8. Family Mycobacteriaceae (I) Flashcards
Motility of the family Mycobacteriaceae
Nonmotile
What is used to stain Mycobacteria?
Ziel-Neelsen
Auromine O stain
Steps in Ziehl-Neelsen acid-fast staining
Carbol fuchsin (1° stain) HCl (decolorizer) Methylene blue (counterstain)
Found in the cell wall of Mycobacteria that enables it to retain the carbol fuchsin stain
Mycolic acids
Enumerate the bacteria that have mycolic acids in their cell wall in decreasing order of chain length
Mycobacteria
Nocardia
Corynebacteria
True/False. Mycobacterium tuberculosis has an animal reservoir
False. M. tuberculosis is an exclusive human pathogen
An animal pathogen that is closely related to M. tuberculosis that causes a disease in people that is indistinguishable from TB
M. bovis
How is M. bovis acquired?
Ingestion of infected meat or milk
MOT for M. tuberculosis
Aerosol droplets from coughing
Common presentation of TB
Chronic pulmonary disease
Nodular structure formed by macrophages, monocytes and neutrophils which triggers an immunologic response
Tubercle/granuloma
Immunologic response to M. tuberculosis infection
Cellular immunity
Delayed-type hypersensitivity
What can be seen in radiographs of disseminated or miliary TB?
“Millet seed”-like lesions
Dissemination of M. tuberculosis organism to the liver, spleen, kidney, bone, brain, meninges, and other parts of the lung with further granuloma formation
Disseminated/miliary TB
Skin test for the delayed-type hypersentivity for TB
PPD test
Antigen reagent in the PPD test
Purified Protein Derivative
Vaccine for TB prophylaxis
Bacillus Calmette Guérin (BCG) vaccine
Drugs taken after a positive tuberculin test to prevent disease
Isoniazid (INH): 6-9 months
Rifampin: 4-9 months
M. tuberculosis drug-resistance is due to
Mutation
How are nontuberculous Mycobacteria acquired?
Environmentally acquired
MOTT that is commonly associated with HIV-related systemic bacterial infection; pulmonary pathogen much like TB
M. avium complex (MAC)
MOTT agent of pulmonary disease in compromised hosts (HIV-infected individuals)
M. kansasii
MOTT agent that causes cutaneous disease from contact with contaminated water
M. marinum
MOTT agent that causes cervical adenitis in children (contaminated raw milk, soil, daily products)
M. scrofulaceum
MOTT that causes skin and soft tissue diseases in various hosts
M. fortuitum
M. chelonae
M. abscessus
MOTT agent that causes leprosy
M. leprae
Nontuberculous Mycobacteria commonly found in tap water
M. gordonae
Is M. gordonae pathogenic or nonpathogenic?
Nonpathogenic
Class of biosafety hood in dealing with AFB
Class 2
Lab diagnosis of TB
- AFB visible by Ziehl-Neelsen or fluorochrome smears
- recovery by culture (gold standard)
Incubation time for Mycobacteria
Up to 8 weeks
Used for rapid diagnosis of TB
Nucleic acid assays (NAA)
2 species under M. avium complex (MAC)
M. avium
Mycoplasma intracellulare
Most commonly isolated AFB among MOTT
M. avium complex
Colony morphology of M. avium complex
Smooth
Cream-colored colonies
MOTT that is rapid growing; grows in 7 days or less on solid media
M. fortuitum-chelonae complex
Staining characteristics of M. fortuitum-chelonae complex
Gram-positive cells with diphtheroid-like morphology
Other name for leprosy
Hansen’s disease
Phases of M. leprae infection
Silent phase
Intermediate phase
Phase of M. leprae infection; multiplication of bacilli
Silent phase
Phase of M. leprae infection; impairment of sensory and peripheral nerves
Intermediate phase
Where can M. leprae be grown?
- Footpads of mice
- Nine-branded armadillos
It cannot be grown on artificial media.
Oxygen requirements of the family Mycobacteriaceae
Obligate aerobes
