Awareness of and Defense Against Mycobacterium Tuberculosis Masks by benbenzhou


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									   Awareness of and Defense Against Mycobacterium Tuberculosis

                      In the Practice of Gross Pathology

       Imagine you are performing your daily duties as a dedicated pathlogists’

assistant when a routine specimen of a testicular mass arrives from the operating

room for frozen section evaluation. You process it like any other specimen that a

surgeon has sent requesting this type of diagnosis; you probably slice through the

specimen, photograph the mass, describe it, and freeze it. You use pressurized quick-

freeze spray in the cryostat, and you also use an aerosol cleaner type spray to clean

the area after you are finished photographing and grossing the specimen. Almost

simultaneously the pathologist informs you and the surgeon that the mass, which

grossly appeared to be some type of tumor, shows “granulomatous inflammation”.

Although this diagnosis can indicate various disease processes, your first thought is-

“Tuberculosis!” and immediately after- “I’ve just sprayed it all over the place!!”

When the diagnosis is relayed to the surgeon, he replies something to the effect of, “I

had a feeling that’s what it was,” which causes you to grimace in frustration and

anger. Does this type of scenario occur in the surgical pathology laboratory? Yes--

all too frequently. Should this type of scenario happen? Absolutely not. The goal of

this paper is to review the danger of Mycobacterium tuberculosis to the surgical

pathology staff, and to promote minimization of this danger by education and

improved laboratory practices.

       While performing traditional and routine duties in the gross cutting room and

during autopsy, the Pathologists’ Assistant faces a spectrum of dangers, including,

but not limited to: blood-borne pathogens, exposure to toxic chemicals, mechanical

injuries from specimens or tools of the trade, and even radiation exposure. Although

formalin exposure and the risk of HIV infection are the most emphasized

occupational hazards in our profession, perhaps the most insidious and under

recognized threat the pathology staff faces is the aerosolization of Mycobacterium

tuberculosis. OSHA mandates yearly formaldehyde and blood-borne pathogen

training for employees exposed to these agents, but there is currently no required

standard for the education and training of laboratory staff who are at risk for

exposure to M. tuberculosis. Some health-care institutions require annual TB

training for all employees, but some only require it for staff who come into contact

with live patients. Despite this lack of consistency and lack of current government

rules to follow, we, as responsible and conscientious members of our profession,

need to be aware of the threat of tuberculosis, and be responsible for protecting others

and ourselves from it.

       Robert Koch stated in 1882 that, “If the number of victims which a disease

claims is the measure of its significance, then all diseases…must rank far behind

tuberculosis.”(1) One hundred twenty years later, even after the discovery of anti-

tuberculosis drugs, the World Health Organization estimates that globally there are

nearly 2 million deaths from tuberculosis annually.(2) The United States is not

spared from this epidemic, as presently an estimated 13 million U.S. adults are

infected with TB.(3) M. tuberculosis is an airborne infection, carried by droplet

nuclei measuring 1-5 microns in size.(4) Not only can these droplet nuclei be

released from an infected person’s respiratory system during coughing, singing,

sneezing, or speaking,(4) but they can also become aerosolized during certain

medical procedures performed on an infected patient’s blood, sputum, and tissues.

Because tuberculosis infection is sometimes latent, miliary (disseminated by the

bloodstream to sites other than the lung), or both, it is not always suspected in an

infected patient. This creates a greater risk to pathology and autopsy staff since they

usually do not take TB precautionary measures when working with infected tissue

unless the disease is known or suspected. It is estimated that as many as half of the

cases of pulmonary tuberculosis seen at autopsy have been diagnosed there (the

autopsy room) for the first time.(5) Considering this information, it is clear that

anyone working in the field of pathology should be aware of the risks of TB

transmission from human tissues.

What are the specific risks?

