Hospital-acquired pneumonia develops in people who have been hospitalized, typically after about 2 days or more of hospitalization. Institution-acquired pneumonia develops in people who reside in nursing homes or who have contact with medical settings, such as dialysis centers.

• Many bacteria, viruses, and even fungi can cause pneumonia in people who are hospitalized or have visited medical institutions.
• The most common symptom of pneumonia is a cough that produces sputum, but chest pain, chills, fever, and shortness of breath are also common.
• Diagnosis is made by listening to the lungs with a stethoscope and by examining x-rays of the chest.
• Antibiotics, antiviral drugs, or antifungal drugs are used, depending on which organism has most likely caused the pneumonia.

One reason that pneumonia acquired in the hospital is more severe is that the infecting organisms tend to be more aggressive and harder to treat. Additionally, people in hospitals and nursing homes tend to be sicker even without pneumonia than those living in the community and therefore are not as able to fight the infection.

Cause

People who are hospitalized and seriously ill, especially if they require assistance in breathing from a mechanical ventilator, are at greatest risk of acquiring pneumonia. Other risk factors include previous antibiotic treatment and coexisting illness such as heart, lung, liver, or kidney dysfunction. People who are older than 70, have had abdominal or chest surgery, take proton pump inhibitors, or have a combination of these factors are at particularly high risk.

People who are debilitated, such as those living in nursing homes, are also at risk.

Organisms that do not normally cause pneumonia in healthy people can cause pneumonia in people who are hospitalized or debilitated. Many such people have an immune system that is not able to resist even mild infectious challenges. The most likely organisms depend on what organisms are prevalent in the hospital and sometimes depend on what other illnesses the person has.

Hospital-acquired pneumonia is more likely than community-acquired pneumonia to be caused by Staphylococcus aureus or a gram-negative bacterium, such as Klebsiella pneumoniae or Pseudomonas aeruginosa. Sometimes pneumonia is caused by Legionella or methicillin-resistant Staphylococcus aureus (MRSA, the super-bug).

Symptoms

Symptoms are generally the same as those for community-acquired pneumonia: a general feeling of weakness (malaise), cough, shortness of breath, and chest pain. Pneumonia in critically ill people, especially those who are on a mechanical ventilator, causes fever and increases the respiratory rate and the heart rate.

Pneumonia acquired in an institutional setting may be more difficult for doctors to recognize than pneumonia acquired in other settings. For example, many people in institutional settings who develop pneumonia, such as the elderly, those with breathing tubes who are receiving mechanical ventilation, and those with dementia, may be unable to describe symptoms such as chest pain, shortness of breath, and weakness.

Did You Know... Pneumonia that is acquired in the hospital or another type of institution tends to be far more severe than pneumonia acquired in the community.

Diagnosis

Hospital-acquired and institution-acquired pneumonia is suspected on the basis of a person's symptoms. The diagnosis is confirmed with a chest x-ray. Blood tests are done. However, these methods are not always accurate. Also, because people may be very sick, doctors may need to identify the organism that is causing pneumonia so that they can determine the best treatment. For these reasons, sometimes doctors use bronchoscopy to confirm pneumonia and obtain a sputum specimen to try to identify the organism. During bronchoscopy, a flexible viewing tube is inserted into the trachea and lungs. Samples of pus, secretions, or even lung tissue can be collected for examination. If no secretions are visible, an area of the lung can be washed with a solution, which can then be retrieved for analysis (bronchoalveolar lavage).

Treatment

Treatment is with antibiotics that are chosen based on which organisms are most likely to be the cause and the specific risk factors the person has. Because of the seriousness of the infection, people in nursing homes are often treated in the hospital. People who are seriously ill may be placed in an intensive care unit and sometimes put on a ventilator. Treatments include intravenous antibiotics, supplemental oxygen, and intravenous fluids. There are several drugs that can be used, including the following:

• Imipenem plus cilastatin
• Meropenem
• Aztreonam
• Piperacillin plus tazobactam
• Ceftazidime
• Cefepime

These drugs are given alone or combined with vancomycin. If MRSA is suspected, an antibiotic called linezolid may be used.

End-of–life Issues: Because some people who live in nursing homes are very ill, pneumonia can be extremely serious. In order to treat pneumonia with the most powerful treatments available, doctors usually have nursing home residents transferred to a hospital. However, pneumonia is often fatal despite such treatment, and the treatment itself may be difficult to tolerate, especially if a mechanical ventilator is needed. People who are expected to die soon may not wish to receive such aggressive treatment. People with severe or terminal disorders should discuss with their doctors and family members their wishes for treatment of pneumonia when they enter a nursing home.

Prognosis

Despite receiving excellent treatment, about 25 to 50% of people who develop hospital-acquired pneumonia die. Whether the cause of death is due to underlying illness or to the pneumonia itself can be difficult to tell.

Spotlight on Aging
Pneumonia occurs more commonly in older than in younger people, and it also tends to be more serious. In many older people, the infection spreads beyond the lungs. Older people have weakened defenses against infection. The mechanisms that clear microorganisms from the airways are not as effective in older people as they are in younger people. Weakness may make coughing less vigorous. Aging also weakens the immune system. Older people at greater risk of developing pneumonia include those Whose lungs have been damaged by smoking or chronic obstructive pulmonary disease (smoking irritates the lining of the lungs and paralyzes the cells that normally sweep and cleanse the airways) Whose lungs have recently been irritated by a mild infection, such as a cold or, especially, influenza Who have a poor cough reflex or who are too weak (or who are in pain from recent surgery or an accident) to cough vigorously Who are less able to fight off infections, including people who are undernourished Who are taking certain drugs, such as corticosteroids Who have certain diseases, such as heart failure or diabetes Who have cancer in or near the airways of the lungs (the cancer may block the airways and trap any microorganisms that have reached the air sacs) Who are paralyzed (for example, because of a spinal injury or stroke) Who are unconscious (in part because they are unable to cough) Infection with some of the microorganisms that cause pneumonia can be prevented with vaccinations. So doctors recommend that people who are 65 or older receive the pneumococcal vaccine. Doctors also recommend that older people in particular receive an annual influenza vaccine because the influenza virus can also cause or contribute to pneumonia. Most older people who get pneumonia are treated in the hospital with intravenous antibiotics. Pneumonia can cause older people to get very sick very quickly, and older people tend to respond less well to oral antibiotics.

Last full review/revision April 2008 by John G. Bartlett, MD