Antibiotic prophylaxis in incisional hernia repair using a prosthesis

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Alternative to mesh repair for ventral hernias: Modified rectus muscle repair

BACKGROUND

Mesh utilization for ventral hernia repair is associated with potential complications such as mesh infections, adhesions, seromas, fistula formation and significant postoperative pain. The modified rectus muscle repair (RMR) is as an option to repair midline ventral hernias without mesh.

AIM

To evaluate the short term outcomes when the modified RMR was used to repair ventral hernias.

METHODS

This was a 5-year prospective study that examined the outcome of all consecutive patients with ventral abdominal wall hernias > 5 cm in maximal diameter who underwent repair using the modified RMR technique in a single surgeon unit. Patients were reviewed in an outpatient clinic at 3, 6 and 12 mo and evaluated for hernia recurrence on clinical examination. Each patient’s abdominal wall was also assessed with using ultrasonography at 24 mo to detect recurrences. All data were examined with SPSS ver 18.0.

RESULTS

Over the 5-year study period, there were 52 patients treated for ventral hernias at this institution. Four patients were excluded and there were 48 in the final study sample, at a mean age of 56 years (range 28-80). The mean maximal diameter of the hernia defect was 7 cm (range 5-12 cm). There were 5 (10.4%) seromas and 1 recurrence (2.1%) at a mean of 36 mo follow-up.

CONCLUSION

The authors recommend the modified RMR as an acceptable alternative to mesh repair of ventral hernias. The seroma rate can be further reduced with routine use of drains. The modified RMR also has the benefit of eliminating all mesh-specific complications.

The European Hernia Society Prehabilitation Project: A Systematic Review of Intra-Operative Prevention Strategies for Surgical Site Occurrences in Ventral Hernia Surgery

Background

Ventral hernia repair is one of the most commonly performed surgical procedures worldwide. To reduce the risk of complications, pre- and intra-operative strategies have received increasing focus in recent years. To assess possible preventive surgical strategies, this European Hernia Society endorsed project was launched. The aim of this review was to evaluate the current literature focusing on pre- and intra-operative strategies for surgical site occurrences (SSO) and specifically surgical site infection (SSI) in ventral hernia repair.

Methods

A systematic review was conducted and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Databases used were Pubmed and Web of Science. Original retrospective or prospective human adult studies describing at least one intra-operative intervention to reduce SSO after ventral hernia repair were considered eligible.

Results

From a total of 4775 results, a total of 18 papers were considered suitable after full text reading. Prehospital chlorhexidine gluconate (CHG) scrub appears to increase the risk of SSO in patients undergoing ventral hernia repair, while there is no association between any type of surgical hat worn and the incidence of postoperative wound events. Intraoperative measures as prophylactic negative pressure therapy, surgical drain placement and the use of quilt sutures seem beneficial for decreasing the incidence of SSO and/or SSI. No positive effect has been shown for antibiotic soaking of a synthetic mesh, nor for the use of fibrin sealants.

Conclusion

This review identified a limited amount of literature describing specific preventive measures and techniques during ventral hernia repair. An advantage of prophylactic negative pressure therapy in prevention of SSI was observed, but different tools to decrease SSIs and SSOs continuously further need our full attention to improve patient outcomes and to lower overall costs.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Melanin pigments extracted from horsehair as antibacterial agents

Here we present the important findings related to biologically derived pigments for potential use as antibacterial agents. Melanin biopigments extracted from Equus ferus hair exhibit a homogeneous elliptical microstructure with highly ordered semicrystalline features. Spectroscopic analysis indicates that melanin contains a high degree of redox active catechol groups, which can produce reactive oxygen species. The antibacterial activity of melanins was tested by incubating Escherichia coli and Staphylococcus aureus with melanins. The results showed 100% bacterial growth inhibition within 4 h. This finding suggests that melanin pigments may serve as naturally occurring antibacterial agents with unique redox chemistry and reactive oxygen species generation capability.

Chinese expert consensus on adult ventral abdominal wall defect repair and reconstruction

BACKGROUND

Surgical management of patients with ventral abdominal wall defects, especially complex abdominal wall defects, remains a challenging problem for abdominal wall reconstructive surgeons. Effective surgical treatment requires appropriate preoperative assessment, surgical planning, and correct operative procedure in order to improve postoperative clinical outcomes and minimize complications. Although substantial advances have been made in surgical techniques and prosthetic technologies, there is still insufficient high-level evidence favoring a specific technique. Broad variability in existing practice patterns, including clinical pre-operative evaluation, surgical techniques and surgical procedure selection, are still common.

DATA SOURCES

With the purpose of providing a best practice algorithm, a comprehensive search was conducted in Medline and PubMed. Sixty-four surgeons considered as experts on abdominal wall defect repair and reconstruction in China were solicited to develop a Chinese consensus and give recommendations to help surgeons standardize their techniques and improve clinical results.

CONCLUSIONS

This consensus serves as a starting point to provide recommendations for adult ventral abdominal wall repair and reconstruction in China and may help build opportunities for international cooperation to refine AWR practice.

