47: Common Infections

Infections remain a major cause of mortality and morbidity in older adults. With significant progress made in cancer management and cardiovascular diseases, deaths caused by infectious diseases appear to be rising. Pneumonia, influenza, and bacteremia are among the top 10 causes of death in older adults. Approximately 1.5–2.0 million infections occur in skilled nursing facilities per year, making their prevalence a major quality-of-care concern. Infections can lead to increased hospitalizations for this population, exposing them to nosocomial pathogens and resultant complications, such as functional disability, delirium, pressure ulcers, and adverse events. Common infections in older adults include urinary tract infections, upper and lower respiratory tract infections, gastroenteritis including Clostridium difficile diarrhea, skin and soft-tissue infections, including surgical site infections, and osteomyelitis. HIV/AIDS in aging populations will also be an emerging concern as those infected as younger adults now have an increasing life expectancy because of the effectiveness of antiretroviral therapy, and because the number of new infections in older adults is also on the rise.

The risks of developing an infection, its severity, and the outcome from that infection depend on the relationship between the virulence of the pathogen, its inoculum, and the host’s defense system. The ability of a pathogen to attach and replicate in a host environment determines its virulence. In aging adults, macrophage function is altered, mucocutaneous defenses are compromised, cytokine production is diminished, and T-cell function is suboptimal. Comorbid conditions, such as renal failure, diabetes, congestive heart failure, chronic lung diseases, and malnutrition, further exacerbate defense mechanisms. A paucity of presenting signs and symptoms leads to delayed recognition of infection, which can result in poor outcomes. Subtle changes in functional and cognitive decline are often early warning signs. Other presenting atypical symptoms include falls, loss of appetite, fatigue, and failure to thrive. Febrile response is often blunted, especially in frail older adults residing in long-term care facilities. As a result, the Practice Guidelines Committee of the Infectious Diseases of America recommends a clinical evaluation for residents in skilled nursing facilities with single oral temperature over 100°F (37.8°C), or persistent oral temperature of over 99°F (37.2°C). Two or more readings of greater than 2°F (1.1°C) over the baseline temperature should also prompt an evaluation by a physician (Table 47–1).

Similar to younger populations, the general principles of antimicrobial use in older adults include early and accurate diagnosis of infection, prompt decision to initiate broad-spectrum antibiotics, with equal attention to narrowing or discontinuation of antibiotics based on clinical progress, and identification of the implicating pathogens. In institutionalized older adults, infectious diseases often become a diagnosis of exclusion, leading to inappropriate antibiotic use. A paucity of clinical findings can pose a challenge to prompt initiation of an appropriate antibiotic regimen. Recent literature identifies the minimum criteria to initiate antibiotics, as well as surveillance definitions of infections in older long-term care residents (Table 47–2). Selection of a specific antimicrobial agent depends on the identification of the pathogen, known local susceptibility patterns, and pharmacokinetics and pharmacodynamics of antibiotics in older adults. Several physiologic changes, such as increased gastric emptying time, reduced gastric acidity, reduced lean body mass, increased fat, reduced albumin, reduced glomerular filtration, and/or reduced hepatic blood flow, can impact antibiotic dosing and response.

Like cardiovascular disease and cancer, in infection, prevention is key. Administration of influenza vaccine to older adults as well as health care workers lowers infection rates, saves lives, and reduces complications. Recommended vaccinations in older adults include yearly influenza vaccine, pneumococcal vaccine once after age 65 years, zoster vaccine, and Tdap if there is anticipated contact with a child less than 12 months of age. Tdap can be replaced by Td if there is no anticipated contact. Optimal management of chronic diseases, prevention of pressure ulcers, attention to infection prevention practices, such as hand hygiene compliance, appropriate gown and glove use, and judicious antibiotic usage, are all additional preventive measures to reduce infections and enhance quality of care in older adults in skilled nursing facilities.

