Legal Eagle Eye Newsletter for the Nursing Profession(5)11 Nov 97

   Quick Summary: The CDC has new Draft Guidelines for Infection Control in Health Care Personnel, 1997 re tuberculosis - strongly recommended for all hospitals.

  Prevention of Nosocomial Transmission of Selected Infections

  Tuberculosis

   Nosocomial transmission of tuberculosis (TB) is well documented, but such transmission in the United States is generally low. However, the risk may be increased in health care facilities located in communities with (a) high rates of HIV; (b) high numbers of persons from TB-endemic countries; and (c) communities with a high prevalence of TB infection. In some areas in the USA, the incidence and prevalence of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) also have increased, and nosocomial MDR-TB outbreaks have occurred. The increased risk of occupational acquisition of TB by health care personnel has been reported for decades and it dramatically decreased following the introduction of effective antituberculous drugs. Skin-test conversion rates among health care personnel following routine skin testing have ranged from 0.11 % to 10%. Among health care personnel with known exposure to an infectious TB patient or involved in prolonged nosocomial outbreaks of TB, the skin-test conversion rates have ranged from 18% to 55%.

   The transmission of TB in health care facilities has been primarily caused by incomplete implementation of recommended TB infection control measures. In 1994, CDC published detailed recommendations for the prevention of transmission of TB in health care settings, Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health Care Facilities, 1994. A summary of the recommendations pertaining to personnel health follow.

a. Strategies for prevention of transmission of TB. The risk of transmission of TB to or from personnel in a health care facility varies according to the type and size of the facility, the prevalence of TB in the community, the patient population served by the facility, the occupational group the person represents, the area of the facility where the person works, and the effectiveness of the facility's TB-control program. A detailed risk assessment is essential in identifying the nature of TB control measures that are appropriate for a particular facility as well as for specific areas and occupational groups within a facility. A risk assessment should include the following:

(a) Review of the community TB profile; (b) review of the number of TB patients who were treated in each area of the facility; (c) review of the drug-susceptibility patterns of TB isolates from patients treated in the facility; (d) an analysis of purified protein derivative (PPD) skin-test results of health care personnel by work area or occupational group; (e) an evaluation of infection control parameters including isolation policies, laboratory diagnostic capabilities, and antitubercular therapy regimens; (f) an observational review of TB infection control practices; and (g) evaluation of the function and maintenance of environmental controls.

   Transmission of TB can be minimized by developing and implementing an effective TB-control program based on a hierarchy of controls, namely, (a) administrative controls, (b) engineering controls, and (c) personal respiratory protection.

b. TB screening program. A tuberculosis screening program for personnel is an integral part of a health care facility's comprehensive TB control program. The screening program should be based on the facility specific risk assessment.

   Baseline PPD testing of all personnel [including personnel with a history of Bacille Calmette-Guerin vaccination (BCG)] during their pre-employment physical examination or when applying for hospital privileges will identify personnel who have been previously infected. For the baseline testing a two-step procedure can be used to minimize the likelihood of confusing reactivity from an old infection (boosting) with reactivity from a recent infection (conversion). Criteria used for interpretation of a PPD test reaction may vary depending on the (a) purpose (diagnostic or epidemiologic) of the test; (b) prevalence of TB infection in the population being tested; (c) immune status of the host; and (d) previous receipt of TB immunization. Detailed recommendations have been published for performing and interpreting skin tests.

c. Follow-up evaluation. The risk assessment will identify which health care personnel have the potential for exposure to M. tuberculosis and determine how frequently they should receive PPD testing. At minimum, annual PPD testing is indicated for personnel with the potential for exposure to TB.

   It is also important to obtain an initial chest x-ray on personnel with positive PPD-test reactions, documented PPD-test conversions, or pulmonary symptoms suggestive of TB. There are no data to support the use of routine chest x-ray examinations on asymptomatic PPD test-negative personnel. In addition, personnel who have positive PPD-test reactions but also received adequate preventive treatment do not need repeat chest films unless they have pulmonary symptoms suggestive of TB. Repeat chest x-ray examinations of such persons have not been shown to be beneficial or cost-effective in monitoring persons for development of disease. However, more frequent monitoring for symptoms of TB may be considered for personnel who convert their PPD test; those persons, if infected, are at increased risk of developing active TB (e.g., HIV-infected or otherwise severely immunocompromised persons).