Impact of Surface Treatment on the Functional Properties Stainless Steel for Biomedical Applications

The main goal of the carried out tests was to analyze the influence of the surface modification of a substrate by depositing composite ZnO layers by the Atomic Layer Deposition (ALD) method. The samples were subjected to preliminary surface modification consisting of being sandblasted and electropolished. A ZnO layer was applied to the prepared substrates by the ALD method. As a precursor of ZnO, diethylzinc (DEZ) was used, which reacted with water, enabling the deposition of the thin films. The chamber temperature was as follows: T = 100–300 °C. The number of cycles was 500 and 1500. As part of the assessment of the physicochemical properties of the resulting surface layers, the tests of chemical composition of the layer, pitting corrosion, impedance corrosion, adhesion to the metal substrate, morphology surface, and wettability were carried out. On the basis of the obtained research, it was found that a composite ZnO layer deposited onto a substrate previously subjected to the electrochemical polishing process has more favorable physicochemical properties. Moreover, an influence of temperature and the number of cycles of the deposition process on the obtained properties was observed, where the ZnO layer was characterized by more favorable properties at a temperature of 200–300 °C at 1500 cycles of the deposition process.

Postoperative Prophylactic Antibiotics Reduce Surgical Site Infection Rates after Ventral Hernia Repair: A Systematic Review

SSIs after ventral hernia repair (VHR) represent a significant complication. The impact of postoperative prophylactic antibiotics on the SSI rates after VHRs is unclear. A systematic review of PubMed and Web of Science databases from inception through March 2016 investigating the effect of postoperative prophylactic antibiotics after VHRs was performed. Strict inclusion and exclusion criteria were implemented, and the methodological quality of the included studies was assessed. After systematic independent assessment of 216 citations, four studies, involving 344 patients, met the inclusion criteria. Among the included studies, 164 patients received >24 hours of postoperative prophylactic antibiotics, whereas 180 patients were controls. The overall incidence of SSI among patients receiving postoperative antibiotics was 14.6 per cent (95% confidence interval [CI], 9.9 to 20.9) which compares favorably with the control group: 35.5 per cent (95% CI, 28.9 to 42.7) (odds ratio: 0.3, 95% CI: 0.2 to 0.5, P < 0.01). Among patient's receiving postoperative antibiotics, the pooled average duration of postoperative antibiotic treatment was 6.2 ± 0.4 days. Based on the available evidence, the use of postoperative prophylactic antibiotics seems to be associated with lower SSI rates after VHRs. Future prospective randomized controlled trials should be conducted to further confirm the efficacy of this prophylactic intervention.

Resistance of Synthetic and Biologic Surgical Meshes to Methicillin-Resistant Staphylococcus aureus Biofilm: An In Vitro Investigation

Surgical meshes have become the standard procedure for a variety of surgical applications with 20 million meshes being implanted each year. The popularity of mesh usage among surgeons is backed by the multiple studies that support its functionality as a tool for improving surgical outcomes. However, their use has also been associated with infectious surgical complications and many surgeons have turned to biologic meshes. While there have been several studies investigating synthetic meshes, there is limited data comparing synthetic and biologic meshes in vitro in an infection model. This study evaluates the in vitro susceptibility of both synthetic and biologic meshes to single-species methicillin-resistant Staphylococcus aureus (MRSA) biofilms. This research compares biofilm biomass, average thickness, and coverage between the three meshes through florescent in situ hybridization (FISH), confocal scanning microscopy (CSLM), and image analysis. We also report the varying levels of planktonic and attached bacteria through sonication and cfu counts. While the data illustrates increased biofilm formation on biologic mesh in vitro, the study must further be investigated in vivo to confirm the study observations.

The Management of Mesh Infection After Laparoscopic Inguinal Hernia Repair

We present our experience in managing mesh infection after laparoscopic inguinal hernia repair. We analyzed 19 patients with extensive mesh infection treated between 2012 and 2017 via laparoscopic mesh excision after preoperative workup. After mesh removal and insertion of a drain into the preperitoneal space, the peritoneal flap was closed with 3/0 absorbable consecutive suture. The operative course in all patients was uneventful. Sigmoidectomy for a fistula was required in 1 patient. Two patients required a second laparoscopic surgery for infection on the contralateral side and residual mesh around the pubic bone. In total, 3 cases of recurrence were identified during follow-up. Laparoscopic mesh excision is an effective and minimally invasive method for the management of infection that also avoids unnecessary disruption of healthy layers of the abdominal wall.

Surgical site infection: the "Achilles Heel" of all types of abdominal wall hernia reconstruction

PURPOSE

Surgical site infection is the most common hospital-acquired infection in surgical patients. Recently, public health organizations have updated prevention guidelines. This review discusses surgical site infections as a complication of abdominal wall reconstruction.

METHODS

The authors reviewed guidelines on prevention of surgical site infections from the Center for Disease Control and Prevention, World Health Organization, and National Institute for Health and Care Excellence and put them into context with the relevant abdominal wall reconstruction literature. This was the subject of the Nyhus-Wantz lecture given at The International Hernia Congress on March 14, 2018 in Miami, FL and is summarized here.

RESULTS

Routine use of preoperative antibiotics in prosthetic groin hernia repair is not supported by the available literature. High-quality data on antibiotic prophylaxis in ventral (both primary and incisional) hernia repair is lacking, but it is widely utilized and may reduce SSIs. Recommended preventative strategies discussed in this manuscript include: treatment of remote site infections, perioperative normothermia and normoglycemia, avoidance of hypoxemia, antiseptic preparation of surgical team hands and patient skin, treatment of obesity, smoking cessation, correction of malnutrition, and physical conditioning.

