Preventing Transmission of TB

March 1, 2001

Preventing Transmission of TB

By Judene Bartley, MS, MPH, and Gina Pugliese, RN, MS

Although
there has been a steady decline of cases of tuberculosis (TB) in the US, this
decrease will continue only if attention is paid to identifying patients with
TB, initiating proper treatment, and implementing measures to reduce the risk of
transmission to others during periods of infectivity.

Worldwide, there are an estimated eight million new cases of TB each year and
three million deaths are attributed to this disease annually.1 In the
US, there was a steady decline in the number of new cases of TB from 90 cases
per 100,000 population in 1950 to 9.4 cases per 100,000 in 1984. As the number
of cases decreased, the US government decreased funding for TB and shifted the
money to other public health problems. As a result, many of the TB control
efforts were greatly reduced. After 1984, the US had a steady increase in the
number of cases of TB. From 1985 to 1992, the number of reported cases of TB
increased 20%, resulting in 52,000 excess cases of TB. Persons from 25 to 44
years of age accounted for more than 80% of the total increase in cases during
this time interval. Several factors are thought to have contributed to this
increase, including the HIV epidemic, large outbreaks of multidrug-resistant TB
(MDR-TB), an increase in cases occurring in persons who immigrated to the US
from areas of the world with a high prevalence of TB, and an increase in active
transmission of TB caused by inadequate healthcare resources. The decline in the
number of new cases of TB in the US started in 1993 and has continued through
today. The rate of new cases of TB has decreased to 6.4 per 100,000 in 1999, the
lowest since US national TB surveillance began in 1953.

In general, persons who become infected with M. tb have a 10% risk for
developing active TB during their lifetime. This risk is greatest within the
first two years after infection. HIV is the strongest risk factor for
progression of latent TB infection to active TB. Persons with latent TB
infection who become co-infected with HIV have a 8 to 10% risk per year for
developing active TB. HIV-infected persons who are already severely
immunosuppressed and who become newly infected with M. tb have an even
greater risk for developing active TB.

The probability that a person who is exposed to TB will become infected
depends on the concentration of droplet nuclei in the air and the duration of
exposure. Characteristics of the TB patient that enhance transmission include:

  • Disease of the lungs, airways, or larynx.
  • Presence of acid-fast-bacilli in the sputum.
  • Failure of patients to cover their mouth or nose when coughing or
    sneezing.
  • Presence of cavitation on the radiograph.
  • Inappropriate or short duration of treatment.
  • Procedures that induce coughing or aerosolization of M. tb (endotracheal
    intubation, suctioning, bronchoscopy, sputum induction, suctioning, surgical
    drainage and irrigation of a TB abscess, and surgical debridement of a
    tuberculous skin ulcer, administration of aerosolized pentamidine, and
    autopsy).

Environmental factors that increase risk of transmission include:

  • Exposure in a small enclosed space.
  • Inadequate local or general ventilation that results in insufficient
    dilution and/or removal of infectious droplet nuclei.
  • Recirculation of air containing infectious droplet nuclei.

The characteristics of the persons exposed to TB that may affect risk of
becoming infected are not well defined. In general, persons who have been
infected previously with M. tb may be less susceptible to subsequent infection.
However, reinfection can occur among those previously infected, especially if
they are severely immunocompromised. Vaccination with Bacille of Calmette and
Guerin (BCG) probably does not affect the risk of infection; rather it decreases
the risk for progressing from latent TB.

Although children who have TB may be less likely than adults to be
infectious, they should be evaluated for potential infectiousness with the same
criteria as for adults. Pediatric patients that may be infectious include those
with laryngeal or extensive pulmonary involvement, pronounced cough, positive
sputum for AFB, cavitary TB, or for those whom cough-inducing procedures are
performed. The source case for pediatric TB patients often occurs in a member of
the child's family; therefore, parents and other visitors of all pediatric TB
patients should be evaluated for TB.

Drug Resistance

In
the US, from 1993 through 1996, overall resistance to at least isoniazid was
8.4%; rifampin 3.0%; both isoniazid and rifampin (classified as MDR-TB) 2.2%;
pyrazinamide 3.0%; streptomycin 6.2%; and ethambutol hydrochloride 2.2%.3
Rates of resistance were significantly higher for case patients with a prior TB
episode. Compared with previous US surveys in 1991 and 1992, isoniazid
resistance has remained relatively stable. In addition, the percentage of MDR-TB
has decreased, although the national trend was significantly influenced by the
marked decrease in New York City.

