MAC

Question 1

MAC is a group of free living

Answer 1

non TB mycobacteria that are ubiquitous to environment seen in aerolized water, piped hot water systemis bathrooms, house dust, soil, birds, and farm animals.

Question 2

how do people get MAC?

Answer 2

inhalation of aerosolized municipal water but transmission can occur through contaminated soil, food and animals (birds)

Question 3

who gets worse course with MAC dx?

Answer 3

severe immunodeficiency (AIDS)

chronic pulmonary infections in those with underlying lung dx

non smoking women

>50 years old

Question 4

does MAC need airborne precautions

Answer 4

no

Question 5

hot tub lung

Answer 5

hypersensitivity pneumoitis - can be seen in pts with recent exposure to contaminated hot tub water.

Question 6

acute flu like illness with dypsnea, cough, malaise, fever0

Answer 6

MAC,

Question 7

treatment of hypersensitivity pneumonitis or hot tub lung

Answer 7

generally self limited infection and resolves with close observation, supportive care and avoidance of hot tub. But if symptoms persist may need short course of steroids

Question 8

acute flu like illness and severe headaches, dyspnea cough, malaise and recent exposure to birds

Answer 8

see chlamydia psittaci and has severe headaches.

Question 9

How does pseudomonal infections present

Answer 9

as folliculitis and not pneumonia.

Question 10

HIV negative MAC can be seen in pts with and without underlying lung disease and this presents as

Answer 10

cough

MAC infections are generally in pts who have underlying lung dx (cystic fibrosis, COPD, alpha 1 antitrypsin def).

Can also happen in people who have prior lung dx (hot tub lung)

Question 11

what is MAC and MAI?

Answer 11

MAC is mycobacterium avium complex and includes others like M avium and M intracellulare and so they together are term M avium-intracellulare or MAI

Question 12

diagnosis of MAC

Answer 12

Diagnosis is based on clinical + microbiological evidence

clinical with CXR with nodular or cavitary lesions OR CT with multifocal bronchiectasis and nodules

PLUS

microbiological >2 positive sputum cultures for MAC

1 positive culture from bronchial wash/lavage

lung biopsy with consistent findings and positive culture.

Criteria must also exclude other causes

Question 13

treatment of MAC or MAI

Answer 13

at least 1 year of combination of 3 drugs:

• macrolide (clarithromycin or azithromycin),
• ethambutol,
• rifamycin (rafampin or rifabutin)

Question 14

four drug therapy is for

Answer 14

mycobacterium tuberculosis

Question 15

do we use a tuberculin skin test for diagnosis of MAC?

Answer 15

no it’s only meant for latent myco TB testing and not for MAC testing.

Question 16

clinical features of MAC infection in those with underlying chronic pulm dx and those without pulm dx

Answer 16

Question 17

Diagnosis of MAC

Answer 17

Question 18

Since MAC can contaminate or colonize sputum need to confirm MAC infection with:

Answer 18

2 positive sputum cultures.

If with only one AMC positive sputum culture need another one to establish diagnosis. If repeat sputum culture is negative, need a positive culture from BAL specimen to treat.

Question 19

CT scan of MAC infecgtions

Answer 19

can have nodular opacities and see bronchiectasis and see it affected in the right middle lobe and left lingula and other structural lung dx.

Only do CT guided biopsy of pulmonary nodule if repeat sputum cultures or BAL are negative for MAC in order to establish diagnosis.

Question 20

Opportunistic infections in HIV

Answer 20

We no longer provide MAC prophylaxis.

See MAC infections with CD4 <50

Question 21

features of non HIV MAC based on if there’s presence of underlying lung disease

Answer 21

Question 22

treatment of HIV and MAC

Answer 22