New in vitro model evaluating antiseptics' efficacy in biofilm-associated Staphylococcus aureus prosthetic vascular graft infection

Octenidine with hyaluronan dressing versus a silver dressing in hard-to-heal wounds: a post-marketing study

OBJECTIVE

This study was conducted to provide comparative data on the clinical efficacy and safety of a novel hard-to-heal wound dressing (Sorelex; Contipro a.s., Czech Republic) that combines octenidine and hyaluronan, compared with a silver-based dressing.

METHOD

This multicentre, open-label, randomised, post-market, clinical follow-up study provides a comparison of a octenidine and hyaluronan combination with a standard-of-care (SoC) silver-containing dressing. The investigators evaluated the management of infection in the hard-to-heal wounds based on recorded changes in the appearance of the wound bed tissue and the presence of clinical signs of infection after three weeks of treatment. Other relevant assessed parameters of wound healing were: wound size; exudation level; wound pain level; and surrounding skin appearance.

RESULTS

The study cohort included 48 patients in the Sorelex arm and 39 patients in the SoC arm. Both products evinced numerous parameters of wound infection management: reductions in the wound bed slough; marked decreases in wound size; the formation of re-epithelialisation and granulation tissue; and improved pain management. Sorelex significantly improved the condition of surrounding skin after three weeks of treatment, unlike SoC. Sorelex reduced wound area significantly more than SoC (p=0.04). No statistically significant differences were detected in other assessed parameters between the two study arms. All the participating investigators expressed their satisfaction with both products. No adverse reactions to Sorelex were recorded over the mean treatment period of 53 days.

CONCLUSION

The octenidine and hyaluronan combination provides a new alternative choice of dressing for the treatment of infected hard-to-heal wounds when compared with a silver-based product.

A Narrative Review of Experimental Assessment to Study Vascular Biomaterials Infections and Infectability

Objective

Many experimental studies have been conducted to evaluate vascular and endovascular graft infections (VGEIs) and infectability in order to elaborate strategies to prevent or to treat their occurrence. A systematic literature search was conducted to collect and summarise key features of infection and infectability assessment techniques in VGEI experimental models.

Methods

The literature search was conducted using the Medline and Cochrane databases, with no limit on the date of publication, until 10 August 2021. Ex vivo, in vitro, and in vivo animal studies on VGEIs, published in English or French, were selected. Cross references retrieved from selected articles on PubMed database were also included in the search. Data were collected on the techniques and the protocols performed for vascular graft infection and infectability assessment.

Results

A total of 243 studies were included in the review: 55 in vitro studies, 169 animal studies, 17 combining the two models, and two ex vivo studies. Many experimental techniques were performed, with a lot of protocol discrepancies. The main experiments conducted were bacterial culture, with (n = 82 studies) or without sonication (n = 120), histopathology (n = 69), scanning electron microscopy (n = 36), and graft diffusion tests (n = 28). These techniques were used to answer different research questions corresponding to different graft infection steps, such as microbial adhesion and/or viability, biofilm biomass or organisation, human cell reaction, or antimicrobial activity.

Conclusion

Many experimental tools are available to study VGEIs, but to improve their reproducibility and scientific reliability research protocols must be standardised and include sonication of grafts before microbiological culture. Moreover, the key role of the biofilm in VGEI physiopathology must be taken into account in future studies.

Infection of Vascular Prostheses: A Comprehensive Review

Vascular graft or endograft infection (VGEI) is a complex disease that complicates vascular-surgery and endovascular-surgery procedures and determines high morbidity and mortality. This review article provides the most updated general evidence on the pathogenesis, prevention, diagnosis, and treatment of VGEI. Several microorganisms are involved in VGEI development, but the most frequent one, responsible for over 75% of infections, is Staphylococcus aureus. Specific clinical, surgical, radiologic, and laboratory criteria are pivotal for the diagnosis of VGEI. Surgery and antimicrobial therapy are cornerstones in treatment for most patients with VGEI. For patients unfit for surgery, alternative treatment is available to improve the clinical course of VGEI.

Biofilms in Chronic Wound Infections: Innovative Antimicrobial Approaches Using the In Vitro Lubbock Chronic Wound Biofilm Model

Chronic wounds have harmful effects on both patients and healthcare systems. Wound chronicity is attributed to an impaired healing process due to several host and local factors that affect healing pathways. The resulting ulcers contain a wide variety of microorganisms that are mostly resistant to antimicrobials and possess the ability to form mono/poly-microbial biofilms. The search for new, effective and safe compounds to handle chronic wounds has come a long way throughout the history of medicine, which has included several studies and trials of conventional treatments. Treatments focus on fighting the microbial colonization that develops in the wound by multidrug resistant pathogens. The development of molecular medicine, especially in antibacterial agents, needs an in vitro model similar to the in vivo chronic wound environment to evaluate the efficacy of antimicrobial agents. The Lubbock chronic wound biofilm (LCWB) model is an in vitro model developed to mimic the pathogen colonization and the biofilm formation of a real chronic wound, and it is suitable to screen the antibacterial activity of innovative compounds. In this review, we focused on the characteristics of chronic wound biofilms and the contribution of the LCWB model both to the study of wound poly-microbial biofilms and as a model for novel treatment strategies.

