Decreased immune competence increases the risk for infection. Cell mediated immunity is known to decrease with age. T lymphocytic function is altered, and the older adult is at greater risk not only for infection, but also for the development of malignancies. Not only is T lymphocytic function altered, but also humoral immunity is decreased with a decreased antibody response to specific antigens (Phair, 1983).
Aging is also associated with an increase in the number of autoantibodies. These changes are magnified by nutritional deficiencies, disease, and increasing disability. These decreased host defenses in the older adult increase both the risk of development of infection and the risk of increased morbidity associated with the infection.
Along with a decrease in immune competence, older adults are found to have reduced sensitivity of several homeostatic mechanisms that will also predispose them to the development of infection. Documentation of a blunted or absent fever response to infectious disease has been noted (Norman, 1984). Lower mean temperatures are observed, as well as a decreased peak fever response. Increased incidence of afebrile response to infection has been associated with increased morbidity and mortality (Norman, 1985).
Decreased catecholamine responsiveness can impair the older adult's ability to raise his or her heart rate in response to the increased metabolic needs associated with infection. That, along with decreased baroreceptor response, decreased cardiac output, and the decreased concentrating ability of the kidney can alter postural reflexes and fluid and electrolyte balance. Alteration of these normal homeostatic mechanisms decreases the older adult's homeostatic reserve and increases the morbidity associated with infectious disease (Piano, 1989).
Physiologic changes in skin integrity also increase the risk of skin infections in the older adult. Thinning of the epidermis, slowing of cell replacement, loss of elasticity of dermal tissue, and decreased vascularity decrease the skin's normal protective ability and increase the risk of breaks in integrity. Once the skin integrity is impaired, the chance for bacterial and fungal infection increases.
Changes within the respiratory system are of special importance because of both the increasing incidence and the morbidity and mortality of pneumonia. Weakening of the respiratory muscles, decreased chest expansion, and increased residual volume all decrease respiratory reserve. Of special importance is the decrease in both cough effectiveness and ciliary activity. The combined effect of these physiologic changes is a decrease in functional reserve and an increase in susceptibility to respiratory pathogens.
There is an increased susceptibility to urinary tract infections (UTIs) in older adults with Foley catheters, immobility, and chronic diseases such as diabetes. The risk increases with advancing age, institutionalization, and increasing debility. Bladder muscle weakens with age and residual volume increases (Nickel, 1992). Incomplete emptying of the bladder increases the opportunity for colonization by microorganisms. Bladder outlet obstruction secondary to benign prostatic hypertrophy also predisposes older adults to UTI.
Pneumonia is the fourth leading cause of death among older adults (Niederman, 1991). Chronic disease (such as chronic obstructive pulmonary disease - COPD), nutritional deficiencies, changes in mental status, and functional limitation in activities of daily living (ADL) are all important predisposing factors. The most common bacterial pneumonias seen in community dwelling elderly are due to Streptococcus pneumoniae, Hemophilus influenzae, and Mycoplasma pneumoniae. Nosocomial pneumonias associated with care in hospitals or long-term care facilities vary according to institution. The most common causes of nosocomial pneumonia are Staphylococcus aureus, and the gram-negative bacilli Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli (Gleckman, 1983a).
The incidence of viral pneumonia has increased in the older population, and influenza is the fifth leading cause of death in individuals over 65 (Cesario, 1992). Decreased cell mediated immunity is associated with increased susceptibility. Chronic disease, debility, and institutional living are all known predisposing factors. Efforts to immunize older adults, with specific targeting to those with chronic disease and functional limitations, are a direct result of the increased morbidity associated with influenza. Secondary infection with bacterial pneumonias complicates the course of viral pneumonia, and increases morbidity and mortality.
Aspiration pneumonia also takes on specific importance. It is well documented that the posterior pharyngés of older adults are colonized by gram-negative bacteria (La Force, 1981). Chronic disease, debility, abnormal swallowing reflexes, and past history of stroke all increase risk of aspiration; chronic aspiration is associated with the development of gram-negative pneumonias.
The presentation of pneumonia in the older adult is often atypical. The decreased immune responsiveness associated with age and the diminished inflammatory response associated with chronic disease and debility play an important role. Fever is delayed. Signs of consolidation such as crackles, wheezing, pleuritic chest pain, and bronchial breath sounds have been shown to be absent in 30% of patients with documented consolidated pneumonia (Brown, 1993; Fox, 1988). Subtle signs of anorexia, change in mental status, change in normal activity pattern, weight loss, and failure to thrive are common atypical symptoms presented by this age group. Dehydration, chronic disease, and increasing debility not only will predispose to pneumonia, but also will add to the difficulty of early diagnosis. Mortality has been shown to be as high as 30%.
Older adults represent a disproportionately large share of the reported cases of active tuberculosis because they currently comprise the majority of the reservoir of previously infected cases. The noted decrease in immune function, the presence of chronic disease, and nutritional deficiencies all increase the likelihood of reactivation of the disease later in life.
The clinical presentation of tuberculosis in mis age group is often atypical. Cough, weight loss, and weakness are all common findings. These signs and symptoms also are commonly seen with other chronic conditions; due to their chronicity, vague nature, and mildness they do not increase the health care provider's suspicion of tuberculosis. Night sweats, chest pain, and hemoptysis are seen infrequently as an initiating complaint. Associated chronic conditions, such as COPD and congestive heart failure, mask the signs and symptoms of tuberculosis and delay diagnosis (Blagg, 1983).
Urinary Tract Infections
Urinary tract infections (UTIs) increase in incidence in the older population. Asymptomatic bacteriuria occurs in 20% of women over 65 and in at least 10% of men, and these percentages increase with age (BaIdasarre, 1991). Symptomatic UTIs are less common than asymptomatic bacteriuria. Uncomplicated UTIs can be classified as those that occur as a result of ascending infections in the presence of no known structural abnormality. They are not associated with systemic symptoms and are more common in women due to shortening of the urethra and increased opportunity for fecal contamination. UTIs due to structural abnormalities are associated with increased morbidity and mortality.
Incomplete emptying of the bladder secondary to benign prostatic hypertrophy, Foley catheter obstruction, bladder diverticulitis, bladder prolapse, or neurogenic bladder predisposes the older adult to a more complicated course. Other factors that increase risk are chronic prostatitis, instrumentation of the urinary tract, and contamination of the perineal floor secondary to fecal incontinence.
Atypical Presentations ot Common Infections
Decreased host defenses again play an important role in both the presentation and course of a UTI in the older adult. Typical symptoms of lower tract infections, including dysuria, frequency, and urgency are often present in community dwelling elderly with a symptomatic UTI. The presence of frequency, urgency, and stress incontinence can also be attributed to decreased bladder capacity and decreased sphincter control. These are common physiologic changes in the genitourinary system associated with aging that may make the diagnosis of UTI more difficult. A new episode of incontinence is often a hallmark sign of LTTI, especially in the female patient.
Those older adults who have documented asymptomatic bacteriuria do not have signs and symptoms of lower tract disease. Atypical presentations are more common in older adults with infections of the upper tract. Fever is often absent or delayed and the individual may be hypothermic. Confusion, disorientation, nausea, vomiting, and abdominal pain may be presenting symptoms. Gleckman et al (1983b) reported that the initial diagnosis of pyelonephritis was missed in more than 21% of patients due to initial presentation with gastrointestinal or pulmonary symptoms. Pyelonephritis is the most common cause of bacteremia in the older adult, and the presence of an indwelling Foley catheter increases the risk. Symptoms of lower tract disease will not be present in these patients. Obstruction of the catheter markedly increases the risk for bacteremia.
The most common bacteria involved in UTIs in this population is Escherichia colt. There is an increased risk of infection with gram-negative bacteria such as Proteus, Pseudomonas, Klebsiella, Providencia, and Serratia, especially in the presence of a Foley catheter, instrumentation of the genitourinary tract, institutional living, and debility (Sobel, 1991).
The skin provides the body's first line defense against pathogens. Physiologic changes in the skin that are associated with aging can disrupt mis normal defense mechanism and make older adults more susceptible to infection. Thinning of the epidermis, decreasing vascular supply, and increased drying increase the fragility of the skin of older adults. Increased fragility in the presence of nutritional deficiency, decreased mobility, diabetes, and peripheral vascular disease all increase the risk of secondary infection. Deficits in both the immune and inflammatory responses decrease the older adult's ability to provide first line defense, and will increase the morbidity and mortality associated with infection. Pressure ulcers, venous stasis ulcers, and diabetic foot ulcers are commonly complicated by evidence of cellulitis and poor healing (Stolley, 1991). Other factors that can affect healing are impaired vascular response, anemia, obesity, moisture, and incontinence. Skin infections in this population, as in the younger population, are largely caused by Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus groups A and D, although there is a higher incidence of gram-negative infections with Pseudomonas, Proteus, E coli, and anaerobic bacteria. Gram- negative bacteria are more likely to be cultured from deep tissue infections, such as those associated with diabetic ulcerations.
