Biofilms and effective porosity of hernia mesh: are they silent assassins?

Soft, Long-Lived, Bioresorbable Electronic Surgical Mesh with Wireless Pressure Monitor and On-Demand Drug Delivery

Current research in the area of surgical mesh implants is somewhat limited to traditional designs and synthesis of various mesh materials, whereas meshes with multiple functions may be an effective approach to address long-standing challenges including postoperative complications. Herein, a bioresorbable electronic surgical mesh is presented that offers high mechanical strength over extended timeframes, wireless post-operative pressure monitoring, and on-demand drug delivery for the restoration of tissue structure and function. The study of materials and mesh layouts provides a wide range of tunability of mechanical and biochemical properties. Dissolvable dielectric composite with porous structure in a pyramidal shape enhances sensitivity of a wireless capacitive pressure sensor, and resistive microheaters integrated with inductive coils provide thermo-responsive drug delivery system for an antibacterial agent. In vivo evaluations demonstrate reliable, long-lived operation, and effective treatment for abdominal hernia defects, by clear evidence of suppressed complications such as adhesion formation and infections.

In vitro and in vivo evaluation of diethyldithiocarbamate with copper ions and its liposomal formulation for the treatment of Staphylococcus aureus and Staphylococcus epidermidis biofilms

Surgical site infections (SSIs) are mainly caused by Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) biofilms. Biofilms are aggregates of bacteria embedded in a self-produced matrix that offers protection against antibiotics and promotes the spread of antibiotic-resistance in bacteria. Consequently, antibiotic treatment frequently fails, resulting in the need for alternative therapies. The present study describes the in vitro efficacy of the Cu(DDC)₂ complex (2:1 M ratio of diethyldithiocarbamate (DDC^-) and Cu²⁺) with additional Cu²⁺ against S. aureus and S. epidermidis biofilms in models mimicking SSIs and in vitro antibacterial activity of a liposomal Cu(DDC)₂ + Cu²⁺ formulation. The in vitro activity on S. aureus and S. epidermidis biofilms grown on two hernia mesh materials and in a wound model was determined by colony forming unit (CFU) counting. Cu²⁺-liposomes and Cu(DDC)₂-liposomes were prepared, and their antibacterial activity was assessed in vitro using the alamarBlue assay and CFU counting and in vivo using a Galleria mellonella infection model. The combination of 35 μM DDC^- and 128 μM Cu²⁺ inhibited S. aureus and S. epidermidis biofilms on meshes and in a wound infection model. Cu(DDC)₂-liposomes + free Cu²⁺ displayed similar antibiofilm activity to free Cu(DDC)₂ + Cu²⁺, and significantly increased the survival of S. epidermidis-infected larvae. Whilst Cu(DDC)₂ + Cu²⁺ showed substantial antibiofilm activity in vitro against clinically relevant biofilms, its application in mammalian in vivo models is limited by solubility. The liposomal Cu(DDC)₂ + Cu²⁺ formulation showed antibiofilm activity in vitro and antibacterial activity and low toxicity in G. mellonella, making it a suitable water-soluble formulation for future application on infected wounds in animal trials.

Hernia Mesh Complications: Management of Mesh Infections and Enteroprosthetic Fistula

The potential consequences of mesh infection mandate careful consideration of surgical approach, mesh selection, and preoperative patient optimization when planning for ventral hernia repair. Intraperitoneal mesh, microporous or laminar mesh, and multifilament mesh typically require explantation, whereas macroporous, monofilament mesh in an extraperitoneal position is often salvageable. Delayed presentation of mesh infection should raise the suspicion for enteroprosthetic fistula when intraperitoneal mesh is present. When mesh excision is necessary, the surgeon must carefully consider both the risk of recurrent infection as well as hernia recurrence when deciding on single-stage definitive reconstruction versus primary closure with delayed reconstruction.

