Low-level exposure of MRSA to octenidine dihydrochloride does not select for resistance

Synthesis and broad-spectrum biocidal effect of novel gemini quaternary ammonium compounds

Since the discovery of antimicrobial agents, the misuse of antibiotics has led to the emergence of bacterial strains resistant to both antibiotics and common disinfectants like quaternary ammonium compounds (QACs). A new class, 'gemini' QACs, which contain two polar heads, has shown promise. Octenidine (OCT), a representative of this group, is effective against resistant microorganisms but has limitations such as low solubility and high cytotoxicity. In this study, we developed 16 novel OCT derivatives. These compounds were subjected to in silico screening to predict their membrane permeation. Testing against nosocomial bacterial strains (G+ and G-) and their biofilms revealed that most compounds were highly effective against G+ bacteria, while compounds 7, 8, and 10-12 were effective against G- bacteria. Notably, compounds 6-8 were significantly more effective than OCT and BAC standards across the bacterial panel. Compound 12 stood out due to its low cytotoxicity and broad-spectrum antimicrobial activity, comparable to OCT. It also demonstrated impressive antifungal activity. Compound 1 was highly selective to fungi and four times more effective than OCT without its cytotoxicity. Several compounds, including 4, 6, 8, 9, 10, and 12, showed strong virucidal activity against murine cytomegalovirus and herpes simplex virus 1. In conclusion, these gemini QACs, especially compound 12, offer a promising alternative to current disinfectants, addressing emerging resistances with their enhanced antimicrobial, antifungal, and virucidal properties.

Antiseptic management of critical wounds: differential bacterial response upon exposure to antiseptics and first insights into antiseptic/phage interactions

BACKGROUND

With the antibiotic crisis, the topical antibacterial control including chronic wounds gains increasing importance. However, little is known regarding tolerance development when bacteria face repetitive exposure to the identical antiseptics as commonly found in clinical practice.

MATERIALS AND METHODS

Clinical isolates foremost of chronic wounds were exposed in vitro to dilutions of two antiseptics used for wound therapy: polyhexanide or octenidine. Adaptive response was determined by growth/kill curves, minimal inhibitory concentration (MIC), and whole genome sequencing. Antiseptic/bacteriophage combinations were studied by liquid-infection assays and bacterial plating.

RESULTS

Polyhexanide acted stronger against Escherichia coli and Proteus mirabilis while octenidine was more potent against Staphylococcus aureus . Otherwise, the antiseptic efficacy varied across isolates of Klebsiella pneumoniae , Pseudomonas aeruginosa , and Acinetobacter baumannii . Upon repetitive exposure with constant antiseptic concentrations P. aeruginosa and P. mirabilis adaptation was evident by a reduced lag-phase and a twofold increased MIC. Under increasing octenidine concentrations, P. aeruginosa adapted to an eightfold higher dosage with mutations in smvA , opgH , and kinB affecting an efflux pump, alginate and biofilm formation, respectively. S. aureus adapted to a fourfold increase of polyhexanide with a mutation in the multiple peptide resistance factor MprF, also conferring cross-resistance to daptomycin. Antiseptic/bacteriophage combinations enhanced bacterial inhibition and delayed adaptation.

CONCLUSION

Different bacterial species/strains respond unequally to low-level antiseptic concentrations. Bacterial adaptation potential at phenotypic and genotypic levels may indicate the necessity for a more nuanced selection of antiseptics. Bacteriophages represent a promising yet underexplored strategy for supporting antiseptic treatment, which may be particularly beneficial for the management of critical wounds.

On-Demand Sequential Release of Dual Drug from pH-Responsive Electrospun Janus Nanofiber Membranes toward Wound Healing and Infection Control

Drugs against bacteria and abnormal cells, such as antibiotics and anticancer drugs, may save human lives. However, drug resistance is becoming more common in the clinical world. Nowadays, a synergistic action of multiple bioactive compounds and their combination with smart nanoplatforms has been considered an alternative therapeutic strategy to fight drug resistance in multidrug-resistant cancers and microorganisms. The present study reports a one-step fabrication of innovative pH-responsive Janus nanofibers loaded with two active compounds, each in separate polymer compartments for synergistic combination therapy. By dissolving one of the compartments from the nanofibers, we could clearly demonstrate a highly yielded anisotropic Janus structure with two faces by scanning electron microscopy (SEM) analysis. To better understand the distinctive attributes of Janus nanofibers, several analytical methods, such as X-ray diffraction (XRD), FTIR spectroscopy, and contact angle goniometry, were utilized to examine and compare them to those of monolithic nanofibers. Furthermore, a drug release test was conducted in pH 7.4 and 6.0 media since the properties of Janus nanofibers correlate significantly with different environmental pH levels. This resulted in the on-demand sequential codelivery of octenidine (OCT) and curcumin (CUR) to the corresponding pH stimulus. Accordingly, the antibacterial properties of Janus fibers against Escherichia coli and Staphylococcus aureus, tested in a suspension test, were pH-dependent, i.e., greater in pH 6 due to the synergistic action of two active compounds, and Eudragit E100 (EE), and highly satisfactory. The biocompatibility of the Janus fibers was confirmed in selected tests.

Enhancing Photostability of Complex Lead Halides through Modification with Antibacterial Drug Octenidine

The high power-conversion efficiencies of hybrid perovskite solar cells encourage many researchers. However, their limited photostability represents a serious obstacle to the commercialization of this promising technology. Herein, we present an efficient method for improving the intrinsic photostability of a series of commonly used perovskite material formulations such as MAPbI3, FAPbI3, Cs0.12FA0.88PbI3, and Cs0.10MA0.15FA0.75PbI3 through modification with octenidine dihydroiodide (OctI2), which is a widely used antibacterial drug with two substituted pyridyl groups and two cationic centers in its molecular framework. The most impressive stabilizing effects were observed in the case of FAPbI3 and Cs0.12FA0.88PbI3 absorbers that were manifested in significant suppression or even blocking of the undesirable perovskite films' recrystallization and other decomposition pathways upon continuous 110 mW/cm2 light exposure. The achieved material photostability-within 9000 h for the Oct(FA)n-1PbnI3n+1 (n = 40-400) and 20,000 h for Oct(Cs0.12FA0.88)n-1PbnI3n+1 (where n = 40-400) formulations-matches the highest values ever reported for complex lead halides. It is important to note that the stabilizing effect is maintained when OctI2 is used only as a perovskite surface-modifying agent. Using a two-cation perovskite composition as an example, we showed that the performances of the solar cells based on the developed Oct(Cs0.12FA0.88)399Pb400I1201 absorber material are comparable to that of the reference devices based on the unmodified perovskite composition. These findings indicate a great potential of the proposed approach in the design of new highly photostable and efficient light absorbers. We believe that the results of this study will also help to establish important guidelines for the rational material design to improve the operational stability of perovskite solar cells.

