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Phase 2 Block 1 > General Microbiology > Flashcards

General Microbiology Flashcards

1
Q

What is an infectious agent?

A

Something that invades another living thing

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2
Q

What are the 6 classes of infectious agents in humans?

A

Bacteria (prokaryote, single cell)
Viruses (sub cellular, nonliving)
Fungi (eukaryote, single or multi cell)
Parasites (eukaryotes, single or multicellular)
Prions (transmissible, abnormally folded protein)
Algae (eukaryote, single cell)

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3
Q

What are the key differences between eukaryotes and prokaryotes?

A

Eukaryotes have true nucleus - genetic material inside a membrane and organelles are membrane bound
Prokaryotes don’t have this

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4
Q

This part of the light microscope focuses light onto the specimen

A

Condenser

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5
Q

Where is the light source located for a light microscope?

A

At the base

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6
Q

What structure on the light microscope first magnifies the image of the specimen?

A

Objective lense

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7
Q

What type of light is used in fluorescence microscopy?

A

UV light

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8
Q

What type of dye is used to fluorescent microscopy?

A

Fluorescent dye

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9
Q

This tool is useful for looking at organisms that are hard to grown in culture, detect organisms, or antibodies to organisms

A

Fluorescent microscopy

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10
Q

What is the difference between a scanning electron microscope and transmission electron microscope?

A

SEM low res 3D image of surface
TEM high res 2D image showing detailed internal structure

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11
Q

What are the similarities between SEM and TEM?

A

Both use electrons to create an image

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12
Q

What is the difference between colonization and infection?

A

Colonization bacteria present w/o causing harm to the host
Infection host tissue invasion by disease causing organisms

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13
Q

Are bacteria always harmful?

A

No; Flora/Colonizer
Don’t cause disease
Cooperate with host

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14
Q

What are some benefits of bacteria?

A

Outcompete pathogens
Help host metabolism
Keep host immune system vigilant

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15
Q

What are the 3 types of host-bacteria relationships?

A

Flora/colonizer
Opportunist
Pathogen

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16
Q

Are colonizers always harmless?

A

Can become harmful if host is compromised

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17
Q

What determines the pathogenicity of an organism?

A

Virulence factors

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18
Q

What are the 5 virulence factors?

A

Motility
Adhesion
Protection (capsule or biofilm)
Toxin production
Spore formation

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19
Q

What are the 3 types of toxins made by bacteria?

A

-Neurotoxin
-Enterotoxin impact GI tract —> infectious diarrhea or food poisoning
-Endotoxin bound to surface of bacteria but are release by normal shedding or cell lysis

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20
Q

Why are spores so dangerous?

A

Formed by some bacteria when they’re in unfavourable conditions that are difficult to kill

Spores remain dormant until favourable conditions

Difficult to kill

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21
Q

What are 7 ways (morphology/metabolic activity) of identifying bacteria in the lab?

A
  • Microscopic (shape, size, gram stain)
  • Macroscopic
  • Colony size, colour, shape, odour
  • Colony resistance, substrate use, ability to lyse blood
  • Metabolic (aerobic/anaerobic, growth needs, enzyme production)
  • Serotyping (using antibodies to identify bacteria by antigens)
  • Molecular sequencing
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22
Q

What are obligate aerobes?

A

Absolutely need oxygen to live
Make protective enzymes to break down radicals made r/t respiration

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23
Q

What are obligate anaerobes?

A

Have no enzymes to deal with radicals
Use fermentation to make energy

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24
Q

What is a facultative anaerobe?

A

Pref O2 but don’t need it to survive
Can use respiration or fermentation for energy depending on O2 availability

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25
Q

What type of bacteria (aerobic/anaerobic) grows for longer?

A

Anaerobes - can be incubated for up to 2wks

26
Q

What colour do gram positive bacteria stain?

A

Deep blue or purple

27
Q

What causes bacteria to have a gram positive stain?

A

Gram (+) bacteria have a thick peptidoglycan wall causing it to retain the violet dye used even after alcohol treatment

28
Q

What causes bacteria to have a gram negative stain?

A

Gram (-) bacteria have a thin peptidoglycan wall that doesn’t hold on to the violet dye after alcohol treatment

29
Q

What colour do gram negative bacteria stain?

A

Pink

30
Q

What are the 4 steps for gram staining?

