I) for the prevention of SSIs at each stage of surgical intervention.

Methods

A literature search for selected key words was performed using PubMed. Additional papers were identified based on author expertise.

Results

Scientific evidence demonstrates that PVP-I can be used at every stage of surgical intervention: preoperative, intraoperative, and postoperative. PVP-I is one of the most widely used antiseptics on healthy skin and mucous membranes for preoperative surgical site preparation and is associated with a low SSI rate. For intraoperative irrigation, aqueous PVP-I is the recommended agent and has been demonstrated to decrease SSIs in a range of surgical settings, and for postoperative wound healing, there is a growing body of evidence to support the use of PVP-I.

Conclusions

There is a need for more stringent study designs in clinical trials to enable meaningful comparisons between antiseptic agents, particularly for preoperative skin preparation. The use of a single agent (PVP-I) at each stage of surgical intervention could potentially provide advantages, including economic benefits, over agents that can only be used at discrete stages of the surgical procedure.

Key message

Evidence supports the use of PVP-I at all stages of surgical intervention, from preoperative measures (including skin preparation, preoperative washing, and nasal decolonization) to intraoperative irrigation, through to postoperative wound management. However, there is a need for more stringent study designs in clinical trials to enable meaningful comparisons between antiseptic agents, particularly for preoperative skin preparation.

Fungal quorum-sensing molecules and antiseptics: a promising strategy for biofilm modulation?

New strategies to control fungal biofilms are essential, especially those that interfere in the biofilm organization process and cellular communication, known as quorum sensing. The effect of antiseptics and quorum-sensing molecules (QSMs) have been considered with regard to this; however, little has been elucidated, particularly because studies are often restricted to the action of antiseptics and QSMs against a few fungal genera. In this review, we discuss progress reported in the literature thus far and analyze, through in silico methods, 13 fungal QSMs with regard to their physicochemical, pharmacological, and toxicity properties, including their mutagenicity, tumorigenicity, hepatotoxicity, and nephrotoxicity. From these in silico analyses, we highlight 4-hydroxyphenylacetic acid and tryptophol as having satisfactory properties and, thus, propose that these should be investigated further as antifungal agents. We also recommend future in vitro approaches to determine the association of QSMs with commonly used antiseptics as potential antibiofilm agents.

Polyhexamethylene biguanide and its antimicrobial role in wound healing: a narrative review

A wound offers an ideal environment for the growth and proliferation of a variety of microorganisms which, in some cases, may lead to localised or even systemic infections that can be catastrophic for the patient; the development of biofilms exacerbates these infections. Over the past few decades, there has been a progressive development of antimicrobial resistance (AMR) in microorganisms across the board in healthcare sectors. Such resistant microorganisms have arisen primarily due to the misuse and overuse of antimicrobial treatments, and the subsequent ability of microorganisms to rapidly change and mutate as a defence mechanism against treatment (e.g., antibiotics). These resistant microorganisms are now at such a level that they are of grave concern to the World Health Organization (WHO), and are one of the leading causes of illness and mortality in the 21st century. Treatment of such infections becomes imperative but presents a significant challenge for the clinician in that treatment must be effective but not add to the development of new microbes with AMR. The strategy of antimicrobial stewardship (AMS) has stemmed from the need to counteract these resistant microorganisms and requires that current antimicrobial treatments be used wisely to prevent amplification of AMR. It also requires new, improved or alternative methods of treatment that will not worsen the situation. Thus, any antimicrobial treatment should be effective while not causing further development of resistance. Some antiseptics fall into this category and, in particular, polyhexamethylene hydrochloride biguanide (PHMB) has certain characteristics that make it an ideal solution to this problem of AMR, specifically within wound care applications. PHMB is a broad-spectrum antimicrobial that kills bacteria, fungi, parasites and certain viruses with a high therapeutic index, and is widely used in clinics, homes and industry. It has been used for many years and has not been shown to cause development of resistance; it is safe (non-cytotoxic), not causing damage to newly growing wound tissue. Importantly there is substantial evidence for its effective use in wound care applications, providing a sound basis for evidence-based practice. This review presents the evidence for the use of PHMB treatments in wound care and its alignment with AMS for the prevention and treatment of wound infection.