A Remineralizing and Antibacterial Coating for Arresting Caries

Dental caries is a dynamic disease induced by the unbalance between demineralization of dental hard tissues caused by biofilm and remineralization of them; however, although various effective remineralization methods have been well documented, it is a challenge to reestablish the balance by enhancing remineralization alone while ignoring the antibacterial therapy. Therefore, the integration of remineralizing and antibacterial technologies offers a promising strategy to halt natural caries progression in clinical practice. Here, the conception of interrupting dental caries (IDC) was proposed based on the development of dual-functional coating with remineralizing and antibacterial properties. In this study, bovine serum albumin (BSA) loaded octenidine (OCT) successfully to form a BSA-OCT composite. Subsequently, through fast amyloid-like aggregation, the phase-transited BSA-OCT (PTB-OCT) coating can be covered on teeth, resin composite, or sealant surfaces in 30 min by a simple smearing process. The PTB-OCT coating showed satisfactory effects in promoting the remineralization of demineralized enamel and dentin in vitro. Moreover, this coating also exerted significant acid-resistance stability and anti-biofilm properties. Equally importantly, this coating exhibited promising abilities in reducing the microleakage between the tooth and resin composite in vitro and preventing primary and secondary caries in vivo. In conclusion, this novel dual-functional PTB-OCT coating could reestablish the balance between demineralization and remineralization in the process of caries, thereby potentially preventing or arresting caries.

Application of Nanomaterials in Restorative Dentistry

Dental composite resins are widely popular restoratives, as, when using these tools to restore the tooth, only the infected and affected carious structures are removed. This allows the patient to retain a greater quantity of their natural tooth structure than they would have using conventional principles of cavity preparation. Nanomaterials are a new concept concerning the manipulation of materials on an atomic or molecular level. However, on a nanoscale, the chemical, biological, and physical properties of an atom vary compared to the properties of its naturally occurring compound form. The main idea of shifting focus to the inclusion of nanomaterials is to aid in the detection, treatment, and prevention of the recurrence of a pathology (secondary caries). The primary aim of using nanomaterials in composites is to augment their strength, wear resistance, and microhardness. This usage also reduces polymerization shrinkage. Nanomaterials are capable of enhancing mechanical properties, life, and bond strength between dentin and restoration. This review aims to highlight different research studies and experiments that have been conducted on the use of nanomaterials in restorative dentistry in order to understand the versatility of these materials and their viability in practice.

Chlorhexidine and octenidine susceptibility of bacterial isolates from clinical samples in a three-armed cluster randomised decolonisation trial

BACKGROUND

Routine use of chlorhexidine or octenidine for antiseptic bathing may have unintended consequences. Our analysis aimed to assess the phenotypic susceptibility of bacterial isolates from clinical samples to chlorhexidine and octenidine collected from intensive care units (ICU) that routinely used 2% chlorhexidine-impregnated wash cloths or 0.08% octenidine wash mitts (intervention) or water and soap (control) for daily patient care.

METHODS

This study was conducted within the context of a three armed cluster-randomised controlled decolonisation trial (Registration number DRKS00010475, registration date August 18, 2016). Bacterial isolates were collected prior to and at the end of a 12-month-intervention period from patients with ≥ 3 days length of stay at an ICU assigned to one of two intervention groups or the control group. Phenotypic susceptibility to chlorhexidine and octenidine was assessed by an accredited contract research laboratory determining minimal inhibitory concentrations (MIC) as percentage of extraction solutions used. MIC were reported as estimated concentrations in μg/ml derived from the chlorhexidine and octenidine extraction solutions. Statistical analyses including generalized estimating equation models were applied.

RESULTS

In total, 790 ICU-attributable bacterial isolates from clinical samples (e.g. blood, urine, tracheal aspirate) were eligible for all analyses. Pathogens included were Staphylococcus aureus (n = 155), coagulase-negative staphylococci (CoNS, n = 122), Escherichia coli (n = 227), Klebsiella spp. (n = 150) and Pseudomonas aeruginosa (n = 136). For all species, chlorhexidine and octenidine MIC did not increase from baseline to intervention period in the antiseptic bathing groups. For proportions of bacterial isolates with elevated chlorhexidine / octenidine MIC (≥ species-specific chlorhexidine / octenidine MIC50), adjusted incidence rate ratios (aIRR) showed no differences between the intervention groups and the control group (intervention period).

CONCLUSION

We found no evidence for reduced phenotypic susceptibilities of bacterial isolates from clinical samples to chlorhexidine or octenidine in ICUs 12 months after implementation of routine antiseptic bathing with the respective substances.

Evaluating the effectiveness of octenidine-containing wash mitts in reducing infections in intensive care

Patients in intensive care units (ICUs) are at a greater risk of developing hospital-acquired infections (HCAIs). Decontamination, which usually includes a regimen of body washing with an antimicrobial skin cleanser, is used to prevent HCAIs. Approaches can be: targeted, where carriers are identified and decontaminated; or universal, where all patients undergo a decontamination regimen. Universal rather than targeted decontamination is more effective at reducing infection rates and is more cost-effective. Decontamination in the ICU can lower HCAI rates across the entire hospital. Microbial resistance to chlorhexidine, however, which is the main active agent used for decontamination is increasing, and there are also adverse effects, leading to interest in octenidine as an alternative. This article explores the use of octenidine-containing single-use wash mitts in ICUs, which have been positively evaluated regarding antimicrobial activity, and ease and effectiveness of use.

Hygiene in der Dermatologie – Teil 2: Kommensalen und Infektionserreger, antimikrobielle Behandlung, Hygieneaspekte ausgewählter Infektionskrankheiten

In diesem Beitrag werden Kommensalen und relevante Infektionserreger des dermatologischen Patienten wie auch seiner Umgebung systematisch dargestellt und im Hinblick auf die krankenhaushygienische Bedeutung eingeordnet. Auf der antimikrobiellen Behandlung sowie Hygiene-Maßnahmen ausgewählter dermatologischer Erkrankungen liegt ein weiterer Fokus.

Efficacy of mupirocin, neomycin and octenidine for nasal Staphylococcus aureus decolonisation: a retrospective cohort study

BACKGROUND

Periprosthetic joint infection (PJI) causes significant morbidity. Methicillin sensitive Staphylococcus aureus (MSSA) is the most frequent organism, and the majority are endogenous. Decolonisation reduces PJIs but there is a paucity of evidence comparing treatments. Aims; compare 3 nasal decolonisation treatments at (1) achieving MSSA decolonisation, (2) preventing PJI.

METHODS

Our hospital prospectively collected data on our MSSA decolonisation programme since 2013, including; all MSSA carriers, treatment received, MSSA status at time of surgery and all PJIs. Prior to 2017 MSSA carriers received nasal mupirocin or neomycin, from August 2017 until August 2019 nasal octenidine was used.

RESULTS

During the study period 15,958 primary hip and knee replacements were performed. 3200 (20.1%) were MSSA positive at preoperative screening and received decolonisation treatment, 698 mupirocin, 1210 neomycin and 1221 octenidine. Mupirocin (89.1%) and neomycin (90.9%) were more effective at decolonisation than octenidine (50.0%, P < 0.0001). There was no difference in PJI rates (P = 0.452).

CONCLUSIONS

Mupirocin and neomycin are more effective than octenidine at MSSA decolonisation. There was poor correlation between the MSSA status after treatment (on day of surgery) and PJI rates. Further research is needed to compare alternative MSSA decolonisation treatments.

Wound Antiseptics and European Guidelines for Antiseptic Application in Wound Treatment

Issues arising in wound healing are very common, and chronic wound infections affect approximately 1.5% of the population. The main substances used in wound washing, cleansing and treatment are antiseptics. Today, there are many compounds with a known antiseptic activity. Older antiseptics (e.g., boric acid, ethacridine lactate, potassium permanganate, hydrogen peroxide, iodoform, iodine and dyes) are not recommended for wound treatment due to a number of disadvantages. According to the newest guidelines of the Polish Society for Wound Treatment and the German Consensus on Wound Antisepsis, only the following antiseptics should be taken into account for wound treatment: octenidine (OCT), polihexanide (PHMB), povidone-iodine (PVP-I), sodium hypochlorite (NaOCl) and nanosilver. This article provides an overview of the five antiseptics mentioned above, their chemical properties, wound applications, side effects and safety.