CONCLUSION

Surgical site infections lead to significant morbidity and mortality, hernia recurrences, prolonged hospital stay, and increased hospital costs. This makes surgical site infections the "Achilles Heel" of abdominal wall reconstruction. Strict adherence to standardized guidelines and preoperative optimization of patients' risk profiles are crucial to decrease the incidence of surgical site infections.

Infections associated with mesh repairs of abdominal wall hernias: Are antimicrobial biomaterials the longed-for solution?

The incidence of mesh-related infection after abdominal wall hernia repair is low, generally between 1 and 4%; however, worldwide, this corresponds to tens of thousands of difficult cases to treat annually. Adopting best practices in prevention is one of the keys to reduce the incidence of mesh-related infection. Once the infection is established, however, only a limited number of options are available that provides an efficient and successful treatment outcome. Over the past few years, there has been a tremendous amount of research dedicated to the functionalization of prosthetic meshes with antimicrobial properties, with some receiving regulatory approval and are currently available for clinical use. In this context, it is important to review the clinical importance of mesh infection, its risk factors, prophylaxis and pathogenicity. In addition, we give an overview of the main functionalization approaches that have been applied on meshes to confer anti-bacterial protection, the respective benefits and limitations, and finally some relevant future directions.

Prosthetic Mesh Repair for Incarcerated Inguinal Hernia

BACKGROUND

Incarcerated inguinal hernia is a commonly encountered urgent surgical condition, and tension-free repair is a well-established method for the treatment of non-complicated cases. However, due to the risk of prosthetic material-related infections, the use of mesh in the repair of strangulated or incarcerated hernia has often been subject to debate. Recent studies have demonstrated that biomaterials represent suitable materials for performing urgent hernia repair. Certain studies recommend mesh repair only for cases where no bowel resection is required; other studies, however, recommend mesh repair for patients requiring bowel resection as well.

AIM

The aim of this study was to compare the outcomes of different surgical techniques performed for strangulated hernia, and to evaluate the effect of mesh use on postoperative complications.

STUDY DESIGN

Retrospective cross-sectional study.

METHODS

This retrospective study was performed with 151 patients who had been admitted to our hospital's emergency department to undergo surgery for a diagnosis of incarcerated inguinal hernia. The patients were divided into two groups based on the applied surgical technique. Group 1 consisted of 112 patients treated with mesh-based repair techniques, while Group 2 consisted of 39 patients treated with tissue repair techniques. Patients in Group 1 were further divided into two sub-groups: one consisting of patients undergoing bowel resection (Group 3), and the other consisting of patients not undergoing bowel resection (Group 4).

RESULTS

In Group 1, it was observed that eight (7.14%) of the patients had wound infections, while two (1.78%) had hematomas, four (3.57%) had seromas, and one (0.89%) had relapse. In Group 2, one (2.56%) of the patients had a wound infection, while three (7.69%) had hematomas, one (2.56%) had seroma, and none had relapses. There were no statistically significant differences between the two groups with respect to wound infection, seroma, hematoma, or relapse (p>0.05). In Group 3, it was observed that one (6.7%) of the patients had wound infections, while one (6.7%) had a hematoma, one patient (6.7%) had seroma, and none had relapses. In Group 4, seven (7.2%) of the patients had wound infections, while one (1%) had a hematoma, three (3%) had seromas, and one (1%) had a relapse. There were no significant differences between the two groups with respect to wound infection, seroma, hematoma, or relapse (p>0.05).

CONCLUSION

In urgent groin hernia repair surgeries, polypropylene mesh can be safely used even in the patients undergoing bowel resection.

Predictors of mesh infection and explantation after abdominal wall hernia repair

BACKGROUND

The main objective was to identify predictive factors associated with prosthesis infection and mesh explantation after abdominal wall hernia repair (AWHR).

METHODS

This is a retrospective review of all patients who underwent AWHR from January 2004 to May 2014 at a tertiary center. Multivariate analysis identified predictors of mesh infection and explantation after AWHR.

RESULTS

From 3,470 cases of AWHR, we reported 66 cases (1.9%) of mesh infection, and 48 repairs (72.7%) required mesh explantation. Steroid or immunosuppressive drugs use (odds ratio [OR] 2.22; confidence interval [CI] 1.16 to 3.95), urgent repair (OR 5.06; CI 2.21 to 8.60), and postoperative surgical site infection (OR 2.9; CI 1.55 to 4.10) were predictive of mesh infection. Predictors of mesh explantation were type of mesh (OR 3.13; CI 1.71 to 5.21), onlay position (OR 3.51; CI 1.23 to 6.12), and associated enterotomy in the same procedure (OR 5.17; CI 2.05 to 7.12).

CONCLUSIONS

Immunosuppressive drugs use, urgent repair, and postoperative surgical site infection are predictive of mesh infection. Risk factors of prosthesis explantation are polytetrafluoroethylene mesh, onlay mesh position, and associated enterotomy in the same procedure.