       Frozen sectioning of tissue specimens containing tuberculosis poses a hazard

to the cryostat operator and anyone standing close-by, especially when a quick-freeze

spray is used during the procedure. If the specimen in question is suspected by the

pathologist or the surgeon to contain the bacterium, then the frozen section should be

deferred or done only if absolutely necessary. In an article for Human Pathology,

Dr. Jerome Smith recounts his first encounter with tuberculosis in a frozen section

and stresses how he was reprimanded for cutting infected tissue on a cryostat.(6)

The scenario regarding the granulomatous testicular mass in the first paragraph

actually occurred less than a year ago in the hospital where I’m currently employed.

If a frozen section must be done on a suspicious specimen, persons present within the

vicinity of the cryostat should wear an appropriate respirator or mask (discussed

later), and care should be taken by the cryostat operator to generate as little aerosol as

possible during the procedure. A modicum of caution should be used while

performing all frozen sections, since many times TB is not even suspected until the

frozen section diagnosis is made, as in the testicular mass case.

       Three cases of TB infection associated with frozen section preparation were

reported in 1981(7-8). Two pathologists present during frozen section preparation of

infected lung tissue converted to PPD positive status three months after the

procedure. During the procedure, a heavy aerosol was said to have been created due

to use of a compressed gas coolant.(7) The third case involved a histotechnologist’s

conversion to PPD positive status after also using a compressed gas coolant to freeze

a pulmonary nodule.(8) In this case, the patient from whom the pulmonary nodule

was taken was suspected of having bronchogenic carcinoma, so the frozen section

was probably considered innocuously routine, until the surprise diagnosis of

tuberculosis was made. Both of these articles warn of the creation of aerosol during

frozen sectioning, and the need for caution when using compressed coolant. One of

the authors went further to state, “This technique (gas coolant spray to promote quick

freezing) should be used with extreme caution, if it is used at all.”(7)

       Recent interest has been generated regarding occupational hazards of TB

from two articles which describe M. tuberculosis transmission from cadaver to

funeral home worker during the embalming process.(9-10) The procedures used

during embalming are similar and related to those used during autopsy, and these

additional cases support the evidence that TB can be aerosolized in a way that does

not require a living host for transmission via a functioning respiratory system. The

first case describes the transmission of M. tuberculosis from a 35-year-old male

patient with AIDS to a 45-year-old male embalmer with no history of HIV or TB.

The methods used to support this claim included the use of RFLP (restriction

fragment length polymorphism) analysis of genomic DNA taken from TB isolates

from both individuals. The results showed an identical DNA fingerprint, that when

compared to other M. tuberculosis DNA patterns from the geographic area, was

shown to be unique only to the two patients identified by this study. This molecular

data strongly supports “…the hypothesis that M. tuberculosis was transmitted from

the cadaver to the embalmer during the embalming process.”(9) The report also

states that, “…bacteremia with M. tuberculosis is more common in patients who have

AIDS…and the presence of bacteremia may have increased the likelihood that

aerosols generated during embalming were infectious.” This is a valid concern to

keep in mind while autopsying AIDS patients with or without TB.

       The second case(10) used microbiologic and molecular techniques to compare

the DNA fingerprints from the TB isolates taken from the cadaver and the embalmer.

Both isolates were shown to be a rifampin mono-resistant (RMR) strain of

tuberculosis, and more importantly they both had the same DNA fingerprint. This

study described the embalming process used during this particular case in some

detail, and after considering several possibilities, concluded that the most likely mode

of TB transmission between cadaver and embalmer was aerosolization of the tubercle

bacilli from the suction material generated during embalming. This information can

be applied to the practice of autopsy, as stated by Nolte in a paper on autopsy

biosafety: “Given the uniform use of oscillating saws and spray and aspirator hoses

by prosectors, a fair assumption is that all autopsies generate potentially infectious


       Jerome Smith, MD, a pathologist at the University of Texas stated that,

“Some mighty pathologists of yore succumbed to the disease (tuberculosis) that they

had presumably contracted at the autopsy table.”(6) Although a routine, diagnostic

and educational tool used in the practice of Pathology, the autopsy procedure may be

the greatest source of TB exposure and subsequent infections that members of the

pathology profession encounter. Nonparticipating observers are at risk as well if they

share the same air space as the cadaver. As Nolte states, “An autopsy is an

exceptionally efficient method of transmitting tuberculosis from decedent to those

present in the dissection room.”(11) This statement may sound facetious, but it is

most unfortunately factual.

