Disease Information

Infectious Diseases: Infections in Immunocompromised Patients

Alternate Names: None

Definition

Most patients at St. Jude Children’s Research Hospital have weakened immune systems. St. Jude's goal is developing effective ways of preventing serious infections among children whose immune systems are weakened by cancer chemotherapy or bone marrow transplantation. The following information focuses primarily on patients who become immunocompromised as a result of treatment for their disease.

Immunocompromised patients are susceptible to bacterial, fungal, and viral infections that healthy immune systems usually conquer. They are also susceptible to common infections of childhood. Often, the symptoms tend to be worse.

There are several reasons why powerful treatments such as chemotherapy and radiation weaken the immune system.

• These therapies break down the tissue of natural infection barriers such as the skin and covering of the gastrointestinal tract. Bacteria and fungi travel through these openings and infect the patient. Many hospital procedures such as finger sticks, bone marrow aspirations, and venipunctures (inserting a needle into a vein) can disrupt barriers put up by the immune system and allow infectious agents to invade the body.
  
• Hospitalization itself may increase the risk of infection. Hospitals tend to be home to more antibiotic-resistant bacteria. This fact is of course a problem for seriously ill children, because they spend a lot of time in the hospital.
  
• Chemotherapy and radiation treatments can harm or destroy white blood cells such as T-cells, B-cells, and neutrophils -- key components of the immune system. These cells help the body recognize infecting agents that invade the body and help protect you from either getting infected or help fight off the infection.
  
• Patients who undergo splenectomy (removal of the spleen) are at increased risk for infection. The spleen acts as a filter and manufactures important antibodies (components of immune system that fight specific antigens [infectious agents]).
  
• Use of steroids, sometimes prescribed to St. Jude patients, can weaken the immune system by affecting how the white blood cells work.

Influencing Factors

• The patient is immunocompromised either because of an acquired or inherited immune deficiency disorder.
  
• The patient is immunocompromised because of powerful treatments for cancer or blood disorders that leave the immune system severely weakened.
  
• Some cancers are associated with immune problems that predispose patients to certain infections.

Clinical Features and Symptoms

• Patients, parents and health care workers must be extremely vigilant for signs of infection.
  
• Because white blood cells are compromised, normal immune responses often don’t occur in these patients. For example, swelling, redness or pus is a normal sign of skin infection, but these patients likely would not exhibit symptoms.
  
• Fever and/or pain at the area of infection are most common symptoms of infection in immunocompromised patients. One tiny bump could possibly be a sign that something is wrong.

Treatment Strategies

• Infections are treated aggressively as early as possible and may require hospitalization.
  
• Bacterial infections are the cause of 85-90 percent of infections associated with new fevers. As a result, physicians will prescribe an antibiotic regimen (treatment) first. This antibiotic regimen typically covers a broad spectrum to fight the wide variety of bacteria that can potentially infect these patients.
  
• If the infection does not clear up in a few days, a regimen of antifungal drugs usually follows. It is also used when patients have been diagnosed with a fungal infection.
  
• Severely affected patients may receive replacements of white blood cells.
  
• Patients who develop specific documented infections such as bacteremia (bacteria in the blood) ear infection, sinusitis, pneumonia, gastrointestinal disorders, liver infections, meningitis, encephalitis, cardiovascular infections, and skin infections are treated for the specific infection.
  

Prevention techniques

• Thorough handwashing is still one of the best ways to prevent infections. Immunocompromised patients should not be exposed to anyone who has not washed his or her hands. For this reason, handwashing areas are located directly outside inpatient rooms at St. Jude.
  
• Special air filtration systems are employed by many hospitals to cut down on bacterial and fungal colonization and infection.
  
• Preventive regimens of antibacterial, antifungal, and antiviral drugs can be used if deemed necessary.
  
• Most patients receive preventive antibiotics to fight Pneumocystis carinii (jiroveci), which causes a fatal form of pneumonia. Successful treatment of this disease was pioneered by Walter Hughes, MD, former chair of the St. Jude infectious diseases department.
  
• Patients should also avoid dusty area, crowds, and sick people.
  
• Patients are also instructed to keep the mouth and rectal areas clean, especially after chemotherapy.

Current Research

• Researchers at St. Jude are developing better methods for early diagnosis of infections.
  
• Scientists at St. Jude are developing preventive regimens for fungal infections.

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