Evaluation of Methylene Blue as An Effective Antiseptic for Medicinal Leeches (Hirudo verbana).

Objective: Medicinal leeches (Hirudo spp.) have been used for therapeutic purposes in humans since ancient times. Because of their growth conditions, leeches carry certain bacteria and endosymbionts (e.g., Aeromonas spp). In both leech farms and hirudotherapy clinics, there are no reliable antiseptics that can be used with leeches. This study aimed to determine whether methylene blue (MB) is a safe antiseptic for medicinal leeches and assess its safe usage. Methods: This study evaluated the efficacy of MB by determining lethal concentrations (LC), effective concentrations (EC), and lethal times (LT) for the medicinal leech Hirudo verbena Carena, 1820. A total of 570 H. verbana specimens obtained from a local farm were used in this study. Eighteen different concentrations of MB (between 1 ppm and 512 ppm) were tested. Results: The LC50 and EC50 values for H. verbana were determined to be 60.381 (53.674-66.636) ppm and 2.013 (1.789-2.221) ppm, respectively. The LT50 durations for MB concentrations of 32 and 512 ppm were calculated as 212.92 h (138.43 h-1485.78 h) and 17.82 h (8.08 h-23.90 h), respectively. Conclusion: The results show that MB concentrations between 2 and 19 ppm can be safely used as antiseptics in hirudotherapy clinics and leech farms to address bacterial concerns caused by medicinal leeches.

Efficacy of Chlorhexidine Impregnated Wipes for the Local Dysbiosis in Atopic Dogs: A Multicentric Prospective Study.

(1) Background: Dysbiosis is frequently observed in Canine Atopic Dermatitis (CAD). Antimicrobial treatment may be necessary to treat flare ups and the use of topical treatments is beneficial to prevent the development of bacterial resistance. Wipes are an easy way to apply antiseptic agents on the skin. The aim of this study was to evaluate the benefits of 3% chlorhexidine impregnated wipes (Pyoskin® wipes, MP Labo, France) on local areas of dysbiosis in dogs with CAD. (2) Methods: A total of 20 dogs suffering from CAD presented with localised areas of dysbiosis were included in this study. Affected areas were cleansed with the daily application of chlorhexidine wipes once a day for 14 days. Follow-up visits were scheduled after one and two weeks. Clinical signs (lesions and pruritus), dysbiosis scored by cytological counts (cocci and Malassezia) and investigator and owner global appreciation were evaluated. (3) Results: A statistically significant decrease in clinical scores and cytological counts were observed as soon as D7 and until D14. Both owner and investigator appreciation were considered high (4) Conclusions: The use of chlorhexidine impregnated wipes is a useful and easy way to manage localised dysbiosis in atopic dogs and allows limiting of systemic medication to prevent bacterial resistance.

Amnion as an Innovative Antiseptic Carrier: A Comparison of the Efficacy of Allogeneic and Xenogeneic Transplantations in the Context of Burn Therapy.

Background and Objectives: The amniotic membrane is widely used in the treatment of chronic wounds, in toxic epidermal necrolysis (TEN), and in the treatment of burns. In our clinical practice, we use amniotic dressings on shallow skin wounds caused by burns. Counteracting infections is an important aspect of working with burn wounds. Therefore, the main goals of this work are to demonstrate the usefulness of amniotic membrane soaked in antiseptics for the prevention of wound infections and to compare the antibacterial efficacy of selected variants of allogeneic and xenogeneic amniotic membrane grafts soaked in specific antiseptic agents. Materials and Methods: The studied material consisted of human and pig placenta. The human and animal amnions were divided in two parts. The first part consisted of amniotic discs placed on rigid mesh discs and preparing the fresh amnion. The second part of the amnion was frozen at a temperature of -80 °C for 24 h. Then, it was radio-sterilized with a dose of 35 kGy. The amniotic discs were placed on rigid mesh to prepare the radiation-sterilized amnion. The amniotic discs were placed in a 12-well plate and immersed in 3 mL of the appropriate antiseptic solutions: Prontosan, Braunol, Borasol, Microdacyn, Octenilin, Sutrisept, and NaCl as a control. The amniotic discs were incubated in antiseptics for 3 h. The microbiological tests were conducted by placing the antiseptic-infused amniotic discs on microbiological media inoculated with hospital strains. Results: The largest average zone of growth inhibition was observed in dressings soaked with Sutrisept, Braunol, and Prontosan. The greatest inhibition of bacterial growth was achieved for radiation-sterilized porcine amnion impregnated with Braunol and Sutrisept, as well as for radiation-sterilized human amnion impregnated with Braunol. Conclusions: Human and porcine amniotic membrane is effective in carrying antiseptics. Radiation-sterilized amnion seems to inhibit the growth of microorganisms better than fresh amnion.

