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Fighting the TB dragon.

As the battle to stem the transmission of tuberculosis rages, OSHA and the CDC have joined forces to increase awareness of this adversary and improve occupational safety practices.

ON OCT. 12, 1993, the Centers for Disease Control and Prevention (CDC) released new draft guidelines--replacing previously published recommendations--on the prevention of transmission of tuberculosis.(TB) in health care facilities.|1~ Only 4 days earlier, the Occupational Safety and Health Administration (OSHA) released an enforcement policy and inspection procedures concerning occupational exposure to TB.

Coincidence? Absolutely not. Since OSHA can provide the bite for the CDC's bark (the CDC can only offer recommendations), the two groups have decided to work together to help protect health care workers from this dangerous disease. OSHA is enforcing the already existing CDC recommendations primarily through the use of the general duty clause as part of employers' responsibilities to protect employees from occupational hazards, set forth in the Occupational Safety and Health Act of 1970.

* Why the TB resurgence? TB transmission continues to pose a monstrous threat to health care workers and patients alike. The situation can be attributed, at least in part, to the heavy emphasis placed on energy conservation during the '70s, which led to the design of poorly ventilated buildings. Other contributing factors to the current TB outbreaks are the AIDS epidemic, poverty, overcrowding in big cities, and a dramatic reduction in public health dollars spent to curb this disease once it was thought to be under control. Perhaps most troublesome are the dangerous multidrug-resistant strains of Mycobacterium tuberculosis (MDR TB), which are largely an outgrowth of people with unrecognized pulmonary TB not receiving effective therapy. While some people begin treatment, they fail to follow it through to completion.

* CDC's control hierarchy. The CDC's TB infection control program follows the premise that active TB must be recognized early, contained, and treated so it does not become a source of infection for others. Throughout the process, the CDC stresses the need for all health care workers to observe a hierarchy of control measures.

The first and most important level of the CDC's hierarchy supports the use of administrative measures designed to reduce employees' risk of exposure to persons with infectious TB. This level includes developing company policies to insure the rapid detection, isolation, evaluation, and treatment of individuals likely to have TB. Such employee work practices can streamline the prevention process, the CDC believes. Lack of attention on the front end will lead to almost certain defeat of infection control.

The second level of the hierarchy is the use of engineering controls--mechanisms that help to reduce the concentration in the environment of infectious droplet nuclei containing viable tubercle bacilli. The CDC's philosophy: Why continue to fight the alligators if we can eliminate them permanently by draining the swamp? Such controls include using 100% exhaust ventilation in TB isolation rooms so that air is exhausted to the outside rather than recirculated. Another alternative is to use directional airflow, so that air is pulled away from areas adjacent to infectious sources.

The third level of the hierarchy urges workers to use personal respiratory protective equipment whenever it is uncertain that engineering controls will provide adequate protection. A phlebotomist entering an isolation room to draw blood from a TB patient who has been coughing would be a prime candidate for this equipment, for example. Respirators should also be worn by workers performing cough-inducing procedures (e.g., endotracheal intubation, diagnostic sputum induction) on TB patients as well as by those who transport TB patients in emergency vehicles.

* Respiratory protection. An effective respiratory protection device, according to the CDC, is one that will filter particles 1 ||micro~meter~ in size in an unloaded state with a filter efficiency equal to or greater than 95%. It must also have a face-seal leakage of no more than 10%.

To date, the only respirator that meets these criteria is the NIOSH-certified, powered, half-mask respirator with HEPA filter, which fits a variety of facial sizes and characteristics. (Note: Face-piece fit should be checked by the user every time the respirator is worn.) In addition to wearing this device, the CDC urges health care facilities to implement a comprehensive respiratory protection program that incorporates written standard operating procedures; medical screening of workers required to wear the device; applicable employee training; face-seal tests and checks; and the inspection, cleaning, maintenance, and storage of respirators.

* More safeguards. As further protection for health care workers, the CDC is strongly urging that a number of specific measures be taken in every health care environment to significantly reduce the risk of TB transmission. How many of the following safety practices are observed in your health care facility?