General Principles in Older Adults

Urinary tract infection (UTI) remains the most common and the most overdiagnosed bacterial infection in older adults. Asymptomatic bacteriuria is frequent in older adults, both in the community and in health care institutions. Prevalence of asymptomatic bacteriuria ranges from 2% to 10% in the community and can be as high as 40% to 50% in skilled nursing facilities. Bacteriuria is nearly universal after 30 days of urinary catheterization. Asymptomatic bacteriuria with a paucity of typical infectious symptoms creates a challenging diagnostic dilemma for clinicians and frequently leads to overprescription of antimicrobials, particularly among patients who have a fever and an indwelling urinary catheter.

The risk factors for UTIs include prostatic hypertrophy with retention, prior history of recurrent UTIs, loss of the protective effect of estrogen on bladder mucosa, functional disability, cognitive impairment, and presence of a urinary catheter. Approximately 5% to 10% of skilled nursing facility residents have a urinary catheter. It is estimated that 50% of these people will have symptomatic catheter-associated UTI. UTI is a frequent cause of bacteremia in both community-dwelling and institutionalized older adults.

Prevention

Indwelling urinary catheter removal when appropriate, adequate nutrition and hydration, and reducing functional disability can reduce the frequency and adverse consequences from UTIs. Whenever possible, indwelling urinary catheters should be discontinued. If absolutely indicated, indwelling urinary catheters can be replaced with a condom catheter or intermittent straight catheterization when appropriate. Chronic indwelling urinary catheters require diligent health care worker attention to maintain a closed drainage system, and to keep the drainage bag positioned below the level of the bladder. Hand hygiene compliance, as well as glove use during any catheter manipulation, are important components of infection prevention. Routine urinalysis, bladder irrigations or catheter changes are not useful in UTI prevention.

Independence in ambulation reduces the risk of hospitalization from a UTI in skilled nursing facility residents. Low-dose prophylactic antibiotics can be considered in women with more than 3 symptomatic UTIs a year and no other urologic abnormalities. The role of prophylactic antibiotics in institutionalized older adults remains unclear; however, there is no indication that prophylactic antibiotics are effective. Although oral estrogens have not been shown to be effective in reducing UTIs, vaginal estrogens may be effective in community-dwelling older adults with recurrent UTIs. Anecdotal evidence suggests that cranberry juice may be effective in reducing asymptomatic bacteriuria, but its effectiveness in reducing symptomatic UTIs needs to be established.

Clinical Findings

Presenting findings of symptomatic UTIs among community-dwelling older adults include dysuria, increased urgency and frequency of urination, worsening of incontinence, hematuria, changed character of urine, and suprapubic discomfort. Pyelonephritis can present as fever, vomiting, and abdominal pain. A paucity of these signs and symptoms in older, frail, cognitively impaired skilled nursing facility residents is relatively common and poses a substantial and frequent clinical challenge. A change in the character of urine can be caused by either an infection or dehydration. Residents with cognitive impairment may not be able to communicate their symptoms. Fever can be infrequent. Despite these challenges, a careful history, physical examination, discussion with nursing and other ancillary staff, and rehydration can lead to reduced inappropriate antimicrobial usage in institutionalized older adults. Recent studies show that the triad of dysuria, change in character of urine, and recent mental status change is most predictive of a symptomatic UTI. Pyuria is usually present in the setting of both symptomatic and asymptomatic bacteriuria, hence pyuria alone cannot be diagnostic of UTI. A positive urine culture is usually required to accurately diagnose a symptomatic UTI. Although a positive culture alone is not adequate to define a symptomatic UTI, a negative culture in the setting of nonspecific findings can help to rule out UTI and reduce inappropriate antimicrobial use.

