The source of post-transplantation infections can be derived from donors or recipients, and also following exposure to community or nosocomial microorganisms (Fishman, 2009; Green and Michaels, 2012). Prophylactic treatments for viruses such as cytomegalovirus (CMV) and fungi, e.g. Pneumocystis, have limited some opportunistic infections following transplantation (Fishman, 2009).

Transplanted organs can aid transmission of viruses, e.g. hepatitis B and C viruses, herpes simplex virus (HSV), and HIV; as well as antimicrobial resistant microorganisms (Fishman, 2009).

Common recipient-derived pathogens include Mycobacterium tuberculosis; viruses such as hepatitis B or C, and HIV; latent viral infections (HSV and varicella zoster virus (VZV)); endemic fungi (Histoplasma capsulatumCoccidioides immitisParacoccidioides braziliensis), and parasites (e.g. Strongyloides stercoralisTrypanosoma cruzi). However, HIV-infected patients maintained on highly active antiretroviral therapy (HAART) have been treated successfully following kidney or liver transplantation (Fishman, 2009).

Cytomegalovirus (CMV) infection is the most common opportunistic infection in kidney transplant recipients, occurring in around 8% of patients. Risk factors for the development of CMV include donor seropositivity (particularly if the recipient is seronegative), use of induction immunosuppression (using T cell depleting antibodies), simultaneous pancreas-kidney (SPK) transplantation, older donors (>60 years), concurrent infection from other viruses and the presence of allograft rejection (Nett et al., 2004; Karuthu and Blumberg, 2012).

The risk factors for infection following transplantation are the dose, duration and sequence of immunosuppressive therapies used. Specifically, risk factors are use of induction therapy; high-dose corticosteroids; plasmapheresis; a high rejection risk; early graft rejection or graft dysfunction; and active or latent infection of donor or recipient. In addition, technical complications during transplantation such as anastamotic leak; bleeding; poor healing of wound infection; prolonged intubation or stay in intensive unit care; and surgical, vascular or urinary catheters, are also risk factors for infection (Fishman, 2009).

The figure below outlines the timeline of post-transplantation infections.

The timeline of post-transplantation infections (Fishman, 2009).

Figure 3: The timeline of post-transplantation infections (Fishman, 2009).

Comprehensive American Society of Transplantation (AST) guidelines on infectious diseases are available (American Society of Transplantation Infectious Diseases Guidelines 3rd Edition, 2013) and the British Transplantation Society Guidelines for the prevention and management of CMV disease after solid organ transplantation have been published (Andrews et al., 2011; British Transplantation Society, 2011).