A

Crystal violet: primary stain
Iodine: helps dye adhere to cell wall
Alcohol: washes away stain from gram (-) cell walls
Safranin or carbol fuchsin: counterstain allowing adherence to gram (-) cell walls

31
Q

What are the 3 types of grouping for cocci bacteria?

A

Diplococci (pairs)
Chains
Clusters

32
Q

What are the 6 types of arrangement of bacilli?

A

Singles
Curved
Pallisade
Streptobacilli
Fusoform
Coccobacilli

33
Q

What 6 characteristics are used to describe colony morphology on a plate?

A

Shape (form, elevation, margin)
Size (pin-point vs large)
Pigment or sheen
Ability to break down blood cells
Mucoid (presence of capsule)
Odour

34
Q

What differences are there between molds and yeasts? (cells, reproduction, temp preference)

A

Molds - Multicellular, filamentous (hyphae); likes colder env (25-30C)

Yeasts - Unicellular, produced by budding; likes growing in warmer env (35-37C)

35
Q

What similarities are there between molds and yeasts?

A

Both are fungi

36
Q

What are dimorphic fungi?

A

Can become mold or yeast depending on env temp

37
Q

Do fungi always need lab testing for diagnosis?

A

No; some can be dx empirically

38
Q

What 5 factors can fungi identification be based on?

A

Microscopic characteristics
Macroscopic characteristics
Growth rate
Metabolism
Protein structure on MALDI-TOF or DNA sequencing

39
Q

What are 4 common medically important dimorphic fungi?

A

Blastomycosis dermatitidis
Coccidiodes immitis
Histoplasma capsulatum
Paracoccidiodes braziliensis

40
Q

What action must be taken if a high risk pathogen is suspected?

A

Notify lab before sending specimen so it can be processed in biosafety lvl 3 space

41
Q

This infectious agent forms rings on blood smear

A

Plasmodium; parasite responsible for malaria

42
Q

What are the 2 classifications of parasites?

A

Protozoa (eukaryote, single cell)
Helminths/worms (eukaryote, multicellular)

43
Q

What is the traditional means for identifying protozoan parasites?

A

Microscopy on blood, stool, or vaginal specimens

44
Q

This technique is replacing microscopy and allows detection of multiple parasites in one sample

A

Molecular detection
Stool multiplex PCR allows for detection of multiple parasites in one sample

45
Q

What are the 4 methods of identifying protozoans?

A

Microscopy
Molecular detection
Serology
Culture

46
Q

What are the 3 methods of helminth identification?

A

Worm morphology
Egg or larva microscopy
Serology

47
Q

Are viruses living cells?

A

No
Consist of DNA/RNA and a protein coat. May or may not have an envelope
Need a host to replicate

48
Q

What are the 5 means of virus classification?

A

Genome
Capsid shape
Presence of envelope
Body site they infect
Source of transmission

49
Q

What 2 types of genome can viruses have?

A

DNA
RNA
Can be single or double stranded

50
Q

What are the 3 types of capsid shapes viruses can have?

A

Polyhedral
Helical/linear
Complex

51
Q

What are the 6 methods of detection/identification of viruses?

A

Molecular (PCR)
Antigen detection (immunofluorescent assay)
Electron microscopy (expensive)
Viral culture (time consuming)
Isolating antibodies
ELISA (IgM and IgG; common in public health labs)

52
Q

What 3 factors impact quality of lab results?

A

Collection
Storage
Transportation

53
Q

These are 4 examples of non-sterile sources of culture samples

A

Urine
Stool
Sputum
Swabs

54
Q

What is a challenge associated with non-sterile site sources?

A

Contain a large amount of colonizing bacteria and pathogens may or may not be present

55
Q

Give examples of sterile fluids/samples

A

Blood
CSF
OR collected tissue
Abd or thoracic fluid
Suprapubic urine

56
Q

Samples collected from ____ sites always represent infection unless poor collection or contamination of sample

A

Sterile

57
Q

What are some things that can contribute to low quality specimens?

A

1/4 blood culture bottles grow skin colonizer
Large number of epithelial cells in sputum on gram stain
Small number of polymorphonuclear cells in gram stain
Mixed growth of organisms

58
Q

What is the least preferred sample collection method?

A

Swabs because they give such a small sample; more is better

59
Q

Microbiology specimens can’t be collected in this substance

A

Formalin or other preservatives

60
Q

Why is prompt transport of a specimen important for microbiology of specimen?

A

Time is bacteria — desired bacteria may be dying and getting outcompeted by non-pathogenic bacteria

Phase 2 Block 1 (19 decks)

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