Treatment

Treatment of asymptomatic bacteriuria is not recommended and may even be harmful. Asymptomatic bacteriuria should only be treated with antibiotics prior to genitourinary procedures or surgery so as to prevent sepsis and bacteremia. Treatment of symptomatic UTI requires appropriate antimicrobial therapy, attention to hydration, and efforts to reduce dysuria. Choice of antimicrobial agent usually depends on the organism isolated from urine cultures and local susceptibility patterns. Broad-spectrum antibiotics targeting Gram-negative organisms and enterococci may be required if the patient appears significantly ill. Oral empiric therapy with trimethoprim/sulfamethoxazole is appropriate for most community-dwelling older adults. Fluoroquinolones can be used in the setting of known or likely trimethoprim-sulfamethoxazole resistance, or if a patient is allergic to sulfa. A combination of beta-lactam/beta-lactamase inhibitors, third-generation cephalosporins, or quinolones is appropriate initial choices if sepsis is suspected. Skilled nursing facility residents with urinary catheters may require a broader spectrum antibiotic regimen to incorporate coverage for resistant Gram-positive organisms such as methicillin-resistant Staphylococcus aureus (MRSA). Once identification and susceptibility test results are available, appropriate antibiotics can be selected and the treatment period determined.

The duration of antimicrobial therapy usually depends on the risk group. Older community-dwelling women with uncomplicated UTIs can usually be effectively treated with a 3-day regimen of trimethoprim-sulfamethoxazole or a quinolone. Ten to 14 days of treatment is usually required for men with a UTI, and for women with more severe symptoms, such as fever or pyelonephritis. For a catheter-associated UTI, a prompt response may indicate that 7 days of therapy is adequate.

General Principles in Older Adults

Hospitalization and deaths as a consequence of pneumonia, influenza, and other respiratory tract infections are common in older adults. Pneumonia in older adults can be community acquired, hospital acquired, or skilled nursing facility acquired. Rates of community-acquired pneumonia increase from 18.2 cases per 1000 person-years in those 65–69 years of age to 52.3 cases per 1000 person-years in those older than 85 years of age. Adults older than age 65 years bear a disproportionately higher brunt of influenza-associated deaths. Deaths among this age group also account for 90% of overall estimated average annual influenza-associated deaths with underlying respiratory and circulatory causes. Outbreaks of seasonal influenza are reported frequently, particularly in the skilled nursing facility setting.

Recent data suggest that pneumonia and respiratory tract infections surpass symptomatic UTIs as the most common infection among skilled nursing facility residents. These residents constitute 10% to 18% of all people hospitalized with pneumonia, corresponding to an average hospital cost of about $10,000 per admission. Aspiration pneumonia is common among this population and is often associated with oropharyngeal dysphagia and regurgitation of gastric contents. Dental plaque contains as many as 25,000 species of bacteria, many of which are likely capable of causing infections under the right conditions.

The risk factors for pneumonia include older age, male gender, history of aspiration, functional disability, history of smoking, chronic bronchitis or emphysema, heart disease, malignancy, neurologic conditions such as cerebrovascular diseases, recent surgery or intensive care unit stay, and presence of a feeding tube. With age, lung parenchyma loses its elastic recoil, there is reduced chest wall compliance, along with a loss of alveoli and alveolar ducts, all of which can increase the risk of pneumonia in the setting of functional disability and acute illness.

Prevention

The prevention strategies for respiratory tract infections are largely driven by risk factors. Yearly influenza vaccination by older adults and health care workers, along with pneumococcal vaccination of older adults can reduce the incidence and complications related to respiratory tract infections in the older population. Daily oral hygiene measures in combination with regular dental care have been shown to reduce the risk associated with aspiration. A systematic review of randomized controlled studies shows that appropriate oral hygiene can prevent respiratory infections in both older hospitalized and skilled nursing facility residents. Smoking cessation can also reduce bronchitis and respiratory infections.

Clinical Findings

Like most other infections, pneumonia in older adults manifests with atypical symptoms and signs such as fatigue, loss of appetite, functional decline, and new confusion. A quarter of this population with pneumonia may not mount a fever and is less likely to present with chills or pleuritic chest pain. Despite these limitations, an increased respiratory rate of greater than 25 breaths/min and hypoxia do portend poor prognosis and are useful tools for risk assessments. Clinical presentation should be confirmed rapidly with diagnostic testing, including chest radiographs, white cell count, and blood cultures. The yield from blood cultures may not be high, but if positive, may help drive appropriate antibiotic choice. Sputum studies are often not helpful or feasible in older adults.

