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The elderly (who tend to have diminished cough and gag reflexes and faltering immune systems) and infants and young children (who have immature immune systems and small airways) are at greater risk of community-acquired pneumonia (CAP) than are young and middle-aged adults.
Certain individuals, such as the elderly, the very young, and those with chronic or severe medical conditions, are of course at higher risk of community-acquired pneumonia (CAP). Hospitalized patients are particularly vulnerable to gram-negative bacteria and staphylococci, which can be very dangerous, particularly in people who are already ill.
People, especially the elderly, who have recently had surgery or suffered a traumatic injury are also more likely to develop pneumonia because they are less able to breathe deeply, cough, and get rid of mucous.
Pneumonia is more likely to occur in people whose immune system is weakened by an existing illness, such as the flu, cancer, or AIDS, and in people with chronic conditions, such as sickle cell disease, heart disease, diabetes, kidney disease, asthma, chronic bronchitis, chronic obstructive pulmonary disease (COPD), emphysema, or cystic fibrosis.
Recruits on military bases and college students are at higher than average risk for Mycoplasma pneumonia , which is usually mild. These groups are at lower risk, however, for more serious types of pneumonia.
Frequent exposure to cigarette smoke can affect the lungs in ways that make a person more likely to develop pneumonia. The risk for pneumonia in smokers of more than a pack a day is three times that of nonsmokers. Those who are chronically exposed to cigarette smoke, which can injure airways and damage the cilia, are also at risk. Toxic fumes, industrial smoke, and other air pollutants may also damage cilia function, which is a defense again bacteria in the lungs.
Alcohol or drug abuse is strongly associated with pneumonia. These substances act as sedatives and can diminish the reflexes that trigger coughing and sneezing. Alcohol also interferes with the actions of macrophages, the white blood cells that destroy bacteria and other microbes. Intravenous drug abusers are at risk for pneumonia from infections that originate at the injection site and spread through the blood stream to the lungs.
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