Infections in Transplant Recipients
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Direct answer
Infections in transplant recipients follow a predictable timeline governed by the degree of immunosuppression. Nosocomial bacteria dominate in the first month, opportunistic viruses and fungi such as cytomegalovirus and Aspergillus cause most infections in months one to six, and community or late viral infections take over after six months. Pre-transplant serology screening and targeted prophylaxis are the main preventive steps.
What you must remember
- First month: Surgical site infection, catheter-related bacteraemia, Clostridioides difficile colitis and multidrug-resistant gram-negative bacilli acquired during the hospital stay.
- Months one to six: The peak window for CMV disease, Pneumocystis pneumonia, Nocardia, Listeria, Toxoplasma and invasive Aspergillus.
- After six months: Community respiratory viruses, varicella-zoster reactivation, BK polyomavirus and EBV-driven post-transplant lymphoproliferative disorder.
- Highest-risk CMV pairing: A seropositive donor with a seronegative recipient, written as D positive and R negative, carries the greatest risk of primary CMV disease.
- CMV prevention: Valganciclovir prophylaxis for high-risk recipients, or preemptive treatment guided by blood viral load monitoring.
- BK polyomavirus: Causes nephropathy in kidney recipients and haemorrhagic cystitis after haematopoietic stem cell transplantation.
- Aspergillus: Angioinvasive pulmonary disease in neutropenic or lung transplant patients, screened with serum galactomannan and prevented with mould-active azoles in high-risk cases.
- Vaccines: Live vaccines are contraindicated after transplantation, and inactivated vaccines are used instead.
A timeline-based approach to prophylaxis
Transplant teams plan prevention by time since surgery, because each infection peaks in a different window. The steps below follow that timeline from the operating table onward.
- Peri-operative period: Antibiotic prophylaxis covers skin flora and gram-negative organisms, and pre-transplant screening for tuberculosis, hepatitis B and C, HIV and CMV is completed beforehand.
- First month: Hospital-acquired infections dominate, so catheter care, wound surveillance and prompt testing for Clostridioides difficile are essential.
- Months one to six: CMV, Pneumocystis, Nocardia and Aspergillus are the main threats, and cotrimoxazole, CMV prophylaxis or preemptive monitoring, and antifungal cover are used according to risk.
- Beyond six months: Varicella-zoster, community respiratory viruses, BK virus and late EBV-driven lymphoproliferation become more common as immunosuppression is reduced.
- Lifelong surveillance: Long-term immunosuppression raises the risk of skin cancers and virus-associated cancers, so screening and inactivated vaccination such as influenza and pneumococcal vaccines continue.
Reviewing the timeline at each visit is what makes the approach work. A new fever or diarrhoea in a patient who has just stopped prophylaxis may signal a late infection, so the exact time since transplant should always be noted alongside the donor serology and graft type.
Where the exam tries to catch you
Transplant infection questions usually test the timing of the infection and the immune status of the donor and recipient.
- Trap: Giving a live varicella or MMR vaccine to a transplant recipient. Correct: Live vaccines are contraindicated after transplantation, so inactivated vaccines are used and pre-transplant immunisation is preferred where time allows.
- Trap: Assuming fever in the second month after transplant is bacterial. Correct: CMV, Pneumocystis and fungal infections peak in this window, so prophylaxis history and specific testing come first.
- Trap: Judging CMV risk from the recipient's serology alone. Correct: The donor and recipient pairing decides risk, and a seropositive donor with a seronegative recipient is the highest-risk combination.
Frequently asked questions
Which infection peaks in the first month after solid organ transplant?
Hospital-acquired infections, including surgical site infections, catheter-related bloodstream infections and Clostridioides difficile colitis, peak in the first month after transplant. Early antibiotic prophylaxis and strict line care are the main preventive measures.
Why is Pneumocystis prophylaxis given after transplant?
Pneumocystis jirovecii pneumonia is a serious opportunistic infection in transplant recipients receiving prolonged immunosuppression. Cotrimoxazole prophylaxis is standard for several months after transplantation, and the exact duration follows the transplant centre protocol.
What makes a D positive and R negative pairing high risk for CMV?
A seronegative recipient receiving an organ from a seropositive donor, written as D positive and R negative, has the highest risk of primary CMV disease. Such recipients are usually given valganciclovir prophylaxis or closely monitored with blood viral load testing.
Which antifungal prophylaxis is used against Aspergillus after transplant?
Mould-active azoles such as voriconazole or posaconazole are used against Aspergillus in high-risk transplant recipients, including lung transplant patients. Serum galactomannan testing helps detect early invasive infection.
Why are live vaccines avoided in transplant recipients?
Live attenuated vaccines can cause disseminated infection in an immunosuppressed patient, so they are contraindicated after transplantation. Inactivated vaccines such as influenza and pneumococcal vaccines are given instead, and pre-transplant immunisation is preferred where time allows.