Important in fighting off infections is a substance called immunoglobulin, produced in response to antigens or infectious agents. The elderly produce normal immunoglobulin to agents they have met before but lower levels of immunoglobulin to new antigens. Antigens are the bodies' natural way to fight off disease. At the same time, elderly are more likely to have underlying diseases, resistance to which is weakened by respiratory infections. Thus pulmonary disorders take a devastating toll in the elderly.
Diagnosis can prove tricky when dealing with pulmonary disorders.
In order to make the diagnosis of both acute exacerbation of bronchitis and pneumonia you will need to produce a specimen satisfactory for bacteriological evaluation. With mucous reduction a natural process of aging, this becomes a difficult step. Secondly, in the elderly, pneumonia does not present the conventional symptoms. An elderly patient may have some acute change in mental or functional status. This may be a sign of an infectious cause, yet there may not be any fibrile response to this infection.