Negative Pressure Wound Therapy to Treat Peri-prosthetic Methicillin-Resistant Staphylococcus aureus Infection after Incisional Herniorrhaphy: A Case Study and Literature Review
Incisional hernias frequently occur after laparotomy. Recurrence rates after primary repair range from 31% to 54%. Repairing the hernia with prosthetic mesh has lowered these recurrence rates to 2% to 10%,1 making this the treatment of choice. However, infection of the prosthetic mesh can be a great challenge to the surgeon, especially in the case of methicillin-resistant Staphylococcus aureus (MRSA) infection. The MRSA-infected patient must be isolated and special care taken to prevent the spread of infection to other patients.2 Prosthetic mesh infection rates of up to 8% have been reported; in some cases, they can be treated only by removing the prosthetic mesh.1,3 Mesh removal often leads to a new incisional hernia.
A patient with a severe MRSA-infected prosthetic mesh after incisional hernia repair was treated with negative pressure wound therapy (NPWT) and secondary closure. The successful outcomes and a review of the literature underscore the need to consider NPWT in similar wound management scenarios.
Seventy-two-year-old Mr. K presented to the authors’ hospital with a large incisional hernia 6 months’ post surgery in Indonesia for an incarcerated umbilical hernia. His medical history was unremarkable for comorbidities and medication. He was a non-smoker and 6 months’ prior had been admitted with a diagnosis of bowel necrosis. His surgery had involved a partial jejunal resection with a primary anastomosis. Mr. K’s postoperative period was complicated by staphylococcal sepsis, which resulted in multi-organ failure that was successfully treated in the intensive care unit. Two months after his surgery (4 months before his current presentation), Mr. K was treated for pneumonia at the authors’ hospital.
When Mr. K experienced abdominal discomfort and pain caused by the incisional hernia, MRSA swabs of his anus, nose, and throat were performed and all were negative. During the hernia repair, multiple adhesions caused the small bowel to perforate and a partial (20 cm) small bowel resection was performed. Because no bowel spill was noted and the fascia could not be closed primarily, the hernia was corrected using a prosthetic mesh.
Subsequently, Mr. K developed a wound infection. A large area of necrotic skin developed and was excised, leaving the mesh completely uncovered in an open wound. At the same time, Mr. K was receiving broad spectrum therapy for pneumonia . He was treated in isolation, his wounds cultured, and eventually MRSA was found. In addition to the systemic antibiotics, the wound was treated with NPWT (V.A.C.® Systems, KCI Netherlands), set at 125 mm Hg, the black polyurethane sponge changed two times weekly. After 1 month of NPWT, the epidermis could be mobilized (loosened, undermining the dermis, creating the skin to mobilize on both sides of the wound) and the defect closed. The wound healed completely and the patient was discharged from further follow-up. [Authors’ note: Because of the MRSA, a camera was not allowed in the room, prohibiting photographic documentation of wound healing.]
Methicillin-resistant S. aureus is a virulent organism that causes significant mortality and morbidity. Shortly after the introduction of methicillin in 1959, outbreaks of MRSA were reported.4 Methicillin-resistant S. aureus increases length of hospital stay and healthcare costs5 and has become endemic in tertiary referral hospitals in most industrialized countries, with generally high occurrence rates in the US, Japan, and southern Europe (eg, >30% of cases occur in Spain, France, and Italy) but occurrence is low (<1%) in Scandinavia.6 Electronically flagging MRSA-contaminated patients and cleaning hospital units is inadequate in reducing MRSA colonization. The only way to effectively contain the infection is to isolate patients with positive MRSA cultures.7
Negative pressure wound therapy involves the application of subatmospheric pressure to a wound using an open-cell foam connected by tube to a vacuum source. A transparent adhesive membrane covers the foam.8 Presumed mechanisms of action include reduced interstitial fluid, lowered interstitial pressure, and reduced bacterial load, although the latter is debated.9 Reported indications for NPWT use range from poststernotomy mediastinitis to chronic lower extremity wounds and bolstering for a split skin graft.10-12 Negative pressure wound therapy also can be used for managing difficult laparostomies.13
Complication rates for NPWT are low — some local skin irritation has been reported.14 Serious complications include toxic shock syndrome (anaerobic sepsis).15,16 Negative pressure wound therapy is contraindicated in the presence of known allergies to any of the components of the NPWT system and for patients receiving anticoagulant therapy.17 The complications and indications of NPWT discussed here are based on case reports and small series.
To date, the largest prospective randomized trial considering the effects of vacuum therapy comprised 54 patients.9 This study shows the positive effect of NPWT on wound healing, expressed as a significant reduction in wound surface area. However, this could not be explained by a significant quantitative reduction of the bacterial load. A recent meta-analysis of NPWT included six randomized controlled trials, with a collective total of 135 patients.18 Because the quality of the studies was poor and the sample sizes were small, the analysis concluded that current evidence is insufficient to support conclusions about the effectiveness of NPWT in the treatment of wounds. In addition, no reports of infected mesh treated with NPWT were found in the published literature. Only two of the randomized studies reported complications, which included distal lower extremity amputation, fistulas, wound infection, and calcaneal fractures. These complications were observed during the NPWT treatment period but whether they occurred as a result of the therapy or because of the patients’ comorbidities is unclear. Additional randomized, controlled trials, currently planned by KCI, are necessary and warranted.
Although the literature is limited and broad conclusions cannot be drawn from the few case reports (including the one presented here), indications are promising for the use of NPWT as an adjunctive therapy to MRSA-infected prosthetic mesh in appropriate patients. Because the only viable alternative is removal of the infected mesh, leaving an incisional herniorrhaphy that requires further surgery, NPWT should become a serious consideration in relevant cases.