Pseudomonas aeruginosa adapts to octenidine via a combination of efflux and membrane remodelling

Pseudomonas aeruginosa is an opportunistic pathogen capable of stably adapting to the antiseptic octenidine by an unknown mechanism. Here we characterise this adaptation, both in the laboratory and a simulated clinical setting, and identify a novel antiseptic resistance mechanism. In both settings, 2 to 4-fold increase in octenidine tolerance was associated with stable mutations and a specific 12 base pair deletion in a putative Tet-repressor family gene (smvR), associated with a constitutive increase in expression of the Major Facilitator Superfamily (MFS) efflux pump SmvA. Adaptation to higher octenidine concentrations led to additional stable mutations, most frequently in phosphatidylserine synthase pssA and occasionally in phosphatidylglycerophosphate synthase pgsA genes, resulting in octenidine tolerance 16- to 256-fold higher than parental strains. Metabolic changes were consistent with mitigation of oxidative stress and altered plasma membrane composition and order. Mutations in SmvAR and phospholipid synthases enable higher level, synergistic tolerance of octenidine.

Effect of octenidine mouthwash on plaque, gingivitis, and oral microbial growth: A systematic review

OBJECTIVE

Octenidine dihydrochloride is an antimicrobial cationic surfactant compound. We conducted a systematic review to determine the efficacy of octenidine-based mouthwash on plaque formation, gingivitis, and oral microbial growth in subjects with or without periodontal disease.

MATERIALS AND METHODS

PubMed/MEDLINE, ScienceDirect, Google Scholar, and Cochrane Library were searched for relevant studies. The review was conducted per PRISMA guidelines. Only randomized controlled trials and observational studies comparing octenidine with placebo or other mouthwashes in healthy subjects with or without periodontal disease, were considered for this review. The endpoints included percentage reduction in plaque index (PI), gingival index (GI), absolute reduction in the mean number of colony-forming units (CFU/ml [log₁₀ ]) and adverse effects (AEs; tooth staining/mucosal tolerance).

RESULTS

Ten randomized controlled and six observational studies fulfilled the selection criteria. Twice or thrice daily rinsing with 0.1% octenidine for 30-60 s produced significant reduction in plaque, gingivitis and oral microbial growth. Compared to control mouthwash or baseline, 0.1% octenidine inhibited plaque formation by ~38.7%-92.9%, which was either equal or greater than that of chlorhexidine gluconate. 0.1% octenidine reduced gingivitis by ~36.4%-68.37% versus control mouthwash or baseline and microbial growth by 0.37-5.3 colony-forming units (vs. chlorhexidine: 0.4-4.23 colony-forming units). Additional benefits of 0.1% octenidine were significant reduction in the number of bleeding sites, papilla bleeding index, sulcus bleeding index, and gingival fluid flow.

CONCLUSION

Within the limitations of this study, there exists moderate evidence that 0.1% OCT was found to be an effective antiplaque agent. Octenidine inhibited plaque formation upto 93% and gingivitis upto 68% versus placebo and was either superior or comparable to chlorhexidine. Octenidine was well-tolerated and safe and can be an effective alternative to CHX and other contemporary mouthwashes.

Octenidine dihydrochloride treatment of a meticillin-resistant Staphylococcus aureus biofilm-infected mouse wound

OBJECTIVE

This study sought to estimate the effect of a liquid octenidine dihydrochloride (OCT)-impregnated gauze dressing in the treatment of meticillin-resistant Staphylococcus aureus (MRSA) biofilm-infected wounds.

METHOD

In this animal study, a six-millimetre punch full-thickness wound on each mouse back was inoculated with MRSA suspension, and then covered with a Tegaderm (3M Health Care, US) dressing for an established biofilm model. Animals were divided into three groups for topical application: control group (treated with phosphate-buffered saline, PBS); mupirocin group (treated with 2% mupirocin); and OCT group (treated with OCT). All applications were administrated once 24 hours post-wounding. The bioburden was determined by counting colony-forming units (cfus) and the biofilm architecture was viewed using fluorescent staining and scanning electron microscopy (SEM) on day two. The tissue repair was evaluated histologically and the related genes were detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) on day 15.

RESULTS

The results suggested OCT accelerated healing and reduced by >3.6 log cfu/g bacterial counts on the wounds relative to the PBS-treated control (p<0.05). Histological analysis showed OCT-treated tissue exhibited lower burden of the inflammatory cells, more mature collagen fibres and well-defined epithelialisation. LIVE/DEAD fluorescent staining and SEM confirmed OCT induced a substantial destruction to biofilm structure. RT-qPCR further demonstrated that OCT therapy could inhibit the expression of MRSA and its biofilm genes by nearly 100% (p<0.05).

CONCLUSION

This investigation provides a rare in vivo experimental basis for OCT improvement on MRSA-infected wound healing and the superior efficacy implies OCT topical application may represent an ideal choice to address established bacterial biofilm in hard-to-heal wounds.

Unraveling the mechanism of octenidine and chlorhexidine on membranes: Does electrostatics matter?

The increasing problem of antibiotic resistance in bacteria requires the development of new antimicrobial candidates. There are several well-known substances with commercial use, but their molecular mode of action is not fully understood. In this work, we focus on two commonly used antimicrobial agents from the detergent family—octenidine dichloride (OCT) and chlorhexidine digluconate (CHX). Both of them are reported to be agents selectively attacking the cell membrane through interaction inducing membrane disruption by emulsification. They are believed to present electrostatic selectivity toward charged lipids. In this study, we tested this hypothesis and revised previously proposed molecular mechanisms of action. Employing a variety of techniques such as molecular dynamics, ζ potential with dynamic light scattering, vesicle fluctuation spectroscopy, carboxyfluorescein leakage measurement, and fluorescence trimethylammonium-diphenylhexatriene- and diphenylhexatriene-based studies for determination of OCT and CHX membrane location, we performed experimental studies using two model membrane systems—zwitterionic PC and negatively charged PG (18:1/18:1):PC (16:0/18:1) 3:7, respectively. These studies were extended by molecular dynamics simulations performed on a three-component bacterial membrane model system to further test interactions with another negatively charged lipid, cardiolipin. In summary, our study demonstrated that detergent selectivity is far more complicated than supposed simple electrostatic interactions. Although OCT does disrupt the membrane, our results suggest that its primary selectivity was more linked to mechanical properties of the membrane. On the other hand, CHX did not disrupt membranes as a primary activity, nor did it show any sign of electrostatic selectivity toward negatively charged membranes at any stage of interactions, which suggests membrane disruption by influencing more discrete membrane properties.

Preoperative Octenidine Application in Breast Reconstruction Surgery

BACKGROUND/AIM

Postoperative infection in implant-based reconstructive breast surgery is a common problem. The preoperative application of a disinfecting washing agent may reduce postoperative infection rates. This retrospective analysis aimed to evaluate whether preoperative Octenisan^® application yields a reduction in postoperative complications or infection rates in breast reconstructive surgery.

