MYCOBACTERIA

Question 1

What kind of pathogen is Mycobacteria?

Answer 1

Acid fast bacteria (bacilli, rods)

Question 2

Where is mycobacteria more common?

Answer 2

Developing countries

Question 3

What are two common strains of mycobacteria?

Answer 3

-Tuberculosis
-M. avium (also considered atypical)

Question 4

What are Atypical strains of Mycobacteria?

Answer 4

-M. abscessus
-M. fortuitum
-M. marinum

Question 5

What do the Atypical strains of mycobacteria cause?

Answer 5

Usually wound and skin infections which are nodular, ulcerative, and can last for months

-Related to environmental inoculation/nosocomial (hospital) infection

-Salt/H20 exposure (sea water) related to M. marinum (Think marinum = aquarium)

Question 6

How can you diagnose an atypical Mycobacteria infection?

Answer 6

Culture or skin biopsy

Question 7

What does atypical Mycobacteria infection treatment depend on?

Answer 7

Depends on site and organism ID consult recommended

Question 8

How is M. avium transmitted? What does it cause?

Answer 8

-Waterborne, soil, etc.
May cause lung disease if inhaled

Question 9

Who is more susceptible to an M. avium infection?

Answer 9

-Advanced age
-Women more commonly than men
-People with lung disease (like CF, COPD)

Question 10

What kinds of infections does M. avium cause?

Answer 10

-Hypersensitivity disease: hot tub lung (inflammation caused by inhaling water droplets from hot tub)

-Disseminated (spread): in immunocompromised patients can be severe and progress, CD4 immune cells <100

-Pulmonary: Nodular, cavitary (spaces in lungs) lung disease

Question 11

How can M. Avium be treated?

Answer 11

Pulmonary: Macrolide+Ethambutol+Rifampin

Disseminated/immunocompromised: Macrolide+Ethambutol+Rifampin for at least 12 months, no sign of MAC disease, and immune CD4 cell count >100 for >6 months

Question 12

How is TB transmitted?

Answer 12

Person to person by inhalation of air droplets

Question 13

What is the pathogenesis of TB?

Answer 13

When in the lungs, TB is phagocytosed by macrophages but not killed and form granulomas

*Can cause active infection in about 10%, others will remain dormant, increased active disease within 1 year of exposure or if immunocompromised

Question 14

What are the signs of an active TB infection?

Answer 14

-Chronic cough greater than 3 weeks
-Hemoptysis (coughing up blood)
-Fever/night sweats
-Weight loss
*Contagious

Question 15

What are the signs of a disseminated TB infection?

Answer 15

Disease in any organ system
-Lymph nodes
-Laryngeal
-GU tract
-Orthopedic
-CNS
-Peritoneum
-Pericardium
*if not in lungs, not usually contagious

Question 16

What are the signs of a latent TB infection?

Answer 16

Cells are walled off in granulomas, can reactivate later in life if immune system is weakened
*not contagious unless reactivated

Question 17

Where does TB commonly infect the lungs?

Answer 17

UPPER LOBE, primary TB will look like pneumonia on an X-ray

Question 18

How can you diagnose a TB infection?

Answer 18

-Sputum collection (3 collections in the morning)
-Chest x-ray or CT scan
-Bronchoscopy
-Gastric Aspirate (collect gastric material)
-Serology (a Quantiferon/T spot test will show presence of mycobacteria)
-TB testing

Question 19

Why could someone have a positive test for TB even though they are not infected?

Answer 19

If they were vaccinated for TB, will give false positive PPD from antibodies

Question 20

How is a TB infection treated?

Answer 20

Active TB:
-Airborne isolation, Notify public health
-Combo of 4 meds: Isoniazid, Rifampin, Pyrazinamide, Ethambutol (standard regimen)
-Second line meds can be used in the case of resistance
-NO SINGLE MEDICATION THERAPY: increases risk of resistance
-6 month treatment

Latent TB:
-Isoniazid for 9 months
-Isoniazid + Rifepentine weekly for 12 weeks
**To prevent reactivation