[Table of Contents]

Volume: 22S1 • April 1996

Guidelines for Preventing the Transmission of Tuberculosis in Canadian Health Care Facilities and Other Institutional Settings

IV. TB MANAGEMENT PROGRAM

D. Strategies for Managing Suspected or Confirmed Infectious TB

Management strategies for handling suspected or confirmed infectious TB in health care facilities should include the following:

• programs for early identification and evaluation of persons with suspected infectious TB;
• immediate isolation of persons with suspected or confirmed infectious TB;
• notification of infection control personnel;
• efficient confirmation of diagnosis;
• early and appropriate initiation of treatment;
• notification of public health authorities;
• identification, assessment and management of contacts, including the provision of isoniazid (INH) preventive therapy for selected contacts; and
• evaluation of TB exposure events.

1. Programs for the Early Identification and Evaluation of Persons with Suspected Infectious TB

• A high index of suspicion is required of individuals who
  • have a chest radiograph suggestive of active TB; or
  • have an AFB smear-positive sputum; or
  • are in one of the risk groups identified in Canada and have two or more of the following symptoms⁽⁴²⁾:
  • chronic cough (over 4 weeks' duration);
  • fever (longer than 1 week);

  • weight loss.

• Appropriate diagnostic measures should be undertaken to either confirm or refute initial suspicions of TB^(9,42,43) (see Section IV.D.4).

• Whenever active TB is suspected or confirmed, the information should be recorded appropriately in the health record.

2. Isolation of Persons with Suspected or Confirmed Infectious TB

Some individuals with AFB-positive smears and non-tuberculosis mycobacterial infection will be placed under isolation precautions if an appropriate level of suspicion is maintained. Isolation precautions may be discontinued for these patients once non-tuberculosis mycobacterial infection is identified and infection with M. tuberculosis is excluded. It is preferable to initially "over" isolate than to delay implementing appropriate isolation precautions.

Additional considerations

• Provision should be made for rapid transfer of patients to another health care setting if adequate isolation facilities are not available.
• Elective procedures should be postponed until the patient is non-infectious.
• Isolation precautions should be continued even in the face of negative AFB smears if there is a high index of suspicion of active TB (i.e., the patient is placed on anti-tuberculosis therapy). Individuals who have a sputum smear that is AFB-negative but culture-positive have been shown to transmit M. tuberculosis to other people, although at a lower rate than individuals who have a sputum smear that is AFB-positive. Almost 50% of persons with active pulmonary TB reported in Canada from 1990-1993 had positive cultures for M. tuberculosis and negative AFB smears⁽⁸⁾.

• Children with pulmonary TB are not usually as infectious as adults because children do not usually develop cavitary or sputum smear-positive TB. However, since there is evidence that children can transmit TB to others⁽³⁵⁾, isolation of children with suspected infectious TB is prudent.

• If uncertainty exists about isolation precautions, consultation with an expert in infection control or TB should be sought.

• on arrival, place patients in designated waiting areas in emergency rooms or clinics that have appropriate engineering controls and are separated from other patients (see Section IV.E); (high-risk facilities should have one or more isolation rooms in the emergency department available with appropriate engineering controls.)
• whenever possible, book appointments at times to minimize the exposure of other patients (e.g., the end of the day);
• provide patients with surgical masks and give instructions regarding their proper use (N.B. Patients should never wear a mask containing an expiratory valve);

• educate patients and their visitors about practices designed to reduce or eliminate production of airborne droplet nuclei (e.g., covering mouth and nose with tissues when coughing)⁽⁵²⁾; and

• conduct the evaluation or procedure as efficiently as possible (e.g., limit waiting time).