       Several papers have demonstrated that even a brief exposure to TB during an

autopsy on an infectious individual carries a high risk of infection.(11-13) A report

of MDR-TB (multi-drug resistant tuberculosis) transmission on persons exposed in a

New York medical examiner’s office showed an increased rate (28%) of skin test

conversion to PPD positive status among workers involved in autopsies on MDR-TB

positive patients.(14) In a study on nosocomial (hospital acquired) transmission of

TB, it was reported that three of five employees present during an autopsy on an

individual with unsuspected disease had skin test conversions after the procedure.(5)

Another autopsy worker who had a prior BCG vaccination (which causes skin test

results to always read positive) developed active TB five months after the infectious

autopsy which is clinically consistent with becoming infected at the time of the

autopsy. An even more frightening article in the Annals of Internal Medicine

reported that none of the workers caring for a particular patient with unsuspected

disease before his death showed a skin test conversion later on; while after a three

hour autopsy on this patient, all five previously negative employees present during

the autopsy subsequently converted to positive PPD status.(13) All five of these

employees used double tie standard surgical masks during the autopsy. Two of the

autopsy workers had positive sputum cultures eight weeks after the autopsy. The

cultures from these two workers and the source patient yielded identical DNA

fingerprints. Fortunately, all five of the skin test converters were treated with

isoniazid or isoniazid and rifampin and did not develop active TB. The article

concludes: “A patient who did not transmit tuberculosis before death released a

prodigious number of tubercle bacilli during autopsy.” The data discussed here

should certainly alert the reader to the immense need for awareness to and personal

protection against TB during all autopsies.

Is formalin fixation adequate protection from infection?

       When dealing with infectious tissues and specimens containing blood and

body fluids, a popular practice is to “throw it in formalin” based on the assumption

that formalin is toxic and will kill or disable whatever pathogens are present within

the tissue and associated blood and body fluids. Formaldehyde is a toxic chemical,

which is known to be bactericidal and virucidal against certain pathogens, but should

not be taken for granted as an effective weapon against all infectious agents,

including TB. Collins writes, “It is generally assumed that M. tuberculosis is not

viable in formalin fixed material, including lung tissue from tuberculosis patients,

and that such material may therefore be handled without risk of infection. The data

supporting this assumption are however, very weak.”(12) A 1951 study reported

cultures from embalmed bodies yielding isolates of M. tuberculosis as long as 60

hours after fixation.(15) In the most recent study of the effect of formalin on M.

tuberculosis, the authors were not able to culture TB in formalin-fixed tissue,

however, they concluded, “…the true disinfection efficacy of formalin for tissues

infected with M. tuberculosis is unclear. Larger, prospective studies…are needed to

establish guidelines to ensure the safety for those handling infected, fixed tissue.”(16)

Jerome Smith gives us an even more descriptive scenario to consider: “Dense

fibrocaseous lesions seen in old chronic active intrapulmonary or plural tuberculosis

may provide sanctuaries in which tubercle bacilli can survive fixation and

decontamination…”(6) Considering the available data, it seems prudent to be

cautious even with formalin-fixed tuberculous specimens, and to consider “fixed” TB

specimens as potentially infectious as fresh specimens containing the disease.

What is the government doing to protect us?

