Principles of Micro 5

Question 1

importance of mannitol salt agar

Answer 1

• has pH indicator so will change color if the bacteria is producing acids
• selective: will grow A and B but not C
• differential: A will look different from B

Question 2

when is sabouraud’s agar used

Answer 2

for fungi

Question 3

advantage of sabouraud’s agar

Answer 3

• antibiotics can be added to inhibit growth of bacteria

- pH can be adjusted

Question 4

basic formulation of sabouraud’s agar

Answer 4

per liter of medium:
10g peptone
40g glucose
15g Agar

Question 5

Not all microorganisms can be grown on an agar plate so what are the exceptions

Answer 5

rickettsiaeceae and chlamydiaceae

Question 6

unique features of rickettsiaeceae (genera: rickettsia, orientia)

Answer 6

• obligate intracellular (need host to grow so cannot grow in an agar – need cell culture, embryonated eggs, animals)
• get ATP, AA, and metabolites from host
• zoonotic so associated with arthropod vector

Question 7

what are the two types of zoonotic features of rickettsiaeceae (genera: rickettsia, orientia)

Answer 7

• R. prowazekii: transmitted via human body louse

- R. rickettsiae: transmitted via wood tick

Question 8

other features of rickettsiaeceae (genera: rickettsia, orientia)

Answer 8

• small
• gram negative; don’t stain well
• LPS weakly toxigenic
• replicate in cell cytoplasm

Question 9

stain used in rickettsiaeceae (genera: rickettsia, orientia)

Answer 9

giemsa or gimenez stains

Question 10

two genera of chlamydiaceae

Answer 10

chlamydia (c. trachomatis)

chlamydiophilia (c. pneumoniae, C. psittaci)

Question 11

features of chlamydiaceae

Answer 11

small varying in size
coccoidal
non motile

Question 12

ecological groups of chlamydiaceae

Answer 12

• human infection

- zoonotic infection (birds –> human)

Question 13

examples of human and zoonotic infection in chlamydiaceae

Answer 13

human: trachoma, lymphogranuloma venereum
zoonotic: psittacosis/ornithosis

Question 14

unique features of chlamydiaceae

Answer 14

• obligatory intracellular
• depend on host for ATP and NAD
• no peptidoglycan
• genus specific LPS

Question 15

chlamydiaceae has life cycles with what two developmental forms

Answer 15

elementary bodies (EB)
reticulate bodies (RB)

Question 16

what can’t be synthesized and detected in chlamydiaceae

Answer 16

can’t synthesize ATP or reoxidize NAD

can’t detect flavoproteins or cytochromes

Question 17

what is the architecture of fungi

Answer 17

• has chitin
• true nucleus, nuclear envelope, pores
• phospholipid bilayer sterol e.g. ergosterol
• mitochondria and other subcellular organells

Question 18

why won’t antibacterial that target bacteria cell wall affect fungi

Answer 18

fungi and bacteria cell wall are made of two different things. fungi’s cell wall is made of chitin while bacteria’s cell wall is made of peptidoglycan

Question 19

why is fungi considered a saprophyte

Answer 19

it absorbs organic compounds produced by breakdown of non living organic matters so dead or decaying plants or animals

Question 20

what are two forms of fungi

Answer 20

macroform fungi

microform fungi

Question 21

what are the two types of microform fungi

Answer 21

yeast

moulds/filamentous fungi

Question 22

are there fungi that can switch form between yeast and moulds/filamentous fungi

Answer 22

yes they are depending on environment

and there are some fungi that are true moulds/filamentous fungi or true yeasts

Question 23

cell type of yeast and its form of reproduction

Answer 23

unicellular

asexual reproduction

Question 24

structure and form of reproduction for moulds/filamentous fungi

Answer 24

structure: long filamentous/tubular structure called hyphae
reproduction: sexual and asexual (produces spores)

Question 25

what is the habitat and classification of moulds/filamentous fungi

Answer 25

habitat: aquatic and terrestrial
classification: based on divisions (similar to phyla) which is based on rRNA analysis

Question 26

if genus is amanita for filamentous/moulds, what is the family, order, class, phylum/division, kingdom

Answer 26

family - amanitaceae
order - agaricales
class - hymenomycetes
phylum/division - basidiomycotes
kingdom - fungi

Question 27

interwoven mat of hyphae

Answer 27

mycelium

Question 28

what is a septate hyphae

Answer 28

barrier between the cells but not a blocking barrier

Question 29

what is present in non septate hyphae

Answer 29

chitin in cell wall

n acetyl glucosamine polymer

Question 30

what is the difference between fungal spores and bacterial spores

Answer 30

fungal spores are reproductive while bacterial spores are for survival

Question 31

features present in hyphae

Answer 31

permanent and differentiation

Question 32

features present in true hyphae

Answer 32

branching and arthrospores &chlamydospores

Question 33

what is the dimorphic nature of fungi

Answer 33

switching between yeast and moulds/filamentous fungi based on environment or temperature changes

Question 34

example of a dimorphic fungi

Answer 34

candida albicans

Question 35

if we took a sample from human tissue, culture, or superficial cutaneous or mucous membrane infections, what form would you find candida albicans

Answer 35

human tissue = yeast
culture = mycelial form
superficial cutaneous or mucous membrane infection = yeast + pseudohyphae

Question 36

what are the options for fungal reproduction

Answer 36

hyphal fragmentation

spores

Question 37

spores in fungal reproduction can reproduce in what way

Answer 37

sexual (meiosis): ascopores (sac like structures) and basidiospores (club shape structure)

asexual (mitosis): sporangiospores and conidiospores (blastospores - budding of yeast)