PATIENTS AND METHODS

Between 2016 and 2019, 127 women received implant-based breast reconstruction at the municipal hospital of Cologne, Holweide, Germany. A total of 197 treatments were performed. After giving consent, patients were asked to use Octenisan^® wash lotion for five days before breast reconstructive surgery. All patients were asked by a simple questionnaire whether they performed showering and washing according to the proposed protocol. In 96 cases patients did adhere to the protocol. In 101 cases they did not. Patient cohorts were then divided into patients who had applied Octenisan^® wash lotion and patients who had not. Endpoints were defined as minor complications with no implant loss and major complications with consecutive implant loss.

RESULTS

Patient adherence to the application regimen was 48.7%. Overall minor complications occurred in 34.4% with preoperative Octenidine usage and 36.6% without preoperative Octenidine usage. Major complications happened in 7% with preoperative Octenidine and 5% without Octenidine. Overall, there was no significant difference concerning minor or major complication rates.

CONCLUSION

Preoperative washing protocols involving the Octenisan^® wash lotion is relatively cheap and easy to follow. There is evidence that washing protocols result in a reduction of S. aureus infections leading to a better perioperative outcome. Octenisan^® is safe to use in implant-based breast reconstructive surgery and is not associated with higher risks for patients. Our study did not yield any significant reduction in perioperative and postoperative complication and infection rates. This is attributed to a relatively low study population. Wash lotion compliance was only 48.7%. Proper patient education is crucial. With those preliminary data, it is now possible to design a larger analysis since patient adherence to washing protocol with Octenisan^® wash lotion has been established.

Topical Antiseptic Formulations for Skin and Soft Tissue Infections

Skin and soft tissue infections (SSTIs) are usually acute conditions of inflammatory microbial occupation of the skin layers and underlying soft tissues. SSTIs are one of the most frequent types of infection, typically requiring medical intervention and contribute to morbidity and mortality in both primary care and hospitalised patients. Due to the dramatic rise of antibiotic resistance, antiseptic agents can be potential alternatives for the prevention and treatment of SSTIs. Notably, they are commonly recommended in many global practical guidelines for use in per- and post- operative procedures. A range of antiseptics, including chlorhexidine, triclosan, alcohol, and povidone-iodine, are used and are mainly formulated as traditional, simple dosage forms such as solutions and semi-solids. However, in recent years, there have been studies reporting the potential for nanotechnology in the delivery of antiseptics. In this review, we have collated the scientific literature that focuses on topical antiseptic formulations for prevention and treatment of SSTIs, and have divided findings into traditional and advanced formulations. We conclude that although nanotechnological formulations have demonstrated potential advantages for delivering drugs; nevertheless, there is still scope for traditional formulations and further development of optimised topical formulations to address the rise of antimicrobial resistance.

Impact of formulary interventions on the minimum inhibitory concentration of methicillin-resistant Staphylococcus aureus to mupirocin, chlorhexidine, and octenidine in a Singapore tertiary institution

Methicillin-resistant Staphylococcus aureus (MRSA) decolonization is an effective measure to prevent clinical infection but resistance is a concern. We aim to evaluate the impact of mupirocin (MUP) ointment formulary removal, plateauing use of chlorhexidine gluconate (CHG), and hospital-wide introduction of octenidine (OCT)-based products on the minimum inhibitory concentration (MIC) of MRSA to MUP, CHG, and OCT in our hospital. A prevalence study was conducted at three time points (TP) on consecutive MRSA screening isolates to evaluate for their MICs to MUP, CHG, and OCT using broth microdilution sensititre plates and detection of the ileS-2 gene encoding high-level MUP resistance in 2013 (pre-intervention TP1; n = 160), 2016 (early post-intervention TP2; n = 99) and 2017 (late post-intervention TP3; n = 76). Statistical analyses were performed using Chi square test with reference from TP1. There was a significant improvement in MUP susceptibility (MIC < 4 mcg/ml) from 71.9% (TP1) to 86.9% (TP2; p = 0.006) to 88.2% (TP3; p = 0.007). The prevalence of MUP high-level resistance (MIC > 256 mcg/ml) reduced from 25.0% (TP1) to 12.1% (TP2; p = 0.014) to 5.3% (TP3; p = 0.001). Likewise, the prevalence of isolates harboring the ileS-2 gene decreased from 28.1% (TP1) to 18.2% (TP2; p = 0.072) to 9.2% (TP3; p = 0.002). OCT MIC range remains stable at 0.5 to 1 mcg/ml across all three TPs. The proportion of isolates with reduced CHG susceptibility (MIC ≥ 4 mcg/ml) increased over the three TPs from 23.1 to 27.2% (p = 0.45) to 42.1% (p = 0.003). Active formulary regulations have an impact on the resistance profile of MRSA and can be used as a strategy to preserve the MRSA decolonization armamentarium.

Resistance and cross-resistance in Staphylococcus spp. strains following prolonged exposure to different antiseptics

OBJECTIVES

This aim of this study was to evaluate the potential of staphylococci to develop resistance and cross-resistance to antibiotics following exposure to antiseptics.

METHODS

The antibiotic susceptibility profile as well as the antiseptic minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were determined for Staphylococcus epidermidis and Staphylococcus aureus clinical isolates and reference strains (methicillin resistant or not) before and after prolonged exposure to low concentrations of two antiseptics, namely chlorhexidine digluconate (CHG) and octenidine dihydrochloride (OCT).

RESULTS

Resistance was observed to both tested antiseptics following exposure. CHG exposure led to increased MICs in five of the six tested strains of S. epidermidis and S. aureus and also led to clinically decreased susceptibility to gentamicin in S. aureus ATCC 43300 (MRSA) and to penicillin and tetracycline in S. aureus ATCC 25923 (MSSA). OCT exposure led to an increased MIC only in S. epidermidis ATCC 12228 (MSSE) and also led to a clinically decreased susceptibility to penicillin in S. aureus clinical strain SAL. One strain (MSSE) showed a four-fold increase in the MIC against CHG. Several strains showed a two-fold increase in the MIC against CHG and only one strain (MSSE) against OCT.

CONCLUSION

These results support the urgent need to apply the same administration rules currently accepted for antibiotics to antiseptics in order to preserve the benefits both of antiseptics and antibiotics.

Control of a multidrug-resistant Acinetobacter baumannii outbreak

This article describes the management of an outbreak of multidrug-resistant Acinetobacter baumannii (MDR-Ab) at an acute NHS Foundation Trust. The outbreak affected two respiratory wards and the initial outbreak lasted 9 months, with the first patient (index case) being identified in April 2015 and the final, tenth case, in September 2015. The outbreak was declared closed in January 2016, but a further two cases were identified in July and August 2016. Of the 12 identified patients, eight were colonised with the bacterium and four were infected. The four infections were of the respiratory tract with MDR-Ab, of identical variable number tandem repeat, isolated from sputum in all cases. All 12 patients were decolonised and this continued throughout the outbreak. Some negative rescreening results were achieved. At the time of the outbreak, decolonisation using octenidine had not been reported in any guidelines. The sensitivity of MDR-Ab to octenidine was microbiologically tested and antibacterial action of octenidine against this organism was demonstrated. The use of octenidine appeared to be one element in helping to control this testing situation. This report seeks to demonstrate not only the complexity of managing and containing an outbreak of MDR-Ab but also how, with the use of a range of effective infection prevention measures, the spread of this pathogen can be successfully controlled. It is hoped that this article will increase awareness among healthcare providers and infection prevention and control (IPC) teams of the threat posed by this organism in the healthcare environment.

