Antibiotic prophylaxis in incisional hernia repair using a prosthesis

Systematic review and meta-analysis of the effectiveness of antibiotic prophylaxis in prevention of wound infection after mesh repair of abdominal wall hernia

BACKGROUND

The aim was to determine whether systemic antibiotic prophylaxis prevented wound infection after repair of abdominal wall hernia with mesh.

METHODS

This was a systematic review of the available literature identified from multiple databases using the terms 'hernia' and 'antibiotic prophylaxis'. Randomized placebo-controlled trials of antibiotic prophylaxis in abdominal wall mesh hernia repair with explicitly defined wound infection criteria and a minimum follow-up of 1 month were included. After independent quality assessment and data extraction, data were pooled for meta-analysis using a random-effects model.

RESULTS

The search process identified eight relevant trials. Two papers on umbilical, incisional or laparoscopic hernias, and six concerning inguinal and femoral (groin) hernias were suitable for meta-analysis. The incidence of infection after groin hernia repair was 38 (3.0 per cent) of 1277 in the placebo group and 18 (1.5 per cent) of 1230 in the antibiotic group. Antibiotic prophylaxis did not significantly reduce the incidence of infection: odds ratio 0.54 (95 per cent confidence interval 0.24 to 1.21); number needed to treat was 74. The number of deep infections was six (0.6 per cent) in the placebo group and three (0.3 per cent) in the antibiotic prophylaxis group: odds ratio 0.50 (95 per cent c.i. 0.12 to 2.09).

CONCLUSION

Antibiotic prophylaxis did not prevent the occurrence of wound infection after groin hernia surgery. More trials are needed for complete evidence in other areas of abdominal wall hernia.

Predictors of wound infection in ventral hernia repair

BACKGROUND

Postoperative wound infection is a significant risk factor for recurrence after ventral hernia repair (VHR). The current study examines patient- and procedure-specific variables associated with wound infection.

METHODS

A cohort of subjects undergoing VHR from 13 regional Veterans Health Administration (VHA) sites was identified. Patient-specific risk variables were obtained from National Surgical Quality Improvement Program (NSQIP) data. Operative variables were obtained from physician-abstracted operative notes. Univariate and multivariable logistic regression analysis was used to model predictors of postoperative wound infection.

RESULTS

A total of 1505 VHR cases were used for analysis; wound infection occurred in 5% (n = 74). Best-fit logistic regression models demonstrated that steroid use, smoking, prolonged operative time, and use of absorbable mesh, acting as a surrogate marker for a more complex procedure, were significant independent predictors of wound infection.

CONCLUSION

Permanent mesh placement was not associated with postoperative wound infection. Smoking was the only modifiable risk factor and preoperative smoking cessation may improve surgical outcomes in VHR.

Influence of polyglecaprone 25 (Monocryl) supplementation on the biocompatibility of a polypropylene mesh for hernia repair

BACKGROUND

Supplementary polyglecaprone 25 (Monocryl) monofilaments were added to a lightweight pure monofilament polypropylene mesh (PP mesh) to improve intraoperative handling (PP+M mesh). This study was designed to evaluate the influence of this additional supplementation on the biocompatibility in a rodent animal model.

METHODS

Two mesh materials, a composite mesh (PP+M) and the pure polypropylene variant (PP), were compared after subcutaneous implantation in a standardized rat model. Histological analysis of the inflammatory response was performed after 28, 56 and 84 days of implantation. Material absorption, inflammatory tissue reaction, fibrosis and granuloma formation were investigated, as well as the percentage of proliferating and apoptotic cells at the interface.

RESULTS

Both mesh materials showed a slight foreign body reaction involving mainly macrophages and foreign body giant cells. Total absorption of the Monocryl filaments of the PP+M mesh occurred between 56 and 84 days of implantation. Both the inflammatory and the fibrotic reaction were decreased (n.s.) in the PP+M mesh group compared to the pure PP mesh. Whereas the percentage of proliferating cells showed no significant difference, the rate of apoptotic cells was significantly decreased in the PP+M mesh group over the whole implantation period.

CONCLUSION

Compared to the pure polypropylene mesh, our data confirm that the use of a polypropylene mesh supplemented with absorbable Monocryl filaments is feasible without additional short-term mesh-related complications in the experimental model or negative side effects on biocompatibility.

Gentamicin supplementation of polyvinylidenfluoride mesh materials for infection prophylaxis

Hernia repair evolved from pure tissue repair to mesh repair due to decreased recurrence rates. However, concern exists about mesh-related infections occurring even several years after initial operation. Therefore, a polyvinylidenfluoride (PVDF) mesh material was constructed and surface modified by plasma-induced graft polymerization of acrylic acid (PVDF+PAAc). Antimicrobial treatment was sought by binding of gentamicin (PVDF+PAAc+Gentamicin). In vitro efficacy and cytotoxicity was measured by agar diffusion test, L929 cytotoxicity testing and by analyzing the amount of gentamicin release from the mesh surface. In vivo biocompatibility was evaluated in 45 Sprague-Dawley rats. 7, 21 and 90 days after mesh implantation the amount of inflammatory and connective tissue as well as the percentage of proliferating (Ki67) and apoptotic cells (TUNEL) were analyzed at the perifilamentary region. Agar diffusion tests showed sufficient local antimicrobiotic effects against the bacteria tested after 24h of incubation. No signs of cytotoxicity could be identified by L929 testing. Furthermore, surface modification did not affect the in vivo biocompatibility. At the end of the observation period, no significant differences were found for the perifilamentary amount of inflammatory cells and connective tissue and the percentage of Ki67 and TUNEL positive stained cells. The presented data confirm that an antibiotic surface modification of PVDF mesh samples is feasible. By analyzing cytotoxicity in vitro as well as biocompatibility in vivo no side effects were observed.