Risk of Nosocomial Transmission

Nosocomial TB has been of significant concern to healthcare workers and the
public and few other problems have had such significant impact on hospital
epidemiology.4 The US has seen dramatic outbreaks of both multidrug-resistant
TB (MDR-TB) and drug-susceptible strains of TB in hospitals with transmission to
both patients and health workers.5,6 CDC tracked an outbreak from a
specific resistant strain as it spread across the US.7

Nosocomial transmission of TB is not a new issue and it has been known for
decades that the risk to healthcare workers is two to ten times greater than
that of the general public. However, the magnitude of these recent outbreaks
that have involved both patients and healthcare workers has caused significant
concern, prompting special infection control measures.

A review of the outbreaks of MDR-TB in the US shows that these outbreaks
involved large numbers of cases with a high prevalence of HIV infection. The
mortality rate was extremely high and the median interval from TB diagnosis to
death was extremely short, the majority being less than four weeks. The high
mortality rate in these outbreaks is explained by the severe degree of
immunosuppression in many of the patients combined with ineffective treatment
for unrecognized drug-resistant disease. Nearly all patients in these outbreaks
had M.tb isolates resistant to both isoniazid and rifampin, the two most
effective drugs available. In four hospitals and the prison system, the outbreak
strain was resistant to seven anti-TB drugs (including streptomycin, ethionamide,
cycloserine, kanamycin, rifabutin, and pyrazinamide). At least 20 healthcare
workers in these facilities developed active TB, and at least nine workers died.

Some of the major factors contributing to the recent outbreaks of both MDR-TB
and drug-susceptible TB in hospitals were breaks in some basic TB control
strategies, such as: delays in diagnosis of TB, delays in identification of drug
resistance, and delays in initiation of appropriate therapy--all of which
resulted in delays in proper isolation and prolonged patient infectiousness.8
Even if a patient was diagnosed with TB, respiratory isolation was often
inadequate. For example, isolation rooms were found to have positive rather than
negative pressure, air was being recirculated from isolation rooms to other high
risk areas, doors to isolation rooms were left open, isolation precautions were
discontinued too soon, and healthcare workers did not wear adequate respiratory
protection. When appropriate TB control measures were implemented, transmission
was significantly reduced or ceased entirely. Unfortunately, many of the
interventions were implemented simultaneously, so the effectiveness of specific
interventions could not be determined.

Outbreaks in hospitals and prisons illustrate the rapid spread and extent of
TB that can occur when people who have undiagnosed or inadequately treated TB,
caused by drug-resistant organisms, are brought together with highly vulnerable,
immunosuppressed patients, in a densely populated environment in the absence of
infection control measures.

There has also been transmission of TB reported in the pediatric setting,
related to frequent suctioning and endotracheal intubation, nursing homes for
the elderly, and the dental setting, dentist to patients.

In 1994, the US Centers for Disease Control and Prevention (CDC) published a
132-page Guideline for Preventing the Transmission of Mycobacterium TB in Health
Care Facilities.6 Follow-up studies by the CDC at several of the
hospitals where outbreaks occurred have shown that patient-to-patient and
patient-to-healthcare worker transmission was stopped after implementation of
these recommended guidelines.8

These nosocomial outbreaks and the concern for healthcare worker safety in
the US was the impetus for the US Occupational Safety and Health Administration
(OSHA) to get involved and inspect hospitals for compliance with CDC measures to
reduce occupational exposure to TB. Non-compliance with the basic requirements
can result in significant monetary fines.

Drug susceptibility patterns of M.tb isolates from TB patients treated
in the facility should be reviewed to identify frequency and patterns of drug
resistance. PPD skin test conversion rates should be analyzed for each
department or occupational group and be compared to rates for workers in areas
where exposure to TB is unlikely.

