Combatting Infection in Immunocompromised Individuals

Shana Gleeson, MD, manages infections in people whose immune systems are suppressed due to medication, treatment, or disease. The assistant professor of medicine (infectious diseases) at Yale School of Medicine specializes in the care of those who have had kidney, liver, heart, lung, and bone marrow transplants.

A wide range of pathology and infections are found in transplant recipients, according to Gleeson. “There are opportunistic infections that you don’t usually find in immunocompetent individuals but can be very problematic in someone who’s immunosuppressed,” Gleeson explains. “And there are common infections that can be more severe or have a more subtle presentation in this population.”

In a Q&A, Gleeson discusses the risk of infection among transplant recipients, common and opportunistic infections, and how infectious diseases connect us all.

Organ recipients take lifelong medication that weakens the immune system to prevent their bodies from rejecting the new organ. But the immune system cells that reject an organ also fight viruses and bacteria. So in weakening the immune system to tolerate the new organ, we increase the risk of getting infections and severe disease from those infections. Even the usually harmless microscopic organisms we breathe in, like Nocardia, can cause infection in an immunosuppressed person.

There are very common infections, like urinary tract infections, that transplant recipients may have more trouble with or have more frequently. On the opportunistic side, there are fungal infections in places like the lungs and sinuses, much more so than in the general population.

We also find the reactivation of viral infections, such as cytomegalovirus (CMV), in the setting of immune suppression after an organ transplant. CMV is one of the herpes viruses, which many people have and is latent in the body. When the virus reactivates, it can cause illness in immunosuppressed people. Most commonly, I see it in the gastrointestinal tract, where it causes a bowel infection, but it can also affect the lungs, eyes, and other areas.

On the diagnostic side, I’ve learned to be vigilant, keep an open mind, and have a high index of suspicion. When people are on immunosuppressive medications, their symptoms can be more subtle because they have a limited inflammatory response.

Sometimes treatment courses need to be a little longer, particularly with opportunistic infections. Instead of a week of treatment, someone might need several weeks of antibiotics or several months of antifungals. Nocardia infections, if they are severe, can require treatment for up to a year.

I take care of patients from all different walks of life, and you don't necessarily know who around you is immunosuppressed or who has had a transplant. Some viruses jump from person to person, and we don't know who in our community might be more vulnerable to getting sick. It is important to take care of ourselves and be mindful of how we interact with other people to keep the whole community safe. When it comes to infectious diseases, we’re all connected.

Yale School of Medicine’s Department of Internal Medicine Section of Infectious Diseases engages in comprehensive and innovative patient care, research, and educational activities for a broad range of infectious diseases. Learn more at Infectious Diseases.