The in vitro efficacy of betadine antiseptic solution and colloidal silver gel combination in inhibiting the growth of bacterial biofilms

INTRODUCTION

Betadine (Povidone-Iodine) solution is a topically applied antiseptic, which has been used routinely used in wound care and general surgery to prevent skin and wound infections. However, several studies have documented the ineffectiveness of betadine. Other topical antimicrobial dressings, including those that contain silver, have been used in the management of infected wounds. The present study was undertaken to determine if the combination of 5% betadine solution and silver colloidal gel (Ag-gel) is more effective than either substance alone in inhibiting the growth gram-negative and gram-positive bacteria.

METHODS

The effectiveness of 5% betadine solution and Ag-gel as anti-microbial agents were assessed using both colony forming unit (CFU) assay and confocal laser scanning microscopy (CLSM).

RESULTS

Ag-gel showed complete inhibition on all the bacteria species examined except the Klebsiella pneumoniae clinical isolate (CL) strain while 5% betadine concentrations did not completely kill any of the tested bacteria. In contrast, K. pneumoniae was completely eliminated in the presence of both 5% betadine solution and Ag-gel together. The CLSM showed similar findings to the CFU results examining the 5% betadine solution and Ag-gel combination.

CONCLUSIONS

This study demonstrated that while the individual treatments using either 5% betadine solution and Ag-gel alone were infective antimicrobial agents, the combination of 5% betadine solution and Ag-gel was superior at eliminating all tested bacteria, including K. pneumoniae CL.

Role of antiseptics in the prevention and treatment of infections in nursing homes

Inadequate infection control, wound care, and oral hygiene protocols in nursing homes pose challenges to residents' quality of life. Based on the outcomes from a focus group meeting and a literature search, this narrative review evaluates the current and potential roles of antiseptics within nursing home infection management procedures. We examine contemporary strategies and concerns within the management of meticillin-resistant Staphylococcus aureus (MRSA; including decolonization regimes), chronic wound care, and oral hygiene, and review the available data for the use of antiseptics, with a focus on povidone-iodine. Compared with chlorhexidine, polyhexanide, and silver, povidone-iodine has a broader spectrum of antimicrobial activity, with rapid and potent activity against MRSA and other microbes found in chronic wounds, including biofilms. As no reports of bacterial resistance or cross-resistance following exposure to povidone-iodine exist, it may be preferable for MRSA decolonization compared with mupirocin and chlorhexidine, which can lead to resistant MRSA strains. Povidone-iodine oral products have greater efficacy against oral pathogens compared with other antiseptics such as chlorhexidine mouthwash, highlighting the clinical benefit of povidone-iodine in oral care. Additionally, povidone-iodine-based products, including mouthwash, have demonstrated rapid in-vitro virucidal activity against SARS-CoV-2 and may help reduce its transmission if incorporated into nursing home coronavirus 2019 control protocols. Importantly, povidone-iodine activity is not adversely affected by organic material, such as that found in chronic wounds and the oral cavity. Povidone-iodine is a promising antiseptic agent for the management of infections in the nursing home setting, including MRSA decolonization procedures, chronic wound management, and oral care.

Molecular Iodine Mouthrinse Antimicrobial Activity Against Periodontopathic Bacteria

AIM

This study compared two molecular iodine mouthrinses for their in vitro bactericidal effects against subgingival biofilm bacteria from severe periodontitis patients.

MATERIALS AND METHODS

In a subgingival biofilm eradication assay, dilution aliquots of subgingival microbial specimens from 32 adults with severe periodontitis were mixed in vitro with either a mouthrinse containing 100 parts per million (ppm) molecular iodine (Iorinse®) or one containing 150 ppm molecular iodine (iClean®), followed by mouthrinse neutralization after 60 seconds with 3% sodium thiosulfate. The mixtures, along with unexposed subgingival biofilm aliquots, were inoculated onto enriched Brucella blood agar and incubated anaerobically for 7 days to quantitate total viable bacterial counts and selected red/orange complex periodontal pathogens (Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Campylobacter rectus, and Fusobacterium nucleatum).

RESULTS

Both molecular iodine mouthrinses significantly reduced total viable bacterial counts in the subgingival biofilm samples, with iClean® providing significantly greater in vitro suppression than Iorinse®. Both molecular iodine mouthrinses also significantly reduced total red/orange complex periodontal pathogens, with significantly greater suppression also exhibited by iClean®.