Diagnostic Evaluation and Treatment

Prompt
and accurate laboratory results are important for the proper treatment of
patients with TB. Laboratories must be proficient at processing specimen.
Results of acid-fast bacilli (AFB) sputum smears should be available within 24
hours. TB may be more difficult to diagnose among patients with HIV infection
because of the nonclassical clinical or radiographic presentation, an impaired
response to PPD skin tests, the lower sensitivity of sputum smears for detecting
AFB, and the overgrowth of cultures with Mycobacterium avium complex in
specimens from patients infected with both M. avium and M.tb.

It will also be important to start empiric therapy as soon as TB is suspected
with an appropriate regimen based on the local drug-resistance surveillance
data.6,9 The current US recommendation is to begin empiric therapy
with four drugs (isoniazid, rifampin, pyrazinamide, and ethambutol, or
streptomycin) except in areas where surveillance reveals that the prevalence of
primary resistance to isoniazid is less than or equal to 4%.10 In
those locations with rates less than or equal to 4%, initial regimens of three
drugs (isoniazid, rifampin, and pyrazinamide) are recommended for initial
therapy. Treatment guidelines for TB patients with HIV infection and on specific
treatment have been updated in light of changing drug resistance trends.11,
12

Prompt identification of patients with TB is essential to TB control efforts.6,
13,14
Unless suspect or confirmed TB patients are identified, it will not
matter what other infection control measures are in place. This will require
careful evaluation of patients upon their initial encounter with the healthcare
system with prompt isolation as soon as TB is suspected on clinical grounds
alone and until laboratory and clinical evidence eliminates the diagnosis. The
specific procedure for "early identification and isolation of
patients" will be based on the prevalence and demographic profile of TB
patients in the community. In areas of high prevalence of HIV and TB and because
of the difficulty in recognizing TB in patients with HIV, some facilities have
found it necessary to isolate all patients with HIV infection that present with
clinical symptoms suggestive of TB (e.g., fever, cough) and /or an
abnormal chest radiographs until a diagnosis of TB can be ruled out.15

The procedure for "early identification of TB patients" and the
definition of "suspect" case will determine the number of isolation
rooms that will be needed. There will often be patients who are placed in
isolation because of suspect TB and are later found not to have TB. The best
strategy is to isolate a suspect patient until TB can be ruled out to prevent
possible nosocomial transmission. A number of strategies have been used to
increase the availability of rooms that can be used for isolation, such as the
use of window exhaust fans/units to create negative pressure or portable or
wall-mounted HEPA filtration units.

Giving authority to nursing and physician staff to made independent decisions
to isolate patients with suspect TB and policies for automatic isolation of
certain patients (e.g., with TB in differential diagnosis) can often
reduce delays in initiation of isolation.16 Hospitals that have
monitored for compliance with TB control measures, particularly appropriate
isolation, have demonstrated reductions in the number of days that potentially
infectious patients were not in appropriate isolation.15, 17

The standard method of identifying persons infected with Mycobacterium tb
is the Mantoux tuberculin skin test given intradermally with 0.1 ml of 5
tuberculin units of purified protein derivative (PPD) tuberculin.6, 16
It is clear that PPD skin testing of healthcare workers permits early
recognition of potential episodes of nosocomial transmission and the opportunity
to offer isoniazid or other chemoprophylaxis to workers with skin test
conversion. In addition, it is important to identify workers with active TB that
pose a risk of infection to patients and others. It may be prudent to do
baseline PPD testing of HCWs, particularly in high-risk facilities. The
frequency of additional PPD testing will depend on the level of risk in a
particular facility.

The prevalence of TB in the facility should be considered when choosing the
appropriate cut-point for defining a positive PPD reaction. For example, in
facilities with minimal or low risk of TB exposure, an induration of <
15 mm may be an appropriate cut-point for workers who have no other risk
factors. In other facilities where the risk of TB exposure may be higher, the
appropriate cut point may be < 10 mm.

All results on PPD testing should be recorded in the worker's health record
as well as an aggregate database of all the healthcare worker PPD skin test
results. PPD conversion rates should be calculated for the facility as a whole,
and if appropriate, for specific areas of the facility and occupational groups.
PPD conversion rates should be calculated based on the total number of
previously PPD negative HCWs tested in each area or group (i.e., the
denominator) and the number of PPD test conversions among HCWs in each area or
group (i.e., the numerator).