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

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

Hemocompatibility And Cytotoxicity Of Small-Diameter Bioabsorbable Tissue-Engineered Vascular Grafts Depending On Anti-Thrombogenic And Antimicrobial Coating

Anti-thrombogenic and antimicrobial coatings of polymer grafts constitute a promising approach to preventing infection and thrombosis of vascular grafts. The objective was to study the hemocompatibility and cytotoxicity of PHBV/PCL grafts with iloprost and amphiphilic coating. Material and Methods — Polymer matrices were manufactured by electrospinning a mixture of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL) polymers. Several matrices were modified by complexation between polyvinylpyrrolidone (PVP) and cationic amphiphile and/or iloprost. The amphiphile was covalently cross-linked to the surface of other PHBV/PCL matrices. Unmodified PHBV/PCL matrices were used as the control group. Hemocompatibility and cytotoxicity of scaffolds before and after the modification were evaluated. Results — The hemocompatibility assessment revealed that hemolysis degree did not exceed normal values in all types of matrices. The PHBV/PCL/PVP matrices had increased platelet aggregation on the surface of the grafts. Subsequent addition of iloprost and amphiphile resulted in a sevenfold reduction of platelet aggregation. In PHBV/PCL/PVP matrices, the degree of platelet adhesion increased without changing the platelet deformation index values. Iloprost and amphiphilic coating of PHBV/PCL/PVP matrices diminished the number of adhered platelets and platelet deformation index by 1.5 times. The amphiphile, covalently cross-linked to PHBV/PCL matrices, caused a negative effect on the platelet adhesion, aggregation, and deformation index values. Evaluation of cytotoxicity of PHBV/PCL/PVP matrices, coated with iloprost and/or cationic amphiphile, demonstrated a slight decline in the rates of cell growth and proliferation after three days. Moreover, after three days, cell deaths and a sharp drop in the cell index values were noted in PHBV/PCL matrices with covalently cross-linked amphiphile. Conclusion — Iloprost and amphiphilic coating of PHBV/PCL grafts has increased their hemocompatibility. Also, there were no signs of cytotoxicity while using the complexation technique. However, covalently cross-linked amphiphile caused an increase in the cytotoxicity of matrices, which may have been indicative of the negative effect observed in this type of surface modification.

Cardiovascular Catheterization Using a New Antiseptic Agent Olanexidine Gluconate

Olanexidine gluconate 1.5% (Olanedine^®) is a colorless and transparent antiseptic agent introduced in 2015. In this study, we examined its usefulness and safety for cardiovascular catheterization and compared them to 10% povidone-iodine (PI). The study included 1,001 and 1,000 consecutively enrolled patients using Olanedine^® and PI, respectively [649 (PI, 687) males; mean age: 72.1 ± 9.6 (70.9 ± 9.6) years] who underwent cardiovascular catheterization [diagnostic cardiac catheterization: 624 (509) cases, percutaneous coronary intervention: 288 (390) cases, and endovascular treatment: 89 (101) cases]. Clinically, there were no significant differences in the backgrounds between the two groups. The amount of Olanedine^® used per case was approximately 20 mL. Blood tests were performed before and after catheterization. The presence or absence of discoloration on clothes containing cotton by Olanedine^® was also examined. One mild rash that disappeared within one day occurred in each of the two groups. Some blood tests before and after cardiac catheterization indicated significant differences, but they did not seem to be clinically relevant. The use of Olanedine^® in hemodialysis patients (117 cases) was uneventful. Its use in 37 patients with contraindications for ethanol disinfection was also uneventful. Although PI is extremely difficult to remove from white coats containing cotton, Olanedine^® did not cause any discoloration on clothes. This is the first report of cardiovascular catheterization using Olanedine^®. The efficacy and safety of Olanedine^® and PI seem to be equivalent. Olanedine^® could be a new useful option as a disinfectant of cardiovascular catheterization.

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.

Does washing medical devices before and after use decrease bacterial contamination?: An in vitro study

ABSTRACT

Surface treatment of medical devices may be a way of avoiding the need for replacement of these devices and the comorbidities associated with infection. The aim of this study was to evaluate whether pre- and postcontamination washing of 2 prostheses with different textures can decrease bacterial contamination.The following microorganisms were evaluated: Staphylococcus aureus, Staphylococcus epidermidis, Proteus mirabilis and Enterococcus faecalis. Silicone and expanded polytetrafluoroethylene vascular prostheses were used and divided into 3 groups: prostheses contaminated; prostheses contaminated and treated before contamination; and prostheses contaminated and treated after contamination. Treatments were performed with antibiotic solution, chlorhexidine and lidocaine. After one week of incubation, the prostheses were sown in culture medium, which was incubated for 48 hours. The area of colony formation was evaluated by fractal dimension, an image analysis tool.The antibiotic solution inhibited the growth of S epidermidis and chlorhexidine decrease in 53% the colonization density for S aureus in for both prostheses in the pre-washing. In postcontamination washing, the antibiotic solution inhibited the growth of all bacteria evaluated; there was a 60% decrease in the colonization density of S aureus and absence of colonization for E faecalis with chlorhexidine; and lidocaine inhibited the growth of S aureus in both prostheses.Antibiotic solution showed the highest efficiency in inhibiting bacterial growth, especially for S epidermidis, in both washings. Lidocaine was able to reduce colonization by S aureus in post-contamination washing, showing that it can be used as an alternative adjuvant treatment in these cases.