The clinical presentation of influenza in older adults differs from younger adults with the older population having fewer respiratory symptoms. Cough, fever, and altered mental status predominate as presenting findings in older adults hospitalized with documented influenza. Older adults with influenza may have more gastrointestinal symptoms when compared with other respiratory viruses. Clinical presentation can be confirmed with diagnostic tests such as rapid antigen testing, viral cultures and serology, reverse-transcriptase polymerase chain reaction (PCR) testing, and immunologic assays. Rapid tests that can detect either influenza A or B or both are available and can detect influenza viruses within 30 minutes. The sensitivity and specificity of these tests increase when they are performed close to the illness onset.

Treatment

Several risk indices can predict outcomes and particularly mortality in older adults. These include the pneumonia severity index (a 20-item 2-step system more applicable to younger adults), CURB (4 items: confusion, urea, respiratory rate, and blood pressure), and modified CURB65 (confusion, urea, respiratory rate, blood pressure, and age ≥65 years) from the British Thoracic Society (Table 47–3), and SOAR (systolic blood pressure, age ≥65 years, oxygenation, and respiratory rate). These scoring systems can assist in making treatment recommendations, particularly toward the end of life. These scoring systems can also help identify older adults who can potentially be treated as outpatients.

Empiric therapy varies and depends on several host and environmental factors. For a community-dwelling older adult with no comorbidities, empiric treatment for community-acquired pneumonia includes a macrolide or doxycycline. For older adults with comorbidities such as chronic lung disease, chronic renal failure, diabetes, or immunosuppression, a respiratory quinolone or beta-lactum plus macrolide might be prudent. Older adults with skilled nursing facility-acquired pneumonia or nosocomial hospital-acquired pneumonia may require an initial parental antibiotic regimen such as pipercillin-tazobactam and vancomycin to cover for Pseudomonas, MRSA, and/or other nosocomial Gram-negative organisms. In choosing empiric antimicrobial therapy, local antimicrobial susceptibilities should be considered. Empiric therapy can be narrowed to target a specific pathogen once it has been identified.

General Principles in Older Adults

Gastrointestinal infections are fairly common in older adults. Deaths attributable to diarrheal diseases, like other infections, affect older adults disproportionately. Infection is generally by fecal–oral spread. Hypochlorhydria and achlorhydria, impaired gastric motility, inappropriate use of antibiotics, and waning immunity increase the predisposition to diarrheal illnesses in older adults. Viral gastroenteritis (caused by rotavirus, enteroviruses including Norwalk virus), bacterial gastroenteritis (caused by C. difficile, Bacillus cereus, Escherichia coli, Campylobacter, Clostridium perfringens, or Salmonella) and parasites are well-known causes of diarrhea in skilled nursing facilities.

Prevention

Compliance with hand hygiene guidelines remains key in preventing diarrheal illnesses particularly C. difficile-associated diarrhea and viral gastroenteritis such as norovirus. Yet, hand hygiene compliance rates remain poor in all settings. The use of alcohol-based hand rub has increased hand hygiene rates; however, its effectiveness may be diminished in certain diarrheal illnesses, particularly C. difficile diarrhea. Inappropriate antibiotic use should be reduced whenever possible and may be considered as a quality improvement process measure.

Clinical Findings

Patient history is often an initial guide to appropriate diagnostic evaluation. Information on food history and exposure, travel history, antimicrobial usage, use of immunosuppressive medications, frequency of diarrhea, tenesmus, and presence of blood and mucus in the stool should be obtained at the initial evaluation. History of exposure and symptoms in other family members or close contacts should be obtained as well. The physical exam should initially focus on the severity of the diarrheal illness including symptoms of dehydration, such as dry mucous membranes, fatigue, loss of appetite, change in mentation, reduced blood pressure, and tachycardia. An abdominal exam may be useful, although it can often be misleading because of a paucity of positive findings.

