Evaluation of toxic side effects of clinically used skin antiseptics in vitro

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.

Comparison of different concentrations of chlorhexidine-iodophor composite solution on human skin fibroblasts

OBJECTIVE

Chlorhexidine-iodophor (CHX-IP) composite solution is a polymer of chlorhexidine and iodophor produced with new technology, for use in diabetic foot infection. However, the effect of CHX-IP on the growth activity of fibroblasts remains unknown, thus the effects of different concentrations of CHX-IP composite solution on the viability and micromorphology of human skin fibroblasts were studied in vitro cell culture in this study.

METHOD

A cell viability assay was applied to calculate cell viability and an inverted fluorescence microscope was used to observe cell morphology over five days.

RESULTS

The results showed that the toxic effect of CHX-IP on fibroblasts was solution concentration-dependent and decreased over time. When the concentration of CHX-IP was 5.0mg/ml, 2.5mg/ml, 0.625mg/ml, 0.15625mg/ml, 0.078125mg/ml or 0mg/ml, the difference of optical density (OD) value on different days was statistically significant (p<0.05). There were statistically significant differences in the OD value of fibroblasts among different concentrations of CHX-IP on: day 2 (F=4.809, p=0.004); day 3 (F=21.508, p<0.001); day 4 (F=63.952, p<0.001); and day 5 (F=160.407, p<0.001). In addition, a concentration of 5.0mg/ml CHX-IP resulted in a fibroblastic viability rate of 0% on day 4, when CHX-IP was diluted to 2.5mg/ml or 1.25 mg/ml, fibroblastic viability rate decreased to 0% day 5. However, when the CHX-IP was diluted to 0.15625mg/ml or 0.078125mg/ml, the fibroblastic cell viability rate increased slightly on day 5. The morphology of cells observed under microscope indirectly supported this result.

CONCLUSION

The findings of this study showed that the toxic effect of CHX-IP on fibroblasts was solution concentration-dependent and decreased over time.

A prospective study to analyse the concentration of octenidine in hand wounds after disinfection by LC-MS/MS

Toxic reactions can appear after pressurised flushing of soft tissue with octenidine (OCT) containing disinfectants. Their use for surgical disinfection could complicate the diagnosis of possible contamination. In patients with open lacerations of their hand's subcutaneous tissue samples were taken before and after surgical disinfection with Octenisept® and analysed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). In 16 out of 20 tissue samples, OCT was detected after disinfection (lower limit of quantification (LLOQ)=10 pg/mL/mg). The concentration of OCT was below the LLOQ, estimation of mean of 0.6 pg/mL/mg (0.22-0.98 pg/mL/mg, 95%-CI) before disinfection and mean of 179.4 pg/mL/mg (13.35-432.0 pg/mL/mg, 95%-CI) after disinfection. This study shows that the disinfection of open wounds with Octenisept® leads to a quantifiable concentration of OCT in open wounds. In cases of suspected OCT-mediated toxic reaction, the use of antiseptics containing OCT should be avoided.

Effectiveness of a polyhexamethylene biguanide-containing wound cleansing solution using experimental biofilm models

OBJECTIVE

Antiseptics are widely used in wound management to prevent or treat wound infections, and have been shown to have antibiofilm efficacy. The objective of this study was to assess the effectiveness of a polyhexamethylene biguanide (PHMB)-containing wound cleansing and irrigation solution on model biofilm of pathogens known to cause wound infections compared with a number of other antimicrobial wound cleansing and irrigation solutions.

METHOD

Staphylococcus aureus and Pseudomonas aeruginosa single-species biofilms were cultured using microtitre plate and Centers for Disease Control and Prevention (CDC) biofilm reactor methods. Following a 24-hour incubation period, the biofilms were rinsed to remove planktonic microorganisms and then challenged with wound cleansing and irrigation solutions. Following incubation of the biofilms with a variety of concentrations of the test solutions (50%, 75% or 100%) for 20, 30, 40, 50 or 60 minutes, remaining viable organisms from the treated biofilms were quantified.

RESULTS

The six antimicrobial wound cleansing and irrigation solutions used were all effective in eradicating Staphylococcus aureus biofilm bacteria in both test models. However, the results were more variable for the more tolerant Pseudomonas aeruginosa biofilm. Only one of the six solutions (sea salt and oxychlorite/NaOCl-containing solution) was able to eradicate Pseudomonas aeruginosa biofilm using the microtitre plate assay. Of the six solutions, three (a solution containing PHMB and poloxamer 188 surfactant, a solution containing hypochlorous acid (HOCl) and a solution containing NaOCl/HOCl) showed increasing levels of eradication of Pseudomonas aeruginosa biofilm microorganisms with increasing concentration and exposure time. Using the CDC biofilm reactor model, all six cleansing and irrigation solutions, except for the solution containing HOCl, were able to eradicate Pseudomonas aeruginosa biofilms such that no viable microorganisms were recovered.

CONCLUSION

This study demonstrated that a PHMB-containing wound cleansing and irrigation solution was as effective as other antimicrobial wound irrigation solutions for antibiofilm efficacy. Together with the low toxicity, good safety profile and absence of any reported acquisition of bacterial resistance to PHMB, the antibiofilm effectiveness data support the alignment of this cleansing and irrigation solution with antimicrobial stewardship (AMS) strategies.

Combined Use of Antimicrobial Peptides with Antiseptics against Multidrug-Resistant Bacteria: Pros and Cons

Antimicrobial peptides (AMPs) are acknowledged as a promising template for designing new antimicrobials. At the same time, existing toxicity issues and limitations in their pharmacokinetics make topical application one of the less complicated routes to put AMPs-based therapeutics into actual medical practice. Antiseptics are one of the common components for topical treatment potent against antibiotic-resistant pathogens but often with toxicity limitations of their own. Thus, the interaction of AMPs and antiseptics is an interesting topic that is also less explored than combined action of AMPs and antibiotics. Herein, we analyzed antibacterial, antibiofilm, and cytotoxic activity of combinations of both membranolytic and non-membranolytic AMPs with a number of antiseptic agents. Fractional concentration indices were used as a measure of possible effective concentration reduction achievable due to combined application. Cases of both synergistic and antagonistic interaction with certain antiseptics and surfactants were identified, and trends in the occurrence of these types of interaction were discussed. The data may be of use for AMP-based drug development and suggest that the topic requires further attention for successfully integrating AMPs-based products in the context of complex treatment. AMP/antiseptic combinations show promise for creating topical formulations with improved activity, lowered toxicity, and, presumably, decreased chances of inducing bacterial resistance. However, careful assessment is required to avoid AMP neutralization by certain antiseptic classes in either complex drug design or AMP application alongside other therapeutics/care products.

