Comparison of the adherence of E.Coli and S. Aureus to ten different prosthetic mesh grafts: In vitro experimental study

The Great Debate: Mesh or No Mesh in Contaminated Hernia Repairs?

Abdominal hernia surgeries are commonly performed with many different approaches, and mesh utilization has become a cornerstone in hernia repair, ensuring durable outcomes with minimal recurrence risk. However, managing contaminated hernia repairs presents unique challenges due to the heightened risks of mesh infection. Recent advancements in lightweight macroporous polypropylene meshes offer promising solutions. Studies have highlighted the superiority of macroporous polypropylene meshes compared to primary suture repair and other mesh types in terms of reduced surgical site infection rates and lower hernia recurrence rates. Moreover, utilizing macroporous polypropylene mesh in the retrorectus plane is associated with a favorable salvage rate, underscoring its efficacy in contaminated hernia repairs. At the same time, contrary evidence suggests higher postoperative complications with mesh use in settings of clean-contaminated or contaminated fields. Most significant complications are increased infection rates and similar recurrence rates compared to mesh-free repairs. New synthetic mesh that is being marketed as having better outcomes than other types of mesh and potentially primary repair need to be carefully assessed as biologic mesh once used to also be touted as the mesh to use in such fields, but more research is showing higher complication rates. The risk of infection and consequent morbidity might outweigh the benefit of less recurrence risk with mesh use. Further research, including prospective studies with long-term follow-up, is warranted to elucidate optimal hernia repair strategies in contaminated fields and inform evidence-based practice guidelines.

Meshing around: high-risk hernias and infected mesh

Open laparotomy carries a risk up to 20% for an incisional hernia, making repair one of the most common operations performed by general surgeons in the USA. Despite a multitude of mesh appliances and techniques, no size fits all, and there is continued debate on what is the best mesh type, especially in high-risk patients with contaminated hernias. Infected mesh carries a significant burden to the patient, the surgeon and overall healthcare costs with medical legal implications. A stepwise approach that involves optimization of patient comorbidities, patient selective choice of mesh and technique is imperative in mitigating outcomes and recurrence rates. This review will focus on the avoidance of mesh infection and the selection of mesh in patients with contaminated wounds.

Perspectives in Prevention of Biofilm for Medical Applications

The opportunity of decreasing the development of biofilm on the implant surface is one of the biggest research problems. It is connected with the existing prevention of microorganism hyperplasia. The application of numerous modifications is concerned with surface treatments leading to minimizing bacterial colonization. In the case of non-use antibacterial therapy, this leads to tissue infection. It can lead to a decreased opportunity to fight infection using antibiotherapy. One way is to decrease the increasing biofilm application which requires a method of modification. These techniques ensure properties like homogeneity or repeatability. The structure and chemical composition are changed with methods like CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), sol–gel, or ALD (Atomic Layer Deposition). Antibacterial properties of metals are connected with their impact on proteins and the nuclear proliferation of fibroblasts, causing improvement in biocompatibility and also growth corrosion resistance, and the decline of biofilm adhesion. The prevention of biofilm with medicines and antibiotics is a crowded-out treatment. Traditional methods of preventing biofilm are based on compounds that kill or inhibit the growth of the microbes but at the same time lead to frequent development of resistance to antibiotics. This review summarizes the current knowledge of reducing and preventing the creation of biofilm.

In vivo Analysis of the Resistance of the Meshes to Escherichia coli Infection

Background: The mesh infection is mostly related to the gram-negative bacteria, such as Escherichia coli (E. coli) for emergency surgery of incarcerated hernia. However, few study investigated the effects of E. coli concentration, mesh materials and antibiotic prophylaxis on mesh infection after hernioplasty. The aim of this study was to evaluate the bacterial resistance to E. coli for three different materials of mesh, and to measure the minimum E. coli concentration for mesh infection with and without antibiotic prophylaxis in a rat model.

Methods: Three types of mesh (polytetrafluoroethylene, polypropylene, and biologic meshes) were used in the repair of an acute ventral hernia rat model in the setting of different concentrations of E. coli loads and antibiotics. At the 8th day after surgery, mesh samples were sent for microbiologic and histologic analyses.

Results: The positive rates of bacterial culture increased with E. coli concentration. The biologic mesh showed better bacterial resistance compared to polytetrafluoroethylene mesh and polypropylene mesh when the concentration of E. coli ranges from 10⁶ CFU/ml to 10⁸ CFU/ml (P = 0.002 and P = 0.029, respectively). Prophylactical ceftriaxone treatment could not decrease the colonization rate of E. coli at 10⁶ CFU/ml or 10⁸ CFU/ml in each group (P > 0.05). The scores of neovascularization in polypropylene mesh and biologic mesh were similar, which was higher than that of polytetrafluoroethylene mesh (P < 0.05). Compared with other meshes, biologic mesh showed better tolerance to 10⁶ CFU/ml E. coli with respect to inflammation, depth of inflammation, neovascularization, cellular repopulation and foreign body giant cells.