Postoperative Mesh Infection-Still a Concern in Laparoscopic Era

Introduction of synthetic mesh was a landmark breakthrough in the management of hernia repair and has significantly reduced recurrence rates. But in addition to the benefits, some more problems have come in picture major being 'mesh infection'. Prolene mesh has shown promise when used in abdominal and inguinal hernia repair, especially when used in planned surgeries. This material, derived from monofilament polypropelene, is found to be biologically inert in almost every person. Being a foreign material, a slightest breach in asepsis can lead to favourable environment for bacterial proliferation and form a 'biofilm'. This phenomenon especially after laparoscopic surgeries gives rise to chronic discharging sinus at the port site, abscess formation around mesh and even sepsis. It appears that laparoscopic hernia repair is a promising method but having chances of mesh infection owing to difficult approach and lack of uniformity in sterilization of laparoscopic instruments. Slightest breach in sterility or protocols might lead to such a large ventral wall sinus, increasing morbidity and cost of treatment. Treatment of infected mesh is possible by local debridement, irrigation, mesh removal and systemic antibiotics culminating in increased morbidity over duration of disease, but still it would be worth emphasizing-'Prevention is better than cure'.

Short- and long-term outcomes of incarcerated inguinal hernias repaired by Lichtenstein technique

Introduction

The use of tension-free inguinal hernia repair techniques using commercially available implants is now rather common. However, it is widely accepted that the use of biomaterials should be limited to non-infected surgical fields. As such, most current studies pertain to the application of various implants during the surgical repair of uncomplicated hernias.

Aim

To compare the short- and long-term outcomes of incarcerated inguinal hernia repair using the Lichtenstein or Bassini technique.

Material and methods

Between 1997 and 2012, 107 patients were operated on an emergency basis due to the incarceration of inguinal hernias – 105 subjects were included for further analysis in our study.

Results

Postoperative complications were observed in 13 out of the 84 (15.5%) patients subjected to Lichtenstein repair. In 9 of these patients (10.7%), morbidity was associated with the surgical wound. In 2 cases (2.4%), a small inflammatory infiltration was observed and resolved within a few days. Serous fluid accumulation within the wound was observed in 3 patients (3.6%), but the fluid was successfully drained by puncture. Finally, hematoma formed in 4 cases (4.8%). In total, 4 complications (19%) were recorded in the group of 21 patients who were operated on with the Bassini technique. In 3 of these cases (14.3%), the complications were related to suppuration of the surgical wound.

Conclusions

Polypropylene mesh may be safely implanted during the repair of incarcerated hernia and this approach is reflected by satisfactory long-term outcomes.

Repair of the inguinal hernia using the hernia sac to correct the abdominal wall defect

Surgery of the inguinal hernia is a challenge for the great incidence of recurrences. The aim of this study is demonstrate the usefulness of hernia sac in the repair of inguinal hernia. In 200 patients the hernia sac was used to reinforce the abdominal wall. The patients have been observed two years along and still now few recurrences (20%) have been observed. The hernia sac can be used to repair the inguinal hernia because it's a patient's tissue with no inflammation and rejection.

Preoperative risk reduction: strategies to optimize outcomes

The success of hernia repair is measured by absence of recurrence, appearance of the surgical scar, and perioperative morbidity. Perioperative surgical site occurrence (SSO), defined as infection, seroma, wound ischemia, and dehiscence, increases the risk of recurrent hernia by at least 3-fold. The surgeon should optimize all measures that promote healing, reduce infection, and enhance early postoperative recovery. In the population with ventral hernia, the most common complication in the immediate perioperative period is surgical site infection. This article reviews several preoperative measures that have been reported to decrease SSOs and shorten length of hospital stay.

Comparison of infectious complications with synthetic mesh in ventral hernia repair

BACKGROUND

Infection can be a devastating complication associated with prosthetic incisional hernia repair. It is unclear whether the type of mesh used affects the risk of infection.

METHODS

A retrospective review was performed of all patients who underwent elective incisional hernia repair with permanent prosthetic mesh between January 1, 2000, and August 1, 2007.

RESULTS

A total of 176 patients underwent elective incisional hernia repair with mesh. The overall infection rate with the use of goretex (Flagstaff, AZ, USA) was 12 of 86 (14%) and 2 of 90 (2.2%) in cases in which nongoretex material was used (P = .016). In the goretex group, infection rates were significantly higher in open versus laparoscopic cases (26.5% vs 5.8%, P = .030). Methicillin-resistant Staphylococcus aureus was the most common organism recovered.

CONCLUSIONS

The risk of mesh infection with the use of goretex was found to be higher than with the use of nongoretex mesh. Laparoscopic placement of goretex reduces this risk of infection. No significant differences in recurrence rates were found.

Multilayer, degradable coating as a carrier for the sustained release of antibiotics: preparation and antimicrobial efficacy in vitro

One of the most critical post-surgical complications is mesh-related infection. This paper describes how a commercially available polypropylene (PP) mesh was modified to minimize the risk of post-implantation infection. A dual drug-release coating was created around mesh filaments using an airbrush spray system. This coating was composed of three layers containing ofloxacin and rifampicin dispersed in a degradable polymer reservoir made up of [poly(ε-caprolactone) (PCL) and poly(DL-lactic acid) (PLA)]. Drug release kinetics were managed by varying the structure of the degradable polymer and the multilayer coating. In vitro, this new drug delivery polymer system was seen to be more rapidly invaded by fibroblasts than was the initial PP mesh. Active mesh showed excellent antibacterial properties with regard to microorganism adhesion, biofilm formation and the periprosthetic inhibition of bacterial growth. Sustained release of the two antibiotics from the coated mesh prevented mesh contamination for at least 72 h. This triple-layer coating technology is potentially of great interest for it can be easily extrapolated to other medical devices and drug combinations for the prevention or treatment of other diseases.

