Preventing Transmission of TB

Preventing Transmission of TB

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

Althoughthere has been a steady decline of cases of tuberculosis (TB) in the US, thisdecrease will continue only if attention is paid to identifying patients withTB, initiating proper treatment, and implementing measures to reduce the risk oftransmission to others during periods of infectivity.

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

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

The probability that a person who is exposed to TB will become infecteddepends on the concentration of droplet nuclei in the air and the duration ofexposure. 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 ofbecoming infected are not well defined. In general, persons who have beeninfected previously with M. tb may be less susceptible to subsequent infection.However, reinfection can occur among those previously infected, especially ifthey are severely immunocompromised. Vaccination with Bacille of Calmette andGuerin (BCG) probably does not affect the risk of infection; rather it decreasesthe risk for progressing from latent TB.

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

Drug Resistance

Inthe US, from 1993 through 1996, overall resistance to at least isoniazid was8.4%; rifampin 3.0%; both isoniazid and rifampin (classified as MDR-TB) 2.2%;pyrazinamide 3.0%; streptomycin 6.2%; and ethambutol hydrochloride 2.2%.³Rates of resistance were significantly higher for case patients with a prior TBepisode. Compared with previous US surveys in 1991 and 1992, isoniazidresistance has remained relatively stable. In addition, the percentage of MDR-TBhas decreased, although the national trend was significantly influenced by themarked decrease in New York City.

Risk of Nosocomial Transmission

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

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

A review of the outbreaks of MDR-TB in the US shows that these outbreaksinvolved large numbers of cases with a high prevalence of HIV infection. Themortality rate was extremely high and the median interval from TB diagnosis todeath was extremely short, the majority being less than four weeks. The highmortality rate in these outbreaks is explained by the severe degree ofimmunosuppression in many of the patients combined with ineffective treatmentfor unrecognized drug-resistant disease. Nearly all patients in these outbreakshad M.tb isolates resistant to both isoniazid and rifampin, the two mosteffective drugs available. In four hospitals and the prison system, the outbreakstrain was resistant to seven anti-TB drugs (including streptomycin, ethionamide,cycloserine, kanamycin, rifabutin, and pyrazinamide). At least 20 healthcareworkers 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-TBand drug-susceptible TB in hospitals were breaks in some basic TB controlstrategies, such as: delays in diagnosis of TB, delays in identification of drugresistance, and delays in initiation of appropriate therapy--all of whichresulted in delays in proper isolation and prolonged patient infectiousness.⁸Even if a patient was diagnosed with TB, respiratory isolation was ofteninadequate. For example, isolation rooms were found to have positive rather thannegative pressure, air was being recirculated from isolation rooms to other highrisk areas, doors to isolation rooms were left open, isolation precautions werediscontinued too soon, and healthcare workers did not wear adequate respiratoryprotection. When appropriate TB control measures were implemented, transmissionwas significantly reduced or ceased entirely. Unfortunately, many of theinterventions were implemented simultaneously, so the effectiveness of specificinterventions could not be determined.

Outbreaks in hospitals and prisons illustrate the rapid spread and extent ofTB 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 ofinfection control measures.

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

In 1994, the US Centers for Disease Control and Prevention (CDC) published a132-page Guideline for Preventing the Transmission of Mycobacterium TB in HealthCare Facilities.⁶ Follow-up studies by the CDC at several of thehospitals where outbreaks occurred have shown that patient-to-patient andpatient-to-healthcare worker transmission was stopped after implementation ofthese recommended guidelines.⁸

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

Drug susceptibility patterns of M.tb isolates from TB patients treatedin the facility should be reviewed to identify frequency and patterns of drugresistance. PPD skin test conversion rates should be analyzed for eachdepartment or occupational group and be compared to rates for workers in areaswhere exposure to TB is unlikely.

Diagnostic Evaluation and Treatment

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

It will also be important to start empiric therapy as soon as TB is suspectedwith an appropriate regimen based on the local drug-resistance surveillancedata.^6,9 The current US recommendation is to begin empiric therapywith four drugs (isoniazid, rifampin, pyrazinamide, and ethambutol, orstreptomycin) except in areas where surveillance reveals that the prevalence ofprimary resistance to isoniazid is less than or equal to 4%.¹⁰ Inthose locations with rates less than or equal to 4%, initial regimens of threedrugs (isoniazid, rifampin, and pyrazinamide) are recommended for initialtherapy. Treatment guidelines for TB patients with HIV infection and on specifictreatment 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 notmatter what other infection control measures are in place. This will requirecareful evaluation of patients upon their initial encounter with the healthcaresystem with prompt isolation as soon as TB is suspected on clinical groundsalone and until laboratory and clinical evidence eliminates the diagnosis. Thespecific procedure for "early identification and isolation ofpatients" will be based on the prevalence and demographic profile of TBpatients in the community. In areas of high prevalence of HIV and TB and becauseof the difficulty in recognizing TB in patients with HIV, some facilities havefound it necessary to isolate all patients with HIV infection that present withclinical symptoms suggestive of TB (e.g., fever, cough) and /or anabnormal chest radiographs until a diagnosis of TB can be ruled out.¹⁵