Conclusion: The biologic mesh had better E. coli resistance compared to polytetrafluoroethylene mesh and polypropylene mesh when the E. coli concentration is higher than 10⁶ CFU/ml in rats. Antibiotic prophylaxis was useful when the contamination was not particularly severe.

Proof of concept, design, and manufacture via 3-D printing of a mesh with bactericidal capacity: Behaviour in vitro and in vivo

Currently, hernia treatment involves implantation of a mesh prosthesis, usually made of polypropylene, and the primary complication is infection of the device, which leads to an exponential increase in morbidity. Three-dimensional printing offers a method of dealing with complications of this magnitude. Therefore, in this study, the bactericidal properties and effectiveness of three-dimensional-printed meshes with polycaprolactone (PCL) and gentamicin were evaluated in vitro in Escherichia coli cultures, and their histological behaviour was examined in vivo. Different PCL meshes were implanted into four groups of rats, with 10 rats in each group: PCL meshes, PCL meshes with alginate and calcium chloride, PCL meshes with gentamicin, and PCL meshes with alginate and gentamicin. Thirty-six microporous meshes were manufactured, and their bactericidal properties were assessed. When the meshes did not include an antibiotic, an inhibition halo was not observed; when the gentamicin was free, an asymmetric inhibition area of 5.65 ± 0.46 cm² was present; when the gentamicin was encapsulated, a rectangular area of 5.40 ± 0.38 cm² was observed. In the rats, macroporous and microporous mesh implants produced mild inflammation and substantial fibrosis with collagen and neovascular foci. A significant difference was observed in fibroblastic activity between the PCL with alginate group and the PCL with alginate and gentamicin group microporous meshes (p = .013) and in collagen deposits between the macroporous and microporous meshes in the PCL mesh group (p = .033). The feasibility of manufacturing drug-doped printed PCL meshes containing alginate and gentamicin was verified, and the meshes exhibited bactericidal effects and good histopathological behaviour.

Fouling-Resistant Hydrogels Prepared by the Swelling-Assisted Infusion and Polymerization of Dopamine

Biofilm-associated infections stemming from medical devices are increasingly challenging to treat due to the spread of antibiotic resistance. In this study, we present a simple strategy that significantly enhances the antifouling performance of covalently crosslinked poly(ethylene glycol) (PEG) and physically crosslinked agar hydrogels by incorporation of the fouling-resistant polymer zwitterion, poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC). Dopamine polymerization was initiated during swelling of the hydrogels, which provided dopamine and pMPC an osmotic driving force into the hydrogel interior. Both PEG and agar hydrogels were synthesized over a broad range of storage moduli (1.7,1300 kPa), which remained statistically equivalent after being functionalized with pMPC and polydopamine (PDA). When challenged with fibrinogen, a model blood-clotting protein, the pMPC/PDA-functionalized PEG and agar hydrogels displayed a >90% reduction in protein adsorption compared to hydrogel controls. Further, greater than an order-of-magnitude reduction in Escherichia coli and Staphylococcus aureus adherence was observed. This study demonstrates a versatile materials platform to enhance the fouling resistance of hydrogels through a pMPC/PDA incorporation strategy that is independent of the chemical composition and network structure of the original hydrogel.

Mesh Infection and Hernia Repair: A Review

BACKGROUND

The use of a prosthetic mesh to repair a tissue defect may produce a series of post-operative complications, among which infection is the most feared and one of the most devastating. When occurring, bacterial adherence and biofilm formation on the mesh surface affect the implant's tissue integration and host tissue regeneration, making preventive measures to control prosthetic infection a major goal of prosthetic mesh improvement.

METHODS

This article reviews the literature on the infection of prosthetic meshes used in hernia repair to describe the in vitro and in vivo models used to examine bacterial adherence and biofilm formation on the surface of different biomaterials. Also discussed are the prophylactic measures used to control implant infection ranging from meshes soaked in antibiotics to mesh coatings that release antimicrobial agents in a controlled manner.

RESULTS

Prosthetic architecture has a direct effect on bacterial adherence and biofilm formation. Absorbable synthetic materials are more prone to bacterial colonization than non-absorbable materials. The reported behavior of collagen biomeshes, also called xenografts, in a contaminated environment has been contradictory, and their use in this setting needs further clinical investigation. New prophylactic mesh designs include surface modifications with an anti-adhesive substance or pre-treatment with antibacterial agents or metal coatings.

CONCLUSIONS

The use of polymer coatings that slowly release non-antibiotic drugs seems to be a good strategy to prevent implant contamination and reduce the onset of resistant bacterial strains. Even though the prophylactic designs described in this review are mainly focused on hernia repair meshes, these strategies can be extrapolated to other implantable devices, regardless of their design, shape or dimension.