Treatment

Initial laboratory tests should include electrolytes and complete blood count. Stool studies for blood cells, stool culture, assessment for ova and parasites, and C. difficile toxin tests are clinically appropriate. Initial treatment should address dehydration and electrolyte disorders. If indicated, antimicrobials should be started promptly as well. In severe cases, vital signs should be closely monitored. Antimotility agents (loperamide, diphenoxylate) are frequently abused in older adults, and their use should be generally restricted.

Travelers’ diarrhea is generally self-limited. Adequate hydration and rest are often sufficient. Using prophylactic quinolones early is sometimes advocated to enhance quality of life during travel. Norovirus can present with nausea, vomiting, and diarrhea. Supportive treatment is key to early recovery. Antibiotic-associated diarrhea is common and is usually self-limited. However, C. difficile-associated diarrhea can often be severe and can lead to increased hospitalization, morbidity, and mortality. Diagnoses of C. difficile diarrhea should be prompt and treatment should include rehydration and removal of any implicating antibiotics, as well as treatment with either metronidazole or oral vancomycin. Use of oral vancomycin might increase the risk of vancomycin-resistant enterococci, but this risk should be balanced against the risk of poor outcomes from suboptimally treated C. difficile diarrhea.

General Principles in Older Adults

Older adults are at greater risk for skin and soft-tissue infections (SSTIs) owing to immunosenescence, multiple comorbid conditions (specifically diabetes, peripheral vascular disease, underlying skin conditions [eg, eczema, venous stasis, and edema]), and/or frequent trauma. Defective cutaneous immunity with aging increases the susceptibility of older adults to SSTIs. Additionally, older adults have a greater likelihood of being bed-bound and hence at an increased risk for pressure ulcers.

Common types of SSTIs in older adults include cellulitis, necrotizing fasciitis, frunculosis, carbunculosis, pressure ulcers, and surgical site infections (SSIs). The incidence of each of these SSTIs varies; 1% to 9% for cellulitis and 2% to 24% for pressure ulcers in long-term care facility residents. Older adults with SSTIs have a higher mortality, morbidity, and attributable hospital costs compared to younger adults with SSTIs. For example, older adults with SSIs are 3 times more likely to die as compared to younger adults with SSIs.

Prevention

The prevention of SSTIs varies by type. Cellulitis can be prevented by elevating the limb to aid adequate fluid drainage and prevent edema, using medical stockings, and treating macerated skin with topical antifungals to prevent recurrences. Similarly, furuncles and carbuncles can be prevented by practicing good hand hygiene, using antibacterial soap baths, and not sharing personal items, which will target infections by community-acquired methicillin-resistant S. aureus (CA-MRSA). Prevention strategies for pressure ulcers include frequent turning of bed-bound patients, good nutrition, and maintaining moist sacral skin. The principles of preventing of SSIs are very similar in older and younger adults including rigorous glucose control, preventing hypothermia, smoking cessation, and appropriate timing and dosing of prophylactic antibiotics.

Clinical Findings

Similar to other infections, SSTIs may manifest atypically in older adults with absence of fever and declining mental status as compared to SSTIs in younger adults. Infected pressure ulcers may go unnoticed in chronically bed-bound older adults.

Cellulitis presents with limb swelling, redness, and tenderness, whereas erysipelas involves the dermis causing a raised rash with sharp borders. Both cellulitis and erysipelas are usually caused by Streptococci species and S. aureus. Necrotizing fasciitis (type 1 and type 2) is a more severe form of SSTI that involves deeper subcutaneous tissue destroying the fascial planes. Type 1 is polymicrobial (E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and anaerobic bacteria), which commonly follows surgical procedures or patients with pressure ulcers, whereas type 2 is monomicrobial (usually Streptococcus pyogenes) and relatively common in older adults with diabetes. In both types of disease, the area is extremely tender and red, often with an exudate. A Gram stain of cells from the edge of the lesion can aid in diagnosis; however, a strong index of clinical suspicion is needed. Pressure ulcers are often polymicrobial and most commonly affect the sacrum, heels, elbows, and lower extremities. Diagnosis is clinical and treatment is dependent on the Gram stain results and culture of the ulcerative matter.