De-repression of the smvA efflux system arises in clinical isolates of Proteus mirabilis and reduces susceptibility to chlorhexidine and other biocides

Proteus mirabilis is a common pathogen of the catheterised urinary tract and often described as intrinsically resistant to the biocide chlorhexidine (CHD). Here we demonstrate that de-repression of the smvA efflux system has occurred in clinical isolates of P. mirabilis and reduces susceptibility to CHD and other cationic biocides. Compared to other isolates examined, P. mirabilis RS47 exhibited a significantly higher CHD MIC (≥512 μg/ml) and significantly greater expression of smvA. Comparison of the RS47 smvA and cognate smvR repressor with sequences from other isolates, indicated that RS47 encodes an inactivated smvR. Complementation of RS47 with a functional smvR from isolate RS50a (which exhibited the lowest smvA expression and lowest CHD MIC) reduced smvA expression by ∼59-fold, and markedly lowered the MIC of CHD and other cationic biocides. Although complementation of RS47 did not reduce MICs to concentrations observed in isolate RS50a, the significantly lower polymyxin B MIC of RS50a indicated that differences in LPS structure are also a factor in P. mirabilis CHD susceptibility. To determine if exposure to CHD can select for mutations in smvR, clinical isolates with the lowest CHD MICs were adapted to grow at increasing concentrations of CHD up to 512 μg/ml. Analysis of the smvR in adapted populations indicated that mutations predicted to inactivate smvR occurred following CHD exposure in some isolates. Collectively, our data show that smvA de-repression contributes to reduced biocide susceptibility in P. mirabilis, but differences in LPS structure between strains are also likely to be an important factor.

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.

Development of a real-time assay to determine the frequency of qac genes in methicillin resistant Staphylococcus aureus

PURPOSE

The emergence of antiseptic resistance and/or antiseptic-resistance genes in methicillin-resistant Staphylococcus aureus (MRSA) may result in failure of decolonization treatments. Plasmid-encoded efflux pump genes qacA/B and qacC (smr) confer tolerance to chlorhexidine and quaternary ammonium compounds. The objective of this study was to develop and validate a multiplex real time-PCR assay for detection of antiseptic-resistance genes, apply the assay on 200 MRSA isolates and explore if carriage of these genes was associated with resistance to topical antibiotics.

METHODOLOGY

A SYBR-Green based multiplex real time-PCR assay was developed to detect qacA/B, qacC, and mecA (internal control) simultaneously. The multiplex assay was compared against conventional single-plex PCR followed by agarose gel electrophoresis, using DNA from the first 73 MRSA isolates, followed by multiplex testing of the remaining 127 MRSA isolates. All 200 MRSA isolates were tested for susceptibility to mupirocin, retapamulin, neomycin, bacitracin and octenidine. The genetic diversity of the isolates was investigated by spa-typing.

RESULTS

The concordance between multiplex and conventional PCR, in assignments of qacA/B and qacC status were 99%(72/73) and 100%(73/73) respectively. Among 200 MRSA isolates, 48(24%) and 44(23%) were found to harbour qacA/B and qacC genes, respectively. These isolates remained susceptible to many common decolonization agents, except mupirocin. The predominant spa-types were t020 and t1081 (41 and 32 isolates respectively).

CONCLUSION

The real-time assay performed acceptably for the detection of qac genes. A high prevalence of antiseptic-resistance genes were detected in the MRSA isolates in our population and appeared to be associated with spa-type t1081.

Responsive antimicrobial dental adhesive based on drug-silica co-assembled particles

Most dental resin composite restorations are replacements for failing restorations. Degradation of the restoration-tooth margins by cariogenic bacteria results in recurrent caries, a leading cause for restoration failure. Incorporating antimicrobial agents in dental adhesives could reduce interfacial bacterial count and reduce recurrent caries rates, inhibit interfacial degradation, and prolong restoration service life, while minimizing systemic exposure. Direct addition of antimicrobial compounds into restorative materials have limited release periods and could affect the integrity of the material. Attempts to incorporate antimicrobial within mesoporous silica nanoparticles showed theoretical promise due to their physical robustness and large available internal volume, yet yielded short-term burst release and limited therapeutic payload. We have developed novel broad-spectrum antimicrobial drug-silica particles co-assembled for long-term release and high payload incorporated into dental adhesives. The release of the drug, octenidine dihydrochloride, is modulated by the oral degradative environment and mathematically modeled to predict effective service life. Steady-state release kills cariogenic bacteria, preventing biofilm formation over the adhesive surface, with no toxicity. This novel material could extend dental restoration service life and may be applied to other long-term medical device-tissue interfaces for responsive drug release upon bacterial infection.

STATEMENT OF SIGNIFICANCE

This study describes a novel dental adhesive that includes a broad-spectrum antimicrobial drug-silica co-assembled particles for long-term antimicrobial effect. The release of the drug, octenidine dihydrochloride, is modulated by the oral degradative environment and mathematically modeled to predict effective release throughout the service life of the restoration. Steady-state drug-release kills caries-forming bacteria, preventing biofilm formation over the adhesive surface, without toxicity. This novel material could extend dental restoration service life and may be applied to other long-term medical device-tissue interfaces for responsive drug release upon bacterial infection. Since recurrent cavities (caries) caused by bacteria are the major reason for dental filling failure, this development represents a significant contribution to the biomaterials field in methodology and material performance.

Increased Usage of Antiseptics Is Associated with Reduced Susceptibility in Clinical Isolates of Staphylococcus aureus

Hospital-acquired infection is a major cause of morbidity and mortality, and regimes to prevent infection are crucial in infection control. These include the decolonization of vulnerable patients with methicillin-resistant Staphylococcus aureus (MRSA) carriage using antiseptics, including chlorhexidine and octenidine. Concern has been raised, however, regarding the possible development of biocide resistance. In this study, we assembled a panel of S. aureus isolates, including isolates collected before the development of chlorhexidine and octenidine and isolates, from a major hospital trust in the United Kingdom during a period when the decolonization regimes were altered. We observed significant increases in the MIC and minimum bactericidal concentration (MBC) of chlorhexidine in isolates from periods of high usage of chlorhexidine. Isolates with increased MICs and MBCs of octenidine rapidly emerged after octenidine was introduced in the trust. There was no apparent cross-resistance between the two biocidal agents. A combination of variable-number tandem repeat (VNTR) analysis, PCR for qac genes, and whole-genome sequencing was used to type isolates and examine possible mechanisms of resistance. There was no expansion of a single strain associated with decreased biocide tolerance, and biocide susceptibility did not correlate with carriage of qac efflux pump genes. Mutations within the NorA or NorB efflux pumps, previously associated with chlorhexidine export, were identified, however, suggesting that this may be an important mechanism of biocide tolerance. We present evidence that isolates are evolving in the face of biocide challenge in patients and that changes in decolonization regimes are reflected in changes in susceptibility of isolates.

Infection in hospitals remains a major cause of death and disease. One way in which we combat this is by decolonizing at-risk patients from carriage of bacteria which can cause disease such as MRSA. This is done with antiseptics, including chlorhexidine and octenidine. There is concern, however, that bacteria may be able to become resistant to these antiseptics. In this study, we looked at isolates of MRSA and found that there was a correlation between the use of antiseptics and increased resistance in the isolates. We also suggest that the mechanism by which these more tolerant isolates may become resistant to antiseptics is that of changing a transport pump that exports these agents. This information suggests that we need to study the impact of antiseptics on clinically important bacteria more closely.