• ensure that procedures are performed in a treatment or procedure room with appropriate engineering controls (see Section IV.E); [this is especially important when cough-inducing procedures (e.g., sputum induction, aerosol treatments and bronchoscopy) are being performed.]
• instruct patients to cover mouth and nose with tissues when coughing or sneezing;
• ensure that only essential personnel are present during the procedure;
• ensure that all persons present during the procedure wear an appropriate mask (see Section IV.F);
• ensure that people enter or leave the procedure room during the procedure only if absolutely necessary (keep the door to the procedure room closed except when people are entering or leaving the room);
• ensure that patients remain in the procedure room until coughing subsides, thereby limiting exposure of other individuals who are in the general waiting or recovery areas;
• allow adequate time between patient procedures so the air will be free of droplet nuclei or place a notice on the procedure room door advising HCWs who must enter the room that appropriate masks should be worn for a specified time (see Section IV.F) [the required length of time is based on the number of air changes and other engineering controls (see Section IV.E), e.g., at six air changes per hour, 69 minutes are required to remove 99.9% of airborne contaminants⁽³⁶⁾ (see Appendix F)]; and
• perform procedures at the end of the schedule, whenever possible.

Isolation precautions for patients with suspected or confirmed infectious TB admitted to acute care facilities

The following isolation precautions should be implemented:

• place patient in single isolation room that has the appropriate engineering controls (see Section IV.E); (high-risk facilities should have one or more isolation rooms available with appropriate engineering controls. If more than one isolation room is required for patients with TB, consideration should be given to locating these rooms in a single area of the health care facility. If the health care facility does not have a room that meets these criteria, a plan for managing this patient must exist. High-risk facilities with intensive care units should have at least one isolation intensive care room with appropriate engineering controls.)
• ensure that the patient remains in the isolation room; (the patient should only leave the room for essential procedures. The patient should wear a mask if he/she must leave the isolation room.)
• keep the door and window to the isolation room closed except when individuals are entering or exiting the room;
• limit the number of people entering the room; (visitors should be restricted to members of the patient's household. Visits by children under 12 should be limited because such children are highly susceptible to infection with M. tuberculosis.)
• ensure that all persons entering the room wear an appropriate mask; (see Section IV.F) and
• instruct patients, visitors, and HCWs about the importance of adhering to TB isolation precautions.

Isolation precautions for individuals with suspected or confirmed infectious TB who are living in long-term care facilities

Transmission of TB to both residents and HCWs has been reported in long-term care facilities^(32,53,54). Residents of long-term care facilities with newly diagnosed infectious TB should be managed according to the same policies and procedures as patients cared for in acute care settings. Some long-term care settings may have appropriate isolation facilities. If appropriate isolation facilities are not available, transfer of the resident to a health care facility equipped to manage TB should be arranged as soon as possible. There may be situations where transfer is delayed or not possible. In such circumstances, the likelihood of transmission of TB may be minimized by the following:

• place the patient in a single room with the door and window closed;
• ensure that all persons entering the room wear an appropriate mask (see Section IV.F);
• initiate appropriate treatment;
• limit the number of people entering the room; (visits by children under 12 should be avoided because they are highly susceptible to infection with M. tuberculosis);
• instruct HCWs, residents and visitors about the importance of adhering to TB isolation precautions;
• initiate contact follow-up according to established guidelines (see Section IV.D.7); and
• discontinue isolation only after the resident is no longer infectious.

Discontinuation of isolation precautions

Isolation precautions should be continued until patients are assessed to be non-infectious. A number of variables influence the length of time an individual remains infectious. These include the level of infectivity (see Section III), the level of competence of the patient's immune response, the duration of, and adherence to, chemotherapy and the presence or absence of drug-resistant TB.

Criteria for discontinuation of isolation precautions should not be based on a fixed interval of treatment (e.g., 2 weeks) but rather on evidence of clinical and, if possible, bacteriologic improvement. Although most individuals experience bacteriologic improvement (e.g., smears of sputum specimens usually become AFB negative) after receiving 2 weeks of appropriate therapy, transmission of multidrug-resistant TB has been reported in U.S. health care facilities from patients where isolation precautions were discontinued after a fixed time interval of 2 weeks of therapy^(1,3).

Although there are no definite criteria for discontinuing TB isolation precautions, the following are suggested as guidelines. Isolation may be discontinued when:

• consecutive sputum smears are negative for AFB on 3 separate days;

  AND

• there is evidence of clinical improvement;

  AND

• there is reasonable evidence of adherence to the medication regimen for a minimum of 2 weeks.

