is a term used to describe an infection of the air spaces within the lung. This can be an infection with bacteria, viruses, or fungus. When most people get really sick from pneumonia, it is because of a bacterial infection. You can get pneumonia from many different sources. Some types of pneumonia are from breathing in airborne bacteria or from droplets of water with the bacteria. Other types of bacteria come from breathing in bacteria that live in the mouth and nose. If someone you know has pneumonia, it is probably best to avoid close contact with that person until the source of the pneumonia is known and a doctor
says its not contagious. Many forms are not contagious and develop in people that have imperfect defenses.
The answer to your last question is no, you shouldn't be tested for pneumonia if you do not have any symptoms. Symptoms of pneumonia include cough, fever, shortness of breath, muscle aches. These symptoms, along with findings on a chest x-ray diagnose pneumonia. The chest x-ray isn't usually done without some of those symptoms.
If you are worried about any symptoms you may be having, you should schedule an appointment with your primary care physician
for further evaluation and treatment if necessary.