Scabies is a commonly missed diagnosis in older adults and hence responsible for outbreaks in skilled nursing facility residents. It is caused by a mite (Sarcoptes scabiei), which can cause normal scabies or crusted scabies, both of which can be difficult to diagnose in older adults. Normal scabies presents as raised, red, itchy lesions called burrows, typically in interdigital areas and ankles. Crusted scabies, on the other hand, presents more atypically (itching being present in only 50% of patients) in older adults owing to their lack of ability to scratch and mount an immune response. The burden of mites on the skin is much higher in crusted scabies than in normal scabies, hence there are more opportunities for outbreaks. Skin scraping and testing helps to confirm the diagnosis for crusted scabies as it is often confused with psoriasis or eczema.

Treatment

Both cellulitis and erysipelas are usually caused by Streptococci species or S. aureus and hence antimicrobial therapy targeting these organisms should be used. Antimicrobial choices include first-generation cephalosporins, vancomycin, and clindamycin. In cases where CA-MRSA is suspected (eg, a purulent SSTI), therapy with vancomycin, daptomycin, clindamycin, or linezolid should be considered. The decision between oral versus intravenous therapy generally depends on the severity at presentation and comorbidities. Necrotizing fasciitis can be especially severe in older adults. Surgical intervention is the gold standard diagnostic and treatment modality. In addition to antimicrobial therapy, it is important in infection management. For severe streptococcal or clostridial necrotizing fasciitis infections, clindamycin and penicillin are the antimicrobials of choice, whereas for mixed polymicrobial infections, a broad coverage for Gram-positive and Gram-negative bacteria and anaerobes is warranted. Because all pressure ulcers, like the skin, are colonized with bacteria, antibiotic therapy is not appropriate for a positive surface-swab culture without the signs and symptoms of infection. True infection of a pressure ulcer (cellulitis, osteomyelitis, or sepsis) is a serious condition, generally requiring broad-spectrum parenteral antibiotics, sometimes leading to surgical debridement in an acute-care facility.

Therapy for rashes without confirming the diagnosis of scabies unnecessarily exposes residents to the toxic effects of the topical agents. Because scabies can be transmitted by linen and clothing, the environment should be cleaned thoroughly. This includes cleaning inanimate surfaces, hot-cycle washing of washable items (clothing, sheets, towels, etc), and carpet cleaning. Topical permethrin cream with a repeat application after a week is the recommended treatment of choice for both kinds of scabies. Oral treatment with Ivermectin may be considered in patients with erosive skin from crusted scabies. Prevention is the key to avoiding outbreaks. Major preventive strategies include cleaning of fomites, adequate hand hygiene and personal protective equipment use by staff, retreatment of patients after a week to prevent reinfestation, and avoiding overcrowding in skilled nursing facilities.

General Principles in Older Adults

With the increasing number of total joint arthroplasties in older adults, the rate of prosthetic joint infections is expected to increase. Prosthetic joint infections in older adults are classified into early onset (within 3 months of surgery; usually caused by more virulent organisms like S. aureus and Gram-negative organisms) and late onset (3–24 months after surgery; caused by coagulase-negative Staphylococcus or Pseudomonas organism). Osteomyelitis (OM) is the second most common musculoskeletal infection after SSTIs in older adults, and manifests in a very similar way as in younger adults. Given the increasing frequency of falls (hence bone trauma) and underlying risk factors including peripheral vascular disease, diabetes, dental procedures, frequent surgeries, and prosthetic joint replacements, the incidence of OM is increasing in older adults. Age is also a very common risk factor for septic arthritis and is often associated with poor outcomes; a recent study showed a mortality of 9.5% in adults older than 80 years of age with septic arthritis. The risk factors for septic arthritis in adults 60 years of age and older include diabetes, neoplasm, and prosthetic joint and underlying joint disease. S. aureus is the most commonly isolated organism; however, group B streptococcus is very common in adults older than age 80. Of note, E. coli should be considered as a possible pathogen in older adults with UTIs and a prosthesis, because of the risk of urosepsis leading to seeding of the prosthesis. Similar to other infections, septic arthritis in older adults might manifest atypically with poor inflammatory response and is often mistaken as preexisting joint disease.