Antimicrobials cetylpyridinium-chloride and miramistin demonstrate non-inferiority and no "protein-error" compared to established wound care antiseptics in vitro

Concern about microbial tolerance and resistance to established antimicrobials drives research into alternatives for local antiseptic wound treatment. Precise efficacy profiles are thereby important in the evaluation of potential alternative antimicrobials, and protein interference ("protein error") is a key factor. Here, the antimicrobial efficacy of cetylpyridinium chloride (CPC) and miramistin (MST) was compared to the established antimicrobials octenidine (OCT), povidon-iodine (PVP-I), polyhexamethylene-biguanide (PHMB) and chlorhexidine (CHX). Efficacy was evaluated after 0.5, 1, 3, 5 and 10 min against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecium and Candida albicans using an in vitro quantitative suspension method (based on DIN EN 13727). To investigate protein interference, 0.3% or 3% bovine albumin was used as the challenge. OCT and PVP-I demonstrated a significant efficacy within 0.5 min, regardless of the microbial organism and protein challenge (p < 0.01). CPC and MST showed no inferiority in efficacy, with only MST needing up to 3 min to achieve the same microbial reduction. PHMB and CHX also achieved significant reduction rates over the tested time-course, yet demonstrated a necessity for prolonged exposure (up to 10 min) for comparable reduction. A protein interference was predominantly observed for PHMB against S. aureus, but without statistically significant differences in antimicrobial efficacy between the 0.3% and 3% protein challenges. All other tested agents showed no relevant interference with the presence of protein. CPC and MST proved to be non-inferior to established wound antiseptics agents in vitro. In fact, CPC showed a more efficient reduction than PHMB and CHX despite there being an introduced protein challenge. Both agents demonstrated no significant "protein error" under challenging conditions (3% albumin), posing them as valid potential candidates for alternative antimicrobials in wound management.

Effects of Chlorhexidine-Iodophor Composite Solution on the Viability and Proliferation of Human Skin Fibroblasts Infected by S. aureus - An in Vitro Experiment

Background: The chlorhexidine-iodophor (CHX-IP) composite solution is a polymer of chlorhexidine and iodophor, applicable to the control of local microbial load and probably toxic to fibroblasts. However, the effect of CHX-IP on the viability and proliferation of human skin fibroblasts infected by Staphylococcus aureus (S. aureus) remains unknown. Objective: The effects of CHX-IP composite solution on the viability and proliferation of human skin fibroblasts infected by S. aureus were investigated in vitro cell culture in this study. Methods: Optimum multiplicity of infection (MOI) was determined to construct the S. aureus-fibroblast co-culture model. Cell Viability Assay was applied to obtain optical density (OD) value and calculate cell viability. 5-ethynyl-2'- deoxyuridine (EdU) assay was used to investigate the effect of CHX-IP on the proliferation of human skin fibroblasts infected by S. aureus. Results: 10:1 was the optimum MOI for the S. aureus-fibroblast co-culture model. The OD value of human skin fibroblasts infected by S. aureus increased in the blank control group, 0.625 mg/ml, 0.3125 mg/ml, 0.15625 mg/ml, and 0.075625 mg/ml groups after four hours. While that of the negative control group, 5 mg/ml, 2.5 mg/ml, and 1.25 mg/ml groups decreased over time. The two-way ANOVA results indicated that the OD value of human skin fibroblasts infected by S. aureus was significantly different among different CHX-IP concentration groups (F = 34.05, P < .001), and the interaction effect between concentration and time was significant (F = 9.442, P < .001). The results of the EdU cell proliferation assay showed that the blank control group, 0.625 mg/ml CHX-IP group, and 0.075625 mg/ml CHX-IP group had an enhanced fibroblasts cell proliferation, while the fibroblasts cell proliferation of the negative control group and 5 mg/ml CHX-IP group was inhibited. Conclusion: The viability and proliferation of human skin fibroblasts infected by S. aureus were inhibited, while specific concentrations of CHX-IP solution can counteract or even reverse the proliferation inhibition effect.

Antibiofilm Properties of Antiseptic Agents Used on Pseudomonas aeruginosa Isolated from Diabetic Foot Ulcers

In diabetic foot ulcers (DFUs), biofilm formation is a major challenge that promotes wound chronicity and delays healing. Antiseptics have been proposed to combat biofilms in the management of DFUs. However, there is limited evidence on the activity of these agents against biofilms, and there are questions as to which agents have the best efficiency. Here, we evaluated the antibiofilm activity of sodium hypochlorite, polyvinylpyrrolidoneIodine (PVPI), polyhexamethylenebiguanide (PHMB) and octenidine against Pseudomonas aeruginosa strains using static and dynamic systems in a chronic-wound-like medium (CWM) that mimics the chronic wound environment. Using Antibiofilmogram®, a technology assessing the ability of antiseptics to reduce the initial phase of biofilm formation, we observed the significant activity of antiseptics against biofilm formation by P. aeruginosa (at 1:40 to 1:8 dilutions). Moreover, 1:100 to 1:3 dilutions of the different antiseptics reduced mature biofilms formed after 72 h by 10-log, although higher concentrations were needed in CWM (1:40 to 1:2). Finally, in the BioFlux200TM model, after biofilm debridement, sodium hypochlorite and PHMB were the most effective antiseptics. In conclusion, our study showed that among the four antiseptics tested, sodium hypochlorite demonstrated the best antibiofilm activity against P. aeruginosa biofilms and represents an alternative in the management of DFUs.

The Toxicity and Antibacterial Effects of Povidone-Iodine Irrigation in Fracture Surgery

Objective

Surgical site infection is a common complication of surgery, especially in orthopedics. Povidone‐Iodine (PI) is one of the oldest and most commonly used disinfectants in surgery. However, the toxicity and antimicrobial effect of PI have not been discussed. In addition, no study has explored the optimum PI concentration for sterilization and tissue healing. This study explores the germicidal efficacy of different concentrations PI, in addition, the toxicity and antibacterial effects of PI irrigation in fracture surgery are also discussed.

Methods

Methicillin‐resistant Staphylococcus aureus and Pseudomonas aeruginosa (P. aeruginosa) were used to evaluate the germicidal efficacy of PI in vitro and in vivo. In vitro, the effects of PI on bacterial growth were analyzed. 2.5%, 1.25%, 0.5%, 0.25%, 0.05%, 0.025%, 0.005%, 0.0025% and 0% PI was added into the bacterial suspension, besides, the bacterial algebra and growth rate were tested. Meanwhile, the fluorescence intensity of viable bacteria was also tested to evaluate the effects of PI on bacterial survival. In vivo, first, femoral fracture with wound infection rat models were established. Second, thyroid gland sections, blood thyroxine, urinary iodine, wound local skin, muscle and bone tissue sections, serum creatinine and alanine aminotransferase, serum and bone local tissue interleukin‐6 (IL‐6), interleukin‐10 (IL‐10), bone morphogenetic protein (BMP‐2), vascular endothelial growth factor (VEGF) and transforming growth factor (TGF‐β1) were detected in rat femoral shaft fracture model with 5%, 2.5%, 0.5%, 0.05%, and 0% PI irrigation. Third, tissue bacteria culture was tested in rat femoral fracture with wound infection model with different concentrations PI irrigation.

Results

In vitro, 2.5%, 1.25%, 0.5% PI inhibited the growth of bacteria. 1.25%, 0.5% PI killed all the bacteria, while 0.25%, 0.05% PI had not killed bacteria after about 10 min. The iodine absorption of 5%, 2.5%, 0.5% PI irrigation did not cause thyroid injury. The 5%, 2.5%, 0.5% PI irrigation did not make serum creatinine and alanine aminotransferase abnormal and can remove bacteria from wounds. The 0.5%, 2.5% PI irrigation can promote tissue healing and increase BMP‐2, VEGF, TGF‐β1, IL‐10, in addition, decrease IL‐6. 5% PI irrigation would inhibit tissue healing, and increase IL‐6, decrease BMP‐2, VEGF, TGF‐β1, IL‐10.

Conclusions

Povidone‐Iodine was a widely used disinfectant and 2.5%, 1.25% and 0.5% PI could effectively kill bacteria. Five percent and lower concentration PI irrigation was safe and could not cause thyroid, kidney and liver damage. The 0.5% PI irrigation was beneficial for tissue healing but 5% PI irrigation was the opposite.

