Microbiology - Mycobacteria

Front 1

What does a positive PPD indicate?

Back 1

1. Current infection 2. Past exposure 3. BCG vaccination

Front 2

What does a negative PPD indicate?

Back 2

1. No infection 2. Anergy (due to: steroids, immunocompromise, malnutrition)

Front 3

Fast-fermenting lactose bacteria

Back 3

Fast fermenters: (EEK! Too fast!) 1. E.coli 2. Enterobacter sp. 3. Klebsiella

Front 4

Slow fermenting lactose bacteria

Back 4

Slow fermenters: 1. Serratia 2. Citrobacter 3. "Others"

Front 5

Tuberculosis infection: Gross mechanism

Back 5

1. Inhaled aerosols from infected adults
2. Land in middle or lower lobes of lung (highest airflow) leading to small area of pneumonitis.
3. Bacteria enter macrophages, multiply, and spread hematogenously.

Front 6

Mechanism of asymptomatic primary TB

Back 6

1. Cell-mediated defense walls off foci of bacteria in caseous granulomas 2. Granulomas heal with fibrosis, calcification and scar formation

Front 7

Difference between Ghon focus and Ghon complex

Back 7

Ghon focus: Calcified tubercle in the middle or lower lung
Ghon complex: Ghon focus accompanied by perihilar or lobar lymph node calcified granulomas

Front 8

What is a Ranke complex?

Back 8

Same as a Ghon complex: Ghon focus (TB granulomas) and perihilar or lobar lymph node calcified granulomas

Front 9

Mechanism of symptomatic primary TB

Back 9

1. Large caseous granulomas develop in the lungs/other organs. 2. In the lungs, caseous material liquifies, is extruded out the bronchi and leaves cavitary lesions behind.

Front 10

Mechanism of secondary Pulmonary TB

Back 10

1. Infection occurs at apical areas of lung around the clavicles due to highest oxygen tension caused by decreased pulmonary circulation.
2. Infected areas grow, caseate, liquify and cavitate.

Front 11

TB reactivation sites

Back 11

1. Pulmonary (Lung parenchyma)
2. Pleura
3. Pericardium
4. Scrofula (Cervical lymph nodes: most common extrapulmonary site worldwide)
5. Kidney (Sterile pyuria)
6. Thoracic and lumbar spine (Pott's disease)
7. Chronic monoarthritis
8. CNS (subacute meningitis or parenchymal tuberculoma)
9. Miliary TB (Millet sized tubercles all over the body)

Front 12

Tuberculosis rule of 5s

Back 12

1. Droplet nuclei are 5 micrometers and contain 5 mycobacteria 2. 5% risk of reactivation in first 2 years and then 5% lifetime risk 3. Patients with HIV ("High five") have 5+5% yearly reactivation risk. 4. Induration measurements: a. HIV: >5 mm b. High risk: >5+5 mm c. Everyone else: >5+5+5 mm

Front 13

Cause of Miliary tuberculosis

Back 13

Severe bacteremia

Front 14

Types of Mycobacteria and what they cause

Back 14

Mycobacterium:
1. Leprae: Leprosy/Hansen's disease
2. Tuberculosis: TB
3. Avium-intracellulare: Disseminated disease in AIDS
4. Scrofulaceum: Cervical lymphadenitis in kids
5. Kansasii: Pulmonary TB-like synmptoms
Mnemonic: Identifying mycobacteria is no Light TASK

Front 15

What disease state does Mycobacterium Avium-intracellulare cause?

Back 15

bugs are multiple drug resistant and cause disseminated disease in AIDS

Front 16

Symptoms of tuberculosis

Back 16

1. Fever 2. Night sweats 3. Weight loss 4. Hemoptysis

Front 17

Langhans type giant cells in which the nuclei are lined up around the periphery of the cell in a horseshoe pattern. Seen in granulomatous conditions like TB

Back 17

What is this?

Front 18

What is Hansen's disease?

Back 18

leprosy

Front 19

What is leprosy caused by?

Back 19

Mycobacterium leprae

Front 20

Characterization and reservoir of Mycobacterium Leprae

Back 20

1. Acid fast bacillus
2. Likes cool temperatures
3. Infects skin and superficial nerves
4. Cannot be grown invitro
5. Reservoir: Armadillos

Front 21

Presentation of lepromatous leprosy

Back 21

"Leonine facies": 1. Loss of eyebrows 2. Nasal collapse 3. Lumpy earlobe

Front 22

Treatment for leprosy

Back 22

Long-term oral dapsone - Alternative: Rifampin or combo clofazimine and dapsone

Front 23

Toxicity of longterm oral dapsone

Back 23

1. Hemolysis 2. Methemoglobinemia

Front 24

2 forms of leprosy

Back 24

1. Lepromatous (Due to failed cell-mediated immunity. Lep. is Lethal)
2. Tuberculoid (self-limiting)