Clinical Findings

Prosthetic joint infections are difficult to diagnose because of the lack of an inflammatory response, especially in patients with delayed onset infections. A Gram stain and culture of joint fluid can be diagnostic. Additionally, the organism can be identified via biopsy of periprosthetic tissue (which might be performed when removing the prosthesis). Older adults with total joint arthroplasty can also present with OM, which usually manifests with loosening of the prosthesis. Elevated erythrocyte sedimentation rate (ESR) in OM differentiates mechanical loosening of a prosthesis from loosening of a prosthesis caused by OM. Similar to younger adults, OM in older adults can be acute, subacute, or chronic. Acute OM is most commonly caused by S. aureus. In older adults, it can occur after an injury, which can cause a closed or open trauma to the bone. Pain is a common presenting finding. Fever and chills may or may not be present.

Subacute OM in older adults is most commonly vertebral, which can be either pyogenic or tuberculous. S. aureus is the most common pathogen in cases of hematogenous spread; however, aerobic Gram-negative organisms are commonly found in men with UTIs and vertebral OM. Computer-guided tomography biopsy helps in definitive diagnosis and treatment based on the underlying organism. Chronic OM is considered if it persists for more than 6 weeks or recurs after initial treatment. In older adults, the 2 main types of chronic OM include mandibular (caused by periodontal disease or poor dentition) and sternal (manifesting weeks to months after an open heart surgery). Among the most common organisms in the mandibular OM are oropharyngeal flora; in sternal OM, S. aureus is the most commonly identified organism. Other causes of chronic OM in older adults include OM complicating pressure ulcers, diabetic foot, and ulcers from peripheral vascular disease.

Treatment

Treatment includes both antimicrobial therapy and surgical debridement. Whether the prosthesis is removed or not depends on the host’s factors, type of prosthesis, and the surgeon. Prevention is similar to preventing SSIs in general, as described previously. ESR is often elevated in OM. Therapy for OM involves extensive surgical debridement and removal of the prosthesis. Therapy for septic arthritis is notably delayed in older adults given their poor inflammatory response and presence of underlying joint disease (rheumatoid arthritis, gout, etc). The therapy for OM is very similar to younger adults and depends on the underlying organism(s). A bone scan is diagnostic in acute OM. Therapy is empiric parenteral antimicrobials directed against S. aureus, followed by specific antimicrobials based on cultures from bone in patients with open fracture or blood in closed trauma patients. These patients often need extensive surgical debridement and even amputations besides antimicrobial therapy.

General Principles in Older Adults

According to the most recent statistics available, there are now more than 1 million adults in the United States infected with HIV which causes AIDS. There are approximately 50,000 people who become newly infected with HIV each year in this country. Of those new infections, more than 4000 occurred in patients older than age 55 years, including 853 people 65 years of age or older. Most new infections occur in men who have sex with men as a risk factor; however, approximately 25% of new cases happen as a result of unprotected heterosexual contact, and therefore women are also at risk. Cumulatively, there are more than 80,000 people older than age 55 years who carry an AIDS diagnosis. Based on this epidemiologic data, it is clear that the HIV epidemic is having a significant effect on the aged population. As patients with established HIV infection age, there are several unique considerations and complications that can emerge, such as increased risk of cardiovascular disease and abnormalities of bone metabolism, as well as overall accelerated aging.

Prevention

It is thought that older patients are now more than ever at risk for contracting HIV as a result of increased sexual activity related to the availability of erectile dysfunction treatments and the overall lack of awareness of HIV risk factors. Furthermore, there is a dearth of HIV education geared toward older demographics. In general, older adults do not consider themselves to be a high-risk group for sexually transmitted diseases, and because women are not concerned about the risk of pregnancy, condom use is often limited. Therefore, taking a sexual history in older adults and educating patients regarding the risk of HIV transmission is important. Discussing the importance of condom use in older patients is critical not only for the prevention of HIV, but also to prevent other sexually transmitted infections such as syphilis, gonorrhea, and chlamydia.

