Surgical site infections in renal transplant recipients can be managed with negative pressure wound therapy (NPWT), however complications associated with the NPWT are uncommon. We describe a case series in which the presence of new, and or, persistent infections in the presence of NPWT has complicated the management of renal transplant recipients in our unit. This has required further surgical or radiological procedures, additional antimicrobial therapy and resulted in prolonged wound healing of up to 200 days. Vigilance, prompt management and recognition of the potential for infections associated with NPWT is required in the management of complex renal transplant recipients.

Lam S, Lau NS, Laurence JM, Verran DJ (2018) Surgical Site Infections Complicating the use of Negative Pressure Wound Therapy in Renal Transplant Recipients: A Case Series. J Surg Transplant Sci 6(2): 1070.

• Renal transplant; Kidney transplant; Negative 
pressure wound therapy; Vacuum assisted closure; 
Surgical site infections

BMI: Body Mass Index; CT: Computed Tomography; MCS: Microscopy Culture Sensitivities; NPWT: Negative Pressure Wound Therapy; SSI: Surgical Site Infection; VAC: Vacuum Assisted Closure

In adult renal transplant recipients, the rate of reported surgical site infections (SSI) varies from 4.8 -18.6% [1-5], and add considerable morbidity to the management of these patients [6]. Surgical site infection can also supervene particularly when the integrity of the abdominal wall is lost in the setting of superficial and/or deep fascial dehiscence [7]. In addition the requirement for immunosuppression along with a number of underlying medical comorbidities in renal transplant recipients may contribute to the incidence of SSI in this population [5,8,9].

Negative pressure wound therapy (NPWT), or vacuum assisted closure (VAC) therapy, has become a useful adjunct in the management of complicated wounds/surgical sites in many surgical disciplines including orthopedics, trauma, vascular and general surgery [10-13], and in the management of surgical site infections involving prosthetic mesh [14]. In addition patient satisfaction is higher with the use of NPWT plus the amount of resources directed towards the delivery of nursing and inhospital care are reduced [11, 15].

Favorable outcomes with the use of NPWT for abdominal wall complications have been reported in renal transplant recipients including recipients with SSI [15,16]. However, no data have been reported for new and/or ongoing surgical site infection supervening as a result of the use of the NPWT for wound complications in adult renal transplant recipients. In this study, we report the first case series of renal transplant recipients being managed with NPWT for abdominal wall surgical site complications who subsequently developed either new or further wound infections in the presence of NPWT.

All adult renal transplant recipients who required NPWT in addition to other surgical management of abdominal wall complications between 1996 -2017 were identified. The experience of managing these patients until 2016 has been previously reported [17]. The patients who developed further surgical site infection in the setting of ongoing use of NPWT were then identified.

Renal transplants were performed in this institution using a standardized operative approach in either iliac fossa. All patients received prophylactic antibiotics on induction. Immunosuppression therapy was as per our unit protocol [18]. The surgical management options for abdominal wall complications detected clinically or radiologically, included opening the wound either at the bedside or in the operating room. This was followed by a wash out and, or further tissue debridement and application of a NPWT dressing. The standard approach to applying the NPWT was to use a piece of black, polyurethane foam tailored to the defect in the abdominal wall followed by an occlusive dressing (Vacuum Assisted Closure, V.A.C Therapy KCI Medical Pty Ltd, USA) [19,20], set at continuous negative pressure of 125mm Hg. The dressing and foam were then changed twice a week. The wounds were all initially swabbed and the swabs sent for microscopy, culture and sensitivities (MCS) analysis. Antibiotics were given empirically in the setting of acute onset of SSI with evidence of spreading infection, and then according to culture sensitivities. The duration of antibiotic therapy was decided on a case by case basis and with infectious disease service input.

Ethics approval was obtained by the Sydney Local Health District Ethics Review Committee with site specific approval for study X18-0052.

There were 951 renal transplants performed in our unit between 1996-2017, of which 23 recipients with abdominal wall complications required further management with NPWT. Whilst 20/23 (86.9%) of the recipients who underwent NPWT achieved successful wound healing the other 3/23 (13.1%) developed further unexpected complications associated with the NPWT in the form of either new and/or further episodes of SSI requiring further management. The 3 cases are reported as follows:

Case 1

A 68-year-old female with a BMI of 34kg/m2 and a history of polycystic kidney disease, underwent a deceased donor renal transplant. Three days post operation, the recipient developed a serous discharge at the supero-lateral aspect of the wound, secondary to a superficial abdominal wall collection. The superficial aspect of the wound was partially re-opened on day 10 due to ongoing discharge and a swab taken and sent for MCS. The wound was also washed out and the NPWT applied. Of note the skin over the medial aspect of the wound remained intact. The wound MCS grew coagulase negative Staphylococcus, Corynebacterium, Enterococcus and Prevotella species. The recipient was treated with intravenous cefazolin and then oral cephalexin. Repeat wound swabs were negative after 1 week.

