Treatment And Prevention

The CDC in conjunction with the American Thoracic Society in 1994 modified its TB treatment recommendations because of the rise of MDR-TB cases (see Table 1)

(30). However, the CDC also recommends that if the frequency of isoniazid resistance is 4% or less in a given community or if the population in question has a low risk for drug resistance, the empiric four-drug regimen is not necessary. Although there has been much concern over the emergence of drug-resistant isolates of Mtb and the complex issue of TB in HIV-infected persons, the vast majority of cases of TB in the elderly in the U.S. is fortunately caused by drug-sensitive strains of Mtb. TB in older persons is an easily treatable and preventable infection and a highly curable disease. As

Table 1

Treatment Regimens and Tuberculosis0

Drugs Frequency

Option 1

Isoniazid, rifampin, Daily pyrazinamide and ethambutol or streptomycin for 8 wk6 followed by isoniazid and rifampin for Daily or 2-3 times weeklyc

16 wk (for susceptible strains)

Option 2

Isoniazid, rifampin, Daily pyrazinamide and ethambutol or streptomycin6 for 2 weeks followed by the same drugs for 6 weeks6 Twice weeklyc then isoniazid and rifampin Twice weeklyc for 16 wk

Option 3

Isoniazid, Three times weeklyc rifampin, pyrazinamide and ethambutol or streptomycin for

24 wk6

6 In areas where primary isoniazid resistance is less than 4%, omit fourth drug; streptomycin is not recommended for the elderly. c Intermittent dosing should be directly observed.

evidenced by several studies most cases of active TB in the elderly result from reactivation of a latent infection. These individuals presumably acquired the infecting organism during the time prior to the availability of effective antituberculous chemotherapy. Hence, unless the older patient is from a country with a high prevalence of drug-resistant Mtb, had previously been inadequately treated with Mtb chemotherapy, or had acquired the infection from a known MDR-TB contact, the overwhelming number of TB cases in the elderly will be highly susceptible to isoniazid and rifampin. Hence, once TB is suspected, appropriate diagnostic tools have been utilized, and reasonable caution exercised to ensure low probability of Mtb drug resistance, antituberculous chemotherapy with standard doses of isoniazid (300 mg/d) and rifampin (600 mg/d) can be instituted (10). An effective alternative for older patients is a regimen commencing with isoniazid (300 mg/d), rifampin (600 mg/d), and pyrazinamide (30 mg/ kg/d up to 2 g) for 2 mo, followed by 4 mo of isoniazid and rifampin. This 6-mo regimen is sufficient for disease at any site, with the exception of tuberculous meningitis, for which treatment with isoniazid and rifampin should be continued for one full yr. Some authorities also recommend that miliary and bone and joint disease be treated for one full year. Although the more intensive, shorter duration, antituberculous drug regi-

mens can generally minimize treatment non compliance and development of drug resistance, particularly when administered by directly observed therapy (DOT), the potential for drug toxicity limits its use in older patients.

Elderly persons are at greater risk for hepatic toxicity from isoniazid; however, this risk is relatively low in frequency and mild in severity. It is recommended that clinical assessments as well as baseline liver function tests be performed prior to the initiation of isoniazid and rifampin (and pyrazinamide) therapy to older persons; periodic laboratory monitoring seems a prudent practice particularly in the frail old who may not be able to communicate warning symptoms of drug toxicities. A rise in the serum aminotransferase (SGOT) level to five times above normal or clinical evidence of hepatitis necessitates the prompt discontinuation of isoniazid (as well as other hepatotoxic drugs); these drugs may subsequently be resumed at lower doses and gradually increased to full doses as tolerated. Relapse with drug rechallenge will require trial of an alternative regimen.

