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Flashcards in RT6 Deck (37)
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1

pathogenesis of mycobacterium tuberculosis

facultative intracellular bacterium which infects alveolar macs

-Prevent oxidative burst & inhibit phagosome-lysosome fusion􏰀 (role of sulfolipids)
-cell wall components (lipids, LAM) and presence of superoxide dismutase make bacterium resistant to lysosomal enzymes and ROS
-siderophores (exochelin) are secreted

2

diagnosing tuberculosis

acid fast stain or rhodamine-auramine fluorescent stain or culture on enriched or special medium -- sputum used

3

culture of tuberculosis is done on what agar

lowenstein jesen agar or oleic acid albumin broth

4

what does tuberculin test prove

prior exposure to mycobacterium tuberculosis (type IV hypersensitivity) and not that someone has tuberculosis

5

treatment of TB

first-line: isoniazid, rifampin, streptomycin, ethambutol
second line: para-aminosalicyclic acid, cycloserine, fluoroquinolones
prevention: BCG vaccine and prophylactic antimycotics

6

what are the primary fungal pathogens

􏰀 Histoplasma capsulatum
􏰀 Blastomyces dermatidis
􏰀 Coccidioides immitis
􏰀 Paracoccidioides dermatidis
(healthy and immunocompromised)

7

what are the opportunistic pathogens

􏰀Cryptococcus neoformans 􏰀􏰀
Aspergillus sp.
􏰀Pneumocystis jiroveci
(immunocompromised)

8

transmission of primary fungal infections

inhalation of aerosols -- no person to person
all are dimorphic btw

9

clinical syndromes of: 􏰀
Histoplasma capsulatum
􏰀Blastomyces dermatidis
Coccidioides immitis
Paracoccidioides dermatidis

histoplasmosis
blastomycosis
coccidioidomycosis
paracoccidioidomycosis

10

clinical symptoms of respiratory fungal infections

-mostly mild fever or cough or asymptomatic
-more severe chills, malaise, fever, chest pain
-sputum production
-weight loss
-granulomatous lesions on skin or mucous membrane
-may mimic TB

11

pathogenesis of the primary fungal infections

reach alveoli --> go from mycelial form to yeast --> colonize respiratory mucosa

12

why do these fungi go to the alveoli

important for iron uptake by fungi

13

laboratory diagnosis

trying to identify the dimorphic fungi
-sputum analyses
-bronchoalveolar lavage
-transtracheal aspirate
-lung biopsy

14

difference between a teleomorph and anamorph

teleomorph - sexually producing form of fungus
anamorph - asexually producing form

15

2 clinically significant form of histoplasma capsulatum

H. capsulatum var capsulatum: Pulmonary & disseminated infections, Eastern US and Latin America, Thinner cell walls; smaller size (2-4 μm)

H. capsulatum var duboisii: Skin and bone lesions, Tropical Africa (“African histoplasmosis”), Thicker walled; larger yeasts (8-15 μm)

16

natural habitat of histoplasma capsulatum

soil with high nitrogen content aka these soils are enriched with bird or bat droppings

17

transmission of histoplasma capsulatum

Microconidia and hyphae are aerosolized and inhaled

18

clinical presentation of histoplasmosis

asymptomatic --> fever, cough, chest pain

19

general features of blastomycosis

contact with soil, found in decaying organic matter

20

presentation of blastomycosis

pulmonary and extrapulmonary disseminated

21

transmission of coccidioidomycosis

inhalation of arthroconidia from soil

22

in coccidioidomycosis, what protects spore from phagocytosis

spherules

23

most virulent of all the human mycotic pathogens

coccidioides sp

24

form of opportunistic pathogens

monomorphic (compare to dimorphic nature of primary fungal infections)

25

predisposing factor for aspergillus

chemo, neutropenia, and assisted ventilation

26

predisposing factor for p. jiroevi (pneumocystis)

chemo, malnutrition, HIV/AIDS

27

predisposing factor for c. neoformans

malnutrition, HIV/AIDS

28

morphological feature of cryptococcus neoformans

encapsulated yeast

29

most common fungal infection seen in aids patients

cryptococcus neoformans

30

transmission of cryptococcus neoformans

inhalation of unencapsulated yeast found in soil enriched with pigeon droppings