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SECTION I - INFECTIOUS AGENT
NAME: Mycobacterium tuberculosis, Mycobacterium bovis
SYNONYM OR CROSS REFERENCE: TB
CHARACTERISTICS: Gram positive rods, slightly curved, cording, acid-fast staining, aerobic, slow-growing.
SECTION II - HEALTH HAZARD
PATHOGENICITY: Initial infection usually unnoticed, tuberculin sensitivity appears in a few weeks and
lesions commonly heal; may progress to pulmonary tuberculosis (fatigue, fever, cough, chest pain, hemoptysis, fibrosis,
cavitation) or extrapulmonary involvement (miliary, meningeal) by lymphohematogenous dissemination; serious outcome
of initial infection more frequent in infants and children; infection with bovine bacillus rare.
EPIDEMIOLOGY: Worldwide (important cause of disability and death in many parts of the world); higher in
males, among poor and in cities; in low incidence areas, most tuberculosis is endogenous (reactivation of initial
latent foci); long exposures of some contacts leads to high risk of infection; epidemics in enclosed areas; M bovis
infection encountered where disease in cattle has not been controlled and raw milk is still used.
HOST RANGE: Primarily humans, cattle, primates, other animals (rodents).
INFECTIOUS DOSE: 10 bacilli by inhalation.
MODE OF TRANSMISSION: Exposure to airborne bacilli from sputum of infected persons; direct invasion of mucous
membranes or breaks in skin; bovine tuberculosis from exposure to infected cattle (airborne, ingestion of raw milk
or dairy products).
INCUBATION PERIOD: From infection to primary lesion or significant tuberculin reaction - 4 to 12 weeks;
risk of progressive pulmonary or extrapulmonary tuberculosis is greatest within 1 to 2 years after infection; may
persist for lifetime as latent infection.
COMMUNICABILITY: Communicable as long as bacilli are discharged in sputum (may be years if untreated); extrapulmonary
TB generally not communicable.
SECTION III - DISSEMINATION
RESERVOIR: Primarily humans; in some areas, diseased cattle (All. bovis).
ZOONOSIS: Yes - inhalation of infected droplets; direct contact with infected animals or tissues of infected
animals.
VECTORS: None
SECTION IV - VIABILITY
DRUG SUSCEPTIBILITY: Sensitive to combination of antimicrobial drugs - isoniazid, rifampin, streptomycin,
ethambutol, pyrazinamide.
SUSCEPTIBILITY TO DISINFECTANTS: Greater resistant to disinfectants and require longer contact times for
most disinfectants to be effective; 5% phenol, 1% sodium hypochlorite (20% commercial bleach) (only if low organic
matter and longer contact times), iodine solutions (high concentration of available iodine required), glutaraldchyde
and formaldehyde (longer contact time) are effective.
PHYSICAL INACTIVATION: Sensitive to moist heat (121o C for at least 15 min).
SURVIVAL OUTSIDE HOST: Guinea pig carcasses - 49 days, carpet - up to 70 days; dust - 90 to 120 days; cockroaches
- 40 days; manure 45 days; paper book - 105 days; sputum (cool, dark location) - 6 to 8 months; clothing 45 days.
SECTION V - MEDICAL
SURVEILLANCE: Skin testing with PPD (purified protein derivative) of previously skin-tested-negative
personnel; chest X-ray.
FIRST AID/TREATMENT: Combination antibiotic therapy; typically isoniazid, rifampin and pyrazinamide.
IMMUNIZATION: Licensed attenuated live vaccine (BCG) available, but not routinely carried out.
PROPHYLAXIS: Preventative treatment with INH (risk of hepatitis for those over 35 years old).
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: Incidence of tuberculosis in laboratory workers working with M tuberculosis
is three times higher than those not working with agent; fourth most commonly reported lab infection; 176 reported
cases with 4 deaths.
SOURCES/SPECIMENS: Sputum, gastric lavage fluids, CFS fluid, urine, lesions from a variety of tissues; naturally
or experimentally infected non-human primates (high conversion rate for workers); litter from other infected animals
(guinea pigs, mice).
PRIMARY HAZARDS: Inhalation of infectious aerosols; accidental parenteral inoculation, direct contact of
mucous membranes, ingestion.
SPECIAL HAZARDS: Bacilli may survive in heat-fixed smears and may be aerosolized in the preparation of frozen
sections and during manipulation of cultures; high rate of isolation of acid fast organisms from clinical specimens
(>10%), sputum, and other specimens from suspected or known cases.
SECTION VII - RECOMMENDED PRECAUTIONS
CONT NT REQUIREMENTS: Biosafety level 2 practices, containment equipment and facilities for primary culture
of sputum and preparing smears; biosafety level 3 practices, containment equipment and facilities for the propagation
and manipulation of cultures of M tuberculosis or M bovis and for animal studies utilizing non-human primates.
PROTECTIVE CLOTHING: Laboratory coat and gloves when manipulating specimens; gloves and gown with tight
wrists and ties in back when manipulating cultures.
OTHER PRECAUTIONS: Appropriate practices and precautions to minimize the production of infectious aerosols.
SECTION VIII - HANDLING INFORMATION
SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover spill with paper towels and
apply 5% phenol, starting at perimeter and working towards the center; allow sufficient contact time (30 min) before
clean up.
DISPOSAL: Decontaminate before disposal; steam sterilization, incineration.
STORAGE: In sealed containers that are appropriately labeled.
Date prepared: October 11, 1997 Prepared by- Canadian Office of Biosafety
Information edited by the Colorado State University Office of Biosafety- June 16, 1998.
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