Filamentous and Mycobacteria

Question 1

Mycobactericea

Answer 1

part of CMN group (corynebacteria, mycobacteria, and nocardia)
rod-like to filamentous
mycobacteria and nocardia are acid fast (Ziehl-Neelsen stain)
cord factors

Question 2

M. tuberculosis

Answer 2

tuberculosis, airborne

Question 3

M. bovis

Answer 3

unpasteurized milk

Question 4

M. leprae

Answer 4

tuberculoid or lepromatous (Hansen disease)

Question 5

nontuberculous mycobacteria

Answer 5

all other mycobacteria

Question 6

tuberculosis

Answer 6

Primary infection: Ghon complex (parenchymal lesion + involved lymph nodes
Secondary infection: reactivation of walled-off lesions, usually apical
Miliary TB: tubercle erodes into vessel
Non-pulmonary: TB may present with cervical lymphadenitis (scrofula)
In immunosuppressed: may see TB w/o granulomas
BCG vaccine (not used in U.S.)

Question 7

Hansen disease (leprosy)

Answer 7

M. leprae replicates best on cooler temperature of skin
Tuberculoid form (immunocompetent): 5 of fewer skin lesion with absence of organisms on smears
Lepromatous (immunocompromised): 6 or more lesions with possible visualization of bacilli on smear
Dx: M. leprae grown on footpads of armadillos, + lepromin (M. leprae Ags) only in tuberculoid form

Question 8

Non-TB Mycobacteria

Answer 8

Mycobacterium avium complex: M. avium, M, intracellulare
Infections in immunocompromised hosts
Can cause pulmonary disease resembling tuberculosis, lymphadenitis, skin disease, soft tissue disease or disseminated disease

Question 9

Nocardia

Answer 9

G+ filamentous
aerobic
opportunistic intracellular pathogens

Question 10

Actinomycosis

Answer 10

G+ anaerobic
Cause painful abscesses in mouth, lungs, and GI tract
Sulfur granules
Dx: anaerobic cultures