Pneumonia - Risk Factors

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People With Compromised Immune Systems. People with impaired immune systems are extremely susceptible to pneumonia. It is a common problem in people with HIV and AIDS. A wide variety of organisms, including Myobacterium species, Histoplasma capsulatum, Coccidioides immitis, Aspergillus species, cytomegalovirus, and Toxoplasma gondii, can cause pneumonia.

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In addition to AIDS, other conditions that compromise the immune system include:

• Adult and pediatric cancers, especially leukemia and Hodgkin's lymphoma
• Chemotherapy
• Organ transplantation

Patients who are on corticosteroids or other medications that suppress the immune system are also prone to infection.

Also, drugs that treat gastroesophageal reflux (GERD) may slightly increase one's risk for community-acquired pneumonia. Patients at high risk for pneumonia should take gastric acid-suppressing drugs only when necessary and at the lowest possible dose. This association is strongest with protein pump inhibitors (PPIs) such as Prilosec and Nexium. Reducing levels of germ-killing stomach acid may allow germs to spread in the upper gastrointestinal tract and move into the respiratory tract. The risk posed by these medications is highest in:

• Children
• Patients with asthma, COPD, and compromised immune systems
• The elderly

Researchers have found that the risk is strongest when people have recently begun treatment with PPIs, and lessens over time.

Swallowing disorders, including dysphagia. Difficulty swallowing has a variety of causes, including:

• Abnormalities of the muscles of the esophagus
• Illnesses that affect swallowing, such as stroke, traumatic brain injury, or Parkinson's disease
• Surgery or radiation treatment for cancers of the mouth, throat, or esophagus

All of these may increase the risk of aspiration pneumonia.