* Write a TB infection control program that documents all aspects of TB control and clearly explains the hierarchy of controls.

* Assign supervisory responsibility of this program to persons with expertise in infection control and occupational health/engineering.

* Evaluate the risk of TB transmission in all areas of your facility. Every area should be classified as having either low, intermediate, or high risk, based on the number of infectious patients admitted to that area as well as on the number of health care worker purified protein derivative (PPD) test conversions, which may indicate patient-to-worker transmission. Says the CDC, the Mantoux test is the most reliable and best standardized technique for TB testing.

* Develop and institute policies to ensure the early detection of infectious patients. An example would be a symptom screen for every patient upon admission to the ER. Patients demonstrating TB symptoms should then undergo radiologic and bacteriologic screening.

* Promptly initiate TB precautions in outpatient settings by, for example, placing TB patients in separate waiting areas and requiring them to either wear a mask or cover their mouths and noses with tissues when coughing or sneezing.

* Isolate infectious inpatients until they have been placed on effective therapy and show clinical improvement, i.e., no evidence of acid-fast bacilli on sputum smears taken on 3 consecutive days.

* Provide engineering controls such as altered ventilation in every health care facility. TB isolation rooms should be under negative pressure relative to the hallway and all air should be exhausted to the outside without being recirculated.

* Mandate that workers wear respiratory protection in high risk areas, such as TB isolation rooms, where administrative and engineering controls are likely to prove inadequate.

* Perform cough-inducing procedures on TB patients only when absolutely necessary and then only in a TB isolation room or other area that provides local exhaust.

* Provide TB training applicable to their jobs to all health care workers when they are first hired and periodically thereafter.

* Establish a TB screening and prevention program for all workers. Personnel who test positive for PPD must be identified quickly, evaluated to rule out active TB, and treated, if indicated. Also, workers should be warned that if they are HIV positive, they are high-risk candidates for TB infection.

* Restrict workers with active pulmonary TB from working until they are no longer infectious.

* Lab specifics. For recommendations specific to the clinical lab, the CDC directs readers to Biosafety in Microbiological and Biomedical Laboratories.|2~ According to this booklet, American Thoracic Society (ATS) Level I labs that prepare acid-fast smears and culture sputa or other specimens for TB can conduct these tests at Biosafety Level 2 as long as they first treat the specimens in a Class I or II biological safety cabinet. ATS Level II and III lab practices, however, which includes propagation and manipulation of M. tuberculosis cultures, have been moved to Biosafety Level 3 practices, containment equipment, and facilities. (For a review of the ATS levels of service, see "Tuberculosis alert: An old killer returns," MLO, May 1993, Table 1, p. 54.) This CDC/NIH booklet continues: "Properly maintained biological safety cabinets are used (Class II or III) for all manipulation of infectious material. Outside of a biological safety cabinet, appropriate combinations of personal protective equipment are used (e.g., special protective clothing, masks, gloves, face protection, or respirators) in combination with physical containment devices (e.g., centrifuge safety cups, sealed centrifuge rotors . . .). Protective lab clothing such as solid-front or wrap-around gowns, scrub suits, or coveralls must be worn in, and not worn outside, the lab. Reusable laboratory clothing is to be decontaminated before being laundered. Respiratory protection is worn when aerosols cannot be safely contained (i.e., outside of a biological safety cabinet . . .)."

* OSHA adds teeth. OSHA's Oct. 8 special enforcement policy, which will be the basis for the group's inspection criteria, became effective immediately, except for a 90-day implementation period for respiratory protection requirements.|3~ Among facilities being targeted for inspection: all health care settings, correctional institutions, homeless shelters, long-term care facilities for the elderly, and drug treatment centers. At this time, inspections will be conducted only in response to employee complaints or as part of OSHA's industrial hygiene compliance inspections where the CDC has identified workers as having a greater incidence of TB infection.

