Mycology/Mycobacteriology

Question 1

What 3 components are typical of fungal cell wall?

Answer 1

1-Mannan
2-Glucan
3-Chitin

Question 2

Single cells that grow in a creamy mucoid colony and are facultative anaerobes are what?

Answer 2

Yeast

Question 3

Multicellular filamentous (hyphae and mycelium) fuzzy colonies that are obligate aerobes are likely what?

Answer 3

Mold

Question 4

Ture hyphae or germ tubes are __________ whereas pseudohyphea are ________ tubes.

Answer 4

continuous, segmented

Question 5

Hyphae with dark lines delineating each segment are called?

Answer 5

Septate hypha (aspergillus sp.)

Question 6

What are the two kinds of reproduction?

Answer 6

• Asexual/anamorph (budding or conidia)

- Sexual/teleomorph (spores possible)

Question 7

Fungi that are a mold at one temp (25-30 C) and yeast at another (35-37 C) are called what?

Answer 7

Dimorphic fungi

Question 8

What are the 3 main groups of pathogenic fungi?

Answer 8

1-Dimorphic
2-opportunistic
3-cutaneous

Question 9

What are two important opportunistic fungi?

Answer 9

• Candida Spp

- Rhizopus Spp

Question 10

What are 5 risk factors for fungal infections?

Answer 10

1-Immunocompromised
2-Premature infants
3-Critically ill/hospitalized
4-Travelers and residents of endemic areas
5-Direct contact with animals/infected materials

Question 11

What are the 3 common methods for direct specimen diagnostic testing?

Answer 11

1-Direct microscopy
2-Culture
3-Histopathology

Question 12

What are the advantages and disadvantages of Direct microscopy diagnosis?

Answer 12

• Fast and cheap

- Insensitive

Question 13

What are the advantages and disadvantages of Culture diagnosis?

Answer 13

• Gold standard from sterile body site
• Allows genus/species level of ID
• Delayed results
• Difficult to obtain
• insensitive

Question 14

What are the advantages and disadvantages for histopathology diagnosis?

Answer 14

-Gold standard for invasive disease

• Difficult to obtain
• not species specific

Question 15

What are two current methods for identification starting with a pure culture?

Answer 15

1-Proteomic identification (MALDI)

2-Targeted gene sequencing

Question 16

What are the two most common Candida species?

Answer 16

C. Albicans

C. Glabrata

Question 17

What are three most common species that cause mucormycosis?

Answer 17

1-Mucor
2-Rhizopus
3-Rhizomucor

*Thrive in high glucose and acidic environment

Question 18

Bacilli that are obligate aerobes with mycolic acid in their cell wall are called what?

Answer 18

Mycobacteria

*cell wall is high lipid and is waxy

Question 19

What is the most common/important mycolic acid in mycobacteria?

Answer 19

lipoarabinomannan

Question 20

What stain involves binding carbol fuchsin dye that is resistant to decolorization by acid?

Answer 20

Acid Fast Bacilli (AFB)

*M. Tuberculosis

Question 21

What are the three most common mycobacteria?

Answer 21

1-M. Tuberculosis
2-M. Bovis
3-M Bovis Baville calmette-Guerin (BCG)

Question 22

What is an example of a special grower? One that cannot be grown in lab?

Answer 22

M. Leprae (leprosy)

Question 23

Rapid growers take how long to grow?

Answer 23

3-5 days

Question 24

What is a common way for Mycobacterium tuberculosis to be transmitted?

Answer 24

respiratory route through aerosolized particles (Sneezing, coughing, breathing)

Question 25

What are the 3 types of MTB infections?

Answer 25

- Primary - Latent - Reactivated

Question 26

What are the two categories of those at high risk for developing TB?

Answer 26

1-Increased exposure to TB disease (Health care, prisons, drug users, immigrants) 2-Clinical conditions increasing risk of progression (AIDS, transplant,

Question 27

Two step TB testing is done why?

Answer 27

To take advantage of the booster effect. First test may just "prime" immune system to respond the second second time if previous exposed

Question 28

Blood test to check for TB measure what?

Answer 28

Interferon-Gamma release in samples exposed to antigen

Question 29

What are 3 main clinical features of tuberculosis?

Answer 29

1-Cough with sputum 2-Shortness of breathe (dypsnea) 3-Fever/weight loss (action of IL-1 and TNF-a)

Question 30

What are three common ways of collecting a specimen for diagnosis?

Answer 30

1-Respiratory sample (morning sputa, gastric aspirate) 2-Sterile tissue/body fluid (CSF, Bone, Pleural fluid) 3-Urine if Urinary tract disease signs

Question 31

What are 4 methods to identify tuberculosis in the specimen?

Answer 31

1-AFB stain 2-PCR 3-Broth-based culture 4-Agar-based culture

Question 32

What are the four Runyon groups of non tuberculosis mycobacteria (NTM)?

Answer 32

1-Photochromogens 2-Scotochromogens 3-Nonchromogenic 4-Rapid Growers

Question 33

What characterizes a photochromogen?

Answer 33

- slow growth - yellow-orange pigment in light - M. Kansasii, M. Marinum (fish tank pathogen)

Question 34

What characterizes a Scotochromogen?

Answer 34

- slow growth - Yellow-orange pigment in light or dark - M Scrofulacium (swamp water)

Question 35

What characterizes a Nonchromogenic

Answer 35

- slow growth - no pigment - M. Avium-intracellulare

Question 36

What characterizes a rapid grower?

Answer 36

- colony in 5 days - no pigment - M. Fortuitum, M. Chelonae-abscessus

Question 37

Rapid growers are common of what type of infection?

Answer 37

Skin and soft tissue such as in cystic fibrosis or lung transplant

Question 38

Lepromatous leprosy is ________ whereas tuberculoid leprosy is ______________

Answer 38

Widespread, well demarcated lesions

Question 39

MTB and leprosy are spread _______ to _________ whereas NTM are contracted due to __________ exposure

Answer 39

Person, person, environmental