Micro - Clinical Bacteriology (Gram + Branching Filaments & Mycobacterium)

Question 1

What are the Gram positive branching filament bacteria? What do they resemble?

Answer 1

(1) Actinomyces (2) Nocardia; Fungi

Question 2

For Actinomcyes and Nocardia, which is each of the following: (1) Anaerobe (2) Aerobe (3) Acid Fast (4) Non acid fast?

Answer 2

(1) Actinomyces (2) Nocardia (3) Nocardia (4) Actinomyces

Question 3

Where is Actinomyces found? Where is Nocardia found?

Answer 3

Normal oral flora; Found in soil

Question 4

What signs/symptoms should you associate with Actinomyces?

Answer 4

(1) Oral/facial abscesses that drain through sinus tracts (2) Forms yellow “sulfur granules”

Question 5

What signs/symptoms should you associate with Nocardia?

Answer 5

(1) Pulmonary infections in immunocompromised (2) Cutaneous infections after trauma in immunocompetent

Question 6

How does Nocardia affect immunocompromised versus immunocompetent patients?

Answer 6

Immunocompromised = Pulmonary infections; Immunocompetent = Cutaneous infections after trauma

Question 7

How do you treat Actinomyces?

Answer 7

Penicillin

Question 8

How do you treat Nocardia?

Answer 8

Sulfonamides

Question 9

In what context/case(s) would a patient have a PPD+?

Answer 9

If current infection, past exposure, or BCG vaccinated

Question 10

In what context/case(s) would a patient have a PPD-?

Answer 10

If no infection or anergic (steroids, malnutrition, immunocompromise) and in sarcoidosis

Question 11

What are the two kinds of tuberculosis following infection? To which patient population does each apply?

Answer 11

(1) Primary tuberculosis - Nonimmune host (usually child) (2) Secondary tuberculosis - Partially immune hypersensitized host (usually adult) = Reinfection

Question 12

What process/event leads to Secondary tuberculosis?

Answer 12

Reinfection

Question 13

What finding(s) is/are associated with Primary tuberculosis?

Answer 13

Ghon complex = Hilar nodes + Ghon focus (usually in mid zone of lung)

Question 14

What finding(s) is/are associated with Secondary tuberculosis?

Answer 14

Fibrocaseous cavitary lesion (usually upper lobes)

Question 15

What other kind of tuberculosis results from reactivation tuberculosis of the lungs? What specific findings are associated with this?

Answer 15

Extrapulmonary tuberculosis: CNS (parenchymal tuberculoma or meningitis), Vertebral body (Pott’s disease), Lymphadenitis, Renal, GI

Question 16

What are 4 potential initial consequences of Primary tuberculosis?

Answer 16

(1) Heals by fibrosis (2) Progressive lung disease (HIV, malnutrition) (3) Severe bacteremia (4) Preallergic lymphatic or hematogenous dissemination

Question 17

What is/are the significant outcome(s) when Primary tuberculosis heals by fibrosis?

Answer 17

Immunity and hypersensitivity –> Tuberculin positive

Question 18

What is/are the significant outcome(s) when Primary tuberculosis leads to progressive lung disease? In what kind of patients is this likely to occur?

Answer 18

Death (rare); HIV, malnutrition

Question 19

What is/are the significant outcome(s) when Primary tuberculosis leads to severe bacteremia?

Answer 19

Miliary tuberculosis –> Death

Question 20

What is/are the significant outcome(s) when Primary tuberculosis leads to preallergic lymphatic or hematogenous dissemination?

Answer 20

Dormant tubercle bacilli in several organs –> Reactivation in adult life

Question 21

Again, what are the 4 options for initial consequences of Primary tuberculosis? What are the outcomes associated with each?

