mycobacteria Flashcards
mycobacterium
intracellular slender rods with cell walls, acid-fast
mycobacterium tuberculosis culture
colonies on Lowenstein-Jensen agar after 8 weeks of incubation
- strictly aerobic
- most species grow slowly
mycobacterium tuberculosis pathogenesis
- inhalation of aerosols
- mycobacteria reach alveoli and multiply in pulmonary macrophages
- virulence depends on its ability to survive and grow within host cells
primary tuberculosis
- TB skin test positive
- radiograph negative
90% of primary tuberculosis turns into
latent-dormant tuberculosis
latent-dormant tuberculosis
- TB skin test positive
- Radiograph negative for active disease
10% of primary tuberculosis turns into
progressive primary (active) infection
progressive primary (active) infection
- TB skin test positive
- radiograph positive
- sputum positive
90% of latent-dormant tuberculosis turns into
no disease
10% of latent-dormant tuberculosis turns into
secondary (reactivation) tuberculosis
secondary (reactivation) tuberculosis
- TB skin test positive
- Radiograph positive
- sputum positive
tuberculin test
injected into the dermis and it swells (if its big then its positive)
tuberculosis treatment
multiple-drug regiment and prolonged treatment
- combination of INH and Rifampin for up to 9 months
m. tuberculosis immunity
stimulates both humoral and a cell-mediated immune response
- delayed hypersensitivity
mycobacterium tuberculosis in cattle
granuloma in the lymph nodes of the head, lungs, intestine and carcass
mycobacterium paratuberculosis
chronic: causes Johne’s disease
- adult wild and domestic ruminants such as cattle, sheep, and goats
- thickening of the intestines
johne’s disease transmission
- ingestion of an organism
- carrier animals, so called “fecal shedders” are the most important source of infection
johne’s disease symptoms
gradual and chronic weight loss and emaciation
- rough hair coat and dry skin
- reduced milk production
mycobacterium leprae
- leprosy (hansen’s disease)
- skin lesions and nerve damage
- cannot be cultured on artificial media
- armadillos are a natural reservoir of M. leprae in the US
epidemiology of m. leprae
highly infectious
- person to person spread or through inhalation of infectious aerosols
cell mediated response to leprosy
milder tuberculoid leprosy
humoral (antibody) response to leprosy
more severe lepromatous leprosy
tuberculoid leprosy
few skin lesions will small numbers of m. leprae at the site of the leison
lepromatous leprosy
many skin lesions with large numbers of m. leprae at the site of the lesion
which type of mycobacterium does not grow in culture?
leprae