If a sputum is unobtainable (e.g., sputum expectoration or gastric lavage), discontinuation of isolation may be based on the following:

• level of infectivity (see Section III); and
• evidence of clinical improvement; and
• reasonable evidence of adherence to the medication regimen for a minimum of 2 weeks; and
• assumed absence of drug-resistant TB.

3. Notification of Infection Control Personnel

• educate HCWs about the rationale for isolation precautions;
• encourage patients' and HCWs' adherence to isolation precautions;
• ensure that occupational health personnel are notified so that contact follow-up of HCWs may be initiated (see Section IV.D.7); and
• ensure that public health authorities are notified so that contact follow-up of family, emergency responders and visitors may be initiated (see Section IV.D.6).

4. Confirmation of Diagnosis

Laboratory specimens

• For patients suspected of having pulmonary TB, a deep-coughed specimen of sputum should be obtained promptly. If this sputum specimen is AFB-negative on smear, two successive early morning sputum specimens should be obtained.

  • If spontaneous sputum (respiratory mucus) specimens cannot be obtained, induced sputum specimens or gastric washings should be obtained on 3 successive days.

  • More invasive procedures should be used only when sputum induction fails to produce a specimen. Invasive procedures may include obtaining bronchoalveolar washings or direct transthoracic aspirates. All necessary specimens should be obtained during a single procedure.

• For patients suspected of having extrapulmonary TB, appropriate specimens should be obtained, whenever possible, and sent for AFB staining, as well as for culture and sensitivity. Tissue specimens obtained for mycobacterial culture should be placed in a container with saline for transport to the laboratory.
• Blood cultures for mycobacterium species may also be obtained using special mycobacteria media.
• Proper collection, handling and identification of specimens should be ensured^(42,43,55).

• The laboratory should ensure that AFB smear results, using either Ziehl-Neelsen or rhodamine/auramine stains, are available within 48 hours of specimen collection.
• Radiometric detection methods (e.g., BACTECTM) are highly reliable and take as little as 10 days (mean 10 to 14 days) to detect the presence of mycobacterial growth. Final identification requires a further 1 to 2 days if a DNA probe is used or 4 to 5 days if the traditional NAP test is used. Drug susceptibility testing may be initiated once growth has been detected. Drug susceptibility results are usually available 5 to 6 days later.
• Traditional culture methods require 6 to 8 weeks to identify M. tuberculosis and another 6 to 8 weeks to determine the drug susceptibility pattern^{(41,42,55,56)}.

5. Initiation of Treatment

6. Notification of Public Health Authorities

The health care facility TB management program should specify who is responsible for notifying the public health authorities. This person should

• report any patient or HCW with confirmed TB to ensure appropriate community contact investigation and follow-up;
• report the results of species identification and drug susceptibility testing as soon as they are available; and
• ensure that a discharge plan is in place before the patient is released to facilitate follow-up and continuation of therapy; (the discharge plan should ensure coordination between the health care facility, local public health authorities and the physician providing ongoing personal health care.)

7. Identification, Assessment and Management of Contacts

Identification of contacts

The first step in contact follow-up is to interview the patient and review his/her health record to determine who may have been exposed to the patient prior to the use of appropriate isolation precautions. It is necessary to identify where the patient has been in the facility and any individuals who may have been in contact with the patient.

• The person with infectious TB may have been in ambulances, patient units, emergency rooms, outpatient clinics, operating rooms, recreational areas, treatment and procedure rooms, and rooms for radiologic and other diagnostic services.
• People who may have been in contact with the person with infectious TB include those providing direct care (e.g., nursing staff, physicians, ambulance attendants, therapists) as well others having direct contact with the patient (e.g., patient room mates, pharmacy staff, laboratory personnel, housekeeping staff, porters, social workers, translators, volunteers, visitors). Depending on the level of infectivity of the patient, subsequent interviews may be required with personnel working elsewhere in the health care facility to determine the degree of exposure that may have taken place.