The cross-linked bacterial cellulose impregnated with octenidine dihydrochloride-based antiseptic as an antibacterial dressing material for highly-exuding, infected wounds

The highly absorbent, antibacterial dressings with a sustained release of the antimicrobial are considered necessary measures to counteract chronic wound biofilm-based infections. This study aimed to analyze wet and dry bacterial cellulose (BC) materials, modified by chemical cross-linking, and impregnated with an antiseptic based on octenidine dihydrochloride (OCT) in the context of its antibiofilm/antibacterial activity, exudate absorption, and cytotoxicity. The native BC was obtained from cost-effective, ecological-friendly potato juice (leftover from the starch industry). The ability to absorb and retain OCT, exudate absorption capacity, the kinetics of OCT release as well as antibiofilm/antibacterial activity of modified BC materials against biofilm-forming and planktonic bacteria (Staphylococcus aureus and Pseudomonas aeruginosa) were investigated. The performed analyses revealed that modified BC materials, thanks to their layered structure with numerous air spaces, were characterized by sustained exudate absorption and OCT release profile, which allowed them to exhibit high antimicrobial activity for up to 7 days, with a reduction of planktonic and biofilm cells of 84-100% and 69-93%, respectively. The modified BC materials showed also no cytotoxicity against fibroblast cell line L929 in vitro and were characterized by firm adhesion to the curved surfaces. These results indicate that cross-linked BC impregnated with OCT may be a particularly promising dressing material (obtained using sustainable processes), especially in the treatment of biofilm-infected, highly-exuding wounds.

Effect of the most common wound antiseptics on human skin fibroblasts

Background

Antiseptics are used for the cleansing of acute or chronic wounds to eliminate micro‐organisms from the wound bed. However, they have effects on the skin cells.

Aim

To determine the effects of hexetidine, povidone–iodine (PI), undecylenamidopropyl‐betaine/polyhexanide (UBP), chlorhexidine, disodium eosin and hydrogen peroxide on human skin fibroblasts.

Methods

CCD‐1064Sk cells were treated with hexetidine, PI, UBP, chlorhexidine, disodium eosin or hydrogen peroxide. Spectrophotometry was used to measure cell viability and flow cytometry was used to study apoptosis and necrosis after the treatment. In vitro wound scratch assays were performed to determine the gap closure.

Results

All antiseptics significantly reduced the viability of human skin fibroblasts compared with controls. The percentage wound closure was lower with hexetidine, PI and UBP. The scratch assay could not be measured after treatments with chlorhexidine, disodium eosin or hydrogen peroxide, owing to their cytotoxicity. The apoptosis/necrosis experiments evidenced a significant reduction in viable cells compared with controls. An increased percentage of apoptotic cells was observed after treatment with all antiseptics. Compared with controls, the percentage of necrotic cells was significantly increased with all antiseptics except for hexetidine.

Conclusion

The proliferation, migration and viability of human skin fibroblasts are reduced by treatment with hexetidine, PI, UBP, chlorhexidine, disodium eosin and hydrogen peroxide.

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.

The Healing Capability of Clove Flower Extract (CFE) in Streptozotocin-Induced (STZ-Induced) Diabetic Rat Wounds Infected with Multidrug Resistant Bacteria

Treatment of diabetic foot ulcer (DFU) is of great challenge as it is shown to be infected by multidrug resistant bacteria (MDR bacteria). Sixty four bacterial isolates were isolated from DFU cases; antibiotic susceptibility tests were carried out for all of them. One bacterial isolate (number 11) was shown to resist the action of 8 out of 12 antibiotics used and was identified by both a Vitek-2 system and 16S rRNA fingerprints as belonging to Proteus mirabilis, and was designated Proteus mirabilis LC587231 (P. mirabilis). Clove flower extract (CFE) inhibited distinctively the P. mirabilis bacterium obtained. GC-MS spectroscopy showed that this CFE contained nine bioactive compounds. The effect of CFE on wound healing of Type 1 diabetic albino rats (Rattus norvegicus) was studied. The results indicated that topical application of CFE hydrogel improved wound size, wound index, mRNA expression of the wound healing markers (Coli1, MMP9, Fibronectin, PCNA, and TGFβ), growth factor signaling pathways (PPAR-α, PGC1-α, GLP-1, GLPr-1, EGF-β, EGF-βr, VEGF-β, and FGF-β), inflammatory cytokine expression (IL8, TNFα, NFKβ, IL1β, and MCP1), as well as anti-inflammatory cytokines (IL4 & IL10), pro-apoptotic markers (FAS, FAS-L, BAX, BAX/BCL-2, Caspase-3, P53, P38), as well as an antiapoptotic one (BCL2). Furthermore, it improved the wound oxidative state and reduced the wound microbial load, as the cefepime therapy improved the wound healing parameters. Based on the previous notions, it could be concluded that CFE represents a valid antibiotics alternative for DFU therapy since it improves diabetic wound healing and exerts antibacterial activity either in vitro or in vivo.

Effect of Chlorhexidine Digluconate in Early Wound Healing of Human Gingival Tissues. A Histological, Immunohistochemical and Biomolecular Analysis

Chlorhexidine digluconate (CHX) is considered the gold standard for oral cavity antiseptic treatment. Nevertheless, several in vitro studies have reported detrimental effects in oral tissue repair. The aim of the present study was to evaluate the in vivo effect of post-surgical CHX mouth rinse on gingival tissue (G) 24 h after injury. G biopsies were obtained in three patients 24 h after surgery with the indication of post-surgical 0.12% CHX use and were compared with those obtained from the same patients without any antiseptic use. Changes in collagen production, cell proliferation, and apoptosis were examined by histological and Ki-67/P53 immunohistochemical analysis. Fibrotic markers (COL1A1, αSMA), proapoptotic protein (BAX) expression, and wound healing-related gene modulation (RAC1, SERPINE1, TIMP1) were analyzed by quantitative real-time PCR analysis. CHX was able to reduce cellular proliferation and increase collagen deposition, proapoptotic molecule and fibrotic marker expression, and myofibroblast differentiation, reduce expression of RAC1 and trigger expression of SERPINE1 and TIMP1, showing “scar wound healing response” pattern. This study assessed for the first time the in vivo effects of CHX on gingival tissue. The demonstration of a CHX-induced fibrotic transformation, leading to scar repair, supports the need for new post-surgical clinical protocols based on a strategic and personalized use of CHX.

Long-Term Outcome Assessment Between Antiseptic and Normal Saline for Negative Pressure Wound Therapy with Instillation

Objective: To analyze long-term outcomes following inpatient treatment of infected wounds with antimicrobial or normal saline instillation during negative pressure wound therapy (NPWT). Approach: This was a single-center retrospective study analyzing the course of patients receiving 0.9% normal saline or 0.1% polyhexanide plus 0.1% betaine as instillation for wounds requiring surgery. Measured outcomes included rates of dehiscence, new wounds, re-operations, amputations, and mortality over 5 years. The article adheres to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Results: Forty-two patients received normal saline instillation and 41 the antiseptic solution. Rates of dehiscence, wound recurrence, and re-operations in the saline and antiseptic cohorts were 6.3% and 5.6%, 9.4% and 5.6%, and 14.3% and 9.8%, respectively (p > 0.05). In patients requiring further surgery, time to wound closure averaged 104 and 130 days in the saline and antiseptic cohorts, respectively (p = 0.81). Five-year amputation and mortality rates were 14.3% and 22% (p = 0.36) and 24% and 17% (p = 0.45) in the saline and antiseptic cohorts, respectively. Innovation: To compare clinical outcomes associated with two fundamentally different instillation solutions over the full wound care episode and elucidate the potential impact of these results for future applications. Conclusion: This is the first evaluation of nonsurrogate outcomes of different instillations for NPWT in infected wounds. The results indicate that normal saline instillation outcomes are comparable to those of 0.1% polyhexanide plus 0.1% betaine. The clinical success, cost benefit, and accessibility of normal saline can expand the utilization of this therapeutic approach for larger patient populations.

