The management of mesh-site infection is challenging and requires an individualized approach combining medical and surgical approaches, as well as respecting well-established surgical principles. Superficial wound infections can be successfully managed without the removal of the mesh, however, this is controversial, and not all surgeons agree with this approach. Although, several studies have shown that in certain instances a conservative approach may be successful for salvaging a contaminated mesh [33–36], in most cases antibiotics and wound drainage are not sufficient to eradicate the infection [37, 38].

There are no recommendations on how long a conservative strategy should be continued. It has been suggested that polypropylene and polyester meshes can be treated conservatively in a higher proportion that a mesh-like ePTFE [39]. If conservative treatment fails, the complete surgical removal of the mesh is mandatory to reduce the risk of infection recurrence or severe complications , such as visceral adhesions that may lead to obstruction and fistulae. Clearly, this depends on where the mesh is placed. Assuming the mesh is placed intra-peritoneally, such as in case of laparoscopic hernia repair, salvaging such mesh without explanting it would be difficult, if not impossible. When there is large wound infection, where the mesh is “floating” in the pus, such mesh needs to be removed at once. A conservative surgical approach including abscess drainage, incomplete sinus excision, or partial mesh excision usually fail and may result in recurrent mesh infections.

The operative strategy, when it is possible, should always include the complete removal of the infected mesh and sinus tract tissues surrounding the mesh [39]. Patients who present with systemic symptoms and signs of wound infection should undergo prompt empiric antibiotic therapy and aggressive surgical debridement to remove infected tissue and the mesh. Infected material should be sent for culture and susceptibility test should be performed to define targeted antimicrobial therapy.

The most serious concern when one removes the infected mesh and surrounding tissue is the defect that is created. How to deal with this new defect, it is a difficult issue. The reconstruction of even simple abdominal wall defects after infected mesh is removed can be challenging. Worse, if there is a large defect created, this represents a real challenge for both surgeon and for the patient. When the defects are contaminated and large, a satisfactory functional reconstruction can be difficult to achieve. In a recent case (performed by RL) an indolent walled off abscess on the left lower chest wall, in a 48-year-old male, post-heart transplant involving 9, 10, 11 ribs that required partial resection of ribs, created a large defect. This was reconstructed using “sandwich” technique with underlay and onlay biological mesh.

While there are three options to deal with the situation after removing the contaminated mesh, the intra-operative options are [39] (a) removing the mesh and do not replace it with a new mesh; (b) re-implantating a new synthetic mesh; and (c) replacement of the infected synthetic with a biological mesh, we clearly do not suggest option b, although there is a literature to support such approach. We suggest native tissue coverage if at all possible. The two viable options are (a) and (c). While, most of us would agree that option (a) is the best, one has to understand that this approach can result in a very high recurrence rate and the second operation should be planned at a later time. This needs to be communicated clearly to the patient.

The basic principle is source control, that is to remove the infected mesh. We suggest that such wounds are treated with negative pressure wound therapy, until is closed completely. If and when so much abdominal wall is resected, that we are unable to reconstruct the wall using native tissue, this becomes more challenging, and advanced surgical procedures such as tissue transfer may be required. Without a functional abdominal wall, the patient has a hernia by definition and requires a second surgical intervention to repair the abdominal wall defect as a planned abdominal reconstruction [40]. It is not clear, when repair of such hernia should take place, however, we suggest individualization of care for each patient. In rare cases, especially in groin region, the removal of the infected mesh may not result in recurrent herniation if sufficient fibrous scarring remains [41].

The second option (or option b above) is to replace the infected polypropylene mesh with a new polypropylene mesh. A retrospective study of short- and long-term results of patients undergoing removal of infected mesh and reconstruction of the abdominal wall with synthetic simultaneous mesh replacement was published in 2015 by Birolini et al. [42]. Simultaneous mesh replacement by standard polypropylene mesh as an onlay graft prevented hernia recurrence and had an acceptable incidence of postoperative acute infection. The study reviewed 41 patients undergoing removal of an infected or exposed mesh and single-staged reconstruction of the abdominal wall with synthetic mesh replacement over a 16-year period retrospectively. The short-term results showed an uneventful postoperative course after mesh replacement in 27 patients; 6 (14.6%) patients developed a minor wound infection and were treated with dressings and antibiotics; 5 (12%) patients had wound infections requiring debridement and one required complete mesh removal. On the long-term follow-up, there were three hernia recurrences, one of which demanded a reoperation for enterocutaneous fistula; 95% of the patients submitted to mesh replacement were considered cured of mesh infection after a mean follow-up of 74 months [42].