The procedure for "early identification of TB patients" and thedefinition of "suspect" case will determine the number of isolationrooms that will be needed. There will often be patients who are placed inisolation because of suspect TB and are later found not to have TB. The beststrategy is to isolate a suspect patient until TB can be ruled out to preventpossible nosocomial transmission. A number of strategies have been used toincrease the availability of rooms that can be used for isolation, such as theuse of window exhaust fans/units to create negative pressure or portable orwall-mounted HEPA filtration units.

Giving authority to nursing and physician staff to made independent decisionsto isolate patients with suspect TB and policies for automatic isolation ofcertain patients (e.g., with TB in differential diagnosis) can oftenreduce delays in initiation of isolation.¹⁶ Hospitals that havemonitored for compliance with TB control measures, particularly appropriateisolation, have demonstrated reductions in the number of days that potentiallyinfectious patients were not in appropriate isolation.^{15, 17}

The standard method of identifying persons infected with Mycobacterium tbis the Mantoux tuberculin skin test given intradermally with 0.1 ml of 5tuberculin units of purified protein derivative (PPD) tuberculin.^{6, 16}It is clear that PPD skin testing of healthcare workers permits earlyrecognition of potential episodes of nosocomial transmission and the opportunityto offer isoniazid or other chemoprophylaxis to workers with skin testconversion. In addition, it is important to identify workers with active TB thatpose a risk of infection to patients and others. It may be prudent to dobaseline PPD testing of HCWs, particularly in high-risk facilities. Thefrequency of additional PPD testing will depend on the level of risk in aparticular facility.

The prevalence of TB in the facility should be considered when choosing theappropriate cut-point for defining a positive PPD reaction. For example, infacilities 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 riskfactors. In other facilities where the risk of TB exposure may be higher, theappropriate cut point may be < 10 mm.

All results on PPD testing should be recorded in the worker's health recordas well as an aggregate database of all the healthcare worker PPD skin testresults. 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 ofpreviously PPD negative HCWs tested in each area or group (i.e., thedenominator) and the number of PPD test conversions among HCWs in each area orgroup (i.e., the numerator).

The potential for variability of skin test conversions with differentcommercial preparations of PPD is another important issue when evaluating yourskin test conversion rates. A number of recent studies have demonstrated adifference in reactivity between various commercial products.^{18, 19}

The ability of persons who have TB infection to react to PPD may graduallydecline over time. For example, adults who were infected during childhood mayhave a negative skin test reaction. However, when the PPD skin test is given, itmay boost the hypersensitivity, and the reaction to a second skin test may bepositive. This boosted reaction can be misinterpreted as a PPD conversion from anewly acquired infection. The likelihood of boosting increases with age. So,two-step baseline PPD testing is recommended to reduce the likelihood that apositive (boosted reaction) is misinterpreted as a new infection. The second PPDskin test should be performed 1-3 weeks after the first negative test, and ifthe second test is positive, it is most likely a boosted reaction. The two-steptesting can be especially useful and cost effective in situations where workershave received BCG vaccination and in situations when boosting may be due toprior exposure to M. tb and non-TB mycobacteria.^{6, 20} The CDCguidelines recommend two-step baseline PPD testing for all workers withpotential for TB exposure, including those that have had BCG vaccination. For aperson who was vaccinated with BCG, the probability that a PPD test reactionresults from infection with M. tb increases as the size of the reactionincreases, and as the length of time between BCG vaccination and PPD testingincreases.⁶

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

Bacille-Calmette-Guerin (BCG) Vaccination

In the US, BCG vaccine has not been recommended for general use because thepopulation risk for infection with TB is low and the protective efficacyof BCG vaccine is uncertain.²¹ The immune response to BCG vaccinealso interferes with the use of the tuberculin skin test to detect M. tbinfection. BCG also may complicate preventive therapy because of thedifficulties 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 ofengineering 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 ofdroplet nuclei and prevent the escape of droplet nuclei from the TB isolation ortreatment room into the hallway or other areas. Two types of general ventilationsystems are the single-pass system and the recirculation system. The single passsystem supplies air to the TB isolation room from the outside (after heating orcooling) and 100% of the air is exhausted to the outside. In a recirculatingsystem, a small portion of the air is replaced with fresh outside air, whichmust pass through a high-efficiency particulate air (HEPA) filter prior torecirculation into general areas. General ventilation systems must be designedto prevent air stagnation or short-circuiting of air. One method is to supplythe air near the ceiling and exhaust it near the floor.