Update on the role of antiseptics in the management of chronic wounds with critical colonisation and/or biofilm

Biofilms play a major role in delaying chronic wounds from healing. A wound infiltrated with biofilm, or "critically colonised" wound, may become clinically infected if the number of microbes exceeds a critical level. Chronic wound biofilms represent a significant treatment challenge by demonstrating recalcitrance towards antimicrobial agents. However, a "window of opportunity" may exist after wound debridement when biofilms are more susceptible to topical antiseptics. Here, we discuss the role of antiseptics in the management of chronic wounds and biofilm, focusing on povidone-iodine (PVP-I) in comparison with two commonly used antiseptics: polyhexanide (PHMB) and silver. This article is based on the literature reviewed during a focus group meeting on antiseptics in wound care and biofilm management, and on a PubMed search conducted in March 2020. Compared with PHMB and silver, PVP-I has a broader spectrum of antimicrobial activity, potent antibiofilm efficacy, no acquired bacterial resistance or cross-resistance, low cytotoxicity, good tolerability, and an ability to promote wound healing. PVP-I represents a viable therapeutic option in wound care and biofilm management, with the potential to treat biofilm-infiltrated, critically colonised wounds. We propose a practical algorithm to guide the management of chronic, non-healing wounds due to critical colonisation or biofilm, using PVP-I.

Development of an Experimental Ex Vivo Wound Model to Evaluate Antimicrobial Efficacy of Topical Formulations

Wound infections are considered a major cause for wound-associated morbidity. There is a high demand for alternative, robust, and affordable methods that can provide relatable and reproducible results when testing topical treatments, both in research and in the pharmaceutical industry. Here we present an ex vivo wound infection model using porcine skin and a burn wounding method, allowing for the efficacy evaluation of topical antimicrobial formulations. Utilizing this model, we demonstrate the potential of topical treatments after infecting the wounds with clinically significant bacteria, P. aeruginosa and S. aureus. We show that the method is compatible with several analytical tools used to analyze infection and antimicrobial effects. Both bacterial strains successfully infected the wound surface, as well as deeper regions of the tissue. Quantification of viable bacteria on the wound surface and in the tissue, longitudinal measurements of bioluminescence, fluorescence microscopy, and scanning electron microscopy were used to confirm the effects of antibacterial treatments. Furthermore, we show that biofilms are formed on the wound surface, indicating that the demonstrated method mirrors typical in vivo infections.

Negative pressure wound therapy with instillation and dwell time in the wound management of necrotizing fasciitis

OBJECTIVE

Recent literature has shown that negative pressure wound therapy with instillation and dwell time (NPWTi-d) is a valid method of managing complex wounds and gained increasingly wider interest due in part to the increasing complexity of wounds. The purpose of this case study was to obtain information on the profile of NPWTi-d in necrotizing fasciitis patients, investigate the role it play in wound bed preparation, length of hospital stay and number of debridement operations.

METHODS

NPWTi-d has been used in patients with necrotizing fasciitis with either normal saline or Prontosan® solution and complete the treatment were involved in the present study. Following aggressive surgical debridement, NPWTi-d was initiated by instilling solution with a set dwell time of 5-10 min, followed by continuous NPWT of -125 mm Hg for 3-5 h. The system was changed on a 3-5 days schedule until sufficient granulation tissue was evident. Patients received systemic antibiotics and underwent wound debridement as indicated. Data of wound bed preparation, length of hospital stay, duration of NPWTi-d therapy, number of surgical interventions were collected retrospectively from patient medical records.

RESULTS

A total of 32 patients with diagnosis of necrotizing fasciitis received NPWTi-d were included. Granulation tissue was found to be sufficient in 9-16 days. The mean duration of NPWTi-d therapy was 12.5 days prior to wound closure by split-thickness autograft (n = 21), suture (n = 9), or flap transplantation (n = 2).Patients received NPWTi-d treatment over a period of 8-16 days. The mean length of hospitalization was 22.8 days. All wounds were successfully closed and no recurrence of infection or adverse event was observed during NPWTi-d treatment.

CONCLUSION

In these patients, NPWTi-d facilitates wound cleansing and wound bed preparation and offers the clinician an additional tool for the management of necrotizing fasciitis. Further well designed prospective investigations with low risk of bias are needed to confirm these findings in the future work.

The antiseptic Miramistin: a review of its comparative in vitro and clinical activity

Miramistin is a topical antiseptic with broad antimicrobial action, including activity against biofilms and a clinical profile showing good tolerability. Miramistin was developed within a framework of the Soviet Union Cold War Space Program. It is available for clinical use in several prior Soviet bloc countries, but barely known outside of these countries and there is almost no mention of miramistin in the English literature. However, considering emerging antimicrobial resistance, the significant potential of miramistin justifies its re-evaluation for use in other geographical areas and conditions. The review consists of two parts: (i) a review of the existing literature on miramistin in English, Russian and Ukrainian languages; (ii) a summary of most commonly used antiseptics as comparators of miramistin. The oral LD50 was 1200 mg/kg, 1000 mg/kg and 100 g/L in rats, mice and fish, respectively. Based on the results of the review, we suggest possible applications of miramistin and potential benefits over currently used agents. Miramistin offers a novel, low toxicity antiseptic with many potential clinical uses that need better study which could address some of the negative impact of antimicrobial, antiseptic and disinfectant resistance.

Anti-Biofilm Effect of Octenidine and Polyhexanide on Uropathogenic Biofilm-Producing Bacteria

BACKGROUND

A catheter allowing a release of antibacterial substances such as antiseptics into the bladder could be a new way of preventing biofilm formation and subsequent catheter-associated urinary tract infections.

METHODS

Minimal inhibitory and bactericidal concentration (MIC/MBC) determinations in cation-adjusted Mueller-Hinton broth and artificial urine were performed for 4 antiseptics against 3 uropathogenic biofilm producers, Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis. Furthermore, effects of octenidine and polyhexanide against catheter biofilm formation were determined by quantification of biofilm-producing bacteria.

RESULTS

Sodium hypochlorite showed MIC/MBC values between 200 and 800 mg/L for all strains tested. Triclosan was efficient against E. coli and P. mirabilis (MIC ≤2.98 mg/L) but ineffective against P. aeruginosa. Octenidine and polyhexanide showed antibacterial activity against all 3 species tested (MIC 1.95-7.8 and 3.9-31.25 mg/L). Both octenidine and polyhexanide were able to prevent biofilm formation on catheter segments in a concentration dependent manner. Furthermore, adding 250 mg/L of each biocide disrupted biofilms formed by E. coli and P. mirabilis, whereas even 500 mg/L was not sufficient to completely destroy P. aeruginosa biofilms.

CONCLUSION

Octenidine- and polyhexanide-containing antiseptics showed a broad effect against typical uropathogenic biofilm producers even in high dilutions. This study provides a basis for further investigation of the potential of octenidine and polyhexanide as prophylaxis or treatment of catheter biofilms.

