Mycobacteria Flashcards
Mycobacteriaceae oxygen requirements
Obligate aerobes
Mycobacteriaceae spore formation
Non-sporeforming
Mycobacteriaceae growth
Generally slow-growing
Mycobacteriaceae acid-staining
Acid-fast and contain mycolic acid in cell walls
Mycobacteriaceae pathogenesis
Facultative intracellular pathogens
Tubercle bacilli strains of Mycobacteriaceae
- Mycobacteriaceae tuberculosis
- Mycobacteriaceae africanum
- Mycobacteriaceae leprae
- Mycobacteriaceae Boris
Mycobacteriaceae microscopy
Cord growth (serpentine arrangement) of virulent strains
How to identify Mycobacteriaceae
Most labs will use PCR based methods (for most of these conditions CDC wants report on the results in 1-2 weeks max)
Mycobacteriaceae tuberculosis colony morphology
“Like grits on a baking sheet”: rough, dry, granular, ranging from non-pigmented to buff or tan colored colonies
Mycobacteriaceae tuberculosis at-risk population
Immunocompromised, malnourished, individuals exposed to sick people or healthy carriers
Mycobacteriaceae tuberculosis transmission
Person to person aerosol (>1m)
Mycobacteriaceae tuberculosis 3-virulence factors
- Cord factor
- Iron-capturing ability
- Sulfolipids
Mycobacteriaceae tuberculosis cord factor
Glycolipid responsible for serpentine growth pattern: toxic to leukocytes, activates macrophages and dendritic cells, plays a role in the development of the granulomatous lesions
Mycobacteriaceae tuberculosis iron capturing ability
Required for the pathogen’s survival within phagocytes
Mycobacteriaceae tuberculosis sulfolipids
Prevents the fusion of the phagosome to the lysosome, so organism is not exposed to lysosomal enzymes and enables it to live within a cell
Mycobacteriaceae tuberculosis clinical entry
Inhalation (most common), ingestion, via the mucosa of the genital-urinary tract or conjunctiva, or via skin abrasions
- disease mostly due to host immune response
Mycobacteriaceae tuberculosis infectious does
10 cells
Mycobacteriaceae tuberculosis signs and symptoms
Fatigue, fever, unexplained weight loss, night sweats (soaking through all your bedding type sweats)
Pulmonary TB: productive cough longer than 3 weeks w/ hemoptysis (coughing up blood) and chest pain
Extrapulmonary TB: (liver and spleen most common) will vary based on location but jaundice is common
Typical progression of pulmonary tuberculosis
Pneumonia (inflammation
Granuloma (tubercule) formation with fibrosis
Caseous necrosis (breaks down)
Cavity formation— center liquefies and empties into bronchi. Bacteria escapes
Mycobacteriaceae tuberculosis diagnostic criteria
- Mantoux test (tuberculin skin test) using purified protein derivatives (delayed hypersensitivity rxn indicates previous or current infection, OR VACCINATION)
- Chest X-ray to look for granuloma
- Sputum for AFB
- PCR/ culture for direct evidence of active disease
Mycobacteriaceae tuberculosis 4-drugs of treatment
Isoniazid (INH)
Rifampin
Para-aminoslicylic acid
Ethambutol
Mycobacteriaceae tuberculosis control
Vaccination (more common in areas with bovis infections
Prophylactic and therapeutic intervention for all those possibly exposed after someone is diagnosed
Careful case and treatment monitoring (you are regulated to make sure you take ALL of the meds ON TIME, EVERY DAY)
Mycobacteriaceae leprae stain
Acid-fast bacilli
Mycobacteriaceae leprae growth/ infection
Strict human pathogen, cannot be cultivated in-vitro
Mycobacteriaceae leprae infectivity
Infectivity is very low- prolonged contact is required.
Disease state is primarily due to host immune response
Incubation period can last from several months to 20-30 years
Mycobacteriaceae leprae risk-groups
Those who live in tropical settings, and/or those that live in close contact with patients who have untreated, active, predominately multibacillary leprosy, and people living in countries with endemic leprosy
Mycobacteriaceae leprae initial signs and symptoms
Symptoms initially mild- not recognized until cutaneous eruption presents. First, numbness, then inability to sense temperature, then inability to sense pressure, then ability to sense pain, then ability to sense even deep pressure (puncture)
Will notice a hypopigmented (very pale) macule (lesion)
From this stage will develop into the different types
Four types of leprosy
- Borderline tuberculoid leprosy
- Borderline lepromatous leprosy
- Tuberculoid leprosy
- Lepromatous leprosy
Borderline tuberculoid leprosy
Cutaneous lesions are numerous and not we’ll definite
Disease may regress, improve, or stay the same. May initially look like ring-worm
Borderline lepromatous leprosy
Numerous macule-type lesions, as well as papules, plaques, and nodules. Inverted-saucer lesions common. May still have feeling- anesthesia often absent. Disease may remain in this stage, improve or regress.
Tuberculoid leprosy
Strong, cell-mediated response to M. Leprae antigens
Lesions don’t contain many mycobacterium (no AFB on skin test)
Extensive plaques on trunk, face, and limbs
Nerves often thicken and lose function. LEPROMIN TEST WILL BE POSITIVE. Can progress into lepromatous type if left untreated for long time
Lepromatous leprosy
Disfiguring- lesions are large, diffuse, and granulomatus. If nodules are bad enough, may lose parts of the face and digits.
Weak or no cell-mediated responses to antigens, and skin test will contain large bacteria counts (M. Leprae)
LEPROMIN test will not respond (NEGATIVE)
This is the infectious form of leprosy
3 cardinal signs of leprosy
- One or more hypo-pigmented, anesthetic skin patches
- One or more thickened peripheral nerves
- A positive skin smear (microscopy w/ acid-fast stain)
Lepromatous leprosy treatment
Dapsone + rifampicin + clofazimine (typically takes 12+ months to treat)
Tuberculoid leprosy treatment
Dapsone + rifampicin (typically 6+ months to treat)
mycobacterium Adium-intracellular complex (MAC)
Opportunistic ubiquitous pathogen attacking in immunocompromised persons (frequently with AIDS). Produces a tuberculosis or leprosy-like disease (often disseminated in AIDS patients) that is highly resistant to anti-tuberculosis drugs. Requires LONG combination treatment