CONCLUSION

The molecular iodine mouthrinses exerted marked bactericidal activity in vitro against human subgingival biofilm microbial species, including red/orange complex periodontal pathogens associated with severe periodontitis, with iClean® providing significantly better antimicrobial activity than Iorinse®.

CLINICAL SIGNIFICANCE

These findings suggest potential value of molecular iodine mouthrinses in the treatment and prevention of periodontal diseases.

Effect of povidone-iodine and propanol-based mecetronium ethyl sulphate on antimicrobial resistance and virulence in Staphylococcus aureus

Background

Reports are available on cross-resistance between antibiotics and biocides. We evaluated the effect of povidone-iodine (PVP-I) and propanol-based mecetronium ethyl sulphate (PBM) on resistance development, antibiotics cross-resistance, and virulence in Staphylococcus aureus.

Methods

The minimum inhibitory concentration (MIC) of PVP-I and PBM were determined against S. aureus ATCC 25923 using the agar-dilution method. Staphylococcus aureus ATCC 25923 was subjected to subinhibitory concentrations of the tested biocides in ten consecutive passages followed by five passages in a biocide-free medium; MIC was determined after each passage and after the fifth passage in the biocide-free medium. The developed resistant mutant was tested for cross-resistance to different antibiotics using Kirby-Bauer disk diffusion method. Antibiotic susceptibility profiles as well as biocides’ MIC were determined for 97 clinical S. aureus isolates. Isolates were categorized into susceptible and resistant to the tested biocides based on MIC distribution pattern. The virulence of the biocide-resistant mutant and the effect of subinhibitory concentrations of biocides on virulence (biofilm formation, hemolysin activity, and expression of virulence-related genes) were tested.

Results

PVP-I and PBM MIC were 5000 μg/mL and 664 μg/mL. No resistance developed to PVP-I but a 128-fold increase in PBM MIC was recorded, by repeated exposure. The developed PBM-resistant mutant acquired resistance to penicillin, cefoxitin, and ciprofloxacin. No clinical isolates were PVP-I-resistant while 48.5% were PBM-resistant. PBM-resistant isolates were more significantly detected among multidrug-resistant isolates. PVP-I subinhibitory concentrations (¼ and ½ of MIC) completely inhibited biofilm formation and significantly reduced hemolysin activity (7% and 0.28%, respectively). However, subinhibitory concentrations of PBM caused moderate reduction in biofilm activity and non-significant reduction in hemolysin activity. The ½ MIC of PVP-I significantly reduced the expression of hla, ebps, eno, fib, icaA, and icaD genes. The virulence of the biocide-resistant mutant was similar to that of parent strain.

Conclusion

PVP-I is a highly recommended antiseptic for use in healthcare settings to control the evolution of high-risk clones. Exposure to PVP-I causes no resistance-development risk in S. aureus, with virulence inhibition by subinhibitory concentrations. Also, special protocols need to be followed during PBM use in hospitals to avoid the selection of resistant strains.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01178-9.

An in vitro Study of Betadine’s Ability to Eliminate Live Bacteria on the Eye: Should It Be Used for Protection against Endophthalmitis?

Background: Povidone-iodide (Betadine) is an antiseptic that is applied topically and has many uses in the medical community, such as in wound care and pre- and post-operative surgical procedures. This study was done to measure the effectiveness of Betadine solutions in inhibiting the growth of Gram-negative and Gram-positive bacteria. Methods: The ability of 2.5 and 10% Betadine solutions to inhibit bacterial growth was measured against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Acinetobacter baumannii. We grew the bacteria independently and together to simulate a hospital environment. Results: All the bacteria showed zones of inhibition. However, discs were also tested for live bacteria using the colony-forming unit assay. Complete killing was only seen for S. aureus with the 10% Betadine solution. All other bacteria showed growth on the disc. Conclusions: This study showed several things. First, the zone of inhibition assay does not give an accurate assessment of antimicrobial properties when used alone and should be followed by a colony-forming unit assay. Second, 2.5% and 5% Betadine do not have effective antimicrobial properties against any of the bacteria tested, and 10% Betadine is only effective against S. aureus and not effective against the other bacteria tested.