The potential for variability of skin test conversions with different
commercial preparations of PPD is another important issue when evaluating your
skin test conversion rates. A number of recent studies have demonstrated a
difference in reactivity between various commercial products.18, 19

The ability of persons who have TB infection to react to PPD may gradually
decline over time. For example, adults who were infected during childhood may
have a negative skin test reaction. However, when the PPD skin test is given, it
may boost the hypersensitivity, and the reaction to a second skin test may be
positive. This boosted reaction can be misinterpreted as a PPD conversion from a
newly acquired infection. The likelihood of boosting increases with age. So,
two-step baseline PPD testing is recommended to reduce the likelihood that a
positive (boosted reaction) is misinterpreted as a new infection. The second PPD
skin test should be performed 1-3 weeks after the first negative test, and if
the second test is positive, it is most likely a boosted reaction. The two-step
testing can be especially useful and cost effective in situations where workers
have received BCG vaccination and in situations when boosting may be due to
prior exposure to M. tb and non-TB mycobacteria.6, 20 The CDC
guidelines recommend two-step baseline PPD testing for all workers with
potential for TB exposure, including those that have had BCG vaccination. For a
person who was vaccinated with BCG, the probability that a PPD test reaction
results from infection with M. tb increases as the size of the reaction
increases, and as the length of time between BCG vaccination and PPD testing
increases.6

All workers with newly recognized positive PPD skin test results or PPD
conversions should be evaluated for active TB including an examination and chest
radiograph. If active TB is not found, routine chest radiographs should not be
required unless symptoms develop that suggest TB. However, more frequent
monitoring for symptoms may be indicated for recent PPD converters and other PPD-positive
workers who are at increased risk for developing active TB (such as HIV-infected
workers). PPD positive workers who do not have active TB should be evaluated for
preventive therapy.

Bacille-Calmette-Guerin (BCG) Vaccination

In the US, BCG vaccine has not been recommended for general use because the
population risk for infection with TB is low and the protective efficacy
of BCG vaccine is uncertain.21 The immune response to BCG vaccine
also interferes with the use of the tuberculin skin test to detect M. tb
infection. BCG also may complicate preventive therapy because of the
difficulties in distinguishing skin test responses caused by infection with M.
tb
from those caused by immune responses to vaccination.

Environmental TB Controls

Controlling airborne droplet nuclei can be achieved through a variety of
engineering controls. The purpose of these engineering controls is to:

  • Dilute and remove droplet nuclei from the air.
  • Provide optimum airflow (air mixing) patterns to prevent stagnation and
    short-circuiting of the air.
  • To contain the contaminated air in a localized area.
  • To prevent air from escaping from the room into other areas.
  • To remove or filter contaminants from the air.
  • To disinfect the air.

It is necessary to provide an environment that reduces the concentration of
droplet nuclei and prevent the escape of droplet nuclei from the TB isolation or
treatment room into the hallway or other areas. Two types of general ventilation
systems are the single-pass system and the recirculation system. The single pass
system supplies air to the TB isolation room from the outside (after heating or
cooling) and 100% of the air is exhausted to the outside. In a recirculating
system, a small portion of the air is replaced with fresh outside air, which
must pass through a high-efficiency particulate air (HEPA) filter prior to
recirculation into general areas. General ventilation systems must be designed
to prevent air stagnation or short-circuiting of air. One method is to supply
the air near the ceiling and exhaust it near the floor.

To prevent the escape of droplet nuclei, the TB isolation room should be kept
under negative pressure in relation to the hallway. Doors to the room should be
kept closed. The negative pressure should be monitored daily while the room is
being used. It is recommended that there be a minimum of six air exchanges per
hour for TB isolation and treatment rooms. However, these recommendations are
based on comfort and odor control and the effectiveness of this level of airflow
in reducing concentration of droplet nuclei has not been evaluated directly or
adequately.