The third option (option c above) is to replace the explanted synthetic mesh with a biological mesh [13, 43, 44]. In fact, due to the several limitations of non-absorbable synthetic meshes in infected fields, the use of biological scaffolds has started to be explored in abdominal wall reconstruction [45]. Biological prosthesis (BP) are allogenic or xenogenic collagen mesh. They could be cross-linked or not and for this reason they respectively result to be completely or partially remodeling. The differences in remodeling times should be kept in mind in choosing the kind of materials. BP permit and encourage host tissue ingrowth. The partially remodeling prostheses are also optimal for resisting mechanical stress [44]. They are physically modified with cross-linkages between the collagen fibers to increase the strength of the prosthesis. This process stabilizes the implant by preventing its degradation by human or bacterial collagenase [46, 47].

BP have completely changed the way to face the infected prosthesis dilemma. Their advent introduced the tissue engineering in surgical practice [48, 49]. The implantation leads to new healthy tissue deposition and prosthesis remodeling. It also allows pro-/anti-inflammatory factors, and drugs to reach the infected surgical field during the first phases of healing process. This enhances the effect against contamination/infection [50]. Another factor that should be kept into account in choosing which kind of BP to use is the demonstration that non-cross-linked material exhibits more favorable remodeling characteristics [51]. This has a great importance when BP are used as bridge to cover tissue loss. Discordant data have been published about the use of BP to bridge wide defect. In 2013 a critical review in Medline database to specifically identify review articles relating to biologic mesh in contaminated field was published supported biologic mesh use, in the setting of contaminated fields, but these reviews are limited to case series and case reports with low levels of evidence [52, 53].

To better guide surgeons, prospective, randomized trials should be undertaken to evaluate the short- and long-term outcomes associated with biological meshes under the various surgical wound classifications [53]. The Italian Biological Prosthesis Work Group (IBPWG) proposed a decisional model in the use of BP to facilitate the choice between the different types of BP [50].

The aforementioned decisional model suggests that the decision about which prosthesis utilize should always be a dynamic process mediated by the surgeon decisional capability. The principal variables to keep in mind in deciding the kind of BP to use are infection grade and loss of tissue size.

Infection is divided into three possible grade: (1): potentially contaminated; (2): contaminated; (3): infected. The same three step division is adopted for the tissue loss: (1): no tissue loss; (2): 0–5 cm defect; (3): >5 cm defect. By combining together these variables (multiplication) could be obtained a score which suggest the necessity to use either a cross-linked or a non-cross-linked BP.

When the fascia cannot be primarily re-approximated, rather than bridging a defect with mesh alone and covering this repair with subcutaneous tissue and skin, lateral components separation technique allows for primary fascial closure [13] (Chap. 7). It is unclear the most optimal time of performing the lateral component separation . Often, however, large and complex hernia has been already reconstructed with a combination of mesh placement and component separation. This complicates things more. We suggest, however, that even in cases that some sort of component release has been performed, that you revisit during next definitive reconstruction.

Mesh infection is a great challenge for surgeons and most serious complication for the patient that may have significant consequences. Although mesh is uncommon, mesh infections in most cases require the removal of infected meshes resulting in additional surgery, morbidity, and cost.

The pathogenesis of mesh infection is a complex process involving more factors including bacterial virulence, surface physicochemical properties of prosthesis, and alterations in host defense mechanisms. Mesh infections should be distinguished from superficial incisional surgical site infections (SSIs). SSIs occur in the early postoperative period and are not influenced by mesh implantation. Yet, this is not an easy diagnosis to be made. Frequently, deep mesh infections are indolent and present chronic signs and symptoms. They may be initially underestimated. Typically, patients present with sinus formation. The diagnosis of chronic mesh infection should be based on its clinical presentation. Radiological techniques including ultrasound, computerized tomography, and scintigraphy may be useful for diagnosis in uncertain cases.Treatment of mesh infection should be considered on a case-by-case basis. Although a conservative approach may be attempted, it is well known that the fundamental principle for approaching this problem is to remove the mesh completely and when indicated to replace it. After removing the contaminated mesh, the intra-operative options are: (a) no implant of a new mesh; (b) re-implantation of a new synthetic mesh, and (c) replacement of the infected synthetic with a biological mesh. Although biological meshes are higher in cost than synthetic meshes and the long-term durability may be less favorable, they can confer protective factors such as resistance to infection and high biocompatibility when implanted.