Infections in the Elderly

General

PUS Þ Pneumonia, UTI’s and Skin and Soft tissue infections are the primary infections of the elderly

Infections in our aged population represent are the most common reason for hospitalization
infections are responsible for 54% of the acute medical problems in the nursing home, 63% of the deaths and 17-48% of the hospital transfers

Why do the elderly have more infections?

(1) Decremental anatomic and physiologic changes with aging skin elasticity, gastric acidity, chest wall expansion and alveolar elasticity, prostatic secretions, cognitive impairment

(2) ß Cell mediated and humoral immunity

ß delayed type hypersensitivity, ß IL-2 and IFN-gamma; "Clonal exhaustion" Þ ß repertoire of Abs

ß T cell response to mitogens; ß Ab response to primary immunizations

ß response to cortisol in elderly (cortisol does not Ý WBC as much as it does in the young)

Ý IL-6, TNF and IgA

(3) Chronic illnesses and immobility; malnutrition a factor; Immunosuppressive and sedative drugs

(4) Communal living (common dining hall, common staff); invasive devices

Fever in the elderly – often absent; altered fever response with age:

(a) disturbed thermal homeostasis – temp perception, CNS

(b) quantitative and qualitative difference in response to IL-1 and TNF

(d) medications (antipyretics, corticosteroids, NSAIDS)

(e) ß sensitivity of the hypothalamus

(f) lower basal body temperature

(g) malnutrition and chronic debility

(h) co-existing medical conditions

Most common infections in the elderly

In order:

(1) Urinary tract infections (prostatitis, prostatic abscess, pyelonephritis)
(2) Pneumonia – aspiration, community acquired
(3) Tuberculosis – reactivation vs nursing home acquired infection
(4) Pressure sores
(5) Bacteremia
(6) Infective endocarditis
(7) Infectious diarrhea
(8) Meningitis
(9) Septic arthritis
(10) HIV Infection

Pneumonia Community Acquired Pneumonia (CAP) Vs Hosptial Acquired Pneumonia (HAP, or nosocomial pneumonia)

General – CAP occurs 50 times more frequently in persons older than 75 years than in adults < 20 years old

Poor nutrition, obtundation, neuromuscular disease, chronic obstructive pulmonary disease, and Ý incidence of aspiration

6^th most common cause of death in the elderly

Risk Factors – 19 in Total and each is assigned a score (in italics). A score of 90-130 is considered high risk.

(1) Age – Age

(2) Nursing home – 10

(3) Cancer – 30

(4) Liver disease – 20

(5) CHF – 10

(6) CVA – 10

(7) CRI – 10

(8) RR > 30 – 10

(9) BP > 90 – 20

(10) change in mental status – 20

(11) Temp > 40 – 15

(12) Pulse > 126 – 10

(13) pH < 7.35 – 30

(14) BUN> 10.7 – 20

(15) Sodium < 130 – 20

(16) Glucose > 139 – 20

(17) Hct < 30% – 10

(18) pO2 < 60 – 10

(19) Pleural effusion – 10

Etiologies – S. pneumoniae

Nursing Home Þ S. aureus, GNRs, anaerobes (due to aspiration), TB

Chronic Renal Insufficiency Þ Legionaries

Others Þ Influenza A and B, RSV, parainfluenza, H. influenzae, Moraxella catarrhalis, B pertussis

Symptoms – Confusion, obtundation, no fever and lack of cough

Diagnosis – Gram stain, culture, ABGs, CXR, Transtracheal aspiration, BAL, nasopharyngeal swab

Treatment – 3^rd generation cephs; b-lactam b-lactamase inhibitors vs carbapenems or quinolones; amantadine

Resistance – 30% of pneumococci are penicillin resistant; b-lactamase producing enterics

Prevention – pneumococcal polysaccharide vaccine (23-valent) Þ Ý production of IgG but not IgA; still get infection but less morbidity and mortality; influenza vaccine (60-70% effective), Ý immunization

Tuberculosis

Incidence – Ý incidence in the elderly; rate of TB reactivity doubles after 6 months in the nursing home

Cause – Reactivation due to declining cellular immunity; may be due to new infection

Presentations – Atypical; can present like lymphoma, giant cell arteritis or Ca

Prevention – INH for recent converters (10% risk of recent converters to develop TB); do not need to treat people with watch for hepatotoxicity

Urinary Tract Infections

Bacteruria – Ý with age, 10% of men and 20% women will have bacteruria; do not treat asymptomatic bacteruria

Predisposing factors: urinary catheters, prostatic hypertrophy, vaginal atrophy, incontinence, condom catheters, medications, estrogen depletion

Etiology – E. coli, Proteus, Klebsiella, Pseudomonas, enterococci, Staphylococcus aureus.

Treatment + Prevention - antibiotic resistance a real problem; AVOID INSTRUMENTATION

Pressure Sores

Progression - Immobility->ischemia->necrosis; large deep deficits may be masked by small holes

10.4% occurrence rate after one year in the nursing home

Stages: I – redness; II – breakdown; III – full thickness skin loss; IV – muscle and bone

Cellulitis, osteomyelitis (contiguos), bacteremia

Etiology – P. mirabilis, Bacteroides fragilis*, Staphylococcus aureus

Diagnosis – tissue biopsy or needle aspiration

Treatment – antibiotics; Relieve pressure, nutrition, debridement; do not use donuts or apply iodine

Infective Endocarditis (IE)

Indicence – Ý survival of patients with valvular heart disease, prosthetic heart valves, implanted devices predisposes to IE

Diagnosis – Difficult to diagnose, nonspecific symptoms

Etiology – S. bovis, Enterococcus

Complications - CHF, MI, AV block, ring abscess and embolization Þ result in a higher mortality rate

Septic Arthritis

Immunological defects in the setting of joint abnormalities
Knee > wrist > shoulder
Septic arthritis associated with osteomyelitis
Management with surgeon, radiologist, primary care physician

Meningitis

Incidence – Elderly have a higher incidence and case fatality rate (54.8%)

Pathogens – S. pneumoniae*, Listeria monocytogenes, GNRs, M. tuberculosis

Presentation – Atypical with Ý incidence of complications

Gastrointestinal infections

Etiology - 51% of deaths caused by diarrhea in the nursing home
Salmonella due to achlorhydia, antibiotics and meds
Staphylococcal food borne illness

HIV in Elderly

more likely to not be diagnosed in this population
associated with increased incidence of mortality; 10% of all AIDS patients are > 50 years old
dementia; common presenting illness
viral load often different

Prevention of Infection in Elderly

Immunize with Influenza and pneumococcal polysaccharide vaccines; Þ Pneumovax is effective in reducing bacteremic pneumococcal pneumonia in low risk adults (66 and 83%)

Tetanus and diptheria booster every ten years

Amantadine or rimantadine (fewer CNS side effects) in outbreaks of influenza A

Infection control in employees influenza, Hepatitis B and other blood borne pathogens, PPD, education sessions