The American Institute of Architects' revision task force has approved the
2001 revision of the AIA Guidelines for Design and Construction of Hospitals and
Healthcare Facilities. The ventilation requirements for hospitals requires 12
air changes per hour for airborne infection isolation (AII) rooms when major
renovation or new construction is anticipated.22 This new AIA edition
also requires that the daily monitoring of negative pressure be accomplished by
a visible means of detecting the direction of the airflow out of the room, (e.g.,
smoke trails). This change reinforces the findings reported for at least one
state's investigation of room air pressure discrepancies. Alarms or pressure
gauges for isolation rooms showed negative pressure in the respiratory isolation
room (i.e., airflow into the room), contradicting the actual direction of
air flow out of the room, demonstrated by visible smoke trail testing.23

The use of an anteroom is not required in the US, for respiratory isolation,
although it may minimize the potential for escape of droplet nuclei into the
hallway when the door is opened. To maintain negative pressure, all air leaks in
the room, such as around electrical outlets, windows and around plumbing pipes
should be sealed. The updated AIA Guidelines explicitly require a tightly sealed
room. However, they do not require an anteroom but suggest it is desirable for a
room used for highly immunosuppressed patients (e.g., bone marrow
transplant patients) who may have an active, communicable infection.

TB isolation can also be achieved with the use of enclosures, such as tents,
booths or hoods. These may be used, for example in the laboratory processing of
specimens or for administration of aerosolized pentamidine. If the air is
exhausted into the room, a HEPA filter should be used on the discharge vent of
the device. There are other types of local exhaust systems (such as smoke
evacuation devices) that are used during surgical procedures or during
bronchoscopy.

HEPA Filtration

HEPA filters are air cleaning devices that have a documented minimum removal
efficiency of 99.97% of particles < 0.3 microns in diameter. Studies
have shown that HEPA filters are very effective in reducing the concentration of
Aspergillus spores (which range in size from 1 to 6 microns < to below
measurable levels.24 Therefore, HEPA filters can remove infectious
droplet nuclei from the air. HEPA filters can be used in exhaust ducts or in
fixed or portable HEPA room air cleaners in TB isolation rooms or areas. HEPA
filtration units can be mounted on the wall or ceiling of the isolation room.
Portable HEPA filtration units can also be used when there is no general
ventilation system or when increased effectiveness of the room airflow is
desired. Some HEPA filtration units use ultraviolet germicidal irradiation (UVGI)
for disinfection of the air after HEPA filtration. When a HEPA filter is used,
the use of one or more lower efficiency disposable prefilters installed upstream
will extend the useful life of a HEPA filter.

Portable or mounted HEPA units have been found to be an effective alternative
to central ventilation. In a recent experimental study of portable HEPA
filtration units it was found that when these units were used in a
non-ventilated room, they were able to remove over 90% of aerosolized particles
of 0.3 micron size within 5 to 30 minutes.25 In a non-ventilated room
without a portable HEPA unit it took over 170 minutes to clear the air of
aerosolized particles 0.3 micron size.

Ultraviolet Germicidal Irradiation (UVGI)

Research has demonstrated that UVGI is effective in killing or inactivating
tubercle bacilli under experimental conditions.26, 27 Because of the
results of numerous studies and the experiences of TB clinicians during the past
several decades, the use of UVGI has been recommended as a supplement to other
infection control measures.28-32 UVGI can be used inside air ducts,
for upper-room air irradiation, or as a supplement to portable or fixed HEPA
filtration units. The principal advantages of UVGI air disinfection are the ease
of application and relatively low cost. Studies suggest that a 30-watt UV
fixture provides the equivalent of 20 or more room air exchanges depending on
the air mixing and airflow patterns. Clearly there is a role for the use of
upper-room air UVGI irradiation in areas that are difficult to ventilate, such
as waiting rooms, emergency rooms, corridors, and other central areas of a
facility where patients with undiagnosed TB could contaminate the air. The use
of UVGI irradiation in the ducts in one TB hospital in the US has controlled
transmission of TB in this high-risk setting.33

The 2001 AIA Guidelines addressed the concern for unidentified cases of TB in
diagnostic areas. An additional requirement in new construction or major
renovation is the provision for an AII room in emergency rooms. The Guidelines
also require negative airflow (with respect to adjacent areas) in triage and
waiting areas of emergency and diagnostic imaging areas. Permitting
recirculation of the air after passing through HEPA filters offsets the increase
in cost of air that is 100% exhausted to the outside. The recirculation of air
applies only to the air handler that controls the designated area.