Infections associated with prosthetic repairs of abdominal wall hernias: pathology, management and results

PURPOSE

To analyse clinical and demographic factors of patients who suffered infection of the surgical site requiring mesh removal as a complication of prosthetic repairs, details of the hernioplasties in which meshes were implanted and their management and outcomes.

METHODS

Factors related to infection (demographic variables and characteristics of the repairs and mesh utilised) and the management before proceeding to mesh removal were obtained from patient charts. Collected specimens (meshes and tissues) from 32 consecutive patients were cultured and observed microscopically. The outcomes after mesh removal were prospectively evaluated.

RESULTS

Twenty-two patients underwent incisional hernioplasties and ten inguinal hernioplasties; most of the procedures took a long time, and 28 patients presented early wound complications (seroma or haematoma). During the “implantation–removal” interval, some conservative treatments, such as drainages or sinus resection, were attempted under local anaesthesia. Twenty-two meshes were totally removed (nine after partial extraction); in the remaining ten cases partially removal was successful. Most of the meshes (24) were made of multi-filament polypropylene; microscopic observation of neighbouring tissues showed leucocyte infiltration, giant cell reaction, disorganisation of the collagen fibres and abscedation. Treatment of 32 patients required 51 operations. Following mesh removal, there were six recurrences and two fistulas of the bowel. The average follow-up was 40 months (30–97).

CONCLUSIONS

Most of the infections requiring mesh removal were related to prolonged repair operations that presented untreated early postoperative wound complications. Partial extraction of meshes frequently leads to failures and complications. Surgical exploration should be performed under general anaesthesia to accomplish complete mesh extraction.

Abdominal ventral hernia repair with current biological prostheses: an experimental large animal model

Biologic prostheses have emerged to address the limitations of synthetic materials for ventral hernia repairs; however, they lack experimental comparative data. Fifteen swine were randomly assigned to 1 of 3 bioprosthetic groups (DermaMatrix, AlloDerm, and Permacol) after creation of a full thickness ventral fascial defect. At 15 weeks, host incorporation, hernia recurrence, adhesion formation, neovascularization, inflammation, and biomechanical properties were assessed. No animals had hernia recurrence or eventration. DermaMatrix and Alloderm implants demonstrated more adhesions, greater inflammatory infiltration, and more longitudinal laxity, but near identical neovascularization and tensile strength to Permacol. We found that porcine acellular dermal products (Permacol) contain following essential properties of an ideal ventral hernia repair material: low inflammation, less elastin and stretch, lower adhesion rates and cost, and more contracture. The addition of lower cost xenogeneic acellular dermal products to the repertoire of available acellular dermal products demonstrates promise, but requires long-term clinical studies to verify advantages and efficacy.

Mesh infection in ventral incisional hernia repair: incidence, contributing factors, and treatment

BACKGROUND

Prosthetic mesh infection is a catastrophic complication of ventral incisional hernia (VIH) repair.

METHODS

The current surgical literature was reviewed to determine the incidence, microbiology, risk factors, and treatment of mesh infections.

RESULTS

Mesh infections tend to present late. Diagnosis depends on high clinical suspicion and relies on culture of the fluid surrounding the mesh or of the mesh itself. Risk factors may include a high body mass index (obesity); chronic obstructive pulmonary disease; abdominal aortic aneurysm repair; prior surgical site infection; use of larger, microporous, or expanded polytetrafluoroethylene mesh; performance of other procedures via the same incision at the time of repair; longer operative time; lack of tissue coverage of the mesh; enterotomy; and enterocutaneous fistula. The best treatment is prevention. Treatment of mesh infection is evolving on a case-by-case basis from explantation toward mesh salvage, to prevent complications such as hernia recurrence.

CONCLUSION

Higher-quality reporting on mesh infection in VIH repair must be achieved through better classification and quantification of these infections. Tactics to avoid mesh infection should be based on best evidence and high-quality prospective trials and observational studies.

Antibacterial mesh: a novel technique involving naturally occurring cellular proteins

BACKGROUND

Naturally occurring antimicrobial peptides are possibly the "next frontier" in infection prevention. Binding them to mesh could reduce the rate of mesh infections. This study identifies an antimicrobial agent capable of significant antibacterial activity when bound to mesh.

METHODS

Lysozyme, human beta defensin (HBD-3), human cathelicidin (LL-37), and lysostaphin were adsorbed to polypropylene mesh at various concentrations. Treated meshes were placed in a suspension of 1 × 10(6) Staphylococcus aureus. Antibacterial action was monitored by turbidimetric assay, fluorescent imaging, and a colony counting method.

