Mycobacteria Flashcards
What are mycobacteria?
Obligate aerobes
Acid-fast bacteria
What are the major mycobateria?
M. tuberculosis
M. leprae
Atypical mycobacteria (not major pathogens)
About M. tuberculosis
Has existed as a human disease since 3000BCE
Most common infectious cause of mortality WORLDWIDE
Was on decline until AIDS epidemic
Multidrug resistant - MDR
Extensively drug resistant - XDR
M. tuberculosis bacteriology
Acid-fast
Can M. tuberculosis grow in vitro?
Yes, but very slowly
What is the natural host? reservoir of M. tuberculosis?
Humans, which makes it possible to eradicate the disease
Why is M. tuberculosis antibiotic resistant?
Because it is slow growing, and most AntiB target rapid cell growth
Are they intra-/extra- cellular?
Both
Do Mycobacteria produce toxins?
No
Where does their drug resistance come from?
It is chromosomal, there are no known plasmids
M. tuberculosis pathogenesis (3)
It is transmitted primarily through INHALATION of infected aerosols aka AIRBORNE
Can also be transmitted transdermally - sputum to open wound
Or can be trasmitted via the GI infection - through M. bovin found in unpasteurized milk
Does M. tuberculosis have a high or low ID
Low-Aerosols are extremely infectious - ID=10
What occurs after being infected?
Alveolar MO’s phogocytose the inhaled bacilli
Naive MO’s can not kill them and instead the bacteria subvert endocytosis and use the MO as trojan horses to spread to other parts of the body
Travels to extrapulmonary sites where it establishes
LATENT (immunocompetant) or ACTIVE (peds, HIV, immunosupressed) extrapulmonary infection
Where does M. tuberculosis travel to?
Diff body systems that have sufficient O2 concentrations to support obligate aerobes -lymph nodes -kidney -bones -Meninges Swallowing infectious sputum infects GI
What 2 diseases can occur in individual in under 5yrs or immunosuppressed?
- T.B Meningitis - inflammation
2. Miliary TB - spreading of TB all over body
