WHAT ARE THE INFECTIOUS CAUSES OF PNEUMONIA?
Pneumonia is caused by microscopic and submicroscopic organisms that infect the lung tissue. There are four main groups of organisms capable of causing this infection: Bacteria: These are the relatively large organisms that can usually be seen under the microscope. They can invariably be killed or retarded with antibiotics; otherwise healthy patients who develop bacterial pneumonia respond favorably when given the appropriate antibiotic. One unusual bacterium has recently been shown to be responsible for Legionnaire’s disease (discussed in a later section). BacteriaLike: Bacterialike organisms fall somewhere between viruses and bacteria. They share features of both, and microbiologists do not all agree on their classification. One such organism, called mycoplasma, causes a characteristic pneumonia manifested by cough, chest pain, and a patchy infiltrate on the chest xray. Such lung infections are called “atypical pneumonia” to distinguish them from “typical” bacterial pneumonia. We