RESULTS

A very high rate of lysis of S aureus cells was observed in the lysostaphin-treated group as measured by optical density; none survived as seen on colony count assays. Optical density for mesh coated with lysozyme, HBD-3, and LL-37 did not differ from untreated controls, with 100% survival rates by colony counts.

CONCLUSION

Lysostaphin had superior antibacterial activity following adsorption to mesh.

["Onlay" mesh provides significantly better results than "sublay" reconstruction. Prospective randomized multicenter study of abdominal wall reconstruction with sutures only, or with surgical mesh--results of a five-years follow-up]

BACKGROUND

There are several well-known procedures to treat abdominal wall hernias, but the results are quite controversial. The aim of study was to compare the results of different surgical modalities - mesh (onlay vs. sublay position) and suture repair - in the treatment of abdominal wall hernias.

METHODS

A five-year randomized, multicentric, internet-based, clinical trial was started in 2002. 953 patients were included in the study and divided into two groups according to the size of hernia orifice. In group 'A' ( n = 494) the surface of hernia orifice was between 5-25 cm 2 (small hernia), and in group 'B' ( n = 459) it was above 25 cm 2 (large hernia). Patients of these two groups were randomized according to surgery: group 'A' (suture vs. mesh) and in group 'B' (mesh in onlay vs. sublay position). In group 'A' suture repair was performed in 247, and sublay mesh implantation in 247 cases. In group 'B' sublay ( n = 235) and onlay ( n = 224) mesh reconstruction was performed. The patients were followed-up for five years.

RESULTS

734 patients - 77% of all randomized cases - have completed the study. In the small hernia group significantly ( p < 0.001) higher recurrences occurred after suture repair ( n = 50-27%) than in mesh repair ( n = 15-8%). In the large hernia group onlay mesh reconstruction provided significantly better ( p < 0.05) results than sublay reconstruction, recurrence rate was much lower in onlay group [ n = 22 (12%) vs. n = 38 (20%)].

CONCLUSION

Mesh repair provides better results than suture repair. In case of large hernias the recurrence rate is higher after sublay reconstruction. The randomized trial was registered on <a href="http://www.ClinicalTrials.gov">www.ClinicalTrials.gov</a> - ID number: NCT01018524.

Novel in vitro model for assessing susceptibility of synthetic hernia repair meshes to Staphylococcus aureus infection using green fluorescent protein-labeled bacteria and modern imaging techniques

BACKGROUND

Mesh infection complicating hernia repair is a major cause of patient morbidity and results in substantial healthcare expenditures. The various constructs of prosthetic mesh may alter the ability of bacteria to attach and form a biofilm. Few data exist evaluating biofilm formation. Using the Maestro in-Vivo Imaging System (CRi, Inc., Woburn, MA) to detect green fluorescent protein (GFP)-expressing Staphylococcus aureus, we studied the ability of synthetic mesh to withstand bacterial biofilm formation in an in vitro model.

METHODS

We included four meshes: Polypropylene (PP), polypropylene/expanded PTFE (PX), compressed PTFE (cPTFE), and polyester/polyethylene glycol and collagen hydrogel (PE). Five samples of each mesh were exposed to GFP-expressing S. aureus for 18 h at 37°C. Next, green fluorescence was measured using the Maestro Imaging System, with the results expressed in relative fluorescence units (RFU), subtracting the fluorescence of uninfected mesh (control). Each mesh subsequently underwent sonication and quantitative culture of the released bacteria, with the results expressed in colony-forming units (CFU). Analysis of variance was performed to compare the mean values for the different meshes.

RESULTS

There was a statistically significant difference in bacterial fluorescence for the four meshes: PE (49.9 ± 25.5 [standard deviation] RFU), PX (30.8 ± 9.4 RFU), cPTFE (10.1 ± 4.0 RFU), and PP (5.8 ± 7.5 RFU)(p = 0.001). Bacterial counts also were significantly different: PE (2.2 × 10(8) CFU), PX (8.6 × 10(7) CFU), cPTFE (3.7 × 10(7) CFU), and PP (9.1 × 10(7) CFU)(p < 0.001).

CONCLUSION

Using novel imaging technology, this study documented significantly different amounts of S. aureus biofilm formation and proliferation on different mesh constructs, with good agreement between imaging and culture results. A multifilament woven mesh (PE) had the highest degree of biofilm formation. These findings are being evaluated in a clinical infection model.

Open onlay mesh repair for major abdominal wall hernias with selective use of components separation and fibrin sealant

BACKGROUND

The objective of the study was to reassess the efficacy of the open onlay technique for repair of major incisional hernias, utilizing the modern adjuncts of components separation and fibrin sealant to reduce the principal complications of seroma and recurrence. Major incisional hernias were defined as >10 cm transverse diameter.

METHODS

A prospective audit was applied to 116 patients undergoing open onlay incisional hernia repair during a 2-year period at a single institution. Information was collected concerning operative details, postoperative complications, and recurrence. Clinical review at a median 15.2 months postoperatively was followed by a telephoned structured questionnaire to assess quality of life. All patients with pain or suspected recurrence were recalled for examination.

RESULTS

Fascial closure required components separation in 21 (18.1%) patients when tension-free fascia reconstruction was not possible, and fibrin sealant was applied in 22 (18.9%) in whom extensive skin flaps were dissected beyond the semilunar line. Postoperatively, there were 11 (9.5%) seromas and 2 (1.7%) deep wound infections. At 15.2 months' follow-up there were 4 (3.4%) recurrences.