Remote Eradication of Bacteria on Orthopedic Implants via Delayed Delivery of Polycaprolactone Stabilized Polyvinylpyrrolidone Iodine

Bacteria-associated late infection of the orthopedic devices would further lead to the failure of the implantation. However, present ordinary antimicrobial strategies usually deal with early infection but fail to combat the late infection of the implants due to the burst release of the antibiotics. Thus, to fabricate long-term antimicrobial (early antibacterial, late antibacterial) orthopedic implants is essential to address this issue. Herein, we developed a sophisticated MAO-I₂-PCLx coating system incorporating an underlying iodine layer and an upper layer of polycaprolactone (PCL)-controlled coating, which could effectively eradicate the late bacterial infection throughout the implantation. Firstly, micro-arc oxidation was used to form a microarray tubular structure on the surface of the implants, laying the foundation for iodine loading and PCL bonding. Secondly, electrophoresis was applied to load iodine in the tubular structure as an efficient bactericidal agent. Finally, the surface-bonded PCL coating acts as a controller to regulate the release of iodine. The hybrid coatings displayed great stability and control release capacity. Excellent antibacterial ability was validated at 30 days post-implantation via in vitro experiments and in vivo rat osteomyelitis model. Expectedly, it can become a promising bench-to-bedside strategy for current infection challenges in the orthopedic field.

Robbing Peter to Pay Paul: Chlorhexidine gluconate demonstrates short-term efficacy and long-term cytotoxicity

Wound cleansing agents are routine in wound care and preoperative preparation. Antiseptic activity intends to prevent contaminating microbes from establishing an infection while also raising concerns of cytotoxicity and delayed wound healing. We evaluated the cytotoxicity of five clinically used wound cleaning agents (saline, povidone iodine, Dove® and Dial® soaps, and chlorhexidine gluconate [CHG]) using both an ex vivo and in vivo human skin xenograft mouse model, in contrast to classical in vitro models that lack the structural and compositional heterogeneity of human skin. We further established an ex vivo wound contamination model inoculated with ~100 cells of Pseudomonas aeruginosa or Staphylococcus aureus to evaluate antimicrobial efficacy. Scanning electron microscopy and confocal microscopy were used to evaluate phenotypic and spatial characteristics of bacterial cells in wound tissue. CHG significantly reduced metabolic activity of the skin explants, while all treatments except saline affected local cellular viability. CHG cytotoxicity persisted and progressed over 14 days, impairing wound healing in vivo. Within the contamination model, CHG treatment resulted in a significant reduction of P. aeruginosa wound surface counts at 24 h post-treatment. However, this effect was transient and serial application of CHG had no effect on both P. aeruginosa or S. aureus microbial growth. Microscopy revealed that viable cells of P. aeruginosa reside deep within wound tissue post-CHG application, likely serving as a reservoir to re-populate the tissue to a high bioburden. We reveal concerning cytotoxicity and limited antimicrobial activity of CHG in human skin using clinically relevant models, with the ability to resolve spatial localization and temporal dynamics of tissue viability and microbial growth.

Cell Toxicity Study of Antiseptic Solutions Containing Povidone–Iodine and Hydrogen Peroxide

The increasing incidence of periprosthetic joint infections (PJIs) has led to a growing interest in developing strategies to prevent and treat this severe complication. The surgical site’s application of antiseptic solutions to eliminate contaminating bacteria and eradicate the bacterial biofilm has been increasing over time. Even though it has been proven that combining antimicrobials could enhance their activities and help overcome acquired microbial resistance related to the topical use of antibiotics, the toxicity of integrated solutions is not well described. This study aimed to evaluate the cytotoxicity of solutions containing povidone–iodine (PI) and hydrogen peroxide (H2O2), alone or in combination, after 1.3 and 5 min of exposure. Chondrocytes, tenocytes, and fibroblast-like synoviocytes were used for cytotoxicity analysis. Trypan blue stain (0.4% in PBS) was applied to evaluate the dead cells. All solutions tested showed a progressive increase in toxicity as exposure time increased except for PI at 0.3%, which exhibited the lowest toxicity. The combined solutions reported a reduced cellular killing at 3 and 5 min than H2O2 at equal concentrations, similar results to PI solutions.

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.

Skin Minerals: Key Roles of Inorganic Elements in Skin Physiological Functions

As odd as it may seem at first glance, minerals, it is what we are all about…or nearly. Although life on Earth is carbon-based, several other elements present in the planet’s crust are involved in and often indispensable for functioning of living organisms. Many ions are essential, and others show supportive and accessory qualities. They are operative in the skin, supporting specific processes related to the particular situation of this organ at the interface with the environment. Skin bioenergetics, redox balance, epidermal barrier function, and dermal remodeling are amongst crucial activities guided by or taking advantage of mineral elements. Skin regenerative processes and skin ageing can be positively impacted by adequate accessibility, distribution, and balance of inorganic ions.