Pseudomonas aeruginosa adapts to octenidine in the laboratory and a simulated clinical setting, leading to increased tolerance to chlorhexidine and other biocides

BACKGROUND

Octenidine is frequently used for infection prevention in neonatal and burn intensive care units, where Pseudomonas aeruginosa has caused nosocomial outbreaks.

AIM

To investigate the efficacy and impact of using octenidine against P. aeruginosa.

METHODS

Seven clinical isolates of P. aeruginosa were exposed to increasing concentrations of octenidine over several days. Fitness, minimum bactericidal concentrations after 1 min, 5 min and 24 h, and minimum inhibitory concentrations (MICs) of a variety of antimicrobials were measured for the parental and octenidine-adapted P. aeruginosa strains. Octenidine and chlorhexidine MICs of a population of P. aeruginosa isolated from a hospital drain trap, exposed to a diluted octenidine formulation four times daily for three months, were also tested.

FINDINGS

Some planktonic cultures of P. aeruginosa survived >50% of the working concentration of an in-use octenidine formulation at the recommended exposure time. Seven strains of P. aeruginosa stably adapted following continuous exposure to increasing concentrations of octenidine. Adaptation increased tolerance to octenidine formulations and chlorhexidine up to 32-fold. In one strain, it also led to increased MICs of antipseudomonal drugs. Subsequent to continuous octenidine exposure of a multi-species community in a simulated clinical setting, up to eight-fold increased tolerance to octenidine and chlorhexidine of P. aeruginosa was also found, which was lost upon removal of octenidine.

CONCLUSION

Incorrect use of octenidine formulations may lead to inadequate decontamination, and even increased tolerance of P. aeruginosa to octenidine, with resulting cross-resistance to other biocides.

Viable adhered Staphylococcus aureus highly reduced on novel antimicrobial sutures using chlorhexidine and octenidine to avoid surgical site infection (SSI)

BACKGROUND

Surgical sutures can promote migration of bacteria and thus start infections. Antiseptic coating of sutures may inhibit proliferation of adhered bacteria and avoid such complications.

OBJECTIVES

This study investigated the inhibition of viable adhering bacteria on novel antimicrobially coated surgical sutures using chlorhexidine or octenidine, a critical factor for proliferation at the onset of local infections. The medical need, a rapid eradication of bacteria in wounds, can be fulfilled by a high antimicrobial efficacy during the first days after wound closure.

METHODS

As a pretesting on antibacterial efficacy against relevant bacterial pathogens a zone of inhibition assay was conducted with middle ranged concentrated suture coatings (22 μg/cm). For further investigation of adhering bacteria in detail the most clinically relevant Staphylococcus aureus (ATCC®49230™) was used. Absorbable braided sutures were coated with chlorhexidine-laurate, chlorhexidine-palmitate, octenidine-laurate, and octenidine-palmitate. Each coating type resulted in 11, 22, or 33 μg/cm drug content on sutures. Scanning electron microscopy (SEM) was performed once to inspect the coating quality and twice to investigate if bacteria have colonized on sutures. Adhesion experiments were assessed by exposing coated sutures to S. aureus suspensions for 3 h at 37°C. Subsequently, sutures were sonicated and the number of viable bacteria released from the suture surface was determined. Furthermore, the number of viable planktonic bacteria was measured in suspensions containing antimicrobial sutures. Commercially available sutures without drugs (Vicryl®, PGA Resorba®, and Gunze PGA), as well as triclosan-containing Vicryl® Plus were used as control groups.

RESULTS

Zone of inhibition assay documented a multispecies efficacy of novel coated sutures against tested bacterial strains, comparable to most relevant S. aureus over 48 hours. SEM pictures demonstrated uniform layers on coated sutures with higher roughness for palmitate coatings and sustaining integrity of coated sutures. Adherent S. aureus were found via SEM on all types of investigated sutures. The novel antimicrobial sutures showed significantly less viable adhered S. aureus bacteria (up to 6.1 log) compared to Vicryl® Plus (0.5 log). Within 11 μg/cm drug-containing sutures, octenidine-palmitate (OL11) showed the highest number of viable adhered S. aureus (0.5 log), similar to Vicryl® Plus. Chlorhexidine-laurate (CL11) showed the lowest number of S. aureus on sutures (1.7 log), a 1.2 log greater reduction. In addition, planktonic S. aureus in suspensions were highly inhibited by CL11 (0.9 log) represents a 0.6 log greater reduction compared to Vicryl® Plus (0.3 log).

CONCLUSIONS

Novel antimicrobial sutures can potentially limit surgical site infections caused by multiple pathogenic bacterial species. Therefore, a potential inhibition of multispecies biofilm formation is assumed. In detail tested with S. aureus, the chlorhexidine-laurate coating (CL11) best meets the medical requirements for a fast bacterial eradication. This suture coating shows the lowest survival rate of adhering as well as planktonic bacteria, a high drug release during the first-clinically most relevant- 48 hours, as well as biocompatibility. Thus, CL11 coatings should be recommended for prophylactic antimicrobial sutures as an optimal surgical supplement to reduce wound infections. However, animal and clinical investigations are important to prove safety and efficacy for future applications.

Dissemination of high-level mupirocin-resistant CC22-MRSA-IV in Saxony

Mupirocin is used for eradicating methicillin-resistant S. aureus (MRSA) in nasal colonization. A plasmid-borne gene, mupA, is associated with high-level mupirocin resistance. Despite the fact that, among all MRSA from a tertiary care center in the German state of Saxony, the prevalence of mupA, encoding high-level mupirocin resistance, was approximately 1% over a 15-year period from 2000-2015, a sharp increase to nearly 20% was observed in 2016/2017. DNA microarray profiling revealed that this was due to the dissemination of a variant of CC22-MRSA-IV ("Barnim Epidemic Strain" or "UK-EMRSA-15"), which, in addition to mecA, harbors mupA, aacA-aphD, qacA, and - in most isolates - erm(C). In order to prevent therapy failures and a further spread of this strain, the use of mupirocin should be more stringently controlled as well as guided by susceptibility testing. In addition, MRSA decolonization regimens that rely on other substances, such as betaisodona, polyhexanide or octenidine, should be considered.

MRSA prevalence rates detected in a tertiary care hospital in Austria and successful treatment of MRSA positive patients applying a decontamination regime with octenidine

Methicillin-resistant Staphylococcus aureus (MRSA) decontamination regimens predominantly use chlorhexidine bathing in combination with mupirocin nasal ointment. However, resistances in Staphylococcus aureus strains are increasingly common and there is a need of alternative, safe and feasible protocols. This interventional cohort study performed at the Albert Schweitzer Hospital in Graz, Austria, aimed to (1) determine MRSA prevalence at different body sites and (2) assess the efficacy of the decontamination using octenidine-based leave-on products added to existing robust infection control measures. All inpatients of this tertiary care hospital being treated in geriatric medical wards (GWs) and apallic care units (ACUs) were screened for MRSA and decontamination rates were determined after one, two or three decontamination cycles, respectively. At baseline, MRSA was detected in 25 of the 126 patients screened (19.8%). We found MRSA in 13/126 (10.3%) swabs from nasal vestibules, in 12/126 (9.5%) skin swabs, in 11/51 (21.6%) swabs from PEG-stomata or suprapubic catheters and in 8/13 (61.5%) tracheostomata swabs. A maximum of three 5-day decontamination cycles reduced the number of MRSA positive patients by 68.0%. Excluding non-compliant and deceased patients, decontamination reduced MRSA carriage by 93.3% (n = 15). No adverse events related to the applied decontamination regimen occurred. Exclusive screening of the nose might underreport MRSA prevalence rates. In this study, decontamination with octenidine-based leave-on products was safe and effective in a critical patient population.