Factors determining the effectiveness of UVGI include the room configuration,
UVGI lamp placement, and the adequacy of the airflow patterns in bringing
contaminated air into contact with irradiated upper-room air space. Because of
the concerns of overexposure to UV radiation causing keratoconjunctivitis,
workers that may have high intensity exposure should be warned of the hazard and
take special precautions, such as turning off the lamps before entering the
upper room air space or before entering the ducts where UVGI lamps are used.
Only a few seconds of intense direct exposure can cause burns.

Because the intensity of UV lamps fluctuates as they age, there should be a
regular schedule for replacing the lamps. Wall or ceiling mounted fixtures
should have louvers to block the downward radiation levels and the actual UV
tube should not be visible from any normal position in the room.

TB Isolation Practices

Efforts should be made to keep the patient in the room with the door closed.
The patient should wear a surgical mask when being transported outside the room
to other departments. In the US, all workers entering the TB isolation rooms are
required to wear an N-95 respirator certified by the CDC's National Institute of
Occupational Safety and Health (NIOSH). These N-95 respirators meet the CDC's
performance criteria for a respiratory program for TB control.6
Visitors should be offered respiratory protection. Clothing and disposable
inanimate items contaminated with airborne particles or respiratory secretions
have not been associated with the transmission of M. tb. However, as a
general infection control measures, all contaminated disposable patient care
items should be properly discarded. In the clinical laboratory, however, all
specimens and cultures should be disposed of as medical waste, which ideally
includes decontamination on-site prior to disposal. Items decontaminated
off-site must be packaged in accordance with applicable local, state and federal
regulations before removal from the facility.34

A patient may be removed from isolation only when they are on effective
therapy, have improved clinically, and have had three consecutive negative
sputum AFB smears collected on different days.

Respiratory protection

All persons entering rooms where patients with known or suspected TB are
being isolated, should use respiratory protection during cough-induction, when
aerosol-generating procedures are performed, or when engineering controls are
not present. The CDC recommend that respirators used for protection against
transmission of TB meet standard performance criteria.6 These
criteria include:

  • The ability to filter particles 1 micron in size with a filter efficiency
    of 95%.
  • The ability to be fit testing to obtain a face-seal leakage of less than
    10%.
  • The ability to fit different facial sizes and characteristics.
  • The ability to be checked for facepiece fit each time they are put on.

The respirator classified as an N-95 respirator by the CDC's National
Institute of Occupational Safety and Health meets these performance criteria.
This N95 respirator has the ability to filter 95% of particles in the 0.3 micron
size. A disposable N-95 respirator is now in common use by workers in US
hospitals. Although these respirators are disposable, if they are used strictly
for TB control, they may be reused by the same healthcare worker as long as the
respirator remains structurally intact or is not damaged or soiled. (Note: TB
transmission has not been show to occur from contamination of inanimate objects
like masks.) If the respirator becomes soiled with blood or body fluids,
however, it should be considered contaminated and be discarded. Each facility
will need to develop a protocol that addresses the circumstances in which a
disposable respirator will be contaminated.

The CDC also recommends that a complete respiratory protection program be
developed that includes: 1) assignment of responsibility for the program; 2)
written procedures for all aspects of the program; 3) medical screening of
workers of their ability to wear respirators; 4) training and education; 5) fit
testing prior to issuance of respirator and fit checking each time respirator is
donned; 6) procedures for inspection, maintenance, and reuse of respirators, as
well as circumstances to consider it contamination; and 7) periodic program
evaluation.

After an initial fit test and selection of the appropriate size of the
respirator, a repeat fit testing is indicated if workers gain or lose more than
10 pounds and if they have a change in dental structure as a result of losing
teeth or receiving dentures. The respirator manufacturer's instructions should
be followed for fit testing procedures.

Fit checking of the face piece of the respirator to detect leaks is also
recommended each time the respirator is donned. Because there is significant
variation in the recommended procedure between specific products, the
manufacturers recommendations should be followed.

The CDC recommends screening of employees to determine if they are able to
wear a respirator. Other than severe cardiac or pulmonary disease, few medical
conditions would preclude the use of disposable respirators. Many facilities
have implemented a general questionnaire to screen workers for medical
conditions and determine whether further evaluation is needed.

