Tuberculosis

Question 1

What bug causes TB?

Answer 1

Mycobacterium tuberculosis

Question 2

TB was almost eradicated until what epidemic brought about a whole new population of predisposed hosts?

Answer 2

AIDS

Question 3

What strains of TB are particularly concerning?

Answer 3

MDR and XDR

Question 4

Are mycobacteria gram + or gram -?

Answer 4

NEITHER! They stain poorly with gram stain but they stain with ACID-FAST

Question 5

What are the steps in the acid fast staining procedure?

Answer 5

1-stain with carbolfuchsin
2-acid/alcohol decolorization
3-methylene blue counter stain
acid fast+ will be carbolfuchsin color

Question 6

TB transmission is almost always to lung by _______, to lymph nodes, kidney, bones, CNS by ___________, to GI by _____________.

Answer 6

inhalation
hematogenous spread
swallowing infected sputum

Question 7

In an immunocompetant host, what will happen with TB infection?

Answer 7

strong CMI will keep the infection latent for a long time until their immune system is rendered senescent or suppressed and it becomes reactivated

Question 8

in TB hematogenous spread, what types of cells carry the TB?

Answer 8

naive macrophages, activated macrophages kill the TB

Question 9

how does a TB granuloma form?

Answer 9

CD8 cells kill infected macrophages and establish caseating granulomas in whcih infection is contained

Question 10

What immunity factor is important for containing TB?

Answer 10

TNF-a

Question 11

What is the classic presentation of pulmonary Tb?

Answer 11

75% of TB
cough, weight loss, fever, night sweats, hemoptysis, chest pain
sample sputum + CXR

Question 12

M. tuberculosis is _________ aerobe

Answer 12

obligate aerobe

Question 13

what structural component of M. tuberculosis makes it acid fast?

Answer 13

mycolic acids

Question 14

what toxins does mycobacteria create?

Answer 14

NONE

Question 15

What is the reservoir for TB?

Answer 15

HUMANS!

Question 16

transmission of TB?

Answer 16

P2P, resp droplets

Question 17

how does M. tuberculosis survive in macrophages?

Answer 17

prevents fusion of phagosome with lysosome

Question 18

Define Ghon complex

Answer 18

exudative lesion in lungs at site of initial infection, plus draining lymph node (TB)

Question 19

what are older granulomas surrounded by fibrous tissue that have central casseation necrosis and some calcification?

Answer 19

tubercule

may erode and erupt contents

Question 20

define scrofula

Answer 20

cervical adenitis, UNILATERAL, may be Tb or M. scrofulaceum

dx: fine needle aspiration

Question 21

What is Pott’s disease?

Answer 21

disseminated TB in spine, may cause paralysis

Question 22

when might you see erythema nodosum in TB?

Answer 22

primary infection, they are immunogenic from strong CMI

Question 23

what is Miliary TB?

Answer 23

multiple disseminated lesions in lung –> may be deadly

dx: CXR / bright spotlight, lat. XR, chest CT

Question 24

If TB spreads to the GU system, how do you dx?

Answer 24

IV urography, urine culture

Question 25

MRI and spinal tap is used to dx TB when it has infected what part of the body??

Answer 25

CNS

Question 26

how do you dx skeletal TB? GI TB?

Answer 26

skeletal: MRI, joint fluid aspiration GI: Xray, chest CT

Question 27

how does GI TB present and how do you get it?

Answer 27

abd pain, diarrhea, obstruction or hemorrhage in ileocecal region, may be TB or M. bovis from unpasteurized milk

Question 28

When might you see pediatric TB?

Answer 28

recently acquired (trace the source), watch for miliary or meningitis, culture for gastric lavage

Question 29

how do you determine TB exposure?

Answer 29

PPD, TST, IGRA

Question 30

When you determine a patient has TB how long do you wait to preform abx resistance testing?

Answer 30

ASAP, dont wait!

Question 31

How do you treat TB?

Answer 31

isolation for the first 2 wks + 4 drug regimen with added ones depending on resistance always includes isoniazid Direct observed therapy ALWAYS!

Question 32

why don;t we vaccinate for TB in the US?

Answer 32

the BCG vaccine vaccine (live attenuated M. bovis) is used abroad, not cost-effective here, can create weak-moderate false positive TST

Question 33

What is the simplest and most effective way to reduce TB everywhere?

Answer 33

good diet and housing --> keep people healthy so if they are exposed the TB will stay latent which is not infectious!