Polyglactin 910 Meshes Coated with Sustained-Release Cannabigerol Varnish Inhibit Staphylococcus aureus Biofilm Formation and Macrophage Cytokine Secretion: An In Vitro Study

Synthetic surgical meshes are commonly used in abdominal wall reconstruction surgeries to strengthen a weak abdominal wall. Common mesh-related complications include local infection and inflammatory processes. Because cannabigerol (CBG) has both antibacterial and anti-inflammatory properties, we proposed that coating VICRYL (polyglactin 910) mesh with a sustained-release varnish (SRV) containing CBG would prevent these complications. We used an in vitro infection model with Staphylococcus aureus and an in vitro inflammation model of lipopolysaccharide (LPS)-stimulated macrophages. Meshes coated with either SRV-placebo or SRV-CBG were exposed daily to S. aureus in tryptic soy medium (TSB) or macrophage Dulbecco's modified eagle medium (DMEM). Bacterial growth and biofilm formation in the environment and on the meshes were assessed by changes in optical density, bacterial ATP content, metabolic activity, crystal violet staining, spinning disk confocal microscopy (SDCM), and high-resolution scanning electron microscopy (HR-SEM). The anti-inflammatory effect of the culture medium that was exposed daily to the coated meshes was analyzed by measuring the release of the cytokines IL-6 and IL-10 from LPS-stimulated RAW 264.7 macrophages with appropriate ELISA kits. Additionally, a cytotoxicity assay was performed on Vero epithelial cell lines. We observed that compared with SRV-placebo, the segments coated with SRV-CBG inhibited the bacterial growth of S. aureus in the mesh environment for 9 days by 86 ± 4% and prevented biofilm formation and metabolic activity in the surroundings for 9 days, with respective 70 ± 2% and 95 ± 0.2% reductions. The culture medium that was incubated with the SRV-CBG-coated mesh inhibited LPS-induced secretion of IL-6 and IL-10 from the RAW 264.7 macrophages for up to 6 days without affecting macrophage viability. A partial anti-inflammatory effect was also observed with SRV-placebo. The conditioned culture medium was not toxic to Vero epithelial cells, which had an IC₅₀ of 25 µg/mL for CBG. In conclusion, our data indicate a potential role of coating VICRYL mesh with SRV-CBG in preventing infection and inflammation in the initial period after surgery.

Aging of Industrial Polypropylene Surfaces in Detergent Solution and Its Consequences for Biofilm Formation

The performance of plastic components in water-bearing parts of industrial and household appliances, often in the presence of harsh environments and elevated temperatures, critically relies on the mechanical and thermal polymer stability. In this light, the precise knowledge of aging properties of polymers formulated with dedicated antiaging additive packages as well as various fillers is crucial for long-time device warranty. We investigated and analysed the time-dependent, polymer-liquid interface aging of different industrial performance polypropylene samples in aqueous detergent solution at high temperatures (95 °C). Special emphasis was put on the disadvantageous process of consecutive biofilm formation that often follows surface transformation and degradation. Atomic force microscopy, scanning electron microscopy, and infrared spectroscopy were used to monitor and analyse the surface aging process. Additionally, bacterial adhesion and biofilm formation was characterised by colony forming unit assays. One of the key findings is the observation of crystalline, fibre-like growth of ethylene bis stearamide (EBS) on the surface during the aging process. EBS is a widely used process aid and lubricant enabling the proper demoulding of injection moulding plastic parts. The aging-induced surface-covering EBS layers changed the surface morphology and promoted bacterial adhesion as well as biofilm formation of Pseudomonas aeruginosa.

Intestinal erosion caused by meshoma displacement: A case report

BACKGROUND

A meshoma formation and erosion to the small intestine is rare. Herein, we report one case of a meshoma that was not treated early; causing it to displace and erode the small intestine, with infection, complete control of symptoms was achieved after removal of the infected patch mass, no recurrence of hernia after 2 years of follow-up.

CASE SUMMARY

A 62-year-old male patient presented with recurrent abdominal pain repeatedly for 1 wk, which has worsened 2 d before admition, accompanied by fever. Five years before presentation he underwent right inguinal hernia Plug and patch repair approach. Two years ago, a computed tomography scan revealed a right lower abdominal mass with soft tissue density, measuring approximately 30 mm × 17 mm, which was diagnosed as meshoma that was not treated. The patient had poorly controlled diabetes in the past year.

CONCLUSION

The formation of meshoma is rare, and that if not treated in time it might erode and require resection of the involved organ.