Antiseizure Activity of Mitragyna inermis in the Pentylenetetrazol-Induced Seizure Model in Mice: Involvement of Flavonoids and Alkaloids.

Objective: This study aimed to investigate whether Mitragyna inermis (Willd.) Otto Kuntze organic and aqueous extracts are able to control seizures induced by pentylenetetrazol (PTZ) in mice based on flavonoid fingerprints and alkaloidal contents. Materials and Methods: Ethanolic extract and decoction-derived fractions from roots, leaves, and stems were subjected to chromatographic fingerprinting using AlCl3 and screening for their antiseizure effects using PTZ-induced acute seizure model. From the fractions that showed potent bioactivities, plausible antiseizure alkaloids were isolated using thin layer chromatography, and their structures were elucidated using 1H NMR, 2D NMR, 13C NMR, and FAB-HR (+ve or -ve). Results: All fractions, with the exception of the dichloromethane and hexane fractions, revealed remarkable flavonoid fingerprints. An acute PTZ-induced seizure test revealed that ethanolic extract of stem bark [500 mg/kg body weight (bw)], ethyl acetate extract of stem bark (500 mg/kg bw), and aqueous extract of leaves (300 mg/kg bw) significantly delayed the occurrence of hind limb tonic extension (HLTE); however, a non-significant delay was observed in the onset of first myoclonic jerk compared with control animals. Isolation yielded four main alkaloids: that are, pteropodine (1), isopteropodine (2), mitraphylline (3) and corynoxeine (4). Corynoxeine is a new compound derived from M. inermis. Conclusion: This study suggests that flavonoid fingerprints are tracers of M. inermis anticonvulsant ingredients. The stem bark ethanolic and ethyl acetate extracts and leaf aqueous extracts contain anticonvulsant bioactive principles that delay notifying the HLTE occurring in male naval medical research institute mice. Furthermore, alkaloidal contents also remain plausible bioactive anticonvulsant principles. All observations support the traditional use of M. inermis to manage epilepsy. However, further studies are needed to understand the effects of alkaloid fractions, flavonoids, and the isolated compounds as promising antiseizure agents derived from M. inermis in experimental animals.

A Low-Cost Protocol Using the Adjunctive Action of Povidone-Iodine Irrigations and Sodium Hypochlorite Rinsing Solution in Step 2 of Periodontal Therapy for Patients with Stage III-IV Periodontitis: A Single-Blind, Randomized Controlled Trial.