Answer 21

(1) Heals by fibrosis –> Immunity and hypersensitivity –> Tuberculin positive (2) Progressive lung disease (HIV, malnutrition) –> Death (rare) (3) Severe bacteremia –> Miliary tuberculosis –> Death (4) Preallergic lymphatic or hematogenous dissemination –> Dormant tubercle bacilli in several organs –> Reactivation in adult life

Question 22

What pathogen causes TB? What is important to know about its treatment?

Answer 22

Mycobacterium tuberculosis; Often resistant to multiple drugs

Question 23

Which mycobacterium causes pulmonary TB-like symptoms?

Answer 23

M. kansasii

Question 24

What mycobacterium causes disseminated, non-TB disease in AIDS? What is important to know about its treatment? What is its prophylactic treatment?

Answer 24

M. avium-intracellulare; Often resistant to multiple drugs; Azithromycin

Question 25

What kind of organisms are all mycobacteria?

Answer 25

Acid-fast

Question 26

Again, what pathogen causes TB? What are TB symptoms?

Answer 26

Mycobacterium tuberculosis; Fever, night sweats, weight loss, hemoptysis

Question 27

Which mycobacteria are often resistant to multiple drugs?

Answer 27

(1) M. tuberculosis (2) M. avium-intracellulare

Question 28

What kind of symptoms does M. kansasii cause?

Answer 28

Pulmonary TB-like symptoms

Question 29

What kind disease does. M. avium-intracellulare cause, and in what patient population?

Answer 29

Causes disseminated, non-TB disease in AIDS (patients)

Question 30

What 2 virulence factors are found in Mycobacteria?

Answer 30

(1) Cord factor (2) Sulfatides (surface glycolipids)

Question 31

In what kind of bacteria is cord factor found? What is its mechanism?

Answer 31

Virulent strains of Mycobacteria; Inhibits macrophage maturation and induces release of TNF-alpha

Question 32

In what kind of bacteria are sulfatides found? What is its mechanism?

Answer 32

Mycobacteria; Sulfatides (surface glycolipids) inhibit phagolysosomal function

Question 33

What is another name for Leprosy? What pathogen causes it?

Answer 33

Hansen’s disease; Mycobacterium leprae

Question 34

How is M. leprae classified? What kind of temperatures does it like?

Answer 34

Acid-fast bacillus that likes cool temperatures

Question 35

Again, what kind of temperatures does M. leprae like? What does it infect? What is the nickname of the condition that results?

Answer 35

Likes cool temperatures; Infects skin and superficial nerves - “glove and stocking” loss of sensation

Question 36

What is important to know about M. leprae with regard to its lab studies?

Answer 36

Cannot be grown in vitro

Question 37

What is the reservoir of M. leprae in the United States?

Answer 37

Armadillos

Question 38

What is another name for Hansen’s disease? What pathogen causes it? What are the 2 forms of Hansen’s disease?

Answer 38

Leprosy; M. leprae; (1) Lepromatous (2) Tuberculoid

Question 39

How does the Lepromatous form of Hansen’s disease present? How is it characterized?

Answer 39

Presents diffusely over skin and is communicable; Characterized by low cell-mediated immunity with a humoral Th2 response

Question 40

How does the Tuberculoid form of Hansen’s disease present? How is it characterized?

Answer 40

Limited to a few hypoesthetic (reduced sense of touch), hairless skin plaques; Characterized by high cell-mediated immunity with a largely Th1-type immune response

Question 41

Again, what are the 2 forms of Leprosy/Hansen’s disease? What is the treatment for each of these forms?

Answer 41

(1) Lepromatous - Multidrug therapy consisting of Dapsone, Rifampin, and Clofazimine for 2-5 years (2) Tuberculoid - Multidrug therapy consisting of Dapsone and Rifampin for 6 months

Question 42

Which form of Hansen’s disease can be lethal?

Answer 42

Lepromatous; Think: LEpromatous can be LEthal

Question 43

What test may be used as an alternative to PPD, and what is its advantage?

Answer 43

Interferon-gamma release assay (IGRA) is more specific test; has fewer false positives from BCG vaccination