CONCLUSIONS

Open onlay mesh repair for major incisional hernias is a versatile operation applicable to all quadrants of the abdominal wall and gives excellent results when used in association with components separation and fibrin sealant.

Prolene-Monocryl-composite meshes do not increase microvascular Staphylococcus aureus adherence and do not sensitize for leukocytic inflammation

BACKGROUND AND AIMS

Mesh implantation for hernia repair bears the risk of bacterial mesh infection. In this study, we analyzed whether this complication is supported by an increased interaction of bacteria and leukocytes with the microvascular endothelium at the implantation site.

MATERIALS AND METHODS

Ultrapro meshes were implanted into the dorsal skinfold chamber of Syrian golden hamsters. After 12 days, fluorescein isothiocyanate (FITC)-labeled staphylococci were injected in the animals. Subsequently, we analyzed bacterial adherence, leukocyte-endothelial cell interaction, and microhemodynamics in venules of the mesh border zone and of distant control tissue under baseline conditions and during TNF-alpha-induced inflammation using intravital fluorescence microscopy. The results were compared to animals which did not receive any bacteria.

RESULTS

Under baseline conditions, leukocyte-endothelial cell interaction and bacterial adherence were not affected by the implanted biomaterial. TNF-alpha-induced inflammation significantly increased numbers of adherent leukocytes and bacteria in venules located in direct vicinity to the mesh however without any differences to control tissue. Comparable results were found for the leukocyte-endothelial cell interaction when animals were not exposed to bacteria.

CONCLUSION

Implanted Ultrapro meshes do neither increase microvascular Staphylococcus aureus adherence nor sensitize for leukocytic inflammation. Thus, we suggest that a mesh-induced increase of bacterial adherence in vessels of the implantation site cannot be considered as a primary cause for the development of mesh infection.

Experimental evaluation of four biologic prostheses for ventral hernia repair

PURPOSE

To evaluate two bioprostheses derived from bovine pericardium, one cross-linked (Peri-Guard) and the other non-cross-linked (Veritas), and to compare them with Alloderm and Permacol for abdominal wall repair.

METHODS

The four prostheses were tested in acute and chronic hernia models. Prostheses were either sutured to the edge of the abdominal wall defect (inlay) or secured as an underlay with surgical tacks. Evaluation at 3 and 6 months included adhesion formation, defect area size and thickness, tensile strength, and histology.

RESULTS

Mean adhesion coverage area ranged from 25 to 31%. The two cross-linked materials, Permacol and Peri-Guard, showed greater tensile strength. Significant defect contraction followed repair with Veritas, whereas Alloderm stretched. All prostheses had cellular ingrowth and neovascularization by 3 months. No significant differences were found in prosthesis to abdominal wall breaking strength. Operative site infection occurred in six animals (5 Peri-Guard, 1 Veritas), and overlying skin ulceration in six others (6 Peri-Guard).

CONCLUSIONS

Permacol provided a strong and durable repair for up to six months. Peri-Guard was equally strong but prone to infection and to skin ulceration. With time, Veritas and Alloderm lost tensile strength associated with marked thinning and with hernia-like bulging in the case of Alloderm.

Management of Infections of Polytetrafluoroethylene-Based Mesh

BACKGROUND

Mandatory removal of infected expanded polytetrafluoroethylene (ePTFE) mesh has been advocated, leading to a high rate of hernia recurrence. Although salvage of infected mesh has been reported, the feasibility, efficacy, and long-term outcomes of this practice remain unclear. The purpose of this study was to delineate a protocol for salvaging infected ePTFE mesh.

METHODS

We reviewed retrospectively the records of patients with infections of ePTFE-based mesh placed for complex abdominal hernias at a tertiary referral center from October 1997 to September 2005.

RESULTS

Twenty-two patients were treated for ePTFE-based mesh infections. Fifteen patients had undergone laparoscopic repair, and seven patients had undergone open repair. The median time of presentation after repair was 70 days (range 10-480 days). Fourteen patients had an extensive mesh infection and underwent mesh excision, with twelve patients having attempted fascial closure; hernias recurred in all twelve patients. Two patients underwent mesh excision and repair with a biologic mesh. Eight patients had a limited area of mesh involvement; six of these patients underwent surgical debridement, partial excision of the mesh, re-approximation of the remaining mesh with non-absorbable suture and drains, and application of a vacuum-assisted closure system to the open portion of the wound. These patients received four weeks of antibiotics with delayed wound closure. Two patients underwent percutaneous drainage of a perigraft abscess. There was no hernia recurrence in seven patients with a mean follow-up of approximately three years.

CONCLUSIONS

Infections of ePTFE-based mesh can present in early or delayed fashion. Although mesh with extensive infection could not be salvaged, limited mesh infections could be managed successfully with percutaneous or open drainage and prolonged antibiotic courses.

The analysis of infection after polypropylene mesh repair of abdominal wall hernia

AIM

The aim of the study was to evaluate the frequency of superficial and prosthetic mesh infection following polypropylene mesh repair of different abdominal wall hernia in individual patients and to analyze the manifestation, clinical process and outcomes in patients with prosthetic mesh infection.