• No contact follow-up is required if the individual with infectious TB was placed in appropriate isolation upon admission and subsequently managed appropriately.
• There are no specific criteria to assess the significance of the exposure because of the variability in factors that determine the risk of TB transmission. Therefore, one approach is to view the potential for exposure as a series of concentric circles with the infectious patient at the centre. Contacts with the greatest potential for significant exposure (e.g., persons who live in the same dwelling plus relatives, friends or care givers who have frequent, prolonged and close contact) are placed in the ring closest to the patient. Other individuals are placed in the outer circles depending on their exposure. If a high level of TST conversion is found in individuals in the circle closest to the patient, the investigation is expanded, as required, to contacts placed in the outer rings of the circle until high levels of TST conversion are not found. In the health care facility, primary nurses, for example, who regularly cared for the patient and who may be involved with cough-inducing procedures would likely be at greatest risk. The significance of the exposure would need to be assessed, however, in terms of other factors, such as the adequacy of engineering controls.
• Contacts of individuals who have an AFB-negative smear, and who are culture positive must be identified and contact follow-up performed following the principles described in this section. Since the infectivity level of these individuals is low, significant exposure would only occur following prolonged close contact.

  a. For all contacts with a previously documented negative TST or with an unknown TST status but no past history of treatment for active or inactive TB

• A post-exposure TST should be administered as soon as possible (see Appendix B).
• Two-step testing should not be routinely performed during post-exposure testing. Advise on whether or not two-step testing should be performed in a specific post-exposure situation can be obtained from the local public health authorities or experts in tuberculosis control.
• If the first post-exposure test is negative, a TST should be repeated in 3 months since it takes up to 3 months for the immune system to develop a positive TST response following infection.

  b. For contacts with a previously documented positive TST or with a past history of treatment for active or inactive TB

• It is not recommended to perform a TST.
• Conduct an interview to determine if symptoms of TB are present.
• Provide education about the symptoms and signs of active TB.
• Perform a chest radiograph immediately if the person has symptoms of TB.
• Further clinical and radiologic re-evaluation should take place in accordance with local juristidational practice.

• Such persons should be evaluated promptly, both clinically and radiologically, for evidence of active TB.
• Individuals who have a TST conversion and do not have active TB should be offered preventive therapy (see below and Appendix C). These individuals do not need to be excluded from work.
• Individuals who have active TB should undergo further investigation and have appropriate treatment initiated (see Appendix D). These individuals should be excluded from work until they are determined not to be infectious.

• All individuals considered for INH preventive therapy should be informed about the risks of developing TB, the rationale for accepting preventive therapy, the need for appropriate monitoring (which includes baseline liver function tests), and the possibility of adverse drug reactions.
• The health records of patients or HCWs should document whether preventive therapy was offered, accepted and completed.
• HCWs who have documented TST conversions, whose chest x-rays do not indicate active TB, and who refuse INH preventive therapy or are unable to tolerate INH preventive therapy, should be evaluated clinically and radiologically in accordance with local jurisdictional practice. These individuals do not need to be excluded from work.

8. Evaluation of TB Exposure Events

The designated personnel should

• document each exposure event in terms of numbers of contacts, numbers of individuals (patients and HCWs) with documented positive and negative TST reactions prior to the exposure event, number with new positive reactions documented at post-exposure testing, number of individuals with a history of BCG vaccine, number with known post-exposure conversions, number with positive TST accepting preventive therapy, number who completed a course of preventive therapy, number with active TB, number on treatment for active TB, number completing treatment for active TB (see Section IV.C, Appendix E);
• ensure that information is shared with local public health authorities in order to have complete documentation of contact follow-up;

• identify weaknesses in the design and implementation of the TB management program and identify methods to rectify them. Problem areas may be identified by assessing such factors as follows:

  • the length of time required to order isolation precautions, confirm the TB diagnosis, institute treatment, receive laboratory information, conduct a contact evaluation or provide appropriate therapy

  • the duration of, and adherence to, isolation precautions - the appropriateness of treatment and number of patients and HCWs who completed the required course of treatment;

• periodical estimate of the cost of each exposure event; and

• report the findings of the evaluation to appropriate personnel.

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