In severe stages of periodontitis, conventional periodontal therapy and maintenance care are usually insufficient due to the viral and bacterial etiology; thus, a mechanical approach alone may not be sufficient to eliminate a substantial portion of subgingival pathogens, especially in deep periodontal sites. Background and Objectives: This single-blind, randomized clinical trial aimed to compare the clinical and microbiological efficacy of a low-cost protocol using povidone-iodine and sodium hypochlorite formulations as adjuncts to non-surgical therapy for patients with stage IV periodontitis when compared with chlorhexidine, the most commonly employed substance to date for antimicrobial regimens in periodontal therapy. Materials and Methods: Forty-five patients were randomly divided into two groups: control (subgingival instrumentation, chlorhexidine-assisted) and test (antiviral medication, subgingival instrumentation with povidone-iodine, sodium hypochlorite rinsing solution, and antibiotics). Clinical measurements and microbiological analyses were performed at baseline and after three months. Results: After three months, notable differences were found in the bacterial detection scores for Porphyromonas gingivalis (a significant reduction in detection frequency was observed in the test compared to the control (p = 0.021)), and there were significant reductions in detection in the test group for Tannerella forsythia and Treponema denticola, showing undetectable levels (p < 0.0001 for both). In the test group, the pocket probing depth median value was reduced significantly (p = 0.0005); similarly, bleeding on probing showed a marked decrease (p < 0.0001). However, changes in clinical attachment loss and full-mouth plaque score were not statistically significant. Conclusions: Using the proposed protocol, substantial improvements in clinical and microbiological parameters were obtained when compared with the current antimicrobial recommendations.

Supragingival dental biofilm profile and biofilm control during orthodontic treatment with fixed orthodontic appliance: A randomized controlled trial.

OBJECTIVE: The effectiveness of supragingival dental biofilm control during orthodontic treatment and changes in the bacterial profile were analyzed. DESIGN: Sixty-four participants aged 12-22 years (57% female) were included in the study. Participants underwent orthodontic treatment with fixed appliances and were randomly assigned to one of the three groups, which during a period of one month: (I) used chlorhexidine digluconate (CHX), (II) used high concentration of fluoride (F) gel and (III) performed standard oral hygiene. The plaque and gingivitis index, pH of biofilm and white spot lesions (WSL) were assessed. Changes of the bacteria in the biofilm were analyzed by the quantitative polymerase chain reaction RESULTS: Increase in the plaque index, pH of biofilm, and WSL was observed during orthodontic treatment with standard oral hygiene. Large interindividual variability was present, and the effects of one-month use of fluorides and CHX on clinical parameters were not significant. Despite standard hygiene the abundance of studied biofilm bacteria increased - the most Streptoccocus mutans (14.2x) and S. salivarius (3.3x), moderate Veillonella parvula (3x) and the least S. sobrinus (2.3x) and Agregatibacter actinomycetemcomitans (1.9x). The use of CHX reduced S. sobrinus (2.2x) and A. actinomycetemcomitans (1.9x). Fluoride use reduced A. actinomycetemcomitans (1.3x) and S. sobrinus (1.2x). Fluorides better controlled S. mutans than CHX. CONCLUSION: Bacterial biomass in supragingival biofilm increased during treatment with metal orthodontic appliances, with greater increase in cariogenic bacteria than periopathogens. Fluoride controlled S. mutans, while CHX S. sobrinus and A. actinomycetemcomitans.

Tolerability of N-chlorotaurine in comparison with routinely used antiseptics: an in vitro study on chondrocytes.

BACKGROUND: Currently, povidone-iodine (PVP-I) and hydrogen peroxide (H2O2) are frequently used antiseptics in joint infections, but the cytotoxic effects of these solutions are already reported. N-chlorotaurine (NCT) shows a broad-spectrum bactericidal activity and is well tolerated in various tissues, but its effect on human chondrocytes is unknown. The purpose of this study was to assess the cytotoxic effect of NCT, PVP-I, and H2O2 on human chondrocytes compared to a control group in an in vitro setting to get first indications if NCT might be a promising antiseptic in the treatment of septic joint infections for the future. MATERIAL AND METHODS: Chondrocytes extracted from human cartilage were incubated with various concentrations of NCT, PVP-I, and H2O2 for 5 and 30 min respectively. EZ4U cell viability kit was used according to the manufacturer's recommendations determining cell viability. To assess cell viability based on their nuclear morphology, cells were stained with acridine-orange and identified under the fluorescence microscope. RESULTS: EZ4U kit showed after 5 and 30 min of incubation a significant decrease in cell viability at NCT 1%, NCT 0.1%, PVP-I, and H2O2, but not for NCT 0.001% and NCT 0.01%. Acridine-orange staining likewise presented a significant decrease in vital cells for all tested solutions except NCT 0.001% and NCT 0.01% after 5 and 30 min of incubation. CONCLUSION: Our results demonstrate that NCT is well tolerated by chondrocytes in vitro at the tested lower NCT concentrations 0.01% and 0.001% in contrast to the higher NCT concentrations 1% and 0.1%, PVP-I (1.1%), and H2O2 (3%), for which a significant decrease in cell viability was detected. Considering that the in vivo tolerability is usually significantly higher, our findings could be an indication that cartilage tissue in vivo would tolerate the already clinically used 1% NCT solution. In combination with the broad-spectrum bactericidal activity, NCT may be a promising antiseptic for the treatment of septic joint infections.