OSHA is now enforcing the CDC's recommendation that employees wear particulate respirators when entering rooms housing people with suspected or confirmed infectious TB or during other high-hazard procedures. OSHA states, "Employers must provide and ensure the use of NIOSH-approved, high-efficiency particulate air (HEPA) respirators as the minimum acceptable level of respiratory protection. Whenever respirators (including disposables) are required to be used, a complete respiratory protection program must be in place in accordance with 29 CFR 1910.134 (B)."

Also, OSHA is planning to coordinate a national outreach effort to stem future TB transmission. Roger A. Clark, director of compliance programs for OSHA, recently urged all OSHA area and regional offices to work with local health care institutions and professional associations to educate employees and employers regarding TB-associated hazards and safer work practices.

* Time to get serious. Despite a major campaign to alert health care workers and public health professionals to the resurgence of tuberculosis, some three dozen OSHA inspections conducted nationwide to date reveal that most employers have yet to fully implement current CDC guidelines. Hopefully, resolution of issues such as which respirator to use, together with the combined efforts of OSHA and the CDC, will expedite compliance.

Still, we as laboratorians can--and must--continue to be a major force in helping to paralyze tuberculosis. Only through our example can we transmit a powerful educational message throughout the industry and help to defeat this dragon.


1. Centers for Disease Control and Prevention. Guidelines for preventing the transmission of tuberculosis in health care facilities. Federal Register. Oct. 12, 1993; 58(195): 52810-52854.

2. Centers for Disease Control and Prevention/National Institutes of Health. Biosafety in Microbiological and Biomedical Laboratories. Washington, DC: US Government Printing Office: May 1993; 95.

3. Clark RA. Enforcement policy and procedures for exposure to tuberculosis. Washington, DC: Occupational Safety and Health Administration. (Memorandum for regional administrators); Oct. 8, 1993.

Figure 2

Current recommendations on interpreting TB skin tests

1. A reaction of |is greater than or equal to~ 5 mm is classified as positive in:

* Persons with HIV infection or risk factors for HIV infection with unknown HIV status

* Persons who have had recent close contact(1) with persons with active TB

* Persons who have abnormal chest radiographs consistent with old healed TB

2. A reaction of |is less than or equal to~ 10 mm is classified as positive in all persons who do not meet any of the criteria above but who have other risk factors for TB including:

High-risk groups:

* Intravenous drug users known to be HIV seronegative

* Persons with other medical conditions that have been reported to increase the risk of progressing from latent TB infection to active TB, including silicosis, gastrectomy, jejuno-ileal bypass surgery, being 10% or more below ideal body weight, chronic renal failure, diabetes mellitus, high dose corticosteroid and other immuno suppressive therapy, some hematologic disorders (e.g., leukemias and lymphomas), and other malignancies

High-prevalence groups:

* Foreign-born persons from high prevalence countries in Asia, Africa, and Latin America

* Persons from medically underserved low-income populations

* Residents of long-term care facilities (e.g., correctional institutions, nursing homes)

* Persons from high-risk populations in their communities, as determined by local public health authorities

3. Induration of |is greater than or equal to~15 mm is classified as positive for persons who do not meet any of the above criteria.

4. Recent converters are defined on the basis of both induration and age:

* |is greater than or equal to~10-mm increase within a 2-year period is classified as positive for persons |is less than~35 years of age

* |is greater than or equal to~15-mm increase within a 2-year period is classified as positive for persons |is greater than or equal to~35 years of age

* |is greater than or equal to~5-mm increase under certain circumstances (see no. 1 above)

1 Recent close contact implies household contact or unprotected occupational exposure similar in intensity and duration to household contact.

Source: Federal Register, Oct. 12, 1993; 58(195): 52830.

A tuberculosis skin test is conducted as follows: A small dose of PPD antigen is injected beneath the surface of the skin. Between 48 and 72 hours later, the injected area is examined to check for induration--a raised, hard measurable area. To determine if a person is positive, the individual's risk factors must also be determined.

Brown, a member of MLO's Editorial Advisory Board, is director of microbiology, health, and environmental affairs at Roche Biomedical Laboratories, Raritan, N.J.
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Title Annotation:tuberculosis
Author:Brown, James W.
Publication:Medical Laboratory Observer
Date:Feb 1, 1994
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