       At the time of this writing, “Guidelines for Preventing the Transmission of

Mycobacterium tuberculosis in Health-Care Facilities, 1994”, has been published by

the CDC.(4) This publication consists of recommendations and reports—not laws or

requirements. In 1996, OSHA published a directive entitled, “Enforcement

Procedures and Scheduling for Occupational Exposure to Tuberculosis”.(17) This

directive requires employers to schedule routine PPD testing and medical follow-up

for employees exposed to TB; but there are not any laws yet requiring employers to

help prevent and protect health-care workers from initial exposure to TB. The OSHA

rule on occupational exposure has been in the proposed stage since 1997.(3) There is

a need for increased infection control guidelines and enforcement procedures within

autopsy rooms and health-care facilities in general. The United Kingdom requires

that cultures and specimens containing TB, as well as autopsies on known TB

patients be handled in Containment Level 3 laboratories.(12) The U.S. has no such

requirements, and most hospital laboratories in this country are only Level 2

Biosafety facilities. Our current CDC guidelines are in place but are not necessarily

being followed. OSHA states: “…in every recent TB outbreak investigated by the

CDC, noncompliance with CDC’s TB control guidelines was evident.”(18)

Guidelines alone are not enough to combat the TB epidemic; rules and enforcement

procedures are desperately needed as well.

OSHA’s Proposed Rule:

       The proposed standard on occupational exposure to TB covers workers in a

variety of occupational settings, including health-care facilities. The standard

recognizes the danger of TB, the role of HIV infection in increasing the efficacy and

frequency of TB transmission, and the additional danger of multi-drug resistant

TB.(18) The standard calls for employers to adhere to several important and urgently

needed measures, including: identifying all employees at risk of TB exposure and

listing job tasks which involve higher risks of transmission (autopsy is recognized in

this document as a high-hazard procedure), developing an exposure control plan

which includes TB education and training for employees, prompt identification of

individuals with infectious TB, and providing employees with routine skin testing.

The standard also requires employers to utilize proper work practices and engineering

controls in places where patients with TB or their specimens can be found. These

types of controls include maintaining negative pressure isolation rooms, and

providing employees who may be exposed to TB with acceptable respirators;

specifically either NIOSH approved HEPA (high efficiency particulate air) masks, or

N95 respirators. The standard also recommends but does not require additional anti-

TB controls, including HEPA filtration to clean air systems in which TB is carried,

and UVGI (ultra violet germicidal irradiation) systems to kill or inactivate airborne


What can we do to protect ourselves?

       It is more than evident that we as pathologists’ assistants cannot take a

passive role in the fight against TB exposure or wait for directives and new policies

to be handed down to us from our employers or the state and federal governments.

We must be proactive in protecting ourselves against this microscopic, insidious, and

practically ubiquitous infectious organism. There are several types of actions we can

take in order to lessen TB exposure from specimens and autopsy cases that we may

face at any time due to the nature of our specific occupational duties. The easiest and

most obvious form of protection is the use of personal respirators. Wearing a mask is

appropriate whenever exposure to TB is even remotely anticipated. Standard surgical

masks are not adequate protection against TB, as we have seen from the Templeton

study(13). N95 respirators are practical and less costly than HEPA masks, and are

efficient in filtering the infectious droplet nuclei from the air we breathe.(4) These

masks require fit testing before wearing, and your facility should provide this service

as well as providing the masks for employee use. Other work practices we can utilize

to guard against TB include cutting specimens under a hood or very close to a vent,

and by not using gas coolant during frozen sections, as discussed earlier. It is also

important to comply with scheduled TB skin testing, which every health-care facility

is required to provide (17), and to report any confirmed or suspected TB exposure of

employees or others to the immediate head of your department and to infection

control services. We should also try to be active in educating other staff of the

dangers of TB transmission, and to try to become involved in developing TB

prevention plans and policies for the laboratory and autopsy room. Misconceptions

or ignorance of the modes of TB transmission discussed in this paper are prevalent

and must be overcome.

       Perhaps the most important defenses against TB are heightened awareness

and your own common sense. For example, if you receive a surgical specimen for

frozen section that you determine to be suspicious, relay your fears to the pathologist

on duty. The surgeon can be asked for additional information, and the frozen section

may be deferred, or another procedure such as smear or touch-preparation of the

lesion can be performed. Any lesion which is soft, granulomatous-appearing, and

especially caseous-appearing (resembling crumbly or liquefied cheese) should be

treated as suspicious, even if it is not from the lung.

