Hospital-acquired infectious diseases can affect any person regardless of age, sex, or race. These diseases seem to impact the geriatric population to a greater extent, whether because of increased risk factors for acquiring infections or because of inadequate host defense. Although the leading causes of death among the elderly are chronic diseases—such as heart disease, cancer, and stroke—infectious diseases remain among the top 10 causes of death. According to the Centers for Disease Control and Prevention, pneumonia, influenza, and septicemia were responsible for nearly 96,000 deaths (5.5%) of people 65 years of age or older in 1997.1

Geriatric patients are at increased risk for infections secondary to the age-related decline of the immune system, known as immunosenescence. Comorbid conditions such as heart disease, diabetes, or chronic obstructive pulmonary disease often can complicate infections, diminishing the ability to treat them effectively. Frequent hospital visits and extended nursing care stays expose the elderly to higher rates of infections.1 Malnutrition, a major risk factor for infection, is estimated to be present in 15% to 50% of elderly patients who are admitted to the hospital. 1 In addition, functional impairments— such as immobility, incontinence, or dysphagia—can enhance susceptibility to infection by necessitating the use of invasive devices.2

Diagnosis of Infection

Diagnosing infection in elderly patients can be challenging because they may not display classic signs and symptoms. Fever and leukocytosis, 2 major indicators of infection, manifest less frequently or not at all in elderly patients due to their body's inability to mount an immune response. These patients typically present with changes in mental status or a decline in cognitive function, which can be confused with dementia. Other indicators may be subtle or nonspecific complaints—such as falls, delirium, anorexia, or generalized weakness— that often delay care.1,3 Early diagnosis and treatment are critical because of the high morbidity and mortality associated with infections in this population.1

Common Hospital-acquired Infections

Pneumonia is among the most serious and frequent nosocomial infections in the elderly. Aside from decreased immune function, anatomical changes in the lung—such as diminished cough reflexes and mucus clearance—are likely to contribute to the risk for pneumonia. Signs and symptoms are typically subtle, with bacterial causes identifiable in only 20% to 50% of patients.4 Empirical pharmacotherapy directed at the most likely pathogens should be initiated in a timely manner to minimize complications.

Urinary tract infections (UTIs) are the most common type of hospital-acquired infections, estimated to occur in 15% to 30% of hospitalized elderly men and 25% to 50% of elderly women.3 Geriatric patients are predisposed to developing UTIs due to the frequent use of Foley catheters as well as anatomical changes in the urinary tract. Elderly men may have prostate enlargement leading to obstruction of urine flow, whereas women can have incomplete bladder emptying; both conditions provide a great medium for bacterial growth or colonization. Upon clinical diagnosis, treatment is based on the presence of symptoms. Asymptomatic bacteriurias do not necessarily require treatment except in certain patient populations. Preventive measures are encouraged, however— such as minimizing catheter use, reducing duration of use, and changing catheters routinely.4

Counseling the Elderly Patient

Three key areas should be addressed for optimal management of hospital-acquired infectious diseases: infection control, vaccination, and patient education. Infection control is an important component in reducing the risk of nosocomial transmission from patient to patient. Studies have shown that good hand washing in combination with the use of a virucidal foam or alcohol product can reduce the infection rate by up to 50%.2 All health care professionals and visitors should wash their hands prior to and after patient contact. Patients with highly resistant organisms should remain in isolation as required.

Primary prevention with vaccination should be encouraged in all geriatric patients. Recommendations include influenza vaccine annually and pneumococcal vaccine after age 65, unless chronic conditions dictate administration sooner.3 Revaccination for Pneumococcus should be strongly considered for those at highest risk. Family members or caregivers for the elderly also should receive influenza vaccination as a preventive measure.

On discharge from the hospital, the geriatric patient should be educated regarding drug-related matters, including expected adverse effects, the potential for drug interactions, and the importance of compliance. A number of known age-related changes affect the metabolism of drugs in the elderly. Adjusting medications based on the patient's renal function is important to minimize adverse effects, which may be more frequent and severe in the elderly population. This predisposition to adverse effects is related to the physiologic changes of aging, as well as to chronic underlying illnesses, polypharmacy, and inappropriate dosing by prescribers.5

Unfortunately, few clinical trials have been designed to look at effects of drugs in this population.3 Therefore, it is important to educate geriatric patients on the potential for adverse reactions, as well as to screen for drug interactions. Patients should be counseled on the importance of compliance to adequately eradicate the infection. With appropriate drug selection, preventive measures, and patient education, the health care community can attempt to decrease the incidence of death caused by hospital-acquired infections in the elderly.

Dr. Cross is a transplant clinical pharmacist at Piedmont Hospital in Atlanta, Ga.

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