Effect of pre-operative octenidine nasal ointment and showering on surgical site infections in patients undergoing cardiac surgery

OBJECTIVE

To evaluate the effect of pre-operative octenidine (OCT) decolonization on surgical site infection (SSI) rates.

DESIGN

Before-and-after cohort study.

PATIENTS

Patients undergoing an elective isolated coronary artery bypass graft (CABG) procedure: control group (1^st January to 31^st December 2013), N=475; intervention group (1^st January to 31^st December 2014), N=428.

INTERVENTIONS

The intervention consisted of nasal application of OCT ointment three times daily, beginning on the day before surgery, and showering the night before and on the day of surgery with OCT soap.

RESULTS

A median sternotomy was performed in 805 (89.1%) patients and a minimally invasive direct coronary artery bypass procedure was performed in 98 (10.9%) patients. Overall, there was no difference in SSI rates between the control and intervention groups (15.4% vs 13.3%, P=0.39). The rate of harvest site SSIs was significantly lower in patients in the intervention group (2.5% vs 0.5%, P=0.01). Patients who had undergone a median sternotomy in the intervention group had a significantly lower rate of organ/space sternal SSIs (1.9% vs 0.3%, P=0.04). However, there was a trend towards an increased rate of deep incisional sternal SSIs (1.2% vs 2.9%, P=0.08). Multi-variate analysis did not identify a significant protective effect of the intervention (odds ratio 0.79, 95% confidence interval 0.53-1.15, P=0.27).

CONCLUSIONS

Pre-operative decolonization with OCT did not reduce overall SSI rates in patients undergoing an elective isolated CABG procedure, but significantly decreased harvest site and organ/space sternal SSIs. Randomized controlled trials, including controlled patient adherence to the intervention, are required to confirm these observations and to determine the clinical utility of OCT in pre-operative decolonization.

Inactivation of Acinetobacter baumannii Biofilms on Polystyrene, Stainless Steel, and Urinary Catheters by Octenidine Dihydrochloride

Acinetobacter baumannii is a major nosocomial pathogen causing human infections with significant mortality rates. In most cases, infections are acquired through exposure to A. baumannii biofilms that persist on contaminated hospital equipment and surfaces. Thus, it is imperative to develop effective measures for controlling A. baumannii biofilms in nosocomial settings. This study investigated the efficacy of octenidine dihydrochloride (OH), a new generation disinfectant for reducing A. baumannii biofilms on polystyrene, stainless steel and catheters. OH at 0.3% (5 mM), 0.6% (10 mM), and 0.9% (15 mM) was effective in significantly inactivating A. baumannii biofilms on all tested surfaces (P < 0.05). Furthermore, OH was equally effective in inactivating biofilms of multidrug resistant and drug susceptible A. baumannii isolates. In addition, confocal imaging revealed the predominance of dead cells in the OH-treated samples in comparison to the control. Further, scanning electron microscopy of biofilms formed on catheters revealed that OH treatment significantly reduced A. baumannii biofilm populations in corroboration with our antibiofilm assay. These data underscore the efficacy of OH in inactivating A. baumannii biofilms, thereby suggesting its potential use as a disinfectant or a catheter lock solution to control A. baumannii infections.

An observational study of the universal use of octenidine to decrease nosocomial bloodstream infections and MDR organisms

OBJECTIVES

To investigate the effect of universal decolonization with octenidine on the incidence of ICU-acquired bloodstream infections (BSI) and MDR organisms (MDRO).

METHODS

A system-wide change in practice was performed in the ICUs of a university hospital with three campuses (eight medical ICUs and nine surgical ICUs). All ICUs had a general admission screening strategy for MRSA with subsequent isolation in the 12 month baseline period, which was stopped. After a wash-in period of 1 month, decolonization of the nose with octenidine nasal gel and octenidine wash cloths was introduced. The endpoints were ICU-acquired BSI and ICU-acquired MDRO isolates from clinical cultures. Segmented regression analysis of interrupted time series was used to assess the effect of intervention.

RESULTS

A total of 29 532 ICU patients (16 677 surgical and 12 855 medical) were included in the study. The baseline incidence density of ICU-acquired BSI was 5.1 per 1000 patient days and the baseline ICU-acquired MRSA rate was 0.97 per 1000 patient days. Whereas no significant effect on either outcome was found in surgical ICUs, we identified a significant effect on ICU-acquired BSI for the intervention in medical ICUs by means of multivariate analysis (incidence rate ratio 0.78; 95% CI 0.65-0.94). In addition, the intervention was also effective in decreasing ICU-acquired MRSA in medical ICUs (incidence rate ratio 0.58; 95% CI 0.41-0.82). No effect on ICU-acquired VRE and Gram-negative MDRO was found.

CONCLUSIONS

System change was successful by decreasing infection rates in medical ICUs and improving the management in all ICUs.

[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.

Antiseptic Body Washes for Reducing the Transmission of Methicillin-Resistant Staphylococcus aureus: A Cluster Crossover Study

In a cluster cross-over trial, targeted decolonization with octenidine body washes was not associated with reduction in MRSA transmission or infection

Background. Limiting the spread of methicillin-resistant Staphylococcus aureus (MRSA) within healthcare facilities where the organism is highly endemic is a challenge. The use of topical antiseptic agents may help interrupt the transmission of MRSA and reduce the risk of clinical infection. Octenidine dihydrochloride is a topical antiseptic that exhibits in vitro efficacy against a wide variety of bacteria, including S aureus.

Methods. We conducted a prospective cluster crossover study to compare the use of daily octenidine body washes with soap and water in patients identified by active surveillance cultures to be MRSA-colonized, to prevent the acquisition of MRSA in patients with negative screening swabs. Five adult medical and surgical wards and 2 intensive care units were selected. The study involved an initial 6-month phase using octenidine or soap washes followed by a crossover in each ward to the alternative product. The primary and secondary outcomes were the rates of new MRSA acquisitions and MRSA clinical infections, respectively.

Results. A total of 10 936 patients admitted for ≥48 hours was included in the analysis. There was a small reduction in MRSA acquisition in the intervention group compared with controls (3.0% vs 3.3%), but this reduction was not significant (odds ratio, 0.89; 95% confidence interval, .72–1.11; P = .31). There were also no significant differences in clinical MRSA infection or incidence of MRSA bacteremia.

Conclusions. This study suggests that the targeted use of routine antiseptic washes may not in itself be adequate to reduce the transmission of MRSA in an endemic hospital setting.