Knowledge, awareness, and risk practices related to bacterial contamination of antiseptics, disinfectants, and hand hygiene products among healthcare workers in sub-saharan Africa: a cross-sectional survey in three tertiary care hospitals (Benin, Burkina Faso, and DR Congo).

BACKGROUND: Antiseptics, disinfectants, and hand hygiene products can be contaminated with bacteria and cause healthcare-associated infections, which are underreported from low- and middle-income countries. To better understand the user-related risk factors, we conducted a knowledge, awareness, and practice survey among hospital staff in sub-Saharan Africa. METHODS: Self-administered questionnaire distributed among healthcare workers in three tertiary care hospitals (Burkina Faso, Benin, Democratic Republic of the Congo). RESULTS: 617 healthcare workers (85.3% (para)medical and 14.7% auxiliary staff) participated. Less than half (45.5%) had been trained in Infection Prevention & Control (IPC), and only 15.7% were trained < 1 year ago. Near two-thirds (64.2%) preferred liquid soap for hand hygiene, versus 33.1% for alcohol-based hand rub (ABHR). Most (58.3%) expressed confidence in the locally available products. Knowledge of product categories, storage conditions and shelf-life was inadequate: eosin was considered as an antiseptic (47.5% of (para)medical staff), the shelf life and storage conditions (non-transparent container) of freshly prepared chlorine 0.5% were known by only 42.6% and 34.8% of participants, respectively. Approximately one-third of participants approved using tap water for preparation of chlorine 0.5% and liquid soap. Most participants (> 80%) disapproved recycling soft-drink bottles as liquid soap containers. Nearly two-thirds (65.0%) declared that bacteria may be resistant to and survive in ABHR, versus 51.0% and 37.4% for povidone iodine and chlorine 0.5%, respectively. Depicted risk practices (n = 4) were ignored by 30 to 40% of participants: they included touching the rim or content of stock containers with compresses or small containers, storing of cotton balls soaked in an antiseptic, and hand-touching the spout of pump dispenser. Filling containers by topping-up was considered good practice by 18.3% of participants. Half (52.1%) of participants acknowledged indefinite reuse of containers. Besides small differences, the findings were similar across the study sites and professional groups. Among IPC-trained staff, proportions recognizing all 4 risk practices were higher compared to non-trained staff (35.9% versus 23.8%, p < 0.0001). CONCLUSIONS: The present findings can guide tailored training and IPC implementation at the healthcare facility and national levels, and sensitize stakeholders' and funders' interest.

Which antiseptic to use for a caesarean section? A systematic review and network meta-analysis of randomized controlled trials.

