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Infection is an important cause of illness and death among older adults. Infections also make other underlying illnesses worse, often leading to hospital stays that would not otherwise be needed. Respiratory infections (eg, flu, bronchitis, and pneumonia) and infections of the urinary tract (eg, bladder infections) are common among relatively healthy, independent older adults living in the community. Urinary tract infections and pneumonia are also common among people in nursing homes. Infections of skin and soft tissue are also common in nursing homes because pressure ulcers, surgical wounds, and other injuries serve as points for bacteria to enter the body.
Risk of Infection Many factors increase the risk of infection. Some of the more common ones include the following:
These factors are more common among older adults than among younger people. In addition, our immune system may not work as effectively as we get older, which increases our risk even more. This "winding down" of the immune system is a major reason why infection becomes more common with age. Changes in the immune system with age As we age, specific types of immune cells are less able to produce the antibodies needed to fight infection. Even more importantly, there are changes in other defense mechanisms that most people don’t even think of as part of the immune system. The skin and mucous membranes (ie, the lining of the respiratory tract, gut, and urinary system) are very important components of the immune system. These surfaces act as barriers to infection, preventing harmful organisms (ie, bacteria or viruses) on the surface from penetrating further into the body. Bacteria are always present on the skin and mucous membranes. The number and activity of these bacteria are affected by the moisture content of the skin, the amount of acid in the stomach or on the skin surface, sweat, mucus, and the presence of nonharmful (or benign) bacteria that are also present on these surfaces and may "crowd out" the others. The mucous membranes also help prevent infection by trapping organisms in mucus and carrying them to body openings, where they are eliminated in sputum, urine, feces, or vaginal discharge. Some of these defenses may not work as well with age. For example, the mucous lining of the gut may not function as well, changing the population of bacteria that live there. This, in turn, may upset the balance between normal and harmful organisms. In addition, certain skin conditions that increase the risk of infection (eg, pressure ulcers and blisters) are common in older adults. Physical and mechanical barriers to infection may become less effective with age. For example, we have more difficulty swallowing as we get older, which leads to an increased risk of pneumonia from inhaling food or liquids (a process called aspiration). In addition, older adults may not be able to cough strongly enough to bring up phlegm or mucus in the airway. Changes in the lungs, especially the collapse of small airways and the stiffening of lung tissue, also increase the chance of respiratory infection (see also Diseases of the Respiratory Tract). Changes in urine or prostate secretions can decrease the antibacterial nature of these fluids. Also, an older bladder may not empty completely, leaving some urine behind that can provide bacteria with a place to grow. Other illness at the same time Having other illnesses or disorders probably has the greatest effect on the body’s natural ability to fight infection. For example, chronic obstructive lung disease decreases mucus clearance from the airways and other processes, which increase the risk of pneumonia. Similarly, the nerve damage and slow wound healing associated with diabetes increases the risk of serious infection, especially in the limbs (see also Diabetes). Malnutrition has a major influence on the ability to fight infection. Approximately half of adults over 65 years old do not get the daily calories, vitamins, and minerals needed to maintain a healthy immune system. Although many of these individuals live in nursing homes, people living at home can also have a problem with malnutrition, especially if they are depressed, or have poorly controlled diabetes, side effects from certain drugs, or other conditions that interfere with appetite or metabolism. Malnutrition can result in slow wound healing, increased risk of infection, longer hospital stays, and even early death (see also Nutrition). Mental difficulties can also increase the risk of serious infection (see also Delirium and Dementia). People with some mental loss may not wash properly, forget to refrigerate food that can spoil, or do other things that increase the risk of infectious illness. Having other illnesses also complicates infections in older adults. For example, people with mental difficulties may forget to take prescribed antibiotics, or take the wrong drug or dosage. This increases the risk of the infection lasting longer and developing other complications. In turn, this could lead to hospitalization for infections (eg, pneumonia) that could possibly have been treated on an outpatient basis. Signs and Symptoms Fever is the most common sign of serious infection. Any increased temperature in an older person should be carefully evaluated. Open sores or pus (ie, a milky white material) draining from anywhere are also unmistakable signs. Unfortunately, older adults do not always show typical signs and symptoms of infection. For example, up to half of older adults do not run a fever, even in the face of a serious infectious illness such as pneumonia. The reason for this is not known, but is probably due to a loss of ability to regulate body temperature associated with age and frailty. Infection may show up with unusual or general signs and symptoms in older adults. It may first appear as only a rapid loss of function or well-being for no apparent reason. For example, infections may initially result in only a general decline in function, with the person being