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
what differentiates extrapulmonary TB?
involves any other organ system
what is miliary TB?
massive disseminated infx involving multiple organs
what is the key clinical factors in reactivation TB?
- air-liquid filled cavities
- hemoptysis, caseium release
are there any symptoms of LTBI?
no, asymptomatic
how is LTBI proven?
- positive PPD test
- positive quantiferon test
if S/S of TB are present, then what kind of TB is going on?
fuckin TB, of course
how far along is the disease if S/S of TB are noted?
pretty fucking far along, d/t slow growth rate of pathogen
what are some fucking buzz words for TB?
slow, insidious onset/progression
flu like symptoms
anorexia w/ weight loss (fucking redundant)
what are some stupid-ass, barely-usable buzz words for TB?
chronic, persistant cough
pleuritic pain
dyspnea
who’s not as fucked as a TB pt, but still pretty god damn fucked?
close contacts d/t slow onset of symptoms. the dude’s been infectious for a while so there’s a pretty good chance they have an infx (but not necessarily a disease)
what type of pulmonary lesions are usually seen with HIV patients who get MTB?
diffuse pulmonary infiltrates d/t poor CMI response
-therefore, coin-like lesions aren’t common
(jeez, how fuckin bad do you have to treat your body that you can’t even get sick right…fuck)
can a PPD or quantiferon test differentiate between TB and LTBI?
nope, of course not, that would be too easy
is a negative PPD skin test a guaranteed rule out for TB?
no, 20% of MTB infx don’t show positive PPD tests
once again, that would be too fuckin easy
when does a patient seroconvert in order to give a positive PPD test?
3-8 weeks after primary infx
what is the minimum PPD measurement for normal people?
> 15 mm
what is the minimum PPD measurement for other assholes?
> 10 mm
what is the minimum PPD measurement for people stupid enough to get HIV or live with TB pts?
> 5 mm
what vaccination can cause false positives in PPD test?
BCG vaccination
why is quantiferon gold test better than PPD?
basically shits all over PPD’s potential for false negatives, particularly for HCW’s
-damn, I gotta get the quantiferon test next time. fuck this 3 visit BS
do you have to report TB to local health department?
yeah, shit head, it’s a super infectious disease
if you find a single, solitary pulmonary nodule “by chance” in an asymptomatic patient, what’s your DDx?
MTB Nocardia Actinomyces systemic mycoses lung cancer hamartoma/adenochondroma
what’s the first lab indicator of MTB?
acid fast bacilli in sputum
what else besides sputum culture is needed when MTB is suspected?
blood cultures to see if MTB is tearing shit up around the body (hematogenous dissemination)
what the fuck is nucleic acid amplification (NAA) testing?
don’t care, but it’s quicker than culture
what are first line MTB drugs?
isoniazid
rifampin
pyrazinamide
ethambutol
what is MDR in MTB?
doesn’t respond to:
rifampin
INH
what is XDR MTB resistant to?
rifampin
INH
fluoroquinolones
and basically every other fucking drug ever
what’s the general treatment for LTBI?
INH for sick bastard
rifampin for close contacts (and pussies who can’t handle INH)
what is the general treatment for drug senstive TB disease?
isoniazid 18 months
isoniazid + rifampin 9 months
what is the general treatment for drug resistant TB disease?
chemo
resistant: shit load of drugs
MDR: fuck ton of drugs (more than shit load)
treatment for XDR MTB?
cut that shit out
when is treatment started?
only after Dx confirmed. that shit sucks too much to start needlessly
how is spread of TB prevented?
cover your fucking mouth when you cough/sneeze. fucking sick fucks, I swear
is BCG used in US?
nope