On day 24 post-transplant, the recipient developed evidence of a further SSI, and although the supero-lateral aspect of the wound appeared clean, there was new tenderness at the infero medial aspect of the wound. On computed tomography (CT) imaging, there was a small subcutaneous collection, medial to the NPWT foam, this collection was then aspirated percutaneously under ultrasound guidance. The MCS of the aspirated fluid revealed a scanty growth of Enterococcus and Prevotella bivia. The recipient was treated with intravenous cefazolin for 3 days, and then changed to oral amoxicillin and clavulanic acid for a further 5 days. The use of NPWT was continued at the supero lateral aspect of the wound until it healed by 82 days post transplant.

Case 2

A 59-year female with a BMI of 30.1kg/m2 and a background of diabetes and hypertension underwent a deceased donor renal transplant. At 19 days post-transplant, the recipient developed a new superficial abdominal wall collection. There were no signs of spreading infection. The wound was re-opened at the bedside, swabbed, washed out and the NPWT then applied. The initial wound MCS was negative for organisms. On day 59 posttransplant, during a NPWT dressing change, a new pocket of turbid fluid was detected in the abdominal wall superficial to the deep fascia, requiring a further washout and then reapplication of the NPWT. The new wound swab MCS revealed a penicillin sensitive Staphylococcus aureus, and the recipient was treated with oral flucloxacillin.

At 79 days post-transplant, the recipient developed urinary sepsis and acute kidney injury along with a concurrent abscess in the abdominal wall, deep to the NPWT foam. The wound was again opened at the bedside, swabbed, washed out and dressed with simple gauze. The recipient received empirical intravenous tazobactam and piperacillin (Tazocin) and then ceftriaxone for 2 weeks. The wound MCS grew Staphylococcus aureus, mixed skin flora and coliforms whilst the urine MCS was positive for Escherichia Coli and Klebsiella pneumoniae. In light of the sequence of events during the use of NPWT, the surgical site was subsequently managed with simple surgical dressings until it healed, at 109 days post-transplant.

Case 3

A 55-year female with a BMI of 42.3kg/m2 and a background of IgA nephropathy, underwent a deceased donor renal transplant. This was complicated by a deep fascial dehiscence along with a superficial fluid collection, requiring surgical wash out and operative repair at day 20. The abdominal fluid collection was noted to be turbid and hence was swabbed. Deep fascial closure was not possible due to a combination of tissue oedema and tissue loss. Therefore, a tension free repair with a dual layer vicryl and prolene on lay mesh was performed. A 10 Fr Jackson Pratt drain was placed around the allograft and the skin was closed primarily with interrupted nylon sutures. Subsequently the abdominal wall culture was positive for candida albicans, with a decision being made that the recipient required treatment with oral fluconazole for three months.

On post-transplant day 59, the recipient developed a new serous skin discharge along with a superficial collection at the surgical site, requiring reoperative surgery with a wash out, tissue debridement and application of the NPWT dressing being performed. A repeat wound swab revealed scanty growth of candida albicans, requiring the ongoing prescription of fluconazole. The tissue specimen taken during the debridement returned a negative MCS. To subsequently facilitate delayed primary closure of the healing superficial aspect of the surgical site, it was progressively closed with delayed skin sutures and downsizing, and removal of the foam by post-operative day 105.

Five days following the NPWT removal, the recipient represented with an abscess within the surgical site requiring surgery. The superficial wound was reopened, swabbed and debrided with a copious wash out. Of note the mesh had healed into the deep abdominal wall (confirmed on abdominal wall CT imaging), hence the NPWT was then reapplied anterior to the mesh. The recipient received intravenous Tazocin, and then oral amoxicillin and clavulanic acid, with metronidazole and fluconazole for 3 weeks duration. The wound MCS on delayed tissue culture on enrichment growth then revealed a Corynebacterium species 15 days following this repeat surgery. Histopathology of the tissue showed fat necrosis and a foreign body reaction. The surgical site was sufficiently healed with the use of NPWT to allow for simple gauze dressings at 197 days post-transplant, and was then healed 201 days post-transplant.