To prevent the escape of droplet nuclei, the TB isolation room should be keptunder negative pressure in relation to the hallway. Doors to the room should bekept closed. The negative pressure should be monitored daily while the room isbeing used. It is recommended that there be a minimum of six air exchanges perhour for TB isolation and treatment rooms. However, these recommendations arebased on comfort and odor control and the effectiveness of this level of airflowin reducing concentration of droplet nuclei has not been evaluated directly oradequately.

The American Institute of Architects' revision task force has approved the2001 revision of the AIA Guidelines for Design and Construction of Hospitals andHealthcare Facilities. The ventilation requirements for hospitals requires 12air changes per hour for airborne infection isolation (AII) rooms when majorrenovation or new construction is anticipated.²² This new AIA editionalso requires that the daily monitoring of negative pressure be accomplished bya 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 onestate's investigation of room air pressure discrepancies. Alarms or pressuregauges for isolation rooms showed negative pressure in the respiratory isolationroom (i.e., airflow into the room), contradicting the actual direction ofair 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 thehallway when the door is opened. To maintain negative pressure, all air leaks inthe room, such as around electrical outlets, windows and around plumbing pipesshould be sealed. The updated AIA Guidelines explicitly require a tightly sealedroom. However, they do not require an anteroom but suggest it is desirable for aroom used for highly immunosuppressed patients (e.g., bone marrowtransplant 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 ofspecimens or for administration of aerosolized pentamidine. If the air isexhausted into the room, a HEPA filter should be used on the discharge vent ofthe device. There are other types of local exhaust systems (such as smokeevacuation devices) that are used during surgical procedures or duringbronchoscopy.

HEPA Filtration

HEPA filters are air cleaning devices that have a documented minimum removalefficiency of 99.97% of particles < 0.3 microns in diameter. Studieshave shown that HEPA filters are very effective in reducing the concentration ofAspergillus spores (which range in size from 1 to 6 microns < to belowmeasurable levels.²⁴ Therefore, HEPA filters can remove infectiousdroplet nuclei from the air. HEPA filters can be used in exhaust ducts or infixed or portable HEPA room air cleaners in TB isolation rooms or areas. HEPAfiltration 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 generalventilation system or when increased effectiveness of the room airflow isdesired. 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 upstreamwill extend the useful life of a HEPA filter.

Portable or mounted HEPA units have been found to be an effective alternativeto central ventilation. In a recent experimental study of portable HEPAfiltration units it was found that when these units were used in anon-ventilated room, they were able to remove over 90% of aerosolized particlesof 0.3 micron size within 5 to 30 minutes.²⁵ In a non-ventilated roomwithout a portable HEPA unit it took over 170 minutes to clear the air ofaerosolized particles 0.3 micron size.

Ultraviolet Germicidal Irradiation (UVGI)

Research has demonstrated that UVGI is effective in killing or inactivatingtubercle bacilli under experimental conditions.^{26, 27} Because of theresults of numerous studies and the experiences of TB clinicians during the pastseveral decades, the use of UVGI has been recommended as a supplement to otherinfection control measures.^28-32 UVGI can be used inside air ducts,for upper-room air irradiation, or as a supplement to portable or fixed HEPAfiltration units. The principal advantages of UVGI air disinfection are the easeof application and relatively low cost. Studies suggest that a 30-watt UVfixture provides the equivalent of 20 or more room air exchanges depending onthe air mixing and airflow patterns. Clearly there is a role for the use ofupper-room air UVGI irradiation in areas that are difficult to ventilate, suchas waiting rooms, emergency rooms, corridors, and other central areas of afacility where patients with undiagnosed TB could contaminate the air. The useof UVGI irradiation in the ducts in one TB hospital in the US has controlledtransmission of TB in this high-risk setting.³³