Guidelines for pre-operative skin antisepsis recommend using chlorhexidine in an alcohol-based solution. However, other antiseptics such as aqueous povidone-iodine or alcohol-based solutions continue to be used. Randomized controlled trials (RCTs) in caesarean section are rare and do not include all possible comparisons of antiseptics. The aim of this study was to assess the efficacy (reduction of surgical site infections) of chlorhexidine at two different concentrations (0.3% and 2%) and povidone-iodine in aqueous or alcohol-based solutions using a network meta-analysis, including only RCTs of caesarean sections. Fragility indices and prediction intervals were also estimated. A systematic literature review and network meta-analysis were performed. RCTs published up to February 2024 were collected from PubMed, ScienceDirect and the Cochrane Library. Interventions included alcohol-based povidone-iodine, aqueous povidone-iodine, and alcohol-based chlorhexidine 2% and 0.3%. The primary outcome measure was surgical site infection. Nine RCTs with 4915 patients and four interventions were included in the network meta-analysis. All credible intervals of the compared interventions overlapped. Alcohol-based 2% chlorhexidine had the highest probability of being effective in preventing surgical site infections, followed by alcohol-based povidone-iodine. The fragility index ranged from 4 to 18. The prediction intervals were wide. On the basis of rank probabilities, chlorhexidine 2% in an alcohol-based solution was most likely to be effective in preventing surgical site infections after caesarean section, followed by alcohol-based povidone-iodine. Given the paucity of literature and the relatively small difference between povidone-iodine and chlorhexidine found in our meta-analysis, we suggest that either can be used in an alcohol-based solution as antisepsis for planned or emergency caesarean section.

The influence of cationic antiseptics on the processes of light energy conversion in various photosynthetic pigment-protein complexes.

The widespread use of disinfectants and antiseptics, and consequently their release into the environment, determines the relevance of studying their potential impact on the main producers of organic matter on the planet-photosynthetic organisms. The review examines the effects of some biguanides and quaternary ammonium compounds, octenidine, miramistin, chlorhexidine, and picloxidine, on the functioning of the photosynthetic apparatus of various organisms (Strakhovskaya et al. in Photosynth Res 147:197-209, 2021; Knox et al. in Photosynth Res 153:103, 2022; Paschenko et al. in Photosynth Res 155:93-105, 2023a, Photosynth Res 2023b). A common feature of these antiseptics is the combination of hydrophobic and hydrophilic regions in the molecules, the latter carrying a positive charge(s). The comparison of the results obtained with intact bacterial membrane vesicles (chromatophores) and purified pigment-protein complexes (photosystem II and I) of oxygenic organisms allows us to draw conclusions about the mechanisms of the cationic antiseptic action on the functional properties of the components of the photosynthetic apparatus.

Trends in the Incorporation of Antiseptics into Natural Polymer-Based Nanofibrous Mats.

Nanofibrous materials represent a very promising form of advanced carrier systems that can be used industrially, especially in regenerative medicine as highly functional bandages, or advanced wound dressings. By incorporation of antimicrobial additives directly into the structure of the nanofiber carrier, the functionality of the layer is upgraded, depending on the final requirement-bactericidal, bacteriostatic, antiseptic, or a generally antimicrobial effect. Such highly functional nanofibrous layers can be prepared mostly by electrospinning technology from both synthetic and natural polymers. The presence of a natural polymer in the composition is very advantageous. Especially in medical applications where, due to the presence of the material close to the human body, the healing process is more efficient and without the occurrence of an unwanted inflammatory response. However, converting natural polymers into nanofibrous form, with a homogeneously distributed and stable additive, is a great challenge. Thus, a combination of natural and synthetic materials is often used. This review clearly summarizes the issue of the incorporation and effectiveness of different types of antimicrobial substances, such as nanoparticles, antibiotics, common antiseptics, or substances of natural origin, into electrospun nanofibrous layers made of mostly natural polymer materials. A section describing the problematic aspects of antimicrobial polymers is also included.

Reactive skin decontamination lotion (RSDL) safety with clinical antiseptics and hemostatic agents.