Cytotoxicity and Wound Closure Evaluation in Skin Cell Lines after Treatment with Common Antiseptics for Clinical Use

In recent years, new therapies, such as skin cell lines injections, have emerged to promote re-epithelialization of damaged areas such as chronic ulcers or to treat patients with severe burns. Antiseptics are commonly used during wound clinical management to avoid serious infections, but they may delay the healing process due to their apparent cytotoxicity to skin cells. The cytotoxicity of ethanol, chlorhexidine digluconate, sodium hypochlorite, povidone iodine and polyhexanide was evaluated in this in vitro study on human fibroblasts and keratinocytes. Treatments were applied to each cell type culture every 48 h for 14 days. To determine the cytotoxic of antiseptics, cell viability (Live/Dead^®) and cell proliferation (AlamarBlue™) assays were performed on cell monolayers. Cell migration capacity was evaluated with a wound closure assay. Results showed how chlorhexidine digluconate and ethanol significantly reduced the viability of keratinocytes and inhibited cell migration. Povidone iodine followed by chlorhexidine digluconate significantly reduced fibroblast cell viability. Povidone iodine also inhibited cell migration. Sodium hypochlorite was the least detrimental to both cell types. If epithelial integrity is affected, the wound healing process may be altered, so the information gathered in this study may be useful in selecting the least aggressive antiseptic after treatment with new emerging therapies.

Evaluation of the antiseptic activity of 5% alcoholic povidone-iodine solution using four different modes of application: a randomized open-label study

BACKGROUND

Before some invasive procedures, such as injections, surgical incision or intravascular catheter insertions, alcoholic antiseptics (e.g., alcoholic povidone-iodine [PVP-I]) are widely used to prevent infection.

AIM

This randomized, open-label study investigated the impact of mode of application (which includes both application technique and volume) on the antiseptic activity of 5% alcoholic PVP-I solution.

METHODS

Alcoholic PVP-I was administered on the backs of healthy adults using four modes of application: A, concentric circle method, 3mL; B, concentric circle method, 10 mL; C, back-and-forth friction method, 3 mL; D, back-and-forth friction method, 10 mL.

PRIMARY ENDPOINT

antiseptic activity of alcoholic PVP-I, assessed via change from baseline in log₁₀/cm² colony-forming units (CFU) count for total aerobic and facultative anaerobic bacteria. Safety was monitored.

FINDINGS

113 healthy participants were screened; 32 were randomized. Alcoholic PVP-I showed significant antiseptic activity with all modes of application (p<0.001 for each), providing an overall mean decrease from baseline in CFU count of >3 log₁₀/cm² (p<0.001). Significantly greater efficacy was seen with back-and-forth friction (modes C and D) versus concentric circles (modes A and B): covariate adjusted change in log₁₀/cm² CFU count 0.22; 90% confidence intervals: 0.07, 0.37 (p=0.017). No safety issues were observed.

CONCLUSION

Alcoholic PVP-I demonstrated high antiseptic activity for all modes of application. Greater efficacy was achieved with back-and-forth friction versus concentric circles, showing that application technique may influence antiseptic activity; these findings suggest that when comparing the efficacy of antiseptic substances (e.g., alcoholic PVP-I and alcoholic chlorhexidine [CHX]), comparable application techniques should be used.

In vitro inactivation of SARS-CoV-2 using a povidone-iodine oral rinse

BACKGROUND

Healthcare professionals, especially dentists and dental hygienists, are at increased risk for contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through air-borne particles and splatter. This study assessed the in vitro virucidal activity of 0.5% (w/v) povidone-iodine (PVP-I) oral rinse against SARS-CoV-2 to demonstrate its utility as a professional oral rinse.

METHODS

A 0.5% (w/v) PVP-I oral rinse formulation, placebo oral rinse, and positive (70% [v/v] ethanol and water) and negative (water) controls were assessed using the time-kill method. SARS-CoV-2 was propagated in Vero 76 host cells. Following neutralization validation, triplicate tests were performed for each test formulation and virucidal activity measured at 15, 30, and 60 s and 5 min.

