Mycobacteria and Bacillus Flashcards
Mycobacterium tuberculosis
- Obligate aerobe
- Acid-fast rod
Tuberculosis (TB)
- Major human disease
- Association with AIDS (grater effect)
- Drug resistance
Transmission TB
- Human to human
- Airborne droplets
Pathogenesis TB
- Infects lung tissue
- Distributed with macrophages
- Resist lysosomal enzymes
- Inhibits phagosome
- Cord factor (damages mitochondria)
Laboratory Diagnosis TB
-Skin testing (delayed hypersensitivity, tuberculin and protein purified derivative, PPD)
-Chest X-ray
(positive skin test does not indicate disease)
Injection of tuberculin
- Tuberculin is injected between skin layers
- Injection becomes hard and red in a person with tuberculosis
Antibiotic Treatment TB
-Rifampin and Isoniazid
Antibiotic Resistance TB MDR-TB
-Resistant to Isoniazid and Rifampicin
Antibiotic Resistance TB XDR-TB
-Resistance to a quinolone, kanamycin, capreomycin, or amikacin
Vaccination TB
- BCG vaccine (an attenuated strain of M. Bovis)
- Not effective prevention
Mycobacterium leprae
- Leprosy
- Infects the skin
- Chronic disease
Leprosy symptoms
- Ulcers , resorption of bone
- Nerve damage
Tuberculoid Leprosy
- Active cell mediated immunity
- Few organisms
Lepromatous Leprosy
- Immunosuppression
- Many organisms
Phatogenesis M. leprae
- In vitro (Unculturable)
- In vivo (low temp, armadillo model)
Diagnosis of Leprosy
- Lepromin (skin testing)
- Acid fast stains
- Clinical picture
Bacillus Anthracis
- Gram-positive
- Aerobic
- Spore forming bacilli
- Encapsulates in 5% CO2
- Spores formed in soil can last for decades
Anthrax
- Major disease to animals
- The basis for Koch’s postulates
- Humans are incidental host
- Agent of 2001 bioterrorism
Routes of Infection Anthrax
- Direct contact
- Ingestion, infected meat
- Inhalation of infected soil
Form of Anthrax
-Cutaneous
-Pulmonary
Gastrointestinal (not seen in the US)
Cutaneous Anthrax
- Spores enter the broken skin, germinate and rapidly proliferate at site of entry
- Blue-black edema
Inhalation Anthrax
- Spore inhalation and phagocytosis
- germination, replicate and infection of hilar lymph nodes
- Hemorrhagic necrosis of lymph nodes
- Fever, malaise, mayagia and non-productive cough
- Respiratoty failure
Virulence factors Anthrax
-Capsule (Plasmid coded) \+Antiphagocytic \+Plasmid encoded \+Not a good immunogen \+Antibodies to the capsule are not protective against the disease
Exotoxins (Plasmid coded)
+Protective antigen (PA) plus
=edema factor EF
=lethal factor LF
Treatment Anthrax
-Ciprofloxacin with \+Rifampin \+Vancomycin \+Penicillin \+Imipenem \+Clindamycin \+Clarithromycin