Special Considerations for High Risk Procedures

High risk procedures are those that induce coughing and increased the chance
that droplet nuclei are expelled in the air. These include endotracheal
intubation, suctioning, diagnostic sputum induction, aerosol treatments (e.g.,
pentamidine), and bronchoscopy. Other procedures that can generate aerosols
include irrigation of TB abscess or cutting of tissues.

Cough-inducing procedures should be performed using local exhaust ventilation
devices or in a TB isolation room. All workers should wear respiratory
protection. The room or booth should be aired after patient leaves to allow for
removal of airborne contaminants. If a bronchoscopy is being done on a patient
with suspect or confirmed TB, the room should meet the ventilation requirements
for TB isolation or as an alternative, local exhaust (e.g., smoke
evacuators), or portable HEPA filters can be used. In situations in which the
patient having a bronchoscopy is known to have multi-drug resistant TB, some
facilities are using respirators with a higher level or protection, such as a
HEPA respirator, or powered air.

If surgery is necessary on a patient with TB, it should be performed at the
end of the day. An assessment of resources should determine the frequency and
most effective way of managing recognized TB patients who are still considered
communicable. The NIOSH guide may be used to determine time to permit a complete
exchange of air in the OR before considering reuse of the room. Because the air
handler controls air flow for all OR rooms in the surgical suite, the use of a
separate negative pressure room for bronchoscopy procedures is preferred. The
1996-97 AIA Guidelines required bronchoscopy procedure rooms to be at negative
pressure.

Enforcement of TB control

Since 1996, the Occupational Safety and Health Administration (OSHA) has been
inspecting hospitals to assess their TB control programs for preventing
occupational exposures. OSHA also published a proposed standard in 1997 for
Preventing Occupational Exposures to Tuberculosis. Without a final standard,
OSHA is limited to enforcement of worker safety under authority of the general
duty clause of the Occupational Safety and Health Act of 1970 [Section
(5)(a)(1)]. This general duty clause requires employers to furnish employment
free from recognized hazards. It also allows OSHA to enforce well recognized
"industry guidelines or standards of practices" that protect workers
from hazards. However, under the general duty clause, there must be a
"hazard" present (e.g., a case of suspected or confirmed TB) in
the worksite for OSHA to conduct an inspection and cite an employer for lack of
a TB control program. So, at this time, unless a facility has documented a case
of TB in the past six months (a documented hazard), OSHA does not have authority
to cite for lack of a TB control program. OSHA recognizes the CDC's Guidelines
for Preventing the Transmission of Mycobacterium TB in Health Care Facilities,

1994, as an accepted standard of practice, and up to this point, has been
enforcing compliance with the "key" components of these CDC
guidelines. To provide guidance to OSHA compliance officers conducting
inspections, OSHA has outlined feasible "abatement" or control
measures to reduce the risk of the TB hazard in their 1996 Enforcement
Procedures and Scheduling for Occupational Exposure to Tuberculosis.

There have been significant objections from the healthcare community and
professional organizations on the need for an OSHA standard. In addition, an
Institute of Medicine Committee was convened in August of 2000 to address the
need for regulating occupational exposure to TB. The greatest concern is that
OSHA will require elements of a TB control program that go beyond the current
CDC guidelines and that may not be based on scientific evidence of their
effectiveness. Despite the objections, OSHA is putting the final touches on the
proposed TB standard. OSHA has also published a Respiratory Protection Standard
applicable for the use of all respirators except M. tuberculosis and N-95
respirators (29 CFR 1910.134). Until the TB standard is published, OSHA is
enforcing the use of the N95 respirator for TB control.

Until a final decision is made on the regulatory requirements for a TB
control program, efforts must be focused on tailoring control measures that are
based on the incidence of TB in the healthcare setting and the community and the
risk of transmission among patients, workers and visitors.

For a complete list of references, as well as information tables, visit: www.infectioncontroltoday.com

Judene Bartley is vice president of Epidemiology Consulting Service in
Beverly Hills, Mich. She serves as a consultant and advisor on a variety of
infection control issues. Gina Pugliese is the director of the Safety Institute,
Premier Inc. based in Chicago, Ill. She holds faculty appointments at the
University of Illinois School of Public Health and Rush University of Nursing.

For a complete list of references click here