E2- MTB and NTM

Question 1

Are mycobacterium tuberculosis infections common?

Answer 1

Yes, many millions/billions infected but over 90% of healthy persons infected never become ill

Question 2

What strains of mycobacterium tuberculosis are particularly difficult to tx?

Answer 2

MDR (multi-drug resistant) and XDR (extensively drug resistant) strains

Question 3

What are the two main problems for pts with inadequate tx for a mycobacterium tuberculosis ?

Answer 3

Remain infectious

Opportunity for drug resistance

Question 4

Who are the only reservoirs for MTB?

Answer 4

Humans

Question 5

How is MTB transmitted?

Answer 5

Person-to-person via aerosol droplet nuclei

not as dangerous on surfaces

Question 6

What populations have an especially difficult time with MTB and MAC?

Answer 6

AIDs`patients

Question 7

What is an occupational hazard for people who do autopsy and anatomist from accidental exposure to MTB? How can you prevent these?

Answer 7

Prosector’s warts

Gloves

Question 8

What age populations are most commonly affected by MTB?

Answer 8

Bimodal age distributions- infants and older adults

Question 9

Who is at highest risk for MTB infection?

Answer 9

Infants and immunocompromised pts

Question 10

What can result in meningitis?

Answer 10

Hematogenous dissemination of a MTB infection

Question 11

What is a possible etiology of MTB in older pts?

Answer 11

Failure of the immune system

Possible reactivation of latent infection

Question 12

What three things influence the probability of MTB infection?

Answer 12

Environment- crowded conditions
Duration of exposure
Virulence of strains

Question 13

How do many children become infected by MTB?

Answer 13

Close contact with caregivers

Question 14

What are some initial MTB infection risk factors?

Answer 14

Close contact with TB case
Residence in long-term care facility
Low income/inner city housing
Alcohol or IV drug use
Malnutrition
DM
Silicosis- pneumoconiosis (coal minners)
Imunosupression

Question 15

What three species of MTB produce human TB?

Answer 15

Mycobacterium tuberculosis
Mycobacterium bovis (cattle)
Mycobacterium africanum (Wast Africian)

Question 16

How do we control Mycobacterium bovis?

Answer 16

Pasteurization and treatment of infected farm animals

Question 17

How is Mycobacterium africanum spread?

Answer 17

Opportunist infection, especially in immunocompromised HIV pts
Spread by food, no animal reservoirs

Question 18

What aerotolerance is M. tuberculosis? What shape?

Answer 18

Obligate aerobes

Bacillus

Question 19

What vaccine can be used for MTB in high endemic regions?

Answer 19

BCG (Bacille Calmette-Guerin)

Question 20

What can kill M. tuberculosis?

Answer 20

Heat sensitive- killed by pasturization

Question 21

Where does M. tuberculosis grow within a human?

Answer 21

Alveolar macrophages

Question 22

What two qualities does mycolic acid give M. tuberculosis?

Answer 22

Acid fast

Hydrophobic

Question 23

What virulence factors and toxins do MTB have?

Answer 23

No classic virulence factors or toxins, the structural features create the issues

Question 24

What structural components makes MTB virulent?

Answer 24

Mycolic acids
Cord factor
Lipoarabinomannan (LAM)

Question 25

How does mycolic acid add virulence to MTB?

Answer 25

Prevent dehydration and resists H2O2

Question 26

What is a cord factor?

Answer 26

Mycoside- glycolipid mycolic acid + disaccharide

Question 27

How does Lipoarabinomannan (LAM) provide virulence to MTB?

Answer 27

Inhibits cell-mediated immunity | Scavenges ROI

Question 28

What are the five potential outcomes of MTB infection?

Answer 28

1. Immediate resolution 2. Primary disease 3. Progressive primary (active) disease 4. Latent infection 5. Endogenous reaction/secondary infection

Question 29

If there is no active TB because the innate immune system is able to clear the bacteria, what is this called?

Answer 29

Immediate resolution

Question 30

Granuloma formation may progress to what?

Answer 30

Caseous lesions

Question 31

What are areas surrounded by macrophages, multi-nucleated giant cells, fibroblasts, and collagen fibers that harbor viable MTB cells?

Answer 31

Ganulomas

Question 32

Over time, what can form fibrotic tubercle and calcify, and can be seen on X-ray?

Answer 32

Granulomas

Question 33

What is MTB diagnosed?

Answer 33

X-ray Skin test Sputum strain culture Rapid blood test based on IFN-y

Question 34

The USA depends on what for treatment of infection persons?

Answer 34

Recognition, isolation, and treatment of infected persons

Question 35

What kind of testing is used to ID latent TB?

Answer 35

Serial screening

Question 36

Is MAC gram positive/negative/acid fast? What shape?

Answer 36

Weakly gram positive bacilli | Acid fast

Question 37

Where is MAC found?

Answer 37

Water, soil, and plants

Question 38

How is MAC transmitted?

Answer 38

Ingestion of contaminated water or food DISTINCT FROM TB- NO person to person transmission

Question 39

Is patient isolation required for MAC infection?

Answer 39

NO | no person to person transmission

Question 40

What is the leading cause of Nontuberculous mycobacteria (NTM) infection in HIV-positive pts in the US?

Answer 40

MAC

Question 41

What patient populations may get a disseminated MAC infection

Answer 41

AIDS patients

Question 42

How is Nontuberculous mycobacteria (NTM) dx?

Answer 42

Microscopy to reveal acid-fast bacteria and culture Must exclude other etiologies (fungi, TB) -Use PCR to determine 16s rRNA sequence pathogen

Question 43

What must you take into account when treating a MAC infection?

Answer 43

HIV infection status

Question 44

What is an epidemic infection among cystic fibrosis patients?

Answer 44

Mycobacterium abscesses (very difficult to treat in CF due to intrinsic abx resistance)

Question 45

Can latent TB be spread? Should these pts be treated?

Answer 45

Latent TB cannot be spread, but these pts should still be treated

Question 46

What results from lymphohematogenous spread of a primary infection or by a latent focus with subsequent spread?

Answer 46

Miliary tuberculosis

Question 47

What test can be used to detect MTB and Rifampin resistance?

Answer 47

GeneXpert Rapid Test

Question 48

What syndrome is found in elderly female non-smokers and is associated with MAC?

Answer 48

Lady Windermere's syndrome

Question 49

What kind of stains are used for MTB?

Answer 49

Ziehl-Neelson or Kinyoun stains

Question 50

How would you treat a MAC infection in HIV negative patients?

Answer 50

Continue antibiotics until sputum cultures are negative for 1 year

Question 51

How do you prophylactically treat HIV positive patients without a MAC infection?

Answer 51

Chemoprophylaxis in patients with CD4< 50, and can discontinue after 3 months after CD4 >100

Question 52

How do you treat HIV positive patients with a MAC infection?

Answer 52

Lifelong therapy for patients without immune reconstitution | -or begin treatment for 2 weeks then anti-HIV HAART

Question 53

What can be used to treat HSV?

Answer 53

Acyclovir, valacyclovir, and Famciclovir

Question 54

What is the MOA of acyclovir/valacyclovir?

Answer 54

The viral enzyme thymidine kinase phosphorylates acyclovir and this will halt viral DNA replication

Question 55

What is the treatment for parvovirus?

Answer 55

- Most patients make a rapid and full recovery. - NSAIDS - Immunoglobulin for anemic patients