Fungal infections of the skin also increase. The presence of nutritional deficiency, debilitating disease, diabetes, immune deficiency, and chronic use of broad spectrum antibiotics all can play a role in the increased susceptibility to fungal infections. Candidiasis occurs most commonly in the intertriginous areas of the body that are moist, ie, under the breast, in the perineum, and at times at the angle of the mouth when dentures do not fit properly.
The risk of herpes zoster also increases in the older adult. Herpes zoster is a reactivation of a latent varicella virus that is associated with a erythematous-based vesicular rash following a unilateral dermatome. Secondary infection of open weeping lesions can occur due to the loss of the normal epidermal protective covering. Reactivation occurs in older adults whose immune system is deficient, who are experiencing high levels of stress, and who have nutritional deficiencies.
Older adults with documented infection or increased potential to develop an infection need to be carefully monitored. The nurse plays a pivotal role in both prevention of and early recognition of clinical signs and symptoms. Initial nursing assessment for older adults in all settings should include a review of patient history. A history of diabetes mellitus, COPD, cancer, malnutrition, debility, dementia, and frequent infections should all be noted. These will all increase the potential for infection, and should alert the nurse to the need for aggressive intervention. What are the current and past medications the older adult has been taking? Recent use of corticosteroids, chemotherapy, and antibiotics can lead to decreased host defenses and increased predisposition to infection. What is the normal activity pattern of the older adult? Immobility will increase the risk of respiratory and urinary tract infections. A review of the normal dietary intake is important in examining for evidence of nutritional deficiency; nutritional deficiency is associated with decreased host defenses and increased incidence of infection.
A complete head-to-toe assessment will provide the nurse with a baseline picture. Of specific importance is a complete mental status exam. Early signs of infection in the older adult are often only a change in mental status. The initial exam provides the baseline assessment the nurse can use to recognize early changes. A careful evaluation of behavior, verbal response, memory, activity pattern, level of consciousness, and reasoning is important. Often the subtle changes with infection are a change in behavior, such as decreased verbal response, decreased dietary intake, decreased orientation, or decreased involvement in ADL. Without the baseline assessment the nurse will miss subtle early changes.
Assessment of the skin takes on specific importance. Attention should be given to bony prominences and intertriginous areas where fungal infections are more likely to exist. Decreased peripheral circulation will decrease the individual's ability to mount an effective inflammatory response, and can predispose to infection. Decreased peripheral pulses, cool temperature to the skin, and pale color would be important to note; often the erythema, warmth, and swelling that are the hallmarks of infection are diminished in clients with decreased arterial supply.
Careful examination of the respiratory system is important in all cases. Inspection will reveal thoracic abnormalities such as scoliosis and kyphosis that can decrease chest expansion and increase the risk for atelectasis after surgery. Evaluation of the cough reflex and for the presence of a gag reflex are necessary to identify those clients at risk for aspiration. Careful auscultation of the respiratory system is important. Early recognition of changes in the type and characteristics of breath sounds, presence of crackles and wheezing, and rate and depth of respirations can point to the development of respiratory infections. Recognition of those individuals at risk for respiratory infections will assist in the development of nursing measures aimed at prevention.
Assessment of the color and appearance of the urine is of primary importance in the recognition and prevention of UTIs. The body's normal protective mechanism is to maintain urinary flow. Urinary retention interrupts normal flow and provides a growth medium for bacteria. Percussion of the abdomen and palpation over the bladder can assist the nurse in recognition of bladder distension. Careful assessment of the flow of urine from a Foley catheter is important. Patients with a Foley catheter will have bacteriuria. Any obstruction to flow will increase the chance for development of urinary sepsis.
Evaluation of laboratory data is important. Infection is normally associated with leukocytosis, with a specific elevation of polymorphonuclear leukocytes. In older adults, 20% have been shown to have a normal or even low white blood cell count. This finding in the presence of bacteremia can indicate an overwhelming infection. Pyuria is absent in 35% of patients who have asymptomatic UTIs. Bacterial counts on cultures and sensitivities cannot be used as the only indicators of UTI in older adults with Foley catheters in place, as bacteriuria is always present. Blood cultures can be important in those individuals suspected of upper tract disease.
Also of importance is an evaluation of serum albumin. Significant decreases in serum albumin can be associated with malnutrition, and can be seen as a predisposing risk for infection. Monitoring of the complete blood cell count for evidence of anemia is also important. Decreased dietary intake can lead to a deficiency in both iron and folate, and both will lead to anemia with a decrease in Hgb and Hct. Monitoring of arterial blood gases takes on importance in the older adult with pneumonia. Hypoxemia, hypercapnia, and respiratory acidosis are important findings in the client with decreasing respiratory reserve.
