Cell-mediated immunity and part by also humoral immunity diminish in old age.
Possible long-term diseases and age-related physiological changes as well as immunosuppressive medications all impair defence mechanisms and make the diagnostics more difficult.
Typical symptoms of infections are often lacking or they are non-specific (e.g. difficulty in walking, confusion). Even mild infections may cause decompensation of some organ.
Attention should always be paid if a stable condition in an elderly person turns strange in some way, even if there is no deterioration of the general condition nor confusion.
Fever is often absent.
Pneumonia
Predisposing factors for pneumonia in old age are e.g. impaired cough reflex, possible neurological diseases causing impaired functioning of the pharynx and susceptibility to aspiration, obstructive pulmonary diseases, immobilization and heart failure.
The temperature of a pneumonic patient may be normal and cough may be completely absent. Pneumonia may manifest as symptoms of impaired general condition and functioning, confusion, or chest pain.
During an influenza epidemic there are often secondary bacterial pneumonias, which are usually caused by Staphylococcus aureus. In this case cefuroxime is a justifiable antimicrobial choice.
In prolonged lung infection, the possibility of malignancy as well as of tuberculosis (sputum staining and cultures) should be kept in mind.
Urinary tract infections and pyelonephritis
Women are predisposed to urinary tract infections because of age-related atrophy of the vaginal mucosa or prolapses of the vagina or uterus. Men are predisposed because of prostate hyperplasia. The most important external factor predisposing for urinary tract infection is cathetrization. An indwelling catheter should always be removed as soon as possible.
The cause of recurrent infections should be defined and treated. Prophylactic pharmacotherapy should be avoided. In exceptional cases it can be considered for a specific period with, e.g., trimethoprim as one dose at night for 6-12 weeks. Nitrofurantoin and quinolones should be avoided. Use of cranberry juice is probably beneficial. Strengthening of the mucosal membranes with local oestrogen (oestriol, oestradiol) is often effective Vaginal Oestrogens for Preventing Recurrent Urinary Tract Infection in Postmenopausal Women.
Treatment should always be based on symptoms and a bacterial culture of an appropriately taken sample.
Symptomless bacteriuria of the elderly is common and it should not be treated without some specific (dysuria, frequency) symptoms suggestive of an infection. Symptomless bacteriuria should not either be accepted as the reason for the patient's weakened general condition.
Treatment should not be started on the basis of a smell combined with a suspicion of an infection.
Because the sense of visceral pain is decreased with ageing, acute appendicitis and biliary tract infections may be difficult to diagnose. They may silently lead to perforation or acute abdominal catastrophe.
Diverticulosis and diverticulitis are age-related diseases.
Plasma CRP and blood leukocyte count, repeated clinical examination and exclusion of infections affecting other organs and eventually abdominal CT scan help to reach the correct diagnosis.