Reactive skin decontamination lotion (RSDL) is a Health Canada approved product used by the Canadian Armed Forces for removal and inactivation of toxic chemicals on skin. Although it is considered very safe when used as directed, questions have been raised regarding whether topical RSDL in the medical setting will react exothermically with antiseptic compounds on the casualty's epidermis that could result in thermal burns. Benchtop experiments were conducted to investigate reactivity of RSDL with various antiseptic compounds or hemostatic agents. Temperature changes were closely monitored in three different volume ratios, 1:10, 1:1, and 10:1 over a time course of 16 minutes. Chlorine based bleaches versus RSDL were included as a positive control and were the only combination that exhibited a significant exothermic reaction capable of causing minor thermal burns. RSDL was also evaluated with antiseptic solution applied to swine epidermal tissue without observation of visual irritation; then in lacerated skeletal muscle tissue which resulted in no measured temperature change. The conclusion of this study is that antiseptics and hemostatic agents can be used as required on a patient decontaminated with RSDL as no exothermic reaction will occur.

A double-blind trial comparing an antimicrobial combination to standard care in hard-to-heal wounds.

OBJECTIVE: Excessive numbers of bacteria in hard-to-heal wounds impede wound healing. Numerous topical antiseptics have demonstrated effectiveness in benchtop studies; however, few clinical studies have demonstrated efficacy in the target population: patients with hard-to-heal wounds. This study addressed the clinical efficacy of a novel antibiofilm cleanser and gel in reducing bacterial load and improving wound outcomes. METHOD: Hard-to-heal wounds were photographed, measured and evaluated for bacterial load using fluorescence imaging weekly for four weeks. The target ulcers were randomised to be cleaned and treated with either a synergistic antibiofilm cleanser and antibiofilm gel with standard of care (AMC-AMG + SoC) or normal saline wash and an amorphous gel with standard of care (NSS-HG + SoC). RESULTS: A Chi-squared test of independence determined that the relationship between the treatment and the patient reaching 40% percentage area reduction (PAR) in four weeks was not significant (χ2(1, n=54)=0.73; p=0.39 at a significance level of 0.05); however, there was a strong trend favouring the antibiofilm cleanser and gel. A significant reduction (p<0.05) in bacterial load was observed in the antibiofilm group. CONCLUSION: This randomised controlled double-blind proof-of-concept study suggests that the performance of antibiofilm agents in vivo is comparable to that in vitro studies.

Impact of daily octenidine skin washing versus nonwashing on antiseptic tolerance of coagulase-negative staphylococci in two neonatal intensive care units with different skin cleansing practices.

Background: There is wide variation in practices regarding routine bathing/washing of babies in neonatal intensive care units (NICUs). Evidence is lacking as to the benefit of routine antiseptic washes for reducing infection. We aimed to compare the antiseptic tolerance of Coagulase Negative Staphylococci (CoNS) within two UK NICUs with very different approaches to skin washing. Methods: We compared antiseptic susceptibility of CoNS isolated from skin swabs of neonates admitted to the Norfolk and Norwich University Hospital (NNUH) NICU in December 2017-March 2018 with those isolated in the Bradford Royal Infirmary (BRI) NICU in January-March 2020. The NNUH does not practise routine whole-body washing whereas BRI practises daily whole-body washing from post-menstrual age 27 weeks using Octenisan wash lotion (0.3% octenidine; 1 minute contact time before washing off with sterile water). A total of 78 CoNS isolates from BRI and 863 from the NNUH were tested for susceptibility against the antiseptics octenidine (OCT) and chlorhexidine (CHX). Results: Isolates from the BRI with practice of routine washing did not show increased antiseptic tolerance to OCT or CHX. Isolates from the NNUH which does not practise routine whole-body washing and rarely uses octenidine, were comparatively less susceptible to both CHX and OCT antiseptics. Conclusions: Daily whole-body skin washing with OCT does not appear to select for CoNS isolates that are antiseptic tolerant towards OCT and CHX. There remains considerable uncertainty about the impact of different antiseptic regimes on neonatal skin microbiota, the benefit of routine washing, and the development of antiseptic tolerance in the NICU.

