Post-transplantation infection

OVERVIEW

• transplant patients are treated with immunosuppressants to prevent rejection, which makes them susceptible to infection
• risk of infection depends on epidemiological factors (determines exposure) and overall state of immunosuppression (determines susceptibility)

EARLY <1 MONTH

These are related to:

• technical factors
• nosocomial infections
• donor-derived infections, and
• recipient colonisers

Types

• Active infections
  — transmitted with the allograft (usually bacteremia or candidemia) and commonly seed the allograft especially at anastomoses (vascular, tracheal, ureteral, and biliary anastomoses)
  — e.g. MRSA, VRE, candida
  — hence, active bacterial and fungal infections in the recipient must be eradicated before transplantation
• Pulmonary infections (aspiration and postsurgical)
• Infections in devitalized tissues or undrained fluid collections at a high risk for microbial seeding
• C. difficile colitis

MEDIUM 1-6 MONTHS

Types

• Residual infections from the first month
• Immunomodulating viruses
  — particularly CMV but also EBV, herpes simplex virus (HSV), human herpesvirus 6, HBV, HCV, and BK virus
  — often activation of latent infection
• Opportunistic infections
  — Pneumocystis carinii, Aspergillus, and L. monocytogenes
  — parasites in endemic regions e.g. Toxoplasma, Strongyloides, Leishmania

LONGTERM >6 MONTHS

3 groups of patients

• Community-acquired infections in those with good allograft function
  — respiratory viruses, pneumococcal pneumonia, and UTIs
  — opportunistic infections occur only with particularly intense environmental exposures (eg, nocardiosis or aspergillosis after digging in the garden)
• Chronic and/or progressive viral infections
  — e.g. HBV, HCV, CMV, EBV, and papillomavirus
  —  can have direct effects (ie, the impact is generally greatest on the transplanted organ, CMV colitis)
  — can lead to malignancies (eg, HCC after HBV or HCV, lymphoma due to EBV, SqCC due to papillomavirus, and Kaposi’s sarcoma due to HHV 8)
  — can have secondary effects of viral infection (graft rejection and a susceptibility to opportunistic infections)
• Recurrent or chronic rejection with decreased allograft function and needing high-dose immunosuppression
  — opportunistic pathogens such as P. carinii, L. monocytogenes, Nocardia asteroides, Cryptococcus neoformans, and Aspergillus species
  —  may benefit from lifelong prophylaxis (eg, trimethoprim/sulfamethoxazole),  careful attention to environmental exposures, and prolonged antifungal prophylaxis

References and Links

LITFL

• CCC — Infections in the Immunocompromised

Journal articles and textbooks

• Fishman JA. Infections in immunocompromised hosts and organ transplant recipients: essentials. Liver Transpl. 2011 Nov;17 Suppl 3:S34-7. doi: 10.1002/lt.22378. PMID: 21748845.