MTB Flashcards
gram stain morphology of MTB?
acid fast
describe the cell wall of MTB?
gram negative cell wall
stains acid fast
what are the key virulence factors of MTB?
mycolic acids (cause acid fast) trehalos mimycolate (cord factor)
what are the growth requirement for MTB?
facultative intracellular of macrophages
what are the oxygen growth requirements for MTB?
obligate aerobe
how long does it take to culture MTB?
2-3 weeks
what is MTB sensitive to?
UV light moist heat (pasteurization)
what is the transmission for MTB?
from person with pulmonary or laryngeal TB via inhalation of airborne droplets
is MTB highly contagious?
no, not highly contagious
what is the reservoir for MTB?
humans
what age group is most susceptible for MTB infection?
children <4 yo immunocompetent
what age group is most susceptible for reactivation of pulmonary TB?
elderly >65 yo
what percent of MTB patients remain LTBI for life?
90%
what groups are particularly high risk for MTB infx?
foreign
poor
HCW
what groups are high risk for TB after MTB infx?
young, old
CMI compromise
HIV
IVDU
what are common seeding sites for MTB?
apical-posterior areas of lung
lymph nodes
does MTB produce toxins?
no, tissue damage is caused by CMI
what causes caseation necrosis (soft tubercles) in MTB infx?
granuloma formation
is a granuloma evident in CXR?
no, only in tissue biopsy
how does LTBI progress to TB?
weak CMI allows dormant MTB in tubercles to reseed the body
what causes primary pulmonary TB?
weak immune response, fails to localize primary infx
what causes reactivation pulmonary TB?
systemic immunosuppression (HIV, old age)
-most common form of TB in US