Heightened awareness of MDR-TB has prompted public health agencies to institute strict TB identification, isolation, treatment, and prevention guidelines (31). The TB infection control program in most acute care as well as long-term care facilities should consist of three types of control measures: administrative actions (i.e., prompt detection of suspected cases, isolation of infectious patients, and rapid institution of appropriate treatment), engineering controls (negative-pressure ventilation rooms, high efficiency particulate air [HEPA] filtration, and ultraviolet germicidal irradiation, and personal respiratory protection requirements (masks). While instituting such infection control measures in elderly TB patients, clinicians should be cognizant of the presence of concomitant chronic conditions and functional disabilities that often require more assistance and care, as well as the importance of minimizing prolonged isolation or physical incarceration.

Treatment of TB infection (previously referred to as prophylaxis) with isoniazid (300 mg/d) for a minimum of 6 mo is currently recommended for older persons infected with Mtb (as evidenced by a positive tuberculin test) and associated high-risk conditions, as well as persons with tuberculin skin test conversions (see Table 2) (31). A 12-mo regimen of isoniazid is recommended for persons with chest radiographic evidence of prior untreated TB infection and in persons coinfected with HIV.

Tuberculin skin testing is recommended using the two-step technique for all older persons admitted to nursing homes; comprehensive geriatric assessment and complete physical examination of the elderly should also ideally incorporate tuberculin screening in their protocol. For health care professionals, staff, and administrators of facilities providing care to the elderly, the following is a brief summary of the Advisory Committee for Elimination of TB's published recommendations (32).

6.1. Surveillance

1. All new residents on admission and all employees should receive a two-step tuberculin test.

2. All persons with a tuberculin skin test reaction of 10 mm or more of induration should receive a chest radiograph to identify current or past tuberculous disease.

3. Skin-test-negative employees or volunteers having contact (of 10 or more hours per week) with patients should periodically have repeat skin tests, the frequency depending on the risk of tuberculous infection at that facility.

Table 2

Criteria for Positive Tuberculin Skin Reaction"

Skin test criteria (mm induration) Population at risk

>5 mm

Persons with known or suspected HIV infectionb

Close contacts of person(s) with infectious tuberculosisb

Persons with chest radiographs consistent with tuberculo-

sis (e.g., fibrotic changes)b

>10 mm

Recent converters (>10 mm with >6 mm increase within 2

yr; >15 mm for those age > 35 yr)b

Intravenous drug uses known to be HIV seronegativeb

Persons with certain risk factors; silicosis; gastrectomy;-

Jejunoileal bypass; >10% below ideal body weight;

chronic renal failure; diabetes mellitus; corticosteroid

and other immunosuppressive therapy; hematologic

and other malignancies (alcoholics are also considered

high risk)b

Foreign-born from country with high tuberculosis


Medically underserved low-income populations (homeless,

African-Americans, Hispanics, Native Americans)

Residents of long-term care facilities (nursing home, cor-

rectional institutions)c

None of the above factors > 15 mmc

a Reference (31).

b Chemoprophylaxis recommended for all persons regardless of age. c Chemoprophylaxis recommended for persons less then 35 yr. HIV = human immunodeficiency virus.

a Reference (31).

b Chemoprophylaxis recommended for all persons regardless of age. c Chemoprophylaxis recommended for persons less then 35 yr. HIV = human immunodeficiency virus.

4. Repeat skin tests should be performed for tuberculin-negative persons after any suspected exposure to a documented case of active TB.

5. Staff and patients with TB infection or disease should be assessed for HIV infection.

6.2. Containment

Persons with confirmed or suspected infectious TB do not require isolation precautions providing the following conditions are met:

1. Chemotherapy is begun promptly at the time of confirmation or suspicion of diagnosis.

2. Current and recent contacts are evaluated and given appropriate therapy.

3. New contacts can be prevented for a 1-2 wk period.

In the event that these conditions cannot be fulfilled, and in case of homelessness, suspected or known history of noncompliance, MDR-TB, and illicit drug use, the local health department (that should be informed of all suspected or proven TB cases) facilitates methods to achieve appropriate respiratory isolation.

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