Antimicrobial Hypochlorous Wound Irrigation Solutions Demonstrate Lower Anti-biofilm Efficacy Against Bacterial Biofilm in a Complex in-vitro Human Plasma Biofilm Model (hpBIOM) Than Common Wound Antimicrobials

Biofilms pose a relevant factor for wound healing impairment in chronic wounds. With 78% of all chronic wounds being affected by biofilms, research in this area is of high priority, especially since data for evidence-based selection of appropriate antimicrobials and antiseptics is scarce. Therefore, the objective of this study was to evaluate the anti-biofilm efficacy of commercially available hypochlorous wound irrigation solutions compared to established antimicrobials. Using an innovative complex in-vitro human plasma biofilm model (hpBIOM), quantitative reduction of Pseudomonas aeruginosa, Staphylococcus aureus, and Methicillin-resistant S. aureus (MRSA) biofilms by three hypochlorous irrigation solutions [two <0.08% and one 0.2% sodium hypochlorite (NaClO)] was compared to a 0.04% polyhexanide (PHMB) irrigation solution and 0.1% octenidine-dihydrochloride/phenoxyethanol (OCT/PE). Efficacy was compared to a non-challenged planktonic approach, as well as with increased substance volume over a prolonged exposure (up to 72 h). Qualitative visualization of biofilms was performed by scanning electron microscopy (SEM). Both reference agents (OCT/PE and PHMB) induced significant biofilm reductions within 72 h, whereby high volume OCT/PE even managed complete eradication of P. aeruginosa and MRSA biofilms after 72 h. The tested hypochlorous wound irrigation solutions achieved no relevant penetration and eradication of biofilms despite increased volume and exposure. Only 0.2% NaClO managed a low reduction under prolonged exposure. The results demonstrate that low-dosed hypochlorous wound irrigation solutions are significantly less effective than PHMB-based irrigation solution and OCT/PE, thus unsuitable for biofilm eradication on their own. The used complex hpBIOM thereby mimics the highly challenging clinical wound micro-environment, providing a more profound base for future clinical translation.

Anti-staphylococcal activity of quaternized mannan from the yeast Candida albicans

Global increase of antibiotic-resistant pathogens as well as elevated content of drug residues in the foodstuffs and the environment urgently calls for new biocompatible antimicrobial biomaterials. Yeast mannans represent readily available source of biodegradable materials for tailor-made derivatives that could be effective in biomedical applications. Here, antimicrobial properties of quaternized mannans (DS_Q 0.12, 0.24, 0.30, 0.62) from Candida albicans against clinical multi-resistant strains of Staphylococcus aureus are confronted with possible cytotoxicity against human cells. As expected, both effects increase with increasing degree of quaternization. However, it is possible to define the "window", at quaternized mannan with DS_Q 0.30 with good anti-microbial effectiveness and low cytotoxicity. This derivative exhibit minimum inhibitory (MIC) and minimum bactericidal (MBC) concentration from 62.5 to 250 μg/mL and demonstrate good biofilm inhibition effect. Also acceptable values were obtained in hemagglutination and hemolytic activity assays and also in cytotoxicity tests on human fibroblasts.

A Novel Vitamin E TPGS-Based Formulation Enhances Chlorhexidine Bioavailability in Corneal Layers

Keratitis is a severe condition characterized by inflammation of the cornea following a local trauma. The most common ocular disease is the bacterial one, which requires an antibiotic treatment. The major limitation of this therapy is the resistance of the antibiotic. For this reason, alternative procedures have been developed and consist of antimicrobial molecules. One of the most used is the chlorhexidine gluconate, which has shown activity versus Gram-positive and Gram-negative bacteria and fungi. In addition to its efficiency, chlorhexidine shows low toxicity levels for mammalian cells and is a low-cost molecule. Despite its multiple benefits, chlorhexidine, if used at concentrations higher than 0.02% (w/w), can cause local eye irritation. Additionally, its poor penetrability through the cornea makes necessary frequent instillation of eye drops for a prolonged time. Due to these limitations, alternative drug delivery strategies are required. Here, we report a novel formulation based on the combination of d-alpha-tocopherol polyethylene glycol 1000 succinate with chlorhexidine, which results in higher accumulation of the drug in human corneas measured by liquid chromatography and strong antimicrobial activity. Moreover, this formulation does not cause any toxic effect on human cells and is well tolerated by rabbit eyes. Therefore this novel formulation represents a good candidate for the treatment of keratitis that overcomes the risk of antibiotic resistance.

Safety and efficacy profiles of different commercial sodium hypochlorite/hypochlorous acid solutions (NaClO/HClO): antimicrobial efficacy, cytotoxic impact and physicochemical parameters in vitro

Background

Sodium hypochlorite (NaClO, SHC)/hypochlorous acid (HClO, HCA) wound irrigation solutions have experienced a renaissance in the prevention and treatment of low-level wound infections. They are attributed with lower cytotoxicity and have therefore gained increasing attention in daily clinical practice.

Objectives

To determine the cytotoxicity and antimicrobial efficacy of six NaClO/HClO wound irrigation solutions.

Methods

For cytotoxicity evaluation (based on DIN EN 10993-5), human keratinocytes (HaCaT) and human skin fibroblasts (BJ) were used. Staphylococcus aureus and Pseudomonas aeruginosa were used for antimicrobial efficacy evaluation (based on DIN EN 13727). Solutions were evaluated after 1, 5 and 15 min of exposure. Additionally, physicochemical properties (pH and oxidation-reduction potential values) were investigated.

Results

Efficacy and cytotoxicity varied significantly between solutions. Generally, increasing antimicrobial activity was associated with decreasing cell viability. Furthermore, a concentration- and time-dependent impact on pathogens and cells was observed: cytotoxic and antimicrobial activity increased with rising NaClO/HClO solution concentrations and extended exposure times. Based on these in vitro evaluations, the following ranking (lowest to highest microbicidal effect and cytotoxic impact) was found: Microdacyn60® (SHC/HCA-M) < Granudacyn® (SHC/HCA-G) < Veriforte™ (SHC/HCA-V) < KerraSol™ (SHC-K) < Lavanox® (SHC-L) ≪ ActiMaris®forte (SHC/SM-A).

Conclusions

The presented results indicate that microbicidal effects are almost always associated with certain negative side effects on cell proliferation. Efficacy and biocompatibility of NaClO/HClO solutions depend on their specific formulation and physicochemical properties. The investigations also underline the necessity for exact product- and application-specific efficacy profiles.

Potential of Novel Bacterial Cellulose Dressings Chemisorbed with Antiseptics for the Treatment of Oral Biofilm Infections

Infections of the oral cavity are caused by multicellular communities of microbes, referred to as biofilms. Due to the high tolerance of biofilms to antibiotics and specific conditions within the oral cavity, there is an ongoing search for carriers that are able to deliver high local concentrations of potent antimicrobials that can eradicate pathogenic biofilms. Bacterial cellulose, owing to its high flexibility, absorbance, and release potential, meets these demands. In this work we chemisorbed bacterial cellulose with antiseptics containing povidone-iodine or polihexanide and analyzed their ability to eradicate in vitro biofilms formed by oral pathogens, such as Aggregatibacter actinomycetemcomitans, Enterococcus faecalis, Candida albicans, Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa. In tests performed by means of standard laboratory methods and with a long contact time (24 h), all antiseptics released from the cellulose dressings displayed a very high antibiofilm efficacy. On the other hand, when conditions imitating the oral cavity were used and cellulose dressings were applied for a 0.5–1 h contact time, the antiseptics released from the dressings displayed lower, though still acceptable, activity. Our findings indicate that besides species-specific resistance to particular antiseptic agents, environmental and experimental settings play an essential role in outcomes. Finally, in a proof-of-concept experiment performed in an oral cavity typodont model, we demonstrated the high flexibility and adhesiveness of antiseptic-containing cellulose dressings. Our novel findings, if developed in further studies, may lead to the introduction of new types of dressings that are able to efficiently deal with biofilm infections of the oral cavity.

