Mycobacterium Flashcards
Mycobacterium
gram-positive, acid fast positive, rod-shaped bacteria. Do not have outer membrane. Have mycolic acid on their cell wall. Facultative intracellular pathogens
Tuberculosis
Caused by M. tuberculosis and M. bovis.
What is the main cause of tuberculosis in humans?
M. tuberculosis.
Tuberculosis Treatment
six month course of four antimicrobial drugs. Drugs are always used in combination.
Why can’t you treat tuberculosis with one drug?
- extracellular and intracellular location of bacteria
- presence of bacteria in various phases within a lesion
- increased tendency to develop drug resistance due to prolonged treatment
- poor drug distribution in walled off lesions
Multidrug Resistant TB
resistant to at least isoniazid and rifampin
Extensively Drug Resistance TB
resistant to isoniazid and rifampin plus any fluoroquinolone and at least one of three injectable second-line drugs
Tuberculosis Prevention
human vaccine (BCG) only used in endemic countries
Mycobacterium bovis
causes zoonotic TB. Maintained primarily in bovine species but has the broadest host range and geographic distribution of all TB organisms. GI tract main portal of entry
In what state is Mycobacterium bovis common?
Michigan
Mycobacterium bovis Diagnosis
- tuberculin test
- Gamma IFN whole blood test C
- Radiography
- Clinical disease and histopath
- direct acid-fast stain from clinical samples
- culture
- PCR
Tuberculin Hypersensitivity Skin Test
detects cellular immune response. Screening test in caudal tail fold with single strength dose of M. bovis purified protein derivative. Read reaction at injection site after 72 hours.
Mycobacterium bovis Treatment
not recommended for animals. For humans combinations of antimicrobial agents
Mycobacterium avium subsp. paratuberculosis
Causes Johne’s Disease.
Johne’s Disease
chronic progressive granulomatous enteritis of ruminants. Disease of economic importance. Possible etiology in Crohn’s Disease due to its excretion through milk
Mycobacterium paratuberculosis Transmission
young animals are more susceptible
Mycobacterium paratuberculosis iceberg effect
numerous asymptomatic shedders. 35% immune, 60% asymptomatic shedders, 2-5% develop clinical disease
Mycobacterium paratuberculosis Diagnosis
humoral immune response. Low sensitivity and false negative results from anergy. Cell mediated immune response- Johnin hypersensitivity skin test
Mycobacterium paratuberculosis Prevention
culling, detection and isolation or culling asymptomatic shedders, separation of calves at birth, pasture rotation
Mycobacterium paratuberculosis Vaccine
not very effective. Vaccine is restricted to Johne’s disease due to cross reactivity and interference with surveillance. Severe vaccine reactions
Mycobacterium avium intracellular complex
widespread in soil and water, including treated municipal tap water. Numerous strains. Causes opportunistic granulomatous infections in humans, animals, and birds. Primarily a pulmonary pathogen immune comprpmised
Mycobacterium paratuberculosis symptoms
diarrhea, wasting, edema
Mycobacterium leprae
causes leprosy
Mycobacterium Staining
in Geimsa or Gram stain it is negative stained/unstained. Bacilli normally observed
Mycobacterium Diagnosis
staining
biopsy and histopathology
PCR
Mycobacterium Treatment
possibly combination therapy
Most susceptible to Mycobacterium avium subsp paratuberculosis
young animals
Mycobacterium avium subsp paratuberculosis symptoms
diarrhea, edema, wasting