Hernia mesh infection treatment following the repair of abdominal wall hernias: A single-center experience

INTRODUCTION

The mesh-based repair of abdominal wall hernias is a commonly employed approach as it is easy to implement and associated with low rates of hernia recurrence. However, the occurrence of hernia mesh infections following such repair can be extremely serious, and no clinical consensus regarding the optimal treatment of such infections has been established. This study was thus developed to review the management of hernia mesh infection cases treated at our center, summarizing the demographic and clinical characteristics of affected patients and summarizing our associated therapeutic experiences.

METHODS

Data pertaining to 64 cases of hernia mesh infections treated at our center were retrospectively reviewed. Data were obtained from patient medical records, including general situation, hernia type, prior hernia repair approaches, type of mesh, and postoperative condition. Other reviewed outcomes include bacteriological and imaging findings, as well as treatment outcomes. In cases where conservative management was not successful, the approach to mesh removal (laparoscopic vs. open) was made based on the primary surgical approach and the type of material used for the repair.

RESULTS

In total, 42 patients underwent primary open inguinal hernioplasty (including plug repair, preperitoneal mesh repair, and Lichtenstein repair), while 11 patients underwent laparoscopic repair (9 transabdominal preperitoneal, TAPP and 2 totally extraperitoneal,TEP), and 11 patients with incisional hernias underwent the intraperitoneal onlay mesh (IPOM) procedure. Six patients exhibited mesh erosion of the internal organs. Of these patients, 38 underwent mesh removal via open debridement, while 9 underwent laparoscopic exploration and open debridement, and 1 underwent laparoscopic mesh removal. No patients exhibited serious postoperative sequelae, serious complications, or mortality after the treatment of mesh infections.One patient experienced postoperative infection recurrence following partial mesh removal, with the appearance of a small fistula. Hernias recurred in 2 patients following mesh removal, and 1 patient underwent repair via laparoscopic IPOM.

CONCLUSIONS

While conservative treatment can cure early mesh infections, there is nonetheless a risk that these infections will recur. In view of the variety of surgical intervention of abdominal wall hernias at present,treatment of mesh infection should be individualized. Our findings suggest that hernias repaired via the placement of mesh in the preperitoneal space can more readily contribute to internal organ erosion and late-onset infections, with open debridement often being unable to completely remove the mesh without causing collateral damage. Laparoscopic exploration is an effective and minimally invasive approach to detecting internal organ involvement and removing the infected hernia mesh from affected patients.

Are late hernia mesh complications linked to Staphylococci biofilms?

Purpose

The purpose of this study was to investigate the link between bacterial biofilms and negative outcomes of hernia repair surgery. As biofilms are known to play a role in mesh-related infections, we investigated the presence of biofilms on hernia meshes, which had to be explanted due to mesh failure without showing signs of bacterial infection.

Methods

In this retrospective observational study, 20 paraffin-embedded tissue sections from explanted groin hernia meshes were analysed. Meshes have been removed due to chronic pain, hernia recurrence or mesh shrinkage. The presence and bacterial composition of biofilms were determined. First, specimens were stained with fluorescence in situ hybridisation (FISH) probes, specific for Staphylococcus aureus and coagulase-negative staphylococci, and visualised by confocal laser scanning microscopy. Second, DNA was extracted from tissue and identified by S. aureus and S. epidermidis specific PCR.

Results

Confocal microscopy showed evidence of bacterial biofilms on meshes in 15/20 (75.0%) samples, of which 3 were positive for S. aureus, 3 for coagulase-negative staphylococci and 9 for both species. PCR analysis identified biofilms in 17/20 (85.0%) samples, of which 4 were positive for S. aureus, 4 for S. epidermidis and 9 for both species. Combined results from FISH/microscopy and PCR identified staphylococci biofilms in 19/20 (95.0%) mesh samples. Only 1 (5.0%) mesh sample was negative for bacterial biofilm by both techniques.

Conclusion

Results suggest that staphylococci biofilms may be associated with hernia repair failure. A silent, undetected biofilm infection could contribute to mesh complications, chronic pain and exacerbation of disease.