Effect of Commercially Available Wound Irrigation Solutions on Uninfected Host Tissue in a Murine Model.

Background: Commercially available irrigation solutions are used to reduce bacterial contamination and prevent surgical site infections. However, the effect of these solutions on the healing capacity of tissue has not been well-established. The purpose of this study was to investigate the effects of 5 commercially available irrigation solutions on host tissue in a murine model. Methods: There were 5 treatment groups: bacitracin, Clorpactin, Irrisept, Prontosan, Bactisure, and normal saline control. The irrigation solutions were applied to the wound for 30 seconds or 1 minute, as per the manufacturer's instructions, and then washed with normal saline. Mice were sacrificed at 3 days and 10 days. The tissue was examined histologically for inflammation, edema, granulation tissue formation, and re-epithelialization. Granulation tissue formation and re-epithelialization were surrogates for effective wound healing. Results: All of the irrigation solutions had negative effects on host tissue in the acute phase. The inflammation and edema were improved in the later phase (10 days). Recovery and healing of the open wounds were observed for all groups at 10 days. The antiseptic irrigation solutions had similar cytotoxic effects on host tissue at 3 days and did not have delayed or compromised wound healing at 10 days when compared to normal saline control. Conclusions: Single short-duration use of these commercially available antiseptic irrigation solutions appears to be safe in an uninfected wound. Data from this study will provide surgeons with useful information regarding the safety of using antiseptic wound irrigation solutions intraoperatively for prevention of surgical site infections.

Antimicrobials and antiseptics: Lowering effect on ocular surface bacterial flora - A systematic review.

Topical antimicrobials and antiseptics are used perioperatively to reduce the ocular surface bacteria flora (OSBF) that are involved in the development of post-operative infectious complications. However, their effectiveness is still a controversial topic. This systematic review, performed according to the PRISMA guidelines and registered in PROSPERO, aims to provide an overview of the efficacy of the agents currently used in peri-cataract surgery and -intravitreal injections (IVI) in lowering the OSBF. Although effective in lowering OSBF, perioperative topical antimicrobials are associated with the risk of resistance development, with no obvious additional benefit compared with topical antisepsis. Conversely, the effectiveness of topical antiseptics before cataract surgery and IVI is strongly supported. Based on the available evidence, perioperative antimicrobials are not recommended, whereas the perioperative use of antiseptics is strongly recommended as prophylactic treatment for lowering the infection due to OSBF. Post-operative antimicrobials may be considered in eyes at higher risk for infection.

Optimal effective concentration combinations (OPECCs) for binary application of membrane-targeting antiseptics and TMPyP-mediated antimicrobial photodynamic therapy.

The widespread occurrence of multi-resistant bacteria is a health problem of global dimension. Infections caused by multi-resistant pathogens are difficult to treat and often associated with high mortality. Therefore, new treatment strategies are of interest, such as the use of differently acting antibacterial concepts. One of these new concepts is the use of antiseptics in combination with the antibacterial photodynamic therapy (aPDT). Currently, no method has yet been established as a standard procedure for investigating combined effects and evaluating them in a generally valid and unambiguous manner. The focus of this study was on how cationic antiseptics benzalkonium chloride (BAC) and chlorhexidine digluconate (CHX) behave in a combined application with aPDT using the photosensitizer TMPyP. For this purpose, BAC and CHX were applied in combination with the aPDT using TMPyP in non-lethal concentrations to the three bacteria Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. The results of the combination experiments with sublethal concentrations of BAC or CHX with the aPDT showed that the binary application had a lethal effect. Irrespective of the bacteria, the reduction in concentrations in OPECC, compared to individual concentrations, was more than 50% for TMPyP, 23-40% for BAC, and 18-43% for CHX. Furthermore, the optimal effective concentration combinations (OPECCs) could be determined. The latter showed that the combined application allowed the reduction of both concentrations compared to the single application.