Does antibiotic use accelerate or retard cutaneous repair? A systematic review in animal models

Background

The presence of infections is one of the main factors that leads to delays in healing or non-closure of cutaneous wounds. Although the goal of antibiotic use is to treat or prevent infection, there is currently no agreement on the effectiveness of these products.

Aim

The aim of this study was to evaluate the efficacy of antibiotic use during the healing process of skin wounds in animal models not intentionally infected, as well as to analyze the advances and limitations of the studies carried out in this field.

Main methods

This systematic review was performed according to the PRISMA guidelines, using a structured search on the MedLine (PubMed) and Scopus platforms to retrieve studies published until August 29, 2018, 13:35p.m. The studies included were limited to those that used excision or incision wound models and that were not intentionally infected. The data for the animal models, antibiotic used, and the main results of the studies were extracted, and compared where possible. Bias analysis and methodological quality assessments were examined through the SYRCLE’s Risk of Bias tool.

Key findings

Twenty-seven studies were selected. Overall, the effects of the antibiotic on the wound decreased inflammatory cell infiltration and promoted an increased number of fibroblasts, extracellular matrix constituents, re-epithelialization and tissue strength. A great deal of important information about the methodology was not presented, such as: the statistical analysis used, the animal model (sex and age), antibiotic dosage, blinding and randomization of the animals chosen.

Significance

Based on the results found, we believe that antibiotic therapy can be considered a viable alternative for the treatment of cutaneous wounds. However, current evidence obtained from the methodological quality analysis points towards a high risk of bias. This is due to the incomplete characterization of the experimental design and treatment protocol, which compromises the reproducibility of the studies.

Three-dimensional human skin model infected with Staphylococcus aureus as a tool for evaluation of bioactivity and biocompatibility of antiseptics

In the light of pandemic spreads of multi-drug-resistant micro-organisms, alternative antimicrobial strategies to the use of antibiotics are the focus of research attention. As a prerequisite for medical application, the aim of this study was to develop a three-dimensional full skin infection model to evaluate the bioactivity and biocompatibility of antiseptics in application-relevant concentrations. A three-dimensional (3D) full skin model consisting of collagen-embedded fibroblasts as dermis and a fully differentiated epidermis built from keratinocytes was infected with Staphylococcus aureus. Infected skin models were treated for 24 h with the antiseptics polihexanide, octenidine dihydrochloride, chlorhexidine digluconate and povidone-iodine. Infection resulted in detrimental effects, a strong immune response with increased secretion of lactate dehydrogenase and pro-inflammatory cytokines, and increased gene expression of pro-inflammatory cytokines and antimicrobial peptides after 24 h. Application of antiseptics protected the skin models from damage due to S. aureus infection while demonstrating good biocompatibility. The best ratio of bioactivity to biocompatibility was observed for polihexanide. Polihexanide also enhanced the innate immune response by increasing the gene expression levels of antimicrobial peptides such as human β-defensin 2, human β-defensin 3, psoriasin and ribonuclease 7. The developed model provides an excellent tool to investigate the response of human cells to microbial infections in a complex 3D structure. Furthermore, the infection model is appropriate for evaluation of bioactivity and biocompatibility of antiseptics. As such, the model presented in this study is a promising approach to evaluate the mechanisms and effectiveness of new antimicrobial strategies.

The Effects of Surgical Antiseptics and Time Delays on RNA Isolated From Human and Rodent Peripheral Nerves

Peripheral Nerve Injury (PNI) is common following blunt or penetrating trauma with an estimated prevalence of 2% among the trauma population. The resulting economic and societal impacts are significant. Nerve regeneration is a key biological process in those recovering from neural trauma. Real Time-quantitative Polymerase Chain Reaction (RT-qPCR) and RNA sequencing (RNA seq) are investigative methods that are often deployed by researchers to characterize the cellular and molecular mechanisms that underpin this process. However, the ethical and practical challenges associated with studying human nerve injury have meant that studies of nerve injury have largely been limited to rodent models of renervation. In some circumstances it is possible to liberate human nerve tissue for study, for example during reconstructive nerve repair. This complex surgical environment affords numerous challenges for optimizing the yield of RNA in sufficient quantity and quality for downstream RT-qPCR and/or RNA seq applications. This study characterized the effect of: (1) Time delays between surgical liberation and cryopreservation and (2) contact with antiseptic surgical reagents, on the quantity and quality of RNA isolated from human and rodent nerve samples. It was found that time delays of greater than 3 min between surgical liberation and cryopreservation of human nerve samples significantly decreased RNA concentrations to be sub-optimal for downstream RT-qPCR/RNA seq applications (<5 ng/μl). Minimizing the exposure of human nerve samples to antiseptic surgical reagents significantly increased yield of RNA isolated from samples. The detrimental effect of antiseptic reagents on RNA yield was further confirmed in a rodent model where RNA yield was 8.3-fold lower compared to non-exposed samples. In summary, this study has shown that changes to the surgical tissue collection protocol can have significant effects on the yield of RNA isolated from nerve samples. This will enable the optimisation of protocols in future studies, facilitating characterisation of the cellular and molecular mechanisms that underpin the regenerative capacity of the human peripheral nervous system.

The Antiseptic Octenidine Inhibits Langerhans Cell Activation and Modulates Cytokine Expression upon Superficial Wounding with Tape Stripping

Ideal agents for the topical treatment of skin wounds should have antimicrobial efficacy without negative influence on wound healing. Octenidine (OCT) has become a widely used antiseptic in professional wound care, but its influence on several components of the wound healing process remains unclear. In the present study, we have used a superficial wound model using tape stripping on human full-thickness skin ex vivo to investigate the influence of OCT on epidermal Langerhans cells (LCs) and cytokine secretion pattern of skin cells during wound healing in a model without disruption of the normal skin structure. Histological and immunofluorescence studies showed that OCT neither altered human skin architecture nor the viability of skin cells upon 48 hours of culture in unwounded or wounded skin. The epidermis of explants and LCs remained morphologically intact throughout the whole culture period upon OCT treatment. OCT inhibited the upregulation of the maturation marker CD83 on LCs and prevented their emigration in wounded skin. Furthermore, OCT reduced both pro- and anti-inflammatory mediators (IL-8, IL-33, and IL-10), while angiogenesis and growth factor mediators (VEGF and TGF-β1) remained unchanged in skin explant cultures. Our data provide novel insights into the host response to OCT in the biologically relevant environment of viable human (wounded) skin.

Liposomes with an Ethanol Fraction as an Application for Drug Delivery

Liposomes containing a certain amount of ethanol are often referred to in the literature as ethosomes. Liposomes vary in size from 25 nm to 25,000 nm. Ethosomes are defined as lipids composed of phospholipids, ethanol, or isopropyl alcohol in quite high concentrations, and water. They enable active substances to reach the deep skin layers or even the general circulation. The structure of ethosomes allows for an increased penetration of the drug through two effects: the ethanolic effect and the ethosomal effect. Ethosomes can be obtained using three methods: the hot method, the cold method, and the classic method of mechanical dispersion. The literature describes many of the therapeutic groups of drugs that can be enclosed in ethosomal formulations. These include anti-viral drugs, antineoplastic drugs, antifungal drugs, hypnotic drugs, hormones, and many others. Ethosomes show important practical advantages compared to classic liposomes. It is necessary to conduct research with regard to real pharmaceutical systems using advanced physicochemical techniques.