d. Management of personnel after exposure to TB. It is important to perform PPD tests on personnel as soon as possible after TB exposures are recognized. Such immediate PPD testing establishes a baseline by which to monitor subsequent PPD tests. A PPD test, performed 12 weeks after the last exposure, will indicate if infection has occurred. Persons already known to have reactive PPD tests need not be retested. Personnel with evidence of new infection (i.e., PPD-test conversions) need to be evaluated for active TB. If active TB is not diagnosed, preventive therapy should be considered.

e. Preventive therapy. For workers with positive PPD tests who were likely exposed to drug-susceptible TB, preventive therapy with isoniazid is indicated, unless there are contraindications to such therapy. Alternative preventive regimens have been proposed for persons who have positive PPD tests following exposure to drug-resistant TB.

f. Work restrictions. Personnel with active pulmonary or laryngeal TB may be highly infectious; exclusion from duty is indicated until they are noninfectious. If personnel are excluded from duty because of active TB, the facility should have documentation from their health care providers that personnel are noninfectious before they are allowed to return to duty. The documentation needs to include evidence that (a) adequate therapy is being received; (b) the cough has resolved; and (c) three consecutive sputum acid-fast-bacilli (AFB) smears, collected on different days, are negative. After personnel resume duty and while they remain on anti-TB therapy, periodic documentation from their health care providers is needed to show that effective drug therapy is being maintained for the recommended time period and that their sputum AFB smears continue to be negative.

   Work restrictions are not necessary for personnel receiving preventive treatment for latent TB (positive PPD test without active disease) or for personnel with latent TB who do not accept preventive therapy. However, these personnel should be instructed to seek evaluation promptly if they develop symptoms suggestive of TB.

g. Considerations for Bacille Calmette-Guerin Vaccine. BCG has not been routinely used in the United States to protect health care personnel. Nevertheless, because of the resurgence of TB in the United States and new information about the protective effect of BCG, the role of BCG vaccination in the prevention and control of TB in the country has been re-evaluated. The following is a summary of the joint statement by the Advisory Council for the Elimination of Tuberculosis and ACIP regarding the use of BCG in health care personnel.

   Two recent meta-analyses of 18 and 26 BCG studies, respectively, indicate that the efficacy of BCG vaccine in preventing serious TB in children is high (80%) and suggested 50% efficacy in adults, however, the protective efficacy of the vaccine in adolescents and adults, including health care personnel and HIV-infected children and adults, has not been determined.

   BCG vaccination may be indicated for health care personnel in a few geographic areas where the prevalence of MDR-TB is high, transmission of TB is likely, and TB infection control measures have not been successful in controlling nosocomial transmission. BCG vaccination often results in local adverse effects (such as muscular soreness, erythema, purulent drainage, axillary or cervical lymphadenopathy for as long as 3 months after vaccination); serious long-term complications (such as musculoskeletal lesions, multiple lymphadenitis, and disseminated BCG disease) are infrequent. The safety of BCG vaccination in immunocompromised populations (i.e., immunocompromised from immune deficiency diseases, HIV infection, leukemia, lymphoma, or generalized malignancy, or immunosuppressed as a result of therapy with corticosteroids, alkylating drugs, antimetabolites, or radiation) has not been determined by adequate epidemiologic studies. However, because of the possibility of disseminated BCG infection in such persons, BCG vaccination is not recommended for immunocompromised personnel.

   PPD testing is not contraindicated for persons who have received BCG vaccine and can be used to support or exclude the diagnosis of infection with M. tuberculosis. PPD-test reactivity caused by BCG vaccination wanes with time and is unlikely to persist 10 years after vaccination in the absence of infection with M. tuberculosis. After a person has been vaccinated with BCG, the presence or size of a PPD-test reaction cannot be used as a predictor of BCG vaccine efficacy in the vaccine recipient, or as a determinant as to whether the reaction is caused by infection with M. tuberculosis or the prior BCG vaccination. However, a BCG-vaccinated person who has a PPD test reaction of 10 mm induration is considered infected with TB, especially if the vaccinee is a contact of a person with infectious TB, is from a country with high prevalence of TB, or is continually exposed to populations in which the prevalence of TB is high.

FEDERAL REGISTER, September 8, 1997

Pages 47275 - 47327.