METHODS

This was a retrospective analysis of 375 patients with 423 implanted meshes for groin, femoral, umbilical, incisional and epigastric hernias, with a mean follow-up of 15 months (range: 3-73 months).

RESULTS

The total superficial infection rate was 1.65%, and the rate of mesh infection was 0.94%. There were no statistically significant differences in prosthetic mesh infection between monofilament and multifilament meshes as well as between the different repair groups of hernias. The deep incisional surgical site infection after previous operation was established as a significant risk factor for prosthetic mesh infection in incisional hernia repair (P < 0.0001). Five cases of prosthetic mesh infection were presented and analyzed.

CONCLUSIONS

There is no correlation between the superficial and prosthetic mesh infection. There may be difficulties in determining mesh infection and to choose the right tactic. The reconvalescence in all patients with mesh infection was achieved only after removal of the infected mesh.

Is the Lichtenstein Operation of Strangulated Groin Hernia a Safe Procedure?

BACKGROUND

In spite of many published articles describing the hernia repairs, there are only a few original reports concerning the polymer mesh application during emergency procedures for strangulated inguinal hernias. The aim of our study was to evaluate the results of the Lichtenstein and Bassini operations for strangulated groin hernias and to show the changing number of the tension-free repairs.

METHODS

From 1997 to 2004, the Bassini procedure was performed in 21 patients, 6 of whom underwent small intestine resection and 2 others required resection of the necrotic omentum. The strangulated intestinal loop or omentum were released in 13 cases. After the repair 1 patient died of shock caused by intestinal necrosis. Of 56 patients who underwent an emergency Lichtenstein procedure, 55 were followed-up. A small intestine resection was performed in 2 cases to correct segmental necrosis. The gangrenous omental appendix of the sigmoid colon was excised in 1 patient, and necrotic omental fragments were resected in 2 cases. The strangulated intestinal loop or omentum was released in 51 patients. All patients were given wide-spectrum antibiotics intravenously.

RESULTS

Between 1997 and 2000 tension-free procedures were performed in half of the patients undergoing emergency operation for strangulated hernia; between 2001 and 2004 such procedures were employed in more than 90% of the cases. In 2 patients we observed a small inflammatory infiltration of the wound that resolved within several days after Lichtenstein repair. A serous fluid collection was present in 2 cases. The treatment consisted of puncture and was successful in both cases.

CONCLUSIONS

The use of monofilament polypropylene mesh for strangulated inguinal hernia repair is safe, and the risk of the local infectious complications is low.

The management of incisional hernia

Many thousand laparotomy incisions are created each year and the failure rate for closure of these abdominal wounds is between 10-15%, creating a large problem of incisional hernia. In the past many of these hernias have been neglected and treated with abdominal trusses or inadequately managed with high failure rates. The introduction of mesh has not had a significant impact because surgeons are not aware of modern effective techniques which may be used to reconstruct defects of the abdominal wall. This review will cover recent advances in incisional hernia surgery which affect the general surgeon, and also briefly review advanced techniques employed by specialist surgeons in anterior abdominal wall surgery.

In vitro infectability of prosthetic mesh by methicillin-resistant Staphylococcus aureus

Although mesh use is important for effective herniorrhaphy in adults, prosthetic infections can cause serious morbidity. Bacterial adherence to the mesh is a known precursor to prosthetic infection. We compared the ability of common mesh prosthetics to resist bacterial adherence. The meshes studied included polypropylene (Marlex, expanded polytetrafluoroethylene (PTFE) with and without silver chlorhexidine coating (DualMesh Plus and Dualmesh) composite meshes (Composix E/X, Proceed, and Parietex Composite) and lightweight polypropylene meshes (TiMesh, Ultrapro, and Vypro). Fifteen samples of each mesh type were individually inoculated with a suspension of 10(8 )methicillin-resistant Staphylococcus aureus (MRSA) in tryptic soy broth. After incubation at 37 degrees C for 1 h, the mesh pieces were then removed and serially washed. The colony-forming units (CFU) of MRSA present in the initial inoculum, at the end of the 1-h warm-water bath (broth count), and the pooled washes (wash count), were determined using serial dilutions and spot plating. The bacteria not accounted for in the broth or wash counts were considered adhered to the mesh. Samples of each mesh type were also analyzed using scanning electron microscopy (SEM). Data are presented as the mean percentage adherence with ANOVA and Tukey's test used to determine significance (P<0.05). The DualMesh Plus mesh had no detectable MRSA in the broth or the pooled wash samples. Dualmesh had less adherence compared with Marlex, Proceed, and Vypro (P<0.05). Conversely, Vypro had a statistically higher adherence (96%, P<0.05) as compared to TiMesh, Ultrapro, Composix E/X, and Parietex Composite. SEM confirmed bacterial adherence to all the mesh types except DualMesh Plus. The ability of a biomaterial to resist infection has an important clinical significance. DualMesh Plus, due to its antimicrobial coating, is the only mesh type of the nine tested that demonstrated a bactericidal property. Standard PTFE (Dualmesh) also had less bacterial adherence. Vypro demonstrated an increase in bacterial adherence; this was possibly due to the multifilament polyglactin 910 weaved within the prolene component of the mesh.