Extremely Late-Onset Deep Infection Post-inguinal Hernia Repair After Panendoscopy

Mesh infection after hernia repair is a well-known complication, which can have morbid consequences. This report presents a case of a gentleman with mesh infection many years after initial surgery, potentially from bacterial translocation post-colonoscopy, and describes his successful treatment. This case emphasizes the need to consider mesh infection regardless of time from surgery to presentation.

Risks and Prevention of Surgical Site Infection After Hernia Mesh Repair and the Predictive Utility of ACS-NSQIP

AIM

The aim of this paper was to provide a narrative review of surgical site infection after hernia surgery and the influence of perioperative preventative interventions.

METHODS

The review was based on current national and international guidelines and a literature search.

RESULTS

Mesh infection is a highly morbid complication after hernia surgery, and is associated with hospital re-admission, increased health care costs, re-operation, hernia recurrence, impaired quality of life and plaintiff litigation. The American College of Surgeons National Surgical Quality Improvement Program is a particularly useful resource for the study and evidence-based practise of abdominal wall hernia repair.

DISCUSSION

The three major modifiable patient comorbidities significantly associated with postoperative surgical site infection in hernia surgery are obesity, tobacco smoking and diabetes mellitus. Preoperative optimization includes weight loss, cessation of smoking, and control of diabetes. Intraoperative interventions relate, in particular, to the control of fomite mediated transmission in the operating theatre and prevention of mesh contamination with S. aureus CFUs. Risk management strategies should also target the niche ecological conditions which enable bacterial survival and subsequent biofilm formation on an implanted mesh. Outcomes of mesh infection after hernia surgery are closely related to mesh type and porosity, patient smoking status, presence of MRSA, bacterial adhesion and biofilm production. The use of suction drains and the timing of drain removal are controversial and discussed in detail. Finally, the utility of the ACS-NSQIP Surgical Risk Calculator in predicting complications and outcomes in individual patients and the importance of quality improvement initiatives in surgical units are emphasized.

The Role of Mesh Implants in Surgical Treatment of Parastomal Hernia

A parastomal hernia is a common complication following stoma surgery. Due to the large number of hernial relapses and other complications, such as infections, adhesion to the intestines, or the formation of adhesions, the treatment of hernias is still a surgical challenge. The current standard for the preventive and causal treatment of parastomal hernias is to perform a procedure with the use of a mesh implant. Researchers are currently focusing on the analysis of many relevant options, including the type of mesh (synthetic, composite, or biological), the available surgical techniques (Sugarbaker’s, “keyhole”, or “sandwich”), the surgical approach used (open or laparoscopic), and the implant position (onlay, sublay, or intraperitoneal onlay mesh). Current surface modification methods and combinations of different materials are actively explored areas for the creation of biocompatible mesh implants with different properties on the visceral and parietal peritoneal side. It has been shown that placing the implant in the sublay and intraperitoneal onlay mesh positions and the use of a specially developed implant with a 3D structure are associated with a lower frequency of recurrences. It has been shown that the prophylactic use of a mesh during stoma formation significantly reduces the incidence of parastomal hernias and is becoming a standard method in medical practice.

Development of Biocomposite Polymeric Systems Loaded with Antibacterial Nanoparticles for the Coating of Polypropylene Biomaterials

The development of a biocomposite polymeric system for the antibacterial coating of polypropylene mesh materials for hernia repair is reported. Coatings were constituted by a film of chitosan containing randomly dispersed poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles loaded with chlorhexidine or rifampicin. The chlorhexidine-loaded system exhibited a burst release during the first day reaching the release of the loaded drug in three or four days, whereas rifampicin was gradually released for at least 11 days. Both antibacterial coated meshes were highly active against Staphylococcus aureus and Staphylococcus epidermidis (10⁶ CFU/mL), displaying zones of inhibition that lasted for 7 days (chlorhexidine) or 14 days (rifampicin). Apparently, both systems inhibited bacterial growth in the surrounding environment, as well as avoided bacterial adhesion to the mesh surface. These polymeric coatings loaded with biodegradable nanoparticles containing antimicrobials effectively precluded bacterial colonization of the biomaterial. Both biocomposites showed adequate performance and thus could have potential application in the design of antimicrobial coatings for the prophylactic coating of polypropylene materials for hernia repair.