**9.4. Infection**

The use of immunosuppression in ITx poses a significant risk of infection and, historically, high levels of immunosuppressants have been utilized in ITx. Sepsis remains the most common cause of death and graft failure, accounting for over 50% of cases [7]. Bacterial infections are common in the early phase post-ITx and have a significant impact on patient survival. Invasive candidiasis has been reported as the commonest fungal infection [59].

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) viraemias are common and can be implicated in acute and chronic rejection as well as PTLD [60, 61]. CMV status is vital to anticipate the risk of developing de-novo infection in a non-infected recipient from the donor and through reactivation of a latent infection. CMV prophylaxis with oral valganciclovir is often continued for 1 year following ITx [62]. Most programs would not accept CMV-positive donors for CMV-negative recipients as this is high risk and should be avoided [63]. Last but not least, it has been demonstrated that isolated graft CMV disease without overt CMV viraemia can indeed occur [64].

#### **9.5. Post-transplant lymphoproliferative disorder**

In the updated 2016 WHO lymphoma classification, PTLD has been sub-classified as plasmacytic hyperplasia PTLD, infectious mononucleosis PTLD, florid follicular hyperplasia PTLD, polymorphic PTLD, monomorphic PTLD and classical Hodgkin lymphoma PTLD [65]. PTLD following SOT occurs in up to 20% with the highest incidence in intestinal and multi-organ transplants (5–20%), followed by lung and heart transplants (2–10%) and then by renal and liver transplants [66].

About 70% of cases of PTLD are associated with Epstein-Barr virus (EBV), especially in cases which occur early after transplantation. Pathogenesis of the disease is linked to EBV proliferation in the setting of chronic immunosuppression leading to an inhibition of T-cells immune function. However, in 30% of EBV-negative PTLD patients, pathogenesis is not clearly understood [67].

It is believed that in ITx, the lymphatic-rich intestinal allografts in combination with splenectomy and immunosuppression pose an increased risk for PTLD [68]. It has been reported that the presence of PTLD has significantly reduced patient survival within the first posttransplant year [69]. PTLD is treated with immunosuppression reduction and rituximab containing chemotherapy regimes in the presence of CD20 positive cases [70].
