Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Pneumonia is not bronchitis (inflammation of the bronchial tissue), and it's not pleurisy (inflammation of the pleural lining of the lungs and chest), although both can produce some symptoms similar to pneumonias. Please note the use of the word "pneumonias"; it's plural and, in my view, has many different words (over 30, including the veterinary literature) used in both the lay and medical literature to identify subsets of the disease. Unfortunately, this can lead to confusion because there is a considerable amount of imprecision and overlap with these modifiers. We in the medical professions are guilty of developing and then using them; I don't see any evidence that the terminology will improve, so I'll try at least to indicate what several of the prominent pneumonia modifiers mean (and don't mean) and answer the questions asked above in the title.
Infectious pneumonia (bacterial, viral, fungal, and parasitic are all subsets of
infectious pneumonia) means that an infectious agent is causing the pneumonia.
Chemical pneumonia (many types caused by various substances such as chlorine or gasoline fumes) means that the pneumonia results from an irritant, not an infectious or traumatic cause.
Traumatic pneumonia (trauma such as a blunt object striking the chest as in an auto accident or an assault)
is a noninfectious or nonchemical cause of lung tissue inflammation.
Walking pneumonia (First question answer: Pneumonia doesn't
walk, but patients with "walking pneumonia" do!)
is an imprecise term used to describe a person with symptoms of pneumonia that are "mild" enough to allow people to do daily activities and do not require patient hospitalization; it does not describe the cause of the pneumonia-like symptoms and is often used as a preliminary diagnosis without good evidence (a chest X-ray or other tests) that pneumonia is actually present. The major difference between pneumonia and walking pneumonia are the severity of symptoms, with walking pneumonia having the least severe symptoms in most individuals.
Double pneumonia (Second question answer:
is not double talk, but means that both the right and left lung has pneumonia.) means at least two lung lobes (one on the right lung and one in the left) have pneumonia.
The term implies a more severe pneumonia, but the term is imprecise as it doesn't indicate the cause or how severe the pneumonia is.
Atypical pneumonia: The meaning of this word is unfortunately multiple, and it changes depending on the context in which it is used. For example, atypical pneumonia is used by some medical personnel to mean mild or "walking" pneumonia, while others use it to describe pneumonia caused by
Mycoplasma pneumoniae. Still others use the modifier to refer to all pneumonias caused by pathogens from birds that can also infect humans.
Community acquired pneumonia is pneumonia acquired outside of a hospital setting; although usually bacterial and sometimes antibiotic resistant, the term does not describe the cause.
Hospital acquired pneumonia is pneumonia acquired during a hospital stay;
it's usually bacterial and often antibiotic resistant, but the term again does not describe the cause.
Lobar pneumonia is pneumonia that at least in one (and often more) of the lobes of the lung, is consolidated, and is considered a more severe form of pneumonia, no matter what the cause.
Aspiration pneumonia is pneumonia caused by inhaling foods, saliva, vomit, or gastric contents that can act as both a chemical and infectious cause of pneumonia.