confused, falling, or not eating well. Older adults with mental difficulties may not be able to communicate their symptoms accurately, making evaluation even more complicated. Diagnosis and Treatment Routine blood tests can identify signs of inflammation (eg, a high white blood cell count), but these are seen in many conditions other than infection. The most common test to specifically check for infection is a bacterial culture, in which potentially infected material is placed in the laboratory and then watched to see if any bacteria grow. This material could be a sample of urine, blood, tissue, drainage from a wound, or swabs of a particular area such as the throat. Any bacteria that are identified by culture are then tested further to determine which antibiotics will be effective against the infection or, in other words, which antibiotics the bacteria are sensitive to. This information is used as a guide to selecting the right antibiotic for treatment. Viral or fungal infections can also be identified by culture, but the laboratory process is much more complex than that for bacteria. Antibiotics Many antibiotics are available to treat a wide variety of bacterial infections. Antibiotics work by killing or slowing down the growth of infectious bacteria. Antibiotics are effective only when taken at the correct dosage for the correct period of time. Other considerations when taking an antibiotic include taking it with plenty of water, on an empty stomach, or with food. It is important that you understand and follow directions, and take all the medication that you are prescribed. Don’t hesitate to ask your healthcare provider or pharmacist if you are unsure of the instructions. Also, don’t stop taking the antibiotic just because you start to feel better! This means only that the antibiotic is starting to work, not that it has done the whole job. Like all drugs, some antibiotics may cause side effects (see also Drug Treatment). The most common side effect is probably stomach upset, but more serious side effects are possible, depending on the drug. Some antibiotics may also interact with other drugs commonly taken by older adults. Your healthcare provider or pharmacist can provide more information. It is important to remember that antibiotics kill only bacteria. They are useless for viral infections (eg, flu, colds, or measles) or fungal infections (eg, athlete’s foot). Using antibiotics to treat illnesses that are not caused by bacteria leads to antibiotic "resistance" among other bacteria, some of which are in the body normally. This means that these bacteria are no longer affected by one or more antibiotics. When antibiotics are no longer effective against bacterial infections, "super infections" that are extremely difficult to treat can be the result. Your healthcare provider may be hesitant to prescribe an antibiotic for common respiratory infections, such as colds or flu, because of concerns about creating resistance. Resistant bacteria are especially a problem in hospitals, where sick people and resistant organisms come together in large numbers. Other treatments Although antibiotics treat only bacterial infections, there are also some drugs for treating fungal or viral infections. Some are taken orally, and some are applied to the skin surface. May antifungal agents that are applied to the skin are available as over-the-counter treatments for athlete’s foot (see also Foot Problems). Antifungal drugs that are taken orally usually require a prescription. Examples of antiviral drugs include medications for cold sores and newer drugs to treat flu. Many other techniques are used to prevent or treat infection in addition to drugs. These range from simply washing a sore or cut with soap and water, to bandages to protect wounds, to surgery to clean and drain a wound. Infectious Syndromes Several infectious syndromes especially place the older adult at serious risk of illness or death. Blood poisoning The medical term for bacteria circulating in the blood is "bacteremia." This condition is serious, because blood infections can damage the circulatory system and lead to infections in other parts of the body (eg, the lungs or brain). Bacteremia is a common cause for hospitalization among older adults. Major contributing factors include having other illnesses that reduce the body’s ability to fight infection, or having open sores or medical devices (eg, intravenous or urinary catheters) that provide a point of entry for harmful organisms. Common signs of bacteremia include chills, sweating, and fever, although these signs are not always seen in older adults. Treatment includes rapid administration (intravenous) of antibiotics and supportive care. Unfortunately, the prognosis is often poor among older adults, even with appropriate hospitalization and treatment. Prevention is key. This is why healthcare providers pay so much attention to cleanliness and sterile technique (eg, washing an area with iodine before starting an intravenous line). People 65 years old and older account for more than half of all cases of pneumonia, which is especially common in hospitals and nursing homes. Pneumonia is also a common cause of hospitalization and death. Pneumonia can be caused by bacteria or viruses, but with bacterial pneumonia generally being more serious. Bacterial pneumonia often follows a respiratory infection that damages the lungs, such as the flu. This is a major reason why flu vaccination is so important in older adults. Treatment for pneumonia includes appropriate antibiotics (often given via injection), drugs to break up mucus, and supportive care, including administration of oxygen. Treatment for pneumonia is complicated by bacterial resistance, with more and more antibiotics becoming ineffective over time. This is why it is important to reserve antibiotics for use only in situations when bacterial infection is known or likely. Urinary tract infection Urinary tract infection is one of the most common clinical illnesses among older adults, affecting more than 10% of older adults