Prevention. Prevention of infection in the older adult should take on primary importance. Yearly influenza immunizations are encouraged for adults over 65 who do not have an allergy to eggs. Pneumococcal vaccination should also be encouraged. The pneumococcal vaccine needs to be administered only one time and is recommended for all persons over 65, and adults at risk for COPD, asthma, restrictive lung disease, and those with other chronic illnesses. The nurse's role in educating these at-risk populations on the availability and effectiveness of these vaccines is important in prevention.
Education of older adults with respect to nutrition also takes on importance. Reinforcement of the significance of well-balanced nutrition, assessment of current nutritional status, and provision of educational aids that are developed to meet the needs of older adults are all important roles of the nurse. Each client encounter, in both inpatient and outpatient settings, should address these issues. Malnutrition is a significant predisposing factor for infection, skin breakdown, drug interactions, and debility.
Acute Interventions. The nurse's role in the treatment of older adults with infection is an important one. Specific areas of concern are oxygenation, fluid and electrolyte balance, nutrition, cognition, and mobility.
Maintenance of oxygenation is of importance in the older client with pneumonia. Infection increases metabolic and oxygen needs. Increased oxygen needs are met by increasing heart rate; careful monitoring of vital signs at regular intervals is important.
Decreased cough reflex and effectiveness of cilia increase the risk of airway obstruction. Coughing and deep breathing at least every 2 hours is necessary. Maintaining hydration assists in thinning mucous so the older adult can expectorate more effectively. Humidified oxygen is frequently needed. The nurse needs to give special attention to the presence of COPD in the patient's history. COPD patients will require lowdose oxygen to prevent respiratory depression.
Assessment of fluid and electrolyte balance is important in all older adults with infection. Due to the decreased ability to concentrate urine, older adults are at risk to develop dehydration. Fluid intake of 2000 cc to 3000 cc per day, in patients without cardiac or renal contraindications, is needed to thin secretions and decrease opportunity for mucous obstruction. Increased fluids will help prevent urinary stasis and decrease risk of infection. Medications, such as aminoglycosides used to treat gram negative bacterial infections seen in those with pneumonia, UTI, and deep tissue infections, can cause nephrotoxicity. Dehydration will increase the risk of nephrotoxicity. Monitoring of drug levels, blood-urea-nitrogen and creatinine levels, creatinine clearance, urine specific gravity, and strict intake and output are important in these patients.
Anorexia, weight loss, and dehydration are frequently important clinical findings early in infection. Because of chronic illness, depression, and drug interactions, older adults are at increased risk for malnutrition. The effect of malnutrition on immune competence has already been noted. Decreasing immune competence increases bom the risk for and the morbidity of infection. Assessment for evidence of malnutrition - ie, poor skin turgor, fragility of skin and vessels, dry thinning hair, constipation, wasting of muscle mass, and increasing fatigue - is necessary. Monitoring of serum albumin also provides an objective parameter Nursing interventions to improve nutritional status should include small frequent high caloric meals in those patients who can take fluids and food orally. High caloric feedings such as Ensure can be added, but the nurse should be alert to the need for increased water intake to prevent hemoconcentration and elevated blood sugar in the diabetic patient. Patient weight should be recorded daily as well as an accurate assessment of actual caloric intake. At times parenteral nutrition is needed.
Disorientation, lack of interest in activities, and change in behavior are subtle early changes seen in infection. Assessment for cognitive changes should be an integral part of the nursing assessment of the older adult. Recognition of subtle change in behavior can be noted even in those patients with some degree of dementia. Improving observational skills of auxiliary health care providers, such as nursing assistants, can improve early identification and treatment of infectious disease.
Decreased mobility plays an important role in infection in the older adult. Recognition of changes in activity tolerance may be an early indicator of infection. Respiratory excursion is decreased in older adults placed on bed rest. Decreased respiratory effort is associated with atelectasis and pneumonia. Immobility is associated with injury to the skin and predisposes to skin infections. Frequent repositioning of the client will not only protect from skin injury but will also improve respiratory clearance. Early ambulation is important.
Older adults are at increased risk for the development of infectious disease. The increased risk is associated with increased morbidity and mortality. Atypical presentation often delays diagnosis and treatment. Nursing can play a pivotal role in the prevention of infection in the older adult by providing information on the importance of influenza and pneumococcal vaccines, instituting early risk assessment identification, and developing proactive nursing interventions for those individuals at risk.
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Atypical Presentations ot Common Infections