RESULTS

The 0.5% (w/v) PVP-I oral rinse demonstrated effective in vitro virucidal activity against SARS-CoV-2 as early as 15 s after exposure; viral titer was reduced to < 0.67 log₁₀ 50% cell culture infectious dose (CCID₅₀)/0.1 mL (log₁₀ reduction of > 4.0) at 30 s, whereas the placebo oral rinse reduced the SARS-CoV-2 viral titer to 4.67 and 4.5 log₁₀ CCID₅₀/0.1 mL at the 15- and 30-s time points, with a log₁₀ reduction of 0.63 and 0.17, respectively. No toxicity or cytotoxic effects against Vero 76 host cells were observed with the 0.5% (w/v) PVP-I oral rinse; positive and negative controls performed as expected.

CONCLUSIONS

In vitro virucidal activity of 0.5% (w/v) PVP-I oral rinse against SARS-CoV-2 was demonstrated. Rapid inactivation of SARS-CoV-2 was observed with 0.5% (w/v) formulation with a contact duration of 15 s. Clinical investigations are needed to assess the effectiveness of PVP-I oral rinse against SARS-CoV-2 in dental practice.

Changes in reverse transcription polymerase chain reaction cycle threshold values of SARS-CoV-2 with topical povidone iodine use: A single-arm open-label interventional study

Context:

Repurposed povidone iodine (PVP-I) has been suggested as an effective adjuvant against coronavirus disease-2019 (COVID-19).

Aim:

The aim of this study was to assess the changes in RT-PCR cycle threshold (Ct) values of severe acute respiratory Syndrome Coronavirus-2 (SARS-CoV-2) genes with PVP-I intranasal and oral application.

Settings and Design:

A longitudinal (repeated measures) single-arm open-label interventional study was conducted for 200 samples of ten COVID-19 patients in South India.

Methods and Material:

Demographic and clinical information were collected. Intranasal application and oral gargle with 1% PVP-I solution was done four times a day for seven days. Nasopharyngeal and oropharyngeal samples were taken for RT-PCR test at hour-0, hour-2, hour-4 on Day-0, Day-3, Day-6, and hour-0 on Day-9.

Methods and Material:

STATA analysis software version 14.2 was used. McNemar Test was applied for paired samples. Skilling Mack Test was used to assess the association between PVP-I use (intra-day and inter-day) and E gene/N gene Ct values. Pearson correlation coefficients and Bland-Altman plots were used for further analyses.

Results:

Mean (SD) age of the patients was 41.5 (±8.82) years. A total of 100 pairs of nasopharyngeal and oropharyngeal samples were analysed. No significant difference was observed in the Ct values of asymptomatic and symptomatic patients. E gene Ct values (nasopharyngeal) at Hour-0 increased from Day-0 to Day-9 (P = 0.005). Ct value was higher at Hour-2 for most of the samples.

Conclusions:

RT‐PCR results (qualitative) differed at various testing points in the same patients. Lower Ct values were found in the nasopharyngeal samples. Successive increase in E gene Ct values indicates reduced viral load with natural course of COVID-19. PVP-I may have an optimal impact within 2 h of usage.

Clinical trial registration number:

CTRI/2020/05/024962.

Virucidal effect of povidone-iodine against SARS-CoV-2 in vitro

Objective

To evaluate the antiviral activity of the oral disinfectant povidone-iodine (PVP-I) against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV2) in vitro.

Methods

The cytotoxic effects of PVP-I were determined in Vero and Calu-3 cell lines using that by Cell Counting Kit-8 assay. Viral load in the cell culture medium above infected cells was quantitated using real-time polymerase chain reaction. The cytopathic effect (CPE) and viral infective rate were observed by immunofluorescence microscopy.

Results

PVP-I at a concentration >0.5 mg/ml in contact with SARS-CoV-2 for 30 s, 1 min, 2 min and 5 min showed up to 99% viral inhibition. For in vitro testing, upon exposure for 1 min, PVP-I showed a virucidal effect. PVP-I had no cytotoxic effects at the range of concentrations tested (0.125–1 mg/ml; CC₅₀ > 2.75 mM) in Vero and Calu-3 cells.

Conclusion

These results demonstrate that the ideal contact time was 1 min and the optimal concentration was 1 mg/ml, which provides an experimental basis for the use of oral disinfectants in dental hospitals.