Comparison of the bactericidal effect of cold atmospheric pressure plasma (CAPP), antimicrobial photodynamic therapy (aPDT), and polihexanide (PHX) in a novel wet surface model to mimic oral cavity application

PURPOSE

Cold atmospheric pressure plasma (CAPP) is increasingly used for medical applications. The first devices are available from commercial manufactures, promising to improve wound healing and disinfection. The underlying antimicrobial mechanisms of CAPP are discussed, while the first results on its bactericidal efficiency against common bacterial species have already been published, with promising results. Most of the plasma sources used in these studies were built by the investigators themselves, and are not commercially available or licensed for clinical use. To evaluate the postulated bactericidal effects in clinical practice, we studied a commercially available, ready-to-use CAPP-device, which is also designed to be used in the field of dental, oral, and maxillofacial treatment.

MATERIALS AND METHODS

Standardized bacterial cultures of two different pathogens (Acinetobacter baumannii and Staphylococcus aureus) were produced with defined colony-forming unit concentrations. Dilutions of these cultures were treated with a commercially available CAPP product according to the manufacturer's instructions in order to evaluate the antimicrobial activity of the technique. This in vitro study compared the CAPP treatment with established clinical therapies like polihexanide (PHX) and antimicrobial photodynamic therapy (aPDT).

RESULTS

The bactericidal effect was evaluated in terms of reduction in colony-forming units after treatment of the bacterial samples with a defined dose of plasma, aPDT, or PHX. For CAPP, the bactericidal effect was found to be stronger in the Gram-negative isolate (A. baumannii) than in the Gram-positive S. aureus. A strong depth dependency was observed, especially with the Gram-negative isolate. Good bactericidal effects, with a reduction in bacterial load of more than 2 × log₁₀, could only be observed in conditions of 0.3 mm of water-film thickness or less. Such a significant reduction in bactericidal effect depending on depth was not observed using aPDT or PHX in the studied depth range of 0.3-1.8 mm.

CONCLUSION

CAPP treatment performed by the device (Plasma ONE) and configuration we used in this study seems to be ill suited for sufficiently killing Acinetobacter baumannii or Staphylococcus aureus in a moist infection site, as would be expected in the oral cavity. Established local antimicrobial therapies using PHX or aPDT showed better disinfectant properties. The clinical effect of improved wound healing, described by the manufacturer and some scientists, could not be investigated using this model. Given the results, however, it seems unlikely to be a direct consequence of bactericidal effects of CAPP in a wet environment. Further development of CAPP devices, or a different configuration (e.g. with a higher output, resulting in reactive nitrogen species-dominated, gas-phase chemistry), may enhance antibacterial effects in future, while tissue compatibility of such techniques remains to be elucidated further.

Cytotoxicity evaluation of chlorhexidine gluconate on human fibroblasts, myoblasts, and osteoblasts

Introduction: Chlorhexidine gluconate (CHX) is widely used as a preoperative surgical skin-preparation solution and intra-wound irrigation agent, with excellent efficacy against wide variety of bacteria. The cytotoxic effect of CHX on local proliferating cells following orthopaedic procedures is largely undescribed. Our aim was to investigate the in vitro effects of CHX on primary fibroblasts, myoblasts, and osteoblasts. Methods: Cells were exposed to CHX dilutions (0%, 0.002%, 0.02%, 0.2%, and 2%) for either a 1, 2, or 3-minute duration. Cell survival was measured using a cytotoxicity assay (Cell Counting Kit-8). Cell migration was measured using a scratch assay: a "scratch" was made in a cell monolayer following CHX exposure, and time to closure of the scratch was measured. Results: All cells exposed to CHX dilutions of ≥ 0.02% for any exposure duration had cell survival rates of less than 6% relative to untreated controls (p < 0.001). Cells exposed to CHX dilution of 0.002% all had significantly lower survival rates relative to control (p < 0.01) with the exception of 1-minute exposure to fibroblasts, which showed 96.4% cell survival (p = 0.78). Scratch defect closure was seen in < 24 hours in all control conditions. However, cells exposed to CHX dilutions ≥ 0.02% had scratch defects that remained open indefinitely. Conclusions: The clinically used concentration of CHX (2%) permanently halts cell migration and significantly reduces survival of in vitro fibroblasts, myoblasts, and osteoblasts. Further in vivo studies are required to examine and optimize CHX safety and efficacy when applied near open incisions or intra-wound application.

Characterization and antibacterial mechanism of poly(aminoethyl) modified chitin synthesized via a facile one-step pathway

This work aims to synthesize poly(aminoethyl) modified chitin (PAEMC) and ascertain its antibacterial activity and mechanism. FTIR and ¹H NMR results proved aminoethyl moieties were grafted to C6OH and C3OH on chitin backbone in the form of polymerization. XRD and TG/DTG analyses manifested its well-defined crystallinity and thermostability. PAEMC, with average molecular weight (MW) of 851.0 kDa, degree of deacetylation (DD) of 27.95%, and degree of substitution (DS) of 1.77, had good solubility in aqueous solutions over the pH range of 3-12, and also possessed high antimicrobial activity against Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus proteus, and Klebsiella pneumoniae, commonly causing chronic wound infections. Nucleic acid release, protein leakage, increased inner membrane permeability, and decreased cell surface hydrophobicity implied bacterial cytomembranes were substantially compromised in the presence of PAEMC. Microscopically, PAEMC visually perturbed bacteria, illustrating deformed and even collapsed morphologies. Overall, PAEMC possessed good solubility, effectively destroyed bacteria via a membrane damage mechanism, and might serve as an antibacterial agent for treatments of chronic wound infections.

Povidone-iodine Solutions Inhibit Cell Migration and Survival of Osteoblasts, Fibroblasts, and Myoblasts

STUDY DESIGN

In vitro laboratory study.

OBJECTIVE

The purpose of this study was to identify the effect of dilute povidone-iodine (PVI) solutions on human osteoblast, fibroblast and myoblast cells in vitro.

SUMMARY OF BACKGROUND DATA

Dilute PVI wound lavage has been used successfully in spine and joint arthroplasty procedures to prevent postoperative surgical site infection, but their biologic effect on host cells is largely unknown.

METHODS

Human primary osteoblasts, fibroblasts, and myoblasts were expanded in cell culture and subjected to various concentrations of PVI (0%, 0.001%, 0.01%, 0.1%, 0.35%, 1%) for 3 minutes. To assess the effect of PVI on cell migration, a scratch assay was performed, in which a "scratch" was made by a standard pipette tip in a cell monolayer following PVI exposure, and time to closure of the scratch was evaluated. Cell survival and proliferation was measured 48 hours post-PVI exposure using a cell viability and cytotoxicity assay.

RESULTS

Closure of the scratch defect in all cell monolayers was achieved in <24 hours in untreated controls and following exposure to PVI concentrations <0.1%. The scratch defect remained open indefinitely following exposure to PVI concentrations of ≥0.1%. PVI concentrations <0.1% did not have significant effect on survival rates compared with control for all cell types. Cells exposed to PVI ≥ 0.1% had cell survival rates of less than 6% (P < 0.05).

CONCLUSIONS

Clinically used concentration of PVI (0.35%) exerts a pronounced cytotoxic effect on osteoblasts, fibroblast, and myoblasts in vitro. Further investigation is required to systematically study the effect of PVI on tissue healing in vivo and also determine a safe and clinically potent concentration for PVI lavage.

LEVEL OF EVIDENCE

N/A.

The Effect of Antiseptics on Adipose-Derived Stem Cells

BACKGROUND

Although chemical antiseptics are the most basic measure to control wound infection and frequently come into contact with subcutaneous adipose tissue, no studies have evaluated their toxicity on adipose tissue and its cell fractions. In the present study, the effects of five different antiseptics on adipose-derived stem cells were evaluated.