Antibiofilm Effect of Octenidine Hydrochloride on Staphylococcus aureus, MRSA and VRSA

Millions of indwelling devices are implanted in patients every year, and staphylococci (S. aureus, MRSA and vancomycin-resistant S. aureus (VRSA)) are responsible for a majority of infections associated with these devices, thereby leading to treatment failures. Once established, staphylococcal biofilms become resistant to antimicrobial treatment and host response, thereby serving as the etiological agent for recurrent infections. This study investigated the efficacy of octenidine hydrochloride (OH) for inhibiting biofilm synthesis and inactivating fully-formed staphylococcal biofilm on different matrices in the presence and absence of serum protein. Polystyrene plates and stainless steel coupons inoculated with S. aureus, MRSA or VRSA were treated with OH (zero, 0.5, one, 2 mM) at 37 °C for the prevention of biofilm formation. Additionally, the antibiofilm effect of OH (zero, 2.5, five, 10 mM) on fully-formed staphylococcal biofilms on polystyrene plates, stainless steel coupons and urinary catheters was investigated. OH was effective in rapidly inactivating planktonic and biofilm cells of S. aureus, MRSA and VRSA on polystyrene plates, stainless steel coupons and urinary catheters in the presence and absence of serum proteins. The use of two and 10 mM OH completely inactivated S. aureus planktonic cells and biofilm (>6.0 log reduction) on all matrices tested immediately upon exposure. Further, confocal imaging revealed the presence of dead cells and loss in biofilm architecture in the OH-treated samples when compared to intact live biofilm in the control. Results suggest that OH could be applied as an effective antimicrobial to control biofilms of S. aureus, MRSA and VRSA on appropriate hospital surfaces and indwelling devices.

Active wound dressings based on bacterial nanocellulose as drug delivery system for octenidine

Although bacterial nanocellulose (BNC) may serve as an ideal wound dressing, it exhibits no antibacterial properties by itself. Therefore, in the present study BNC was functionalized with the antiseptic drug octenidine. Drug loading and release, mechanical characteristics, biocompatibility, and antimicrobial efficacy were investigated. Octenidine release was based on diffusion and swelling according to the Ritger-Peppas equation and characterized by a time dependent biphasic release profile, with a rapid release in the first 8h, followed by a slower release rate up to 96 h. The comparison between lab-scale and up-scale BNC identified thickness, water content, and the surface area to volume ratio as parameters which have an impact on the control of the release characteristics. Compression and tensile strength remained unchanged upon incorporation of octenidine in BNC. In biological assays, drug-loaded BNC demonstrated high biocompatibility in human keratinocytes and antimicrobial activity against Staphylococcus aureus. In a long-term storage test, the octenidine loaded in BNC was found to be stable, releasable, and biologically active over a period of 6 months without changes. In conclusion, octenidine loaded BNC presents a ready-to-use wound dressing for the treatment of infected wounds that can be stored over 6 months without losing its antibacterial activity.

Daily bathing with octenidine on an intensive care unit is associated with a lower carriage rate of meticillin-resistant Staphylococcus aureus

Routine daily bathing of intensive care (ICU) patients with topical chlorhexidine reduces meticillin-resistant Staphylococcus aureus (MRSA) acquisition. The aim of this study was to investigate whether repeated five-day cycles of daily topical octenidine could result in a similar effect. This was a two-year retrospective, uncontrolled study in a mixed medical and surgical ICU/high dependency unit, demonstrating a 76% reduction in MRSA acquisition but no significant reduction in all ICU-acquired bacteraemias. Chlorhexidine use is increasing but resistance is being reported. This pilot study found a similar reduction in MRSA acquisition with octenidine as an alternative to chlorhexidine. Further study is required to establish causality.

Comparison of the antibacterial effect of silver sulfadiazine 1%, mupirocin 2%, Acticoat and octenidine dihydrochloride in a full-thickness rat burn model contaminated with multi drug resistant Acinetobacter baumannii

In this study, our aim is to compare the efficacy of different topical antibacterial agents in a rat model contaminated with a multi drug resistant (MDR) standard Acinetobacter baumannii strain. The study was carried out on 40 Sprague-Dawley rats of 250-300 g each. For the purposes of this study, the rats were divided into 5 groups, with 8 rats in each group: Group 1 control; Group 2 silver sulfadiazine; Group 3 mupirocin; Group 4 Acticoat group; and Group 5 octenidine dihydrochloride group. Following to the formation of the full-thickness burn areas in rats, the MDR A. baumannii standard strain was inoculated into the burned area. The rats in all the groups were sacrificed at the end of the 10th day and subjected to histopathological and microbiological evaluation. In the histopathological evaluation, the lowest inflammatory cell response and bacterial density in the eschar and muscle tissues were observed in the Acticoat group. While these results were found to be statistically significant compared to the silver sulfadiazine group, only the bacterial density in the muscle tissue was found as significant in comparison to the mupirocin and octenidine groups. In the microbiological evaluation, the lowest growth in the muscle tissue culture among all the groups was observed in the Acticoat group. The growth in the eschar tissue culture was significantly lower in the Acticoat and octenidine groups in comparison to the silver sulfadiazine group. At the end of the study, it has been observed that Acticoat was effective both in eschar and muscle, while octenidine was effective in eschar tissues in a rat burn model contaminated with MDR A. baumannii.

Efficacy of octenidine hydrochloride for reducing Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes on cattle hides

The efficacy of octenidine hydrochloride (OH; 0.025, 0.15, and 0.25%) for inactivating Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes on cattle hides was investigated at 23°C in the presence and absence of bovine feces. All tested concentrations of OH were effective in decreasing more than 5.0 log CFU of bacteria/cm(2) in 5 min (P < 0.01). The results suggest that OH could be used to decontaminate cattle hides; however, further studies under commercial settings are necessary to validate these results.

The percutaneous permeation of a combination of 0.1% octenidine dihydrochloride and 2% 2-phenoxyethanol (octenisept®) through skin of different species in vitro

Background

A water based combination of 0.1% octenidine dihydrochloride and 2% 2 - phenoxyethanol is registered in many European countries as an antiseptic solution (octenisept^®) for topical treatment with high antimicrobial activity for human use, but octenidine based products have not been registered for veterinary use yet. The aim of the present study was to investigate whether octenidine dihydrochloride or 2 -phenoxyethanol, the two main components of this disinfectant, permeate through animal skin in vitro. Therefore, permeation studies were conducted using Franz-type diffusion cells. 2 ml of the test compound were applied onto 1.77 cm² split skin of cats, dogs, cows and horses. To simulate wounded skin, cattle skin was treated with adhesive tapes 100 times, as well. Up to an incubation time of 28 hours samples of the acceptor chamber were taken and were analysed by UV-HPLC. Using the method of the external standard, the apparent permeability coefficient, the flux J_max, and the recovery were calculated. Furthermore, the residues of both components in the skin samples were determined after completion of the diffusion experiment.

Results

After 28 hours no octenidine dihydrochloride was found in the receptor chamber of intact skin samples, while 2.7% of the topical applied octenidine dihydrochloride permeated through barrier disrupted cattle skin. 2 - phenoxyethanol permeated through all skin samples with the highest permeability in equine, followed by bovine, canine to feline skin. Furthermore, both components were found in the stratum corneum and the dermis of all split skin samples with different amounts in the examined species.

Conclusion

For 2-phenoxyethanol the systemic impact of the high absorption rate and a potential toxicological risk have to be investigated in further studies. Due to its low absorption rates through the skin, octenidine dihydrochloride is suitable for superficial skin treatment in the examined species.

Antifouling coatings: recent developments in the design of surfaces that prevent fouling by proteins, bacteria, and marine organisms

The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future.