The susceptibility of prosthetic biomaterials to infection

BACKGROUND

Despite the use of a sterile technique and the administration of prophylactic antibiotics during surgical procedures, mesh infection continues to complicate the use of biomaterials. The purpose of this study was to compare the susceptibility to infection of prosthetic biomaterials in a live-animal model.

METHODS

The following seven prosthetic mesh biomaterials were used in this study. Expanded polytetrafluoroethylene (ePTFE) with silver/chlorhexidine (DM+), ePTFE (DM), porcine intestinal submucosa (S), polypropylene (M), ePTFE/polypropylene (X), hyaluronate/carboxymethylcellulose/polypropylene (SM), and human acellular dermal matrix (A). Lewis rats (n = 108) underwent creation of a single ventral hernia; 105 of them were repaired with a different mesh (2-cm2 piece). Twelve pieces of each mesh were inoculated at the time of hernia repair with 10(8) Staphylococcus aureus (n = 84). Three pieces of each mesh were placed without bacterial inoculation (n = 21). In three animals, no mesh was placed; instead, the peritoneum of the hernia defect was inoculated (n = 3). After 5 days, the animals were killed and the mesh was explanted (peritoneum for the nonmesh control). The mesh was vortex-washed and incubated in tryptic soy broth. Bacterial counts were determined using serial dilutions and spot plates and quantified in colony-forming units (CFU) per square centimeter of mesh present in the vortex wash fluid (wash count) and the soy broth (broth count). Data are presented as the mean log(10), with analysis of variance (ANOVA) and Tukey's test used to determine significance (p < 0.05).

RESULTS

The DM+ material had no detectable live bacteria in the wash or broth counts in 10 of 12 tested samples (p = 0.05). Of the samples that showed bacterial growth, the peritoneum control group had a lower wash count than A (p = 0.05) and the lowest broth count of all the materials except for DM+ (p = 0.05). In addition, SM had a significantly lower wash count than A (p = 0.05), with no broth count difference. In regard to wash and broth counts, DM, M, X, SM, S, and A were no different (p = NS).

CONCLUSIONS

The DM+ material was the least susceptible to infection. Impregnation with silver/chlorhexidine killed the inoculated bacteria, preventing their proliferation on the mesh surface. Other than DM+, native peritoneal tissue appears to be the least susceptible to infection. Silver/chlorhexidine appears to be an effective bactericidal agent for use with mesh biomaterials.

Prevention of adhesion formation to polypropylene mesh by collagen coating: a randomized controlled study in a rat model of ventral hernia repair

INTRODUCTION

In laparoscopic incisional hernia repair with intraperitoneal mesh, concern exists about the development of adhesions between bowel and mesh, predisposing to intestinal obstruction and enterocutaneous fistulas. The aim of this study was to assess whether the addition of a collagen coating on the visceral side of a polypropylene mesh can prevent adhesion formation to the mesh.

METHOD

In 58 rats, a defect in the muscular abdominal wall was created, and a mesh was fixed intraperitoneally to cover the defect. Rats were divided in two groups; polypropylene mesh (control group) and polypropylene mesh with collagen coating (Parieten mesh). Seven and 30 days postoperatively, adhesions and amount and strength of mesh incorporation were assessed. Wound healing was studied by microscopy.

RESULTS

With Parieten mesh, the mesh surface covered by adhesions was reduced after 30 days (42% vs 69%, p = 0.01), but infection rate was increased after both 7 (p = 0.001) and 30 days (p = 0.03), compared to the polypropylene group with no mesh infections. If animals with mesh infection were excluded in the analysis, the mesh surface covered by adhesions was reduced after 7 days (21% vs 76%, p = 0.02), as well as after 30 days (21 vs 69%, p < 0.001). Percentage of mesh incorporation was comparable in both groups. Mean tensile strength of mesh incorporation after 30 days was higher with Parieten mesh.

CONCLUSION

Although the coated Parieten mesh was more susceptible to mesh infection in the current model, a significant reduction of adhesion formation was still seen with the Parieten mesh after 30 days, with comparable mesh incorporation in the abdominal wall.

Simplified technique for incisional hernia repair with mesh prosthesis

This paper describes a simplified technique for the repair of incisional hernias. The previous scar is resected, and the peritoneal sac is carefully dissected until it is completely exposed. The sac is opened to liberate structures adherent to the sac or to the area immediately surrounding the defect. The peritoneum is closed and invaginated to form a sac bed underlying the entire extent of the defect, and the mesh is laid on this sac bed. The mesh is then fixed with "U" stitches, reinforcing these by inserting a second line from the edge of the defect to the mesh. Suture material used is polypropylene 1/0 or 2/0. This procedure has been carried out on 15 patients, and after 1 year of follow-up, there has been no recurrence of the hernia. Operating time was reduced, and the surgical technique was found to be easier. Placing a mesh prosthesis inside the hernia sac and fixing it to the abdominal wall with two lines of suturing simplifies the repair procedure, reduces operating time, and is effective in the repair of all incisional hernias. A study is required to compare this outcome with the different mesh repair techniques.