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Flashcards in RT6 Deck (37)
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1
Q

pathogenesis of mycobacterium tuberculosis

A

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
Q

diagnosing tuberculosis

A

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

3
Q

culture of tuberculosis is done on what agar

A

lowenstein jesen agar or oleic acid albumin broth

4
Q

what does tuberculin test prove

A

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

5
Q

treatment of TB

A

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

6
Q

what are the primary fungal pathogens

A
􏰀 Histoplasma capsulatum
􏰀 Blastomyces dermatidis
􏰀 Coccidioides immitis
􏰀 Paracoccidioides dermatidis
(healthy and immunocompromised)
7
Q

what are the opportunistic pathogens

A

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

8
Q

transmission of primary fungal infections

A

inhalation of aerosols – no person to person

all are dimorphic btw

9
Q
clinical syndromes of: 􏰀  
Histoplasma capsulatum
􏰀Blastomyces dermatidis
Coccidioides immitis
Paracoccidioides dermatidis
A

histoplasmosis
blastomycosis
coccidioidomycosis
paracoccidioidomycosis

10
Q

clinical symptoms of respiratory fungal infections

A
  • 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
Q

pathogenesis of the primary fungal infections

A

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

12
Q

why do these fungi go to the alveoli

A

important for iron uptake by fungi

13
Q

laboratory diagnosis

A

trying to identify the dimorphic fungi

  • sputum analyses
  • bronchoalveolar lavage
  • transtracheal aspirate
  • lung biopsy
14
Q

difference between a teleomorph and anamorph

A

teleomorph - sexually producing form of fungus

anamorph - asexually producing form

15
Q

2 clinically significant form of histoplasma capsulatum

A

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
Q

natural habitat of histoplasma capsulatum

A

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

17
Q

transmission of histoplasma capsulatum

A

Microconidia and hyphae are aerosolized and inhaled

18
Q

clinical presentation of histoplasmosis

A

asymptomatic –> fever, cough, chest pain

19
Q

general features of blastomycosis

A

contact with soil, found in decaying organic matter

20
Q

presentation of blastomycosis

A

pulmonary and extrapulmonary disseminated

21
Q

transmission of coccidioidomycosis

A

inhalation of arthroconidia from soil

22
Q

in coccidioidomycosis, what protects spore from phagocytosis

A

spherules

23
Q

most virulent of all the human mycotic pathogens

A

coccidioides sp

24
Q

form of opportunistic pathogens

A

monomorphic (compare to dimorphic nature of primary fungal infections)

25
Q

predisposing factor for aspergillus

A

chemo, neutropenia, and assisted ventilation

26
Q

predisposing factor for p. jiroevi (pneumocystis)

A

chemo, malnutrition, HIV/AIDS

27
Q

predisposing factor for c. neoformans

A

malnutrition, HIV/AIDS

28
Q

morphological feature of cryptococcus neoformans

A

encapsulated yeast

29
Q

most common fungal infection seen in aids patients

A

cryptococcus neoformans

30
Q

transmission of cryptococcus neoformans

A

inhalation of unencapsulated yeast found in soil enriched with pigeon droppings

31
Q

pathogenesis of cryptococcus neoformans

A

inhalation triggers production of capsule made of GXM (glucuronoxylomannan) –> affinity for CNS –> downregulates immune response –> oxidize exogenous catecholamines which leads to production of melanin that prevents fungi from phagocytic oxidative damage

32
Q

most common serious opportunistic illness in HIV infected individuals

A

pneumocystis

33
Q

general features of pneumocystis/p. jiroveci

A

lacks ergosterol in cell wall, difficult to grow in culture, may or may not be transmissible

34
Q

aspergillus is found

A

decaying matter, soil, air

35
Q

two forms of aspergillus

A

allergic (difficult to diagnose) and invasive (hyphae invade tissue)

36
Q

fungal balls

A

aspergilloma

37
Q

symptoms of aspergilloma

A

deadly invasive, pneumonia, hemoptysis, high mortality