METHODS

Human adipose-derived stem cells were harvested from healthy donors. Adipose-derived stem cell viability was measured after treatment with different concentrations of antiseptics over 5 days. Furthermore, the effect on the proliferation, adipogenic differentiation, and apoptosis/necrosis of adipose-derived stem cells was analyzed. Finally, the mRNA expression of the stem cell markers CD29, CD34, CD73, CD90, and CD105 was detected.

RESULTS

Octenisept and Betaisodona significantly reduced cell proliferation and differentiation and led to considerable adipose-derived stem cell necrosis. Octenisept decreased stem cell viability at the lowest concentrations tested, and all stem cell markers were down-regulated by Octeniseptr and Betaisodona. Lavasept and Prontosan both led to reduced stem cell viability, proliferation, and differentiation, and increased apoptosis/necrosis, although the effects were less pronounced compared with Octenisept and Betaisodona. Adipose-derived stem cells survived treatment with mafenide acetate even at high concentrations, and mafenide acetate showed minimal negative effects on their proliferation, adipogenic differentiation, cell death, and stem cell marker expression.

CONCLUSIONS

Mafenide acetate may be regarded as a feasible antiseptic for the treatment of wounds with exposed adipose tissue because of its low adipose-derived stem cell toxicity. Lavasept and Prontosan are possible alternatives to mafenide acetate. Octenisept and Betaisodona, by contrast, may be used only in highly diluted solutions.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Enhanced wound healing by topical application of ointment containing a low concentration of povidone-iodine

OBJECTIVE

To investigate the effect of a novel topical wound-healing agent, low-concentration povidone-iodine ointment (LPIO) with a hydrophobic white petrolatum-rich base on skin-wound models in rats and rabbits.

METHOD

The therapeutic efficacy of topically applied LPIO was compared to that of standard-concentration povidone-iodine ointment (SPIO) and non-treatment control, using a full-thickness skin-wound model in 24 hairless rats and a full-thickness skin-defect model in rabbit earlobes. The animals were kept under standardised conditions at the Central Research Laboratory of Maruishi Pharmaceutical Co. Ltd. (Osaka, Japan). Therapeutic efficacy was evaluated based on macroscopic wound-size reduction, as well as histopathological and immuno-histochemical examinations.

RESULTS

LPIO enhanced wound healing in rat full-thickness skin ulcers, reducing wound size and inflammation, when compared with that in SPIO and non-treatment control. LPIO also markedly improved wound healing in rabbit earlobe ulcers by significantly improving re-epithelialisation, compared with that in SPIO.

CONCLUSION

The results of this study suggest that LPIO is a useful topical therapy for ulcerative lesions.

[Randomised clinical trial to compare two tracheotomy care methods in an Intensive Care Unit]

INTRODUCTION

Tracheotomy is a common technique in Intensive Care Units (ICU). It is known that nursing care during and after that procedure is directly related to its success, by reducing the possible complications to a minimum, such as the stoma infection, and contributing to a favourable outcome in critical patients.

OBJECTIVES

To compare the use of polyhexanide (PLX) versus saline+povidone iodine (PY) as antiseptics and infection incidence in tracheostomies performed in Intensive Care Units.

MATERIAL AND METHOD

A 2-year, experimental, randomised, open-label trial carried out in a multidiscipline ICU with 32 beds. The study was approved by the Research Ethics Committee of Principality of Asturias.

RESULTS

The overall infection rate observed for every hundred patients was 1.34 (95% CI; 0.81-2.01), with 1.46 when using PLX and 1.21 for PY (P=.685).

CONCLUSIONS

In spite of the experimental treatment (PLX) was shown to be effective in other types of wounds in our study. No significant differences were found between this technique and the standard one. Since there is no national registry of tracheotomy- associated infections, it is not possible to know whether the rate observed is within the usual parameters.

[Severe complications after non-intended usage of octenidine dihydrochloride. A case series with four dogs]

OBJECTIVE

Case series of four dogs in which extensive bite wounds had been treated using octenidine dihydrochloride (Octenivet® or Octenisept®) flushing. The dogs subsequently developed severe local complications.

MATERIAL AND METHODS

Retrospective evaluation of clinical symptoms, diagnostics, therapy and course of the disease.

RESULTS

In four dogs, severe necrosis and persistent edematous changes of the treated area developed after the application of octenidine dihydrochloride. The clinical course was comparable to complications described previously in human medicine. Therapy was protracted and complicated by secondary wound infection.

CONCLUSION AND CLINICAL RELEVANCE

Irrigation of deep wounds, particularly bite wounds, using octenidine dihydrochloride without drainage may lead to persistent edematous changes, inflammatory reactions and necrosis. The inappropriate application of octenidine dihydrochloride for wound irrigation should be avoided in veterinary medicine.

Cell growth and migration under octenidine-antiseptic treatment

OBJECTIVE

The toxicity of octenidine antiseptics in cultured cells contrasts their good tolerability in tissue. This phenomenon prompted us to examine which cell culture conditions allow survival and proliferation and to investigate a possible modulation of toxicity by the extracellular matrix proteoglycan chondroitin sulfate.

METHOD

We tested fibroblasts and MCF7 cells for growth using the MTT test, and assessed wound healing potency with a laceration assay. Expression levels of the genes involved in controlling wound healing were assessed with RT-PCR.

RESULTS

A 24 hour exposure to the octenidine-based solution was found incompatible with cell growth. When octenidine solution (0.5-0.5mg/l) was coated on dishes, growth was profoundly reduced after 24 hours, however there was no cytotoxic effect at 0.012 mg/l. Interestingly, when dishes were first coated with chondroitin sulfate the cytotoxicity of octenidine-based solution was modulated. Cell migration was not inhibited by octenidine-based solution treatment (2 minutes; 15 mg/l). No significant changes in gene expression levels in response to the octenidine-based solution treatment were detected.

CONCLUSION

In cell culture conditions application of the octenidine-based solution without toxicity can be observed, comparable to the minimal application required to give full bactericidal effect. Alteration of toxicity by interaction with chondroitin sulfate in cell culture suggests a similar function for extraceullar matrix in intact tissue.

Human osteoblast damage after antiseptic treatment

PURPOSE

Antiseptics are powerful medical agents used for wound treatment and decontamination and have a high potential for defeating joint infections in septic surgery. Both chlorhexidine and polyhexanide are frequently used in clinical practice and have a broad antimicrobial range, but their effect on human osteoblasts has not been sufficiently studied. Our objective was to investigate the toxic effects of polyhexanide and chlorhexidine on human osteoblasts in vitro to evaluate their clinical applicability in septic surgery.

METHODS

We isolated and cultivated human osteoblasts in vitro and assayed the toxic effects of chlorhexidine 0.1% and polyhexanide 0.04%, concentrations commonly applied in clinical practice. Toxicity analysis was performed by visualisation of cell structure, lactate dehydrogenase (LDH) activity and evaluation of vital cells. Toxicity was evaluated by microscopic inspection of cell morphology, trypan blue staining and determination of LDH release.

RESULTS

Damaged cell structure could be shown by microscopy. Both antiseptics promoted LDH activity after incubation with osteoblasts. The evaluation of vital osteoblasts showed a significant decrease of vital cells.

CONCLUSIONS

Both antiseptics induced significant cell death of osteoblasts at optimum exposure. We therefore recommend cautious use of polyhexanide and chlorhexidine in septic surgery to avoid severe osteoblast toxicity.