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Mycobacteria - Tuberculosis and Nontuberculous Mycobacteria

Runyon Classification

Group Common Human Pathogens

Tuberculosis M. tuberculosis

M. bovis

M. martasan

M. kansasii

M. scrofulacman mycobacteria, tuberculosis

M. xenopei

M. avium

M. mtraceilulara

M. haemophdum mycobacteria, tuberculosis

IV (rapid growers) M. formitum

M. chelonei (M. abscessus)

Tuberculosis

High risk for infection: Urban, low-income, nonwhite racial minorities and ethnic groups; foreign-born (approximately 25%); homeless; residents of correctional facilities

Highest risk for progression to disease:

· Infants and adolescents; recent contacts with an infectious patient; recent skin test convertor; immunodeficiency HIV); IVDU

· Certain diseases - Hodgkin's, lymphoma, diabetes mellitus, chronic renal failure, malnutrition, immunosuppressive drugs (daily steroids)

Transmission: Inhalation (droplet nuclei); duration of infectivity - few weeks (adult, effective therapy, susceptibilities, smear positivity, cough frequency, adherence to therapy)

Tuberculosis

Early Disease (1 to 6 Months after Infection)

· Lymphadenopathy: Hilar, mediastinal, cervical, supraclavicular

· Pulmonary: Lymphadenopathy, lobar, segmental, pleural, miliary

· Extrapulmonary: meningitis, miliary

Late Disease (Months to Years)

· Pulmonary: Reactivation (adolescents, immunocompromised)

· Extrapulmonary: Middle ear, mastoids, bones, joints, skin

Extrapulmonary (miliary, meningitis, bone, joint, renal)

Occurs in approximately 20% of children less than 5 years of age

Tuberculosis: Diagnosis

Tuberculin testing

· Tuberculin reactivity: