Pneumonia: Definition, Diagnosis, Treatment and Prevention

A chest X-ray showing a very prominent wedge-shape area of airspace consolidation in the right lung characteristic of bacterial pneumonia. (Image: Wikipedia Commons)

gelbman-office-shotFor Medical Monday this week, Dr. Brian Gelbman — an Associate Clinical Professor of Medicine at New York Presbyterian Hospital and Weill Cornell Medical College whose special area of interests include early detection of lung cancer and has advanced training in bronchoscopy techniques for diagnosing lung cancer — shares the types of pneumonia, its diagnoses, and treatments.
A basic definition of pneumonia is an infection of the lung. There are many potential sources for the infection, either bacteria, viruses or fungi can cause a pneumonia. Most commonly, we are worried about bacteria as the cause for infection. When this happens to an otherwise healthy individual, doctors will use the label, community acquired pneumonia. This suggests the bacteria was picked up somewhere in the patient’s own environment. Curiously, most cases of bacterial pneumonia are not thought to be contagious, i.e. spread person to person. Most of the bacteria that cause pneumonia, can actually be found normally in our mouths, skin or environment. It is not entirely clear why these ubiquitous bacteria can suddenly cause disease in a healthy individual. One theory is that something happens to temporarily weaken the immune system and make the individual susceptible to an “attack” on the lungs by these otherwise benign bacteria.  The temporary weakness may be due to coexisting infection, e.g a cold or flu virus, or it may be from stress or from being run down. Contrary to what our mothers have told us, being outside in the cold too long has not been demonstrated to cause pneumonia.

To diagnose pneumonia, the doctor should see clear evidence of an infection on the lungs on a chest X-ray. However, chest X-rays can miss pneumonia. Sometimes, the infection is small and hard to see on the chest X-ray, or it can be hiding behind the heart or the ribs. That is why many times when a doctor suspects pneumonia but the patient has a normal chest X-ray, the physician still prescribes antibiotics, just to be sure an infection isn’t lurking. In addition to the X-ray, patients should have the right signs or symptoms to support the pneumonia diagnosis. This includes cough, sputum, fevers and shortness of breath. The absolute best test for detecting pneumonia is a CT scan of the chest. The CT scan will give a complete 3D reconstruction of the chest, essentially there is nowhere for the infection to hide on a CT scan. This isn’t always routinely done because there is a fair amount of radiation exposure from a CT scan, compared with a chest xray (approximately 70 times the radiation dosage). When your doctor says you have “walking pneumonia,” he or she is referring to patients who are well enough to be walking around and not in the hospital, yet have evidence for pneumonia on a chest X-ray.

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  • hillsmom September 26, 2016 at 11:36 pm

    Dear Dr. Pat, Thanks for the explanation. I shall check with my G.P. about it. Also for my DH at his VA team.

  • Patricia Yarberry Allen, M.D. September 26, 2016 at 8:01 pm

    Dear Hillsmom,

    Dr. Gelbman has given our readers up to date advice on immunizations that are recommended to decrease the chance of a type of pneumonia that is common in people with impaired lung function or decrease in immune response to infections. The first vaccination that you received was the old fashioned one. There is now a “booster” vaccine that should be given six to 12 months after the first pneumonia vaccine to people over 65. Call your doctor! No confusion, just new information.
    Dr. Pat

  • hillsmom September 26, 2016 at 1:38 pm

    Now I’m confused…nothing new here. However, some time ago I had a shot for pneumonia which was advised for, ahem, Seniors. At the time, I believe, I was told it was a one time shot. Now you are saying something else…in two parts. Since I still work and am exposed to the public, I do get a yearly flu shot.

    Am I alone in being confused? Thanks…