Randomised Controlled Trials of Alcohol-Based Surgical Site Skin Preparation for the Prevention of Surgical Site Infections: Systematic Review and Meta-Analysis

(1) Background: Surgical site skin preparation is an important approach to prevent postoperative wound infections. International guidelines recommend that alcohol-based combinations be used, however, the optimal combination remains uncertain. This study compares the effectiveness of alcohol-based chlorhexidine and alcohol-based iodophor for surgical site skin preparation for prevention of surgical site infections (SSIs). (2) Methods: Randomised controlled trials comparing alcohol-based interventions for surgical site skin preparation were included. The proportion of SSIs was compared using risk ratios (RR) with 95% confidence intervals (95% CI). The meta-analysis was performed with a fixed effect model using Mantel-Haenszel methods. As an a priori subgroup analysis SSI risk was examined according to different surgical procedural groups. (3) Results: Thirteen studies were included (n = 6023 participants). The use of chlorhexidine-alcohol was associated with a reduction in risk of SSIs compared with iodophor-alcohol (RR 0.790; 95% CI 0.669, 0.932). On sub-group analysis, chlorhexidine-alcohol was associated with a reduction in SSIs in caesarean surgery (RR 0.614; 95% CI 0.453, 0.831) however, chlorhexidine-alcohol was associated with an increased risk of SSI in bone and joint surgery (RR 2.667; 95% CI 1.051, 6.765). When excluding studies at high risk of bias on sensitivity analysis, this difference in alcohol-based combinations for bone and joint surgery was no longer observed (RR 2.636; 95% CI 0.995, 6.983). (4) Conclusions: The use of chlorhexidine-alcohol skin preparations was associated with a reduced risk of SSI compared to iodophor-alcohol agents. However, the efficacy of alcohol-based preparation agents may differ according to the surgical procedure group. This difference must be interpreted with caution given the low number of studies and potential for bias, however, it warrants further investigation into the potential biological and clinical validity of these findings.

Do isolates from pharyngeal and rectal swabs match blood culture bacterial pathogens in septic VLBW infants? A pilot, cross-sectional study

Serial body site swabbing is used to monitor horizontal spread of aggressive bacterial species in the neonatal intensive care unit (NICU). Since colonization/carriage is thought to precede systemic infection, one might expect to retrieve colonizing pathogens from blood cultures. This hypothesis, however, has not been fully investigated in very low birth weight (VLBW) infants that are at high sepsis' risk. The primary outcome was, in a population of VLBW infants with late-onset sepsis, the matching between blood culture results and pathogens isolated from rectal and nose/pharyngeal surveillance swabs in the preceding 2 weeks. The secondary outcomes were the site of swabbing and time interval from colonization to blood culture positivity. Out of 333 VLBW neonates, 80 (24%) were diagnosed with bacterial sepsis. In 46 (57%) neonates, the blood culture showed the same pathogen species cultured from a swab. Of these, 30 were isolated from infants with both body sites colonized with an average time interval of 3.5 days; 2/16 were isolated from rectal swabs and 14 /16 from nose/pharyngeal samples.Conclusion: Our data show a fair correspondence between bacteria colonizing the nasopharynx and/or the rectum and pathogens later isolated from blood cultures. This association depends on the swabbing site, number of sites, and pathogen species. Although these data constitute valuable results, they are not sufficient for providing the sole base of a thoughtful clinical decision. What is Known: • Body site's colonization may precede systemic infection. • Little is known on this mechanism in VLBW infants that are at higher sepsis' risk. What is New: •Colonizing bacteria partially correspond to pathogens of blood cultures in VLBW infants with sepsis. • Correspondence depends on swabbing site, number of sites, and pathogen species.

Sodium triphosphate–capped silver nanoparticles on a decellularized scaffold-based polyurethane vascular patch for bacterial infection inhibition and rapid endothelialization

With increasing incidence rate of cardiovascular diseases and implant-related infections, there is growing demand for vascular patches that can promote endothelialization and resist bacterial infection. In this work, we immobilized sodium triphosphate–capped silver nanoparticles onto a polyurethane film to obtain a composite film and evaluated its in vitro biocompatibility. Subsequently, we anchored sodium triphosphate–capped silver nanoparticles onto a polyurethane-coated decellularized scaffold to prepare a vascular patch and investigated its in vivo performance in a mouse model. The prepared vascular patch demonstrated excellent biocompatibility and potent antibacterial activity against Escherichia coli and Staphylococcus aureus. It still maintained the surgical artery patency at 30 days after implantation. At the same time, the endothelialization at the surgical site was achieved, showing its ability to facilitate endothelialization. Therefore, it may be a promising candidate for combating bacterial infection and treating diseased blood vessels.