       As health-care workers, M. tuberculosis is a danger we face from a variety of

sources; it does not matter whether we work in busy city hospitals or facilities located

in sparsely populated areas. As Pathologists’ Assistants, we face unique and serious

risks of TB transmission during virtually every step of human tissue examination and

processing. If the government and health-care facilities in general have shown less

recognition and given less emphasis to these risks, then conversely we should be

more motivated to promote awareness of these risks and increase our own

responsibilities regarding protection of our coworkers and ourselves. Facts regarding

specific TB transmission in the pathology lab and autopsy room should become part

of our ongoing collective professional knowledge. Educating others, improving our

work practices, and contributing to new policies in order to lessen the risk of

exposure to TB will make our work areas much safer places. This in turn will enable

us to provide better patient care, thereby making us all the more valuable as

professionals who represent the field of Pathology.

1. Ciegelski PJ, Chin DP, Espinal MA, et al. The global tuberculosis situation-
   Progress and problems in the 20th century, prospects for the 21st century.
   Mycobacterial Infections 2002; 16:1-58.

2. Dye C, Scheele S, Dolin P, et al. Global burden of tuberculosis: estimated
   incidence, prevalence, and mortality by country: WHO Global Surveillance and
   Monitoring Project. JAMA 1999; 282:677-686.

3. Occupational exposure to tuberculosis-Proposed Rule. OSHA Federal Register
   62:54159-54309; 29 CFR Part 1910. October 17, 1997.

4. Centers for Disease Control. Guidelines for preventing the transmission of
   Mycobacterium tuberculosis in health-care facilities, 1994. Morbidity and
   Mortality Weekly Report 1994; 43:1-132.

5. Kantor HS, Poblete R, Pusateri SL. Nosocomial transmission of tuberculosis from
   unsuspected disease. The American Journal of Medicine 1988; 84:833-838.

6. Smith JH. The hazard to pathologists from tuberculous specimens. Human
   Pathology 1996; 27:1251-1252.

7. Barrett RN, Renteln HA. Tuberculous infection associated with tissue processing
   Morbidity and Mortality Weekly Report 1981; 30:73-74.

8. Duray PH, Flannery B, Brown S. Tuberculosis infection from preparation of
   frozen sections. New England Journal of Medicine 1981; 305:167.

9. Sterling TR, Pope DS, Bishai WR, et al. Transmission of Mycobacterium
   tuberculosis from a cadaver to an embalmer. New England Journal of Medicine
   2002; 342:246-248.

10. Lauzardo M, Lee P, Duncan H, and Hale Y. Transmission of Mycobacterium
    tuberculosis to a funeral director during routine embalming. Chest 2001; 119: 640-

11. Nolte KB, Taylor DG, Richmond JY. Biosafety considerations for autopsy. The
    American Journal of Forensic Medicine and Pathology 2002; 23:107-122.

12. Collins CH, Grange JM. Tuberculosis acquired in laboratories and necropsy
    rooms. Communicable Disease and Public Health 1999; 2:161-167.

13. Templeton GL, Illing LA, Young L, et al. The risk of transmission of
    Mycobacterium. Annals of Internal Medicine 1995; 122:922-955.

14. Ussery XT, Bierman JA, Valway SE, et al. Transmission of multidrug-resistant
    Mycobacterium tuberculosis among persons exposed in a medical examiner’s
    office, New York. Infection Control Hospital Epidemiology 1995; 16:160-165.

15. Weed LA, Baggentoss AH. The isolation of pathogens from tissues of embalmed
    human bodies. American Journal of Clinical Pathology 1951; 21:1114-1120.

16. Kappel TJ, Reinartz JJ, Schmid JL, et al. The viability of Mycobacterium
    tuberculosis in formalin-fixed pulmonary autopsy tissue: Review of the literature
    and brief report. Human Pathology 1996; 27:1361-1364.

17. Enforcement procedures and scheduling for occupational exposure to tuberculosis.
    OSHA directives CPL 2.106. February 9, 1996.

18. Occupational exposure to tuberculosis. Unified Agenda 1218-AB46-2038. OSHA
    CFR Citation: 29 CFR 1910.1035. December 5, 2001.


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