Infections in transplant recipient

Transplant recipients have weakened immune systems because of the immunosuppressive medications they have to take. This makes them prone to infections. 

Typically, they are at risk of different types of infections depending on how far out they are from transplantation. The risk of infection is often the highest in the immediate post-transplant period and in the setting of organ rejection when the dosages of immunosuppressive medications are the highest. As the transplant recipient recovers, and their immunosuppressive medications are dose reduced, the risk of infections also decreases. 

Infections can be newly acquired by being exposed to microbes after transplant or it can be due to reactivation of dormant infections. 

Transplant recipients are at risk of common infections that the person with normal immunity may develop. For example, they are still at risk of the common cold, chest infections, urinary tract infections, skin infections or gastrointestinal infections. They are also at risk of unusual or atypical infections because of a weakened immune system. 

Common symptoms include fever, cough / breathlessness, rash, changes in mental status, or diarrhea. Having said this, infections can present in an atypical fashion in the transplant recipient. Symptoms may be non-specific, and the only complaint may be lethargy or a sense of feeling poorly. In other instances, transplant recipients may be completely asymptomatic and the only clue might be the abnormal investigation result that their physicians picked up on their routine clinic visit (e.g. abnormal blood counts, deranged kidney function / liver function tests, lung nodule(s) on chest radiograph).

As mentioned earlier, infections in the transplant recipient can come from either the donor or the recipient. Prior to transplantation, both the donors and recipients are extensively worked up to screen for infectious risks. The workup includes detailed history taking, blood tests and radiological imaging. Infections can be treated and catch up vaccinations administered prior to transplant. 

In the early post-transplant period, transplant recipients are looked after in the transplant unit by a specialized team of transplant physicians and allied health staff. In the hospital, staff are advised on strict adherence to hand hygiene and environmental cleaning. 

After the transplant, antibiotic prophylaxis may be administered for a period of time to reduce the risk of some common post-transplant viral and fungal infections. Recipients are also counseled on safe living practices (e.g. the importance of hand hygiene, food & water safety, travel safety, avoidance of crowded areas, avoidance of persons with respiratory symptoms and safe sex practices) to minimise their risk of infection.

The risk of infection after transplant depends on:

We are exposed to many different microbes in the environment in our life time. Such exposure are often benign; patients may remain asymptomatic or develop only mild symptoms. These exposures may result in dormant infections which re-emerge and cause problems in the transplant recipient when they are on immunosuppressive medications. Some examples  of this include infections like tuberculosis and fungal infections. Infections can also come from the donor. 

After transplant, transplant recipients may fall sick after being exposed to sick persons, animals or microbes in the environment. 

During transplant, the recipient undergoes a number of medical procedures. Infections may arise from complications associated with medical instrumentation / medications received (e.g. chemotherapy for bone marrow transplantation). Prolonged periods of bedrest and immobility in the early post transplant period may also result in increased risk of hospital acquired infections such as chest and urinary tract infections. 

The dose of immunosuppresive medications is often the highest in the early post transplant period or during organ rejection. This is also the period when the risk of infections is the highest. With time, as immunosuppression is tapered, the risk of infection is also reduced. 

Transplant related infections are diagnosed based on detailed history taking, physical examination as well as laboratory / radiological investigations. To the astute clinician, the presenting clinical syndrome is often a clue to the diagnosis. 

Frequently, blood / body fluid  is collected for cultures to help isolate the offending microbe. Radiological imaging such as X-rays, computed tomography (CT) or magnetic resonance imaging (MRI) may be performed to help localise the site of infection. Biopsies of tissue may also be performed and tissue sent for cultures and microscopic examination to help clinch the diagnosis.