Respiratory Tract Infections 7

Question 1

what is the function of lipoarabinomannan in the pathogenesis of M. tb

Answer 1

• helps resist lysosomal enzymes and reactive oxygen species

Question 2

which pathogen that causes atypical pneumonia is an obligate intracellular organism?

Answer 2

• chlamydophila pneumonia

Question 3

at what life cycle phase is the chlamydophila pneumonia that we see as inclusion bodies on a histopathological slide?

Answer 3

• reticulate bodies: non infectious but metabolically active

Question 4

Describe the biology of chlamydophila pneumonia

Answer 4

• gram NEGATIVE
• obligate intracellular
• biphasic life cycle: elementary bodies and reticulate bodies
• present as inclusion bodies in the cell
• no special risk groups

Question 5

PPD test looks for prior exposure of tb but cannot differentiate between:

Answer 5

• active or latent Tb or previous vaccination

Question 6

_________ cause of atypical pneumonia is a facultative intracellular pathogen

Answer 6

• legionella pneumophila

Question 7

how does the elementary body of chlamydophila pneumonia survive living inside the host cell?

Answer 7

by inhibiting the fusion of the endosome and lysosome

Question 8

______ cause of atypical pneumonia is an obligate intracellular pathogen

Answer 8

• Chlamydophila pneumonia

Question 9

what are some common clinical manifestations of infection by Legionella pneumophila?

Answer 9

• one of the causes of atypical pneumonia

- look for GI and CNS symptoms along with respiratory disease PLUS: water source and hematuria

Question 10

when treating tb, what other tests would you do?

Answer 10

check for drug resistance

Question 11

_____________ exists as elementary bodies in the ______

Answer 11

chlamydophila pneumonia;

exists as elementary bodies outside in the environment and colonize the upper respiratory tract and move down to LRT

Question 12

buffered charcoal yeast extract is used to culture ________

Answer 12

legionella pneumophila

Question 13

< ____ mm of the induration in the PPD test is a negative test for everyone

Answer 13

5mm

Question 14

what are unique features of the cell wall in mycobacterium tuberculosis?

Answer 14

• mycolic acid: waxy coating

- lipoarabinomannan: acts like LPS and is attached to the cytoplasmic membrane

Question 15

what are the two clinical syndromes that legionella pneumphila can cause and how can you differentiate them?

Answer 15

• legionnaire’s disease
• pontiac fever

pontiac fever is self limiting and does not involve the LRT

Question 16

Describe the biology fo Mycobacterium tuberculosis

Answer 16

• acid fast bacilli
• aerobic
• non spore forming
• grows in long parallel chains: “cords” and grows very slowly

Question 17

how does legionella survive in the cell?

Answer 17

• inhibits fusion of lysosome and endosome (like Chlamydophia pneumonia)

Question 18

what additional symptoms to pneumonia would suspect you to think infection by legionella?

Answer 18

• GI and CNS symptoms
• HYPOnatremia
• elevated hepatic transaminases

Question 19

describe the life cycle of chlamydophila pneumoniae:

Answer 19

• endocytosed as a elementary body
• inhibition of the endosome and phagosome fusion
• conversion to reticulate bodies and replicates via binary fission
• conversion back to elementary bodies
• elementary bodies leave the cell via reverse endocytosis

Question 20

__________ bodies are infectious but NOT metabolically active

Answer 20

elementary bodies;

Question 21

what is a good way to distinguish between the different species of chlamydophila?

Answer 21

the result of the pathogen leaving the host cell:

• C. pneumonia and C. trachomatis does not result in cell lysis
• C. psittaci results in cell lysis

Question 22

_____ bodies are metabolically active but NON infectious

Answer 22

reticulate

Question 23

_________ on the cell membrane of mycobacterium tuberculosis gives it a waxy appearance and makes it resistant to drying

Answer 23

mycolic acid

Question 24

how does mycobacterium tuberculosis survive inside the alveolar macrophage?

Answer 24

• prevents oxidative burst inhibits phagosome-lysosome fusion
• resists lysosomal enzymes and reactive oxygen species

Question 25

CARDS toxin is a virulence factor of ________

Answer 25

mycoplasma pneumonia

Question 26

legionella is most commonly acquired from ______

Answer 26

contaminated water

Question 27

legionella can be cultured on ______

Answer 27

buffered charcoal yeast extract

Question 28

Ziehl- Neelsen stain is used to stain _________

Answer 28

acid fast bacilli such as Mycobacterium tuberculosis

Question 29

risks of getting pneumonia from what pathogen is high in people with lung diseases or alcoholic

Answer 29

Klebsiella

Question 30

> ____mm of the induration in the PPD test is a positive test regardless of the patient's risk factor

Answer 30

15mm

Question 31

__________ medium is used to culture and diagnose M. tuberculosis

Answer 31

- lowenstein- Jensen medium - oliec acid albumin broth wart like colonies that go from green to blue in color

Question 32

the majority of the damage in tb is due to ______

Answer 32

host immune response to the pathogen

Question 33

how does chlamydophila pneumonia eventually leave the host cell?

Answer 33

``` reverse endocytosis (same with C. trachomatis); NO HOST CELL LYSIS (unlike chlamydophila pstacci which will cause cell lysis ) ```

Question 34

describe the biology of legionella

Answer 34

- gram negative rod - motile (polar flagella) - non spore forming - facultative intracellular organism that lives in the alveolar macrophages - culture on buffered charcoal yeast extract agar

Question 35

_______ vaccine is given to kids in endemic countries for prophylactic treatment of tb

Answer 35

BCG (bacillus Calmette Guerin) which is from live attenuated M. Bovis strains mainly used to prevent the miliary tb or tb meningitis in children

Question 36

several people have come to the doctor with symptoms such as pleuritic chest pain, SOB, cough and fever and said that they drank contaminated water. What would you use to strain this most likely pathogen? What would you culture it on?

Answer 36

- methylamine silver stain (NOT GRAM STAIN) | - culture: buffered charcoal yeast extract

Question 37

what are some extrapulmonary manifestations of tb commonly seen in patients with HIV/AIDS

Answer 37

- lymphadenitis - pott disease - tuberculoma (CNS) - meningitis - pericarditis - miliary (m. tb that is spread through blood, like sepsis of m. tb)

Question 38

resistance to TB is largely dependent on ____________

Answer 38

subset of CD4 Helper T cells that produce gamma interferon reason why patients with HIV/AIDS and get tb, most will develop extra pulmonary infection

Question 39

the PPD test is based on a type ____ HS reaction

Answer 39

type 4; looking for prior exposure to mycobacterium tuberculosis

Question 40

the most commonly used laboratory test for diagnosis of legionella is __________

Answer 40

urinary antigen test (only looks for serogroup 1)

Question 41

what structure is responsible or the staining property of M. tuberculosis?

Answer 41

mycolic acid