The 2001 AIA Guidelines addressed the concern for unidentified cases of TB indiagnostic areas. An additional requirement in new construction or majorrenovation is the provision for an AII room in emergency rooms. The Guidelinesalso require negative airflow (with respect to adjacent areas) in triage andwaiting areas of emergency and diagnostic imaging areas. Permittingrecirculation of the air after passing through HEPA filters offsets the increasein cost of air that is 100% exhausted to the outside. The recirculation of airapplies 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 bringingcontaminated air into contact with irradiated upper-room air space. Because ofthe concerns of overexposure to UV radiation causing keratoconjunctivitis,workers that may have high intensity exposure should be warned of the hazard andtake special precautions, such as turning off the lamps before entering theupper 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 aregular schedule for replacing the lamps. Wall or ceiling mounted fixturesshould have louvers to block the downward radiation levels and the actual UVtube 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 roomto other departments. In the US, all workers entering the TB isolation rooms arerequired to wear an N-95 respirator certified by the CDC's National Institute ofOccupational Safety and Health (NIOSH). These N-95 respirators meet the CDC'sperformance criteria for a respiratory program for TB control.⁶Visitors should be offered respiratory protection. Clothing and disposableinanimate items contaminated with airborne particles or respiratory secretionshave not been associated with the transmission of M. tb. However, as ageneral infection control measures, all contaminated disposable patient careitems should be properly discarded. In the clinical laboratory, however, allspecimens and cultures should be disposed of as medical waste, which ideallyincludes decontamination on-site prior to disposal. Items decontaminatedoff-site must be packaged in accordance with applicable local, state and federalregulations before removal from the facility.³⁴

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

Respiratory protection

All persons entering rooms where patients with known or suspected TB arebeing isolated, should use respiratory protection during cough-induction, whenaerosol-generating procedures are performed, or when engineering controls arenot present. The CDC recommend that respirators used for protection againsttransmission of TB meet standard performance criteria.⁶ Thesecriteria 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 NationalInstitute of Occupational Safety and Health meets these performance criteria.This N95 respirator has the ability to filter 95% of particles in the 0.3 micronsize. A disposable N-95 respirator is now in common use by workers in UShospitals. Although these respirators are disposable, if they are used strictlyfor TB control, they may be reused by the same healthcare worker as long as therespirator remains structurally intact or is not damaged or soiled. (Note: TBtransmission has not been show to occur from contamination of inanimate objectslike masks.) If the respirator becomes soiled with blood or body fluids,however, it should be considered contaminated and be discarded. Each facilitywill need to develop a protocol that addresses the circumstances in which adisposable respirator will be contaminated.

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

After an initial fit test and selection of the appropriate size of therespirator, a repeat fit testing is indicated if workers gain or lose more than10 pounds and if they have a change in dental structure as a result of losingteeth or receiving dentures. The respirator manufacturer's instructions shouldbe followed for fit testing procedures.

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

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

Special Considerations for High Risk Procedures

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

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

If surgery is necessary on a patient with TB, it should be performed at theend of the day. An assessment of resources should determine the frequency andmost effective way of managing recognized TB patients who are still consideredcommunicable. The NIOSH guide may be used to determine time to permit a completeexchange of air in the OR before considering reuse of the room. Because the airhandler controls air flow for all OR rooms in the surgical suite, the use of aseparate negative pressure room for bronchoscopy procedures is preferred. The1996-97 AIA Guidelines required bronchoscopy procedure rooms to be at negativepressure.

Enforcement of TB control

Since 1996, the Occupational Safety and Health Administration (OSHA) has beeninspecting hospitals to assess their TB control programs for preventingoccupational exposures. OSHA also published a proposed standard in 1997 forPreventing Occupational Exposures to Tuberculosis. Without a final standard,OSHA is limited to enforcement of worker safety under authority of the generalduty clause of the Occupational Safety and Health Act of 1970 [Section(5)(a)(1)]. This general duty clause requires employers to furnish employmentfree from recognized hazards. It also allows OSHA to enforce well recognized"industry guidelines or standards of practices" that protect workersfrom hazards. However, under the general duty clause, there must be a"hazard" present (e.g., a case of suspected or confirmed TB) inthe worksite for OSHA to conduct an inspection and cite an employer for lack ofa TB control program. So, at this time, unless a facility has documented a caseof TB in the past six months (a documented hazard), OSHA does not have authorityto cite for lack of a TB control program. OSHA recognizes the CDC's Guidelinesfor Preventing the Transmission of Mycobacterium TB in Health Care Facilities,1994, as an accepted standard of practice, and up to this point, has beenenforcing compliance with the "key" components of these CDCguidelines. To provide guidance to OSHA compliance officers conductinginspections, OSHA has outlined feasible "abatement" or controlmeasures to reduce the risk of the TB hazard in their 1996 EnforcementProcedures and Scheduling for Occupational Exposure to Tuberculosis.

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

Until a final decision is made on the regulatory requirements for a TBcontrol program, efforts must be focused on tailoring control measures that arebased on the incidence of TB in the healthcare setting and the community and therisk 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 inBeverly Hills, Mich. She serves as a consultant and advisor on a variety ofinfection control issues. Gina Pugliese is the director of the Safety Institute,Premier Inc. based in Chicago, Ill. She holds faculty appointments at theUniversity of Illinois School of Public Health and Rush University of Nursing.

For a complete list of references click here