Chapter 15: mycobacterium

Question 1

mycobacteria include 2 main species

another one too

Answer 1

mycobacterium tuberculosis

mycobacterium leprae

nontuberculous mycobacteria (NTM)
-more prevalent than other two combined in US

Question 2

mycobacteria descrption

and staining

Answer 2

rods with lipid laden cell walls

-acid fast staining

Question 3

1/3 of all AIDS pts worldwide also have

Answer 3

TB

Question 4

mycobacterium tuberculosis and oxygen

Answer 4

obligate aerobe

• makes sense bc it mainly infects lungs
• grows slowly and takes almost 6 weeks for growth

Question 5

virulence factors tuberculosis

Answer 5

mycolic acid, mycoside

cord factor: parallel growth of bacteria so appear as cords
-inhibit neutrophil migration and damage mitochondria

sulfatides: inhibti phagosome from fusing with lysosome that contains bacteriolcidal enzymes

wax D: adjuvant that may be part of m tuberculosis that activates the protective cell immune system

mike (mycosides) is waxing (wax D) his SUrfboard (sulfatides) and has his surfboard (CORD)
-has cough and weight loss

Question 6

pathogenesis of TB

Answer 6

facultative intracellular growth
-inhaled bacteria cause local infiltration of neutropihls and macrophages, phagocytosed bacteria not killed

cell mediated immunity
-macrophages present to T cells then t cells head to site and activate macrophages in lungs which causes caseous necrosis

Question 7

PPD test

-how done

false positive
false negative

Answer 7

injected antigen under skin gives delayed type hypersensitivity

• latent tuberculosis
• if positive doesn’t mean pt has active TB
• could mean exposure and infection at some time in past

false postive: people people from other countries have had BCG vaccine which prevents severe TB in children but provides minimal immunity into later years

false negative test: pts with TB dont react to PPD bc of anergy, due to steroid use, malnutrition, AIDS

Question 8

primary TB

• symptoms
  
  • asymotinatuc
• immune system
• reactivation

Answer 8

asymptomatic lung infection
cell mediated immunity walls off and suppress bacteria in caseous granulomas which heal with fibrosis and calcification and scar
ghon focus and complex
-

these bacteria lie dormant but can later rise up and cause disease

second infection = secondary or reactivation of TB

Question 9

primary tuberculosis

Answer 9

transmitted via aerosolized droplets from respiratory secretions

inspired droplets go to middle and lower lung zones: small area of pneumonitis with neutrophils and adema

bacteria enter macrophages multiply and spread

Question 10

symptomatic primary tuberculosis
more common in who bc why
symptoms
if not contained then = 
in severe untreated cases?

Answer 10

more common in young, old, immunocompromised

• cell mediated response is not as strong
• enlargement of mediastinal LNs or hilar LNs
• granulomas with calfification
• if not contained = primary progressive disease
• in severe untreated cases lung infiltrates advance to lung necrosis = holes in lungs or cavities

Question 11

secondary or reavtivation tuberculosis
why it reactivates
who is more at risk

Answer 11

temporary immune weakening
risk of reavtivation in all persons is 10% for lifetime
risk of reactivation in HIV infected indicviduals is 10% per year

Question 12

what is the most common disease with tuberculosis

other involvment

Answer 12

pulmonary disease
may involve pleura/pericardium
adrenals
kidneys
LNs
bones
joints
CNS

Question 13

pulmonary tuberculosis

Answer 13

infection occurs in upper lobe
infection grow, caseate, lquify, cavitate
pt presents with lowgrade fever night sweats, weight loss and productive cought with maybe blood

Question 14

pleural and pericardial infection with TB

Answer 14

infected fluid collections around lung or heart

Question 15

LN infection TB

• LN involved most
• this is called

Answer 15

most common extrapulmonary manifestiation of TB

• cervival LNs most involved
• scrofula

Question 16

kidney and TB

Answer 16

sterile pyuria

-increased WBC and RBC but no pacteria on rgam stain or grow in culture

Question 17

skeletal and TB

Answer 17

thoracic and lumbar spine intevertebral discs destoryed and adjcaent vertebrla bodies

potts disease

Question 18

joints and TB

Answer 18

chronic arthritis of 1 joint

Question 19

CNS and TB

Answer 19

subacute meningitis and forms granulomas in the brain

Question 20

miliary tuberculosis

• what is it
• occurs in who

Answer 20

tiny tubercles (granulomas) disseminated all over body like shotgun blast
-occurs in eldery and children

Question 21

big picture TB

Answer 21

TB is chronicdisease
present slowly with weight loss, low grade fever and symptoms related to organ system infected
-can be confused with cancer
-whenever have infection of any organ system, TB will be somewhere on your diff diagnosis list

Question 22

diagnosis

Answer 22

PPD skin test: exposure in past

chest xray: isolated granulomas, ghon focus, ghon complex old scarring in upper lobes

sputum acid fast stain and culuture: if positive then active

rapid molecular detection of MTB: rapid diagnosis

Question 23

tuberculosis rule of fives

Answer 23

droplet nuclei are 5 um
contain 5 myco tuberculosis bacilli
pts infected with mycobacterium tub have 5% risk of reactivation in first 2 years
5% lifetime risk
patients with HIV have 5 + 5 % of reactivation

Question 24

mycobacterium leprae causes

Answer 24

leprosy

Question 25

acid fast rod mycobacterium leprae involves what part of body

Answer 25

cooler parts, damages skin but spares warm parts

damages nerves, eyes, nose, testes

Question 26

2 types of leprosy

Answer 26

lepromatous

tuberculoid

Question 27

lepromatous leprosy

Answer 27

pts cannot mount cell mediated immune respsonse
severest form of leprosy
involves skin, nerves, eyes, testes
-acid fast bacilli are found everywhere
-facial skin thickening can become lionlike (leonine facies)
nasal cartilage destoryed = saddlenose deformity
-infertility
loss of sensation in extremities and glove and stocking distirbution

Question 28

tuberculoid leprosy
cell mediated immunity
-symptoms
-what nerves usually involved

Answer 28

cell mediated defense can occur
milder symptoms
localized superficial, unilateral skin and nerve involvement
-well defined, hypopimented elevated botches
greater auricular, ulnar nerve, posterior tibial ,peroneal nerve

Question 29

nontuberculous mycobacteri: species

common clinical presentation
aids pts
immunocompetent host
lymphadenitis

Answer 29

mycobacterium avium-intracellulare

1) in aids pts: disseminated infection with fevrer, weight loss, hepatitis, diarrhea

2) immunocompetent host
- upper lung cavitary disease in elderly smokers
- middle and lower lung nodular and bronchiectatis disease in middle aged female non smokers

3) lymphadenitis most comonly in children

Question 30

mycobacterium avium-intracellulare is the most common cause of what

Answer 30

NTM lung disease