Bacterial keratitis: identifying the areas of clinical uncertainty

Bacterial keratitis is a common corneal infection that is treated with topical antimicrobials. By the time of presentation there may already be severe visual loss from corneal ulceration and opacity, which may persist despite treatment. There are significant differences in the associated risk factors and the bacterial isolates between high income and low- or middle-income countries, so that general management guidelines may not be appropriate. Although the diagnosis of bacterial keratitis may seem intuitive there are multiple uncertainties about the criteria that are used, which impacts the interpretation of investigations and recruitment to clinical studies. Importantly, the concept that bacterial keratitis can only be confirmed by culture ignores the approximately 50% of cases clinically consistent with bacterial keratitis in which investigations are negative. The aetiology of these culture-negative cases is unknown. Currently, the estimation of bacterial susceptibility to antimicrobials is based on data from systemic administration and achievable serum or tissue concentrations, rather than relevant corneal concentrations and biological activity in the cornea. The provision to the clinician of minimum inhibitory concentrations of the antimicrobials for the isolated bacteria would be an important step forward. An increase in the prevalence of antimicrobial resistance is a concern, but the effect this has on disease outcomes is yet unclear. Virulence factors are not routinely assessed although they may affect the pathogenicity of bacteria within species and affect outcomes. New technologies have been developed to detect and kill bacteria, and their application to bacterial keratitis is discussed. In this review we present the multiple areas of clinical uncertainty that hamper research and the clinical management of bacterial keratitis, and we address some of the assumptions and dogma that have become established in the literature.

Effectiveness of broad-spectrum antiseptics in production of disinfected maggots of Lucilia sericata for use in wound debridement therapy

The establishment of low-cost, effective, safe and practical methods is necessary to increase the use of larval therapy in wound care. Although studies on external disinfection of calliphorid eggs have been reported, many studies lack data on the effect of disinfection on egg viability and the microorganisms found before disinfection. Therefore, the main objective of this study was to compare three antiseptic solutions, that is, chlorhexidine (5%), Dakin's solution (0.5% NaOCl) and povidone-iodine (10%), in terms of their ability to disinfect Lucilia sericata eggs. Egg viability after disinfection and microorganisms present on the eggs and larvae before and after treatment were also examined. None of the antiseptics had a significant effect on egg viability. Disinfection of L. sericata eggs with 0.5% NaOCl was the best method, as sterility tests showed no contamination. Escherichia coli, Bacillus subtilis and Proteus mirabilis were present in all cultures isolated from the non-disinfected eggs and larvae, while Enterococcus faecium, Enterococcus faecalis, Morganella morganii, Corynebacterium spp. and Providencia stuartii were isolated from more than half of the same cultures. Sterility testing of medicinal maggots after disinfection is crucial to prevent secondary infections and achieve a positive therapeutic outcome.

In Vitro Evaluation of the Virucidal Activity of Different Povidone-Iodine Formulations Against Murine and Human Coronaviruses

Introduction

Polyvinylpyrrolidone–iodine (PVP-I) demonstrates broad-spectrum anti-infective activity and is available in different formulations for oral rinse and topical use in medical and personal care settings. The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has underscored the need to supplement available preventive strategies.

Methods

We assessed virucidal activity of PVP-I formulations, including 0.5% (w/v) solution, 5.0% (w/v) solution, 7.5% (w/v) scrub, and 10.0% (w/v) solution, versus placebos when challenged with coronaviruses in two in vitro studies. Murine coronavirus strain A59 (American Type Culture Collection [ATCC]^® VR-764™), human coronavirus strain OC43 (ZeptoMetrix Corp. #0810024CF), human coronavirus strain NL63 (ZeptoMetrix Corp. #0810228CF), and human coronavirus strain 229E (ATCC^® VR-740™) were used as surrogates for SARS-CoV-2. Both studies used the American Society for Testing and Materials in vitro time-kill method.

Results

All active PVP-I formulations in study 1 demonstrated virucidal activity at 15 s, with mean log₁₀ reduction of greater than 4.56 or greater than 99.99% inactivation; a cytotoxic effect against the National Collection of Type Cultures clone 1469 host cells was observed with 5.0% (w/v) solution, 7.5% (w/v) scrub, and 10.0% (w/v) solution. Active PVP-I formulations in study 2 demonstrated effective virucidal activity against coronaviruses in less than 15 s; log₁₀ reduction in viral titer for each coronavirus strain was consistently higher for 10.0% (w/v) solution and 0.5% (w/v) solution versus 7.5% (w/v) scrub.