each year. Infections of the urinary tract are much more common in women than men. The biggest risk factors are urinary catheters and conditions that allow harmful organisms from the gut to come in contact with the urinary openings (eg, fecal incontinence). The most common place of infection is the lower urinary tract, which is made up of the bladder, the urethra (ie, the tube through which urine passes out of the body), and the prostate (in men). Lower tract infections cause painful, burning, strained, frequent, and urgent urination. Fever is not usually seen. The upper urinary tract includes the kidneys and ureters, which are the tubes that carry urine from the kidneys to the bladder. Upper urinary tract infections may cause fever, chills, nausea, and pain in the side, although not all of these symptoms are seen in older adults. Upper urinary tract infections are more serious because of the risk of kidney damage. Treatment in women: In women, treatment of lower urinary tract infection usually consists of several days of antibiotics. Culture and sensitivity tests are often not needed. Treatment for upper urinary tract infection is longer, usually 7—21 days. Similar antibiotics are used for infection in either location, but upper urinary tract infections are more likely to need intravenous antibiotics and more thorough diagnostic tests (eg, culture and sensitivity). Approximately 15%—40% of older women have bacteria in their urine without any symptoms. Treatment is not necessary because the risk of drug side effects and antibiotic resistance are greater than the risk of the infection. For similar reasons, women generally shouldn’t take antibiotics to prevent bladder infections from coming back. Other approaches that may help prevent bladder infections that keep coming back include drinking at least 10 ounces of cranberry juice each day. Treatment in men: Prostate disease and problems with emptying the bladder are the main causes of urinary tract infection in men. For this reason, antibiotic treatment in men, even for routine bladder infections, is usually given for at least 14 days. If the prostate is involved, treatment usually lasts at least 6 weeks. Men are treated with the same types of antibiotics used in women, and culture and sensitivity testing is usually done. Infective endocarditis Inflammation of the lining of the heart cavity and valves is called endocarditis. Infective endocarditis is most common among older Americans, usually as a complication of problems with the heart valves. Endocarditis is especially common during the first 2 months after an artificial valve has been surgically installed. Bacteria can attach to diseased or artificial valves and then spread to the lining of the heart. From there, the bacteria can get into the blood and infect other organs. Fever and a high white blood cell count are commonly seen in endocarditis, but these signs are not always present in older adults. The most common test to diagnose infective endocarditis is a blood culture. An ultrasound examination of the heart–called echocardiography –can help identify problems with the heart valves and support the diagnosis. Echocardiography is similar to sonar, in which sound waves are bounced through the heart to see its structure. A variation of this procedure called transesophageal echocardiography is an especially useful diagnostic tool, but carries greater risk than standard echocardiography because an ultrasound probe is inserted into the esophagus. Infective endocarditis requires 2-6 weeks of antibiotics, which are generally given intravenously. Surgery may be necessary if there are severe valve problems, abscesses, or other serious heart complications. People at high risk of infective endocarditis are often prescribed antibiotics before undergoing medical procedures to prevent bacteria from getting into the blood and heart. These may include dental cleanings and medical procedures involving the upper respiratory tract, gut, or urinary tract. Infection of implanted medical devices Today, many artificial medical devices are surgically implanted to treat a various conditions. These man-made devices are referred to as prostheses and include artificial joints (eg, hips and knees), pacemakers, heart valves, and eye lenses. Prosthetic devices relieve pain (eg, from arthritis), improve function, and otherwise improve quality of life. However, they may also provide a surface on which bacteria can grow. Bacteria can reach the prosthesis during surgery, or later from bacteria spread through the blood or nearby infection. The greatest risk is probably within the first 2 months after the prosthetic device is implanted. Prosthetic devices complicate antibiotic therapy. Because the device itself is not alive, antibiotics (which travel through the blood) cannot reach it effectively. Sometimes, the device must be removed, followed by several weeks of antibiotic treatment. Occasionally, the device can be re-implanted after 6-8 weeks of antibiotic therapy. In rare cases, surgically cleaning the device and long-term antibiotic therapy (eg, 6 months) can cure the infection without having to remove the device. Bone and joint infections Common conditions among older adults, such as arthritis, gout, and artificial joints, result in tissue damage, which increases the risk of bone or joint infection. Bacteria can reach bones and joints through the blood from penetrating wounds or from nearby infected tissue. Bacteria from pressure ulcers or diabetic foot infections are common sources of bone or joint infection, especially among older adults in nursing homes. Antibiotics have trouble reaching joint fluid or damaged bone because these areas have a reduced blood supply. This makes treatment difficult, and antibiotic therapy is often combined with repeated procedures to drain the fluid and surgically clean the area. Surgical wounds are often left open, so that infected material can continue to drain. Culture and sensitivity testing is usually required. HIV infection and AIDS Infection with human