This is the first reported case series of renal transplant recipients who despite being managed in a standard manner with a NPWT dressing regimen for abdominal wall complications, have then all developed ongoing or further tissue invasive sepsis. This is something which has not been previously described in the setting of NPWT being used to manage a spectrum of abdominal wall surgical site complications in renal transplant recipients [15,21-23], including previously in our own unit [17].

There have been a handful of reports of recurrent wound infections being associated with the use of NPWT in other settings, and hence this particular complication is most likely under reported. These cases include the presence of toxic shock syndrome [24], sepsis associated with burn wounds following eschar debridement [25], delayed sepsis in a blast injury wound [26], and recurrent wound abscess formation beneath the foam dressing in acute and chronic wounds treated with NPWT [27]. Moreover, the Food and Drug Administration in the United States have reported a range of complications associated with NPWT include worsening infection, foam related injuries, foam retention or bleeding [28].

Although the mechanisms associated with the onset of SSI type complications with the use of NPWT are unclear, the immunosuppressed state of renal transplant patients may predispose them to developing persistent bacterial colonization and subsequent infection despite the NPWT. Whilst NPWT has been shown to improve wound healing by reducing the bacterial load in animal models [29], other studies have shown an increase in the quantitative counts of bacteria [30]. Furthermore, alterations in the type of bacterial colonies in the wound allows for the proliferation of some types, such as staphylococcus aureus [11,24].The three cases in this series (all transplanted with allografts from deceased donors), sustained infectious complications associated with a variety of organisms including Staphylococcus aureus, Corynebacterium species and fungus. This fits with the types of organisms commonly isolated from SSI in renal transplant recipients which occur within one month post operation and are usually the more common bacterial or fungal pathogens [31]. Of note, Case 3 had an unusual surgical site infection associated with candida, the source of which was never able to be formally determined. It is understood that deceased donor renal allograft recipients are more susceptible to infectious complications and/ or colonization with either bacteria or fungi [32], and that rarely donor derived infections can occur [33].

Case 2 was the only case where urinary sepsis occurred at the same time as the SSI associated with the NPWT foam. The organisms isolated from the urine differed to those isolated from the wound. Our practice with the ureteric stents inserted during the transplant surgery is that they are removed at 6 weeks post transplant. Theureteric stent for case 2 was removed after 5.5 weeks, which was 20 days before the representation of wound sepsis. Whilst there is no apparent correlation between the urine and SSI infections, it is likely the net immunosuppressed state of the patient had increased the vulnerability to pathogens and infections [31]. Indwelling catheter use and ureteric stents have been linked to the high incidence of urine infections in transplant recipients [34], and moreover, deceased donor recipients are also more prone to ureteric stent colonization and infections compared to live donor recipients [32].

An alternative hypothesis for the development of SSI with NPWT is that the polyurethane foam acts as a foreign body, generating an inflammatory reaction in the wound [35], leading to adverse healing and a medium for bacterial colonization [36]. The foreign body reaction observed in the third case is suggestive of this possible mechanism.

Obesity is a known risk factor for abdominal wall complications in renal transplant recipients [4], and it is possible that it may be associated with further SSI in the setting of NPWT noting the average BMI of 35.6 kg/m2 in our cases. It is also hypothesized that in obese patients, the abdominal pannus may have a traction effect which alters the forces across the surgical wound, between the supine and erect positions, which are not mitigated by the NPWT alone.

This case series highlights one of the complications that may be associated with NPWT dressings and more importantly, the added financial cost and burden of managing ongoing surgical site infection in renal transplant recipients. This included prolonged wound healing of up to 200 days requiring further procedures and further use of the NPWT and/or other dressings. Use of the NPWT device with two foam dressing changes cost up to $502 per week, or approximately $14,000 for 200 days for consumables, in addition to the cost of staff time spent on managing the dressings and performing procedures, the cost of additional antibiotics plus the extra in-hospital stay costs. Further strategies and studies to identify the risk factors for SSI associated with the use of NPWT are required. Surveying surgeons on management techniques for NWPT and identifying consensus algorithm/guidelines for management of the complex renal allograft recipient with SSI is one potential option [37,38]. The prophylactic use of combined negative pressure wound and instillation therapy with antiseptics is potentially one strategy that may be used to treat contaminated wounds that cannot be closed primarily [39].

The management of surgical site infections and wound breakdown in adult renal transplant patients is challenging. Whilst the use of NPWT can promote wound healing of the open abdominal wall in this particular cohort, it seems some immunosuppressed patients are predisposed to further episodes of abdominal wall infection. This requires vigilance, early recognition on the part of healthcare providers and prompt management with the use of alternative wound management techniques as required.

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