Conclusion

Both studies demonstrated in vitro virucidal activity of PVP-I formulations when challenged with SARS-CoV-2 surrogate coronaviruses. Although promising, further investigations are needed to evaluate SARS-CoV-2 inactivation.

Low-Concentration (0.66%) Povidone Iodine Treatment of a Corneal Ulcer in a Rheumatoid Arthritis Patient

Patient: Female, 89-year-old

Final Diagnosis: Corneal ulcer

Symptoms: Low vision

Medication:—

Clinical Procedure: —

Specialty: Ophthalmology

Topical effect of benzalkonium bromide on wound healing and potential cellular and molecular mechanisms

Benzalkonium bromide (BB) has been widely used as a skin antiseptic for wound management. However, BB had proinflammation and reactive oxygen species (ROS) induction effect, making its role in wound healing complex and unclear. A rat full-thickness skin defect wound model was established. The effects of BB, povidone iodine (PVP-I), chlorhexidine gluconate (CHG), and normal saline (NS) on wound healing and infection control were then evaluated based on wound healing rate (WHr) and bacterial killing. The wound tissues were sectioned for histopathological evaluation and nuclear factor E2 related factor 2 (Nrf2) expression determination. The ROS production, Nrf2 activation, and heme oxygenase 1 (HO-1) expression of the HaCat cells and the cytotoxicity treated with BB were further explored. Compared with NS, PVP-I, and CHG, BB showed the best wound infection control efficiency while delayed wound healing with the WHr of 91.42 ± 5.12% at day 20. The wound tissue of the BB group showed many inflammatory cells but few granulation tissue and capillaries and no obvious collagen deposition, resulting in the lowest histopathological scores of 4.17 ± 0.75 for BB group. BB showed higher cytotoxicity on HaCat cells with the lowest IC25, IC50, and IC75 of 1.90, 4.16, and 9.09 g/mL compared with PVP-I and CHG. TUNEL staining evaluated the cytotoxicity of BB on wound tissue, which indicates the high apoptosis index BB group (5.05 ± 1.77). Compared with PVP-I and CHG, BB induced much more cell apoptosis. The results of flow cytometry and fluorescence staining showed that PVP-I, CHG, and BB induced ROS production in a concentration-dependent manner and cells treated with BB had the highest ROS production at the same inhibition concentration. The cells and the wound tissues treated with BB showed highest Nrf2 activation and HO-1 expression than PVP-I and CHG. BB was highly efficient in wound infection control while delayed wound healing. The prolonged and strengthened inflammation and the raised ROS production originating from BB administration may contribute to delayed wound healing.

Implementation of daily chlorhexidine bathing in intensive care units for reduction of central line-associated bloodstream infections

BACKGROUND

Daily chlorhexidine bathing has been associated with a reduction in central line-associated bloodstream infections (CLABSI). In the setting of an already established CLABSI surveillance system and an implemented CLABSI prevention bundle, we analysed the effect of daily chlorhexidine bathing in ICU patients on CLABSI incidence and its causative pathogens.

METHODS

This was a before-and-after study in intensive care units (ICUs) at a tertiary-care centre in Switzerland. Prospective surveillance of CLABSIs and their aetiologies was established. The intervention consisted of daily chlorhexidine bathing of ICU patients with a central venous catheter. A baseline period of 19 months was followed by an intervention period of 9 months.

FINDINGS

A total of 5008 patients were included. In the baseline period a mean CLABSI rate of 2.45/1000 catheter days (95% confidence interval (CI) 1.93-3.07) was observed, followed by 1.00/1000 catheter days (95% CI 0.55-1.67; P<0.001) in the intervention period. Introduction of chlorhexidine bathing was independently associated with a reduced risk of CLABSI (adjusted odds ratio 0.47, 95% CI 0.26-0.84, P=0.011). We did not observe a significant change in aetiology except for an increase of Serratia marcescens in the intervention period.

CONCLUSIONS

Introduction of daily chlorhexidine bathing resulted in a decline in CLABSI incidence on ICUs. Starting from a baseline CLABSI rate that can be considered standard in a high-income setting and several measures for CLABSI prevention implemented, chlorhexidine bathing proved helpful for a further reduction.