Clinical Findings

The Centers for Disease Control and Prevention (CDC) now recommends that HIV screening tests be performed as part of routine health care up to the age of 64 years unless the prevalence of HIV in a particular community is documented to be less than 1 per 1000. A thorough sexual history is imperative with all older adults because patients who have high-risk behaviors should be screened on a yearly basis. Approximately 80% of patients who contract HIV will develop the acute retroviral syndrome, which consists of symptoms of fever, lymphadenopathy, pharyngitis, transient rash, myalgias, and, occasionally, aseptic meningitis. These symptoms tend to develop 2–4 weeks after an exposure. The screening test for HIV is a serology that detects antibodies that develop to antigens on the surface of the HIV structure, as well as capsid antigens. These antibodies tend to only fully develop over the course of 4–5 weeks. Therefore, if acute infection is considered, nucleic acid testing in the form of quantitative PCR for HIV is indicated. False-positive and false-negative tests can occur with any testing modality. Thus, HIV infection is only able to be confirmed with both a positive HIV enzyme-linked immunosorbent assay and Western blot test that demonstrates at least 2 bands, including p24, gp41, or gp120/160.

Occasionally patients may present with immune dysfunction related to AIDS if infection is of long standing and undiagnosed. Therefore, HIV screening should be performed in older patients with unexplained thrush, recurrent bacterial pneumonia or any opportunistic infection, such as Pneumocystis pneumonia. The development of opportunistic neoplasms, such as B-cell lymphoma, may also indicate the presence of HIV infection.

Complications

The development of AIDS-associated opportunistic infections and neoplasms are the most well-known complications of HIV infection. However, with effective antiretroviral therapy and earlier diagnosis and treatment, many patients are now leading healthy active lives with close-to-normal immune function. Many of the health problems faced by patients infected with HIV are now related to adverse events related to therapy or the long-term effects of HIV infection independent of immune dysfunction. The D:A:D study demonstrated that there is an excessive risk of myocardial infarction in patients with HIV receiving antiretroviral therapy. Others have shown that patients with HIV infection have a much higher risk of osteoporosis, which is likely related to the effects of certain antiretroviral agents on bone metabolism. There also is an increased risk of non–AIDS-defining cancers in patients with HIV infection. When colon cancer screening is performed, adenomas were found more commonly in HIV-infected patients compared to controls in one study. Human papillomavirus-related rectal cancer is the most common non–AIDS-related neoplasm found in patients with HIV infection. Therefore, routine health care maintenance screening in an aging population with HIV infection remains of paramount importance.

Treatment

Since the advent of the common use of highly active antiretroviral therapy (HAART), the mortality associated with HIV and AIDS has decreased dramatically. However, there are about 15,000 patients per year who die with HIV infection in the United States. When stratifying for survival by age group, those older than age 55 years have a significantly worse prognosis than younger patients, according to epidemiologic data collected by the CDC. This excess mortality has been confirmed in other studies that have shown that the risk of death related to comorbidities is as high as 72% in those older than the age of 50 years compared with 36% for patients up to age 30 years. Because retrospective studies and some prospective trials have demonstrated that patients who initiate HAART early in the course of their infection have fewer non–AIDS-related comorbid complications, the most recent treatment guidelines suggest initiating antiretroviral therapy for all patients with HIV infection regardless of CD4 cell count. Preferred initial combination therapy consists of 2 nucleoside reverse transcriptase inhibitors combined with either a nonnucleoside reverse transcriptase inhibitor, protease inhibitor, or integrase inhibitor. Adherence to antiretroviral is critical because of the risk for the development of resistant virus if exposed to subtherapeutic levels of drug. One study demonstrated significantly better adherence among patients who were older than age 50 years (87.5%) compared with younger patients who took 78.3% of their medication dosages. Older patients who adhered poorly to their regimen were found to have abnormalities on neuropsychological testing. Because older patients are at higher risk for drug interactions and complications of therapy, including toxicity related to bone loss, kidney disease, and cardiovascular disease, intensified monitoring in this group of patients is important.