immunodeficiency virus (HIV) among older adults was initially limited to those who had received transfusions of infected blood. However, increasing numbers of older Americans are acquiring HIV through sexual activity. About 10% of all new diagnoses of acquired immunodeficiency syndrome (AIDS) in the United States are in older adults. Unfortunately, many older people are not aware of HIV risks, probably because HIV was not a problem when they were young adults. General symptoms such as forgetfulness, loss of appetite, weight loss, and pneumonia are often thought of as problems simply related to age, but they can be signs of HIV infection in a patient with HIV risk factors. All it takes to diagnose HIV is a simple blood test. Without treatment, older adults infected with HIV tend to go downhill rapidly. However, older adults usually respond to treatment just as well as younger people. Although therapy cannot cure HIV, it can put off development of AIDS indefinitely. Treatment and prevention of HIV infection are similar in both old and young adults. Your healthcare provider can give you more information on safe sexual activity (eg, condom use), testing, and HIV therapy. Tuberculosis Approximately 1.7 billion people worldwide, including 16 million Americans, are infected with Mycobacterium tuberculosis, the organism that causes tuberculosis (TB). Adults aged 65 and older account for 25% of all active TB cases in the United States. Most of the TB among older Americans is due to infection that happened during the early 1900s, when it was estimated that 80% of all persons were exposed to TB by the age of 30. The classic signs of active TB are cough, sputum, fever, night sweats, and weight loss. However, older adults may not show these classical signs and have only general problems such as fatigue, loss of appetite, or low-grade fever. Most TB in older adults involves the lungs, but other parts of the body are affected in about 25% of cases. The central nervous system, bones, and urinary system are other locations. TB can also spread to many different tissues as tiny, seed-like abscesses (called "miliary" TB). Up to half of older adults living in nursing homes have a positive reaction to a TB test, which is done by injecting a small bleb of material between the layers of the skin). A positive test shows up as redness and swelling at the injection site. A positive test does not necessarily mean that a person has active TB. Someone can have TB organisms within his or her body that are not currently causing active illness. However, these organisms could lead to active illness in the right circumstances. In fact, most active cases of TB in older adults are due to an old infection becoming reactivated. Risk factors for infection or reactivation include malnutrition, diabetes, decreased immune function, and kidney disease. High-risk individuals should be tested for TB regularly. Chest X-rays can show signs of TB within the lungs. However, a sure diagnosis of active TB usually requires culture of the organism from sputum, urine, or another clinical sample. This usually takes several days. New DNA techniques (similar to those used by forensic laboratories) that may be able to give results faster, perhaps within 24 hours, are being developed. Treatment for active TB requires long-term therapy (eg, 6 months) with multiple drugs. Commonly used drugs include isoniazid, rifampin, pyrazinamide, ethambutol, and streptomycin. Treatment usually begins with 3 or 4 drugs administered simultaneously, and then decreases to 2 or 3 drugs after several months. People with a newly positive TB test who are not showing any signs of disease are usually treated with isoniazid for 9 months as preventive therapy. People undergoing long-term treatment or preventive therapy for TB should be closely monitored for side effects, such as nerve or liver problems. Other infectious syndromes Bacterial meningitis, an infection of the membranes that cover the brain, is most common among very young and very old individuals, but most deaths are in older adults. Many of the bacteria associated with meningitis are now resistant to penicillin and similar drugs, so newer antibiotics that are more expensive must be used. Syphilis of the brain can show up many years after venereal infection. This disease causes mental difficulties that can be confused with stroke or dementia in older adults. Common signs of late-stage syphilis include deafness in one ear, walking problems, and eye inflammation. A sure diagnosis of syphilis requires specific laboratory tests, which often require a spinal tap. (A spinal tap is a procedure in which a needle is inserted into the spinal canal to get a small sample of the fluid that surrounds the spinal cord.) Syphilis can be easily treated with penicillin, but permanent brain damage may already have occurred if treatment begins late in the course of the disease. Shingles (also called herpes zoster) is common among older adults, especially those living in nursing homes. Shingles is caused by a reactivation of the virus that causes chicken pox. Shingles generally goes away on its own, but the nerve pain associated with it can be debilitating. Facial nerve palsy (also called Bell’s palsy) is also common in older adults. It can be caused by infection with a cold sore virus, the chickenpox virus, or Lyme disease. Antibiotics should be given for 2 weeks if Lyme disease is suspected. Antiviral therapies can be used if facial nerve palsy is associated with the chickenpox virus. A variety of bacterial infections of the gut are fairly common in older adults. These include diverticulitis, appendicitis, infectious diarrhea, gall bladder infection, and abdominal abscess. Older adults may not have the fever and increased numbers of white blood cells that are usually seen with these conditions in younger adults, so more sophisticated diagnostic tests (eg, CT scan, ultrasound, etc) are often needed. Treatment may require antibiotics or surgery. |
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Published: 5/23/2005