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DWT > Introduction to Bacteria > Flashcards

Introduction to Bacteria Flashcards

1
Q

What type of bacteria is shown from this differential staining?

A

Gram (+)

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2
Q

What type of bacteria is shown from this differential staining?

A

Gram (-)

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3
Q

Describe the differences between gram (+/-) bacteria that make them stain different colors.

A

The structure of their cell walls.

Gram (+) bacteria have a thick, uniform peptidoglycan cell wall.

Gram (-) have a thin peptidoglycan cell wall, plus an outer membrane consisting of lipopolysaccharide (LPS).

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4
Q

Describe the 4 key characteristics of prokaryotes (bacteria).

A
  1. Unicellular
  2. Lack a membrane-bound nucleus
  3. Lack membrane-bound organelles
  4. Smaller & less complex than eukaryotes
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5
Q

What is the process of binary fission?

A

2 daughter cells resulting from a single cell replicating its own DNA

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6
Q

Describe acid-fast bacteria.

A

Bacteria with thick, outer lipid-rich layers comprised of mycolic acids, which render “acid-fast” bacteria that are resistant to becoming decolorized (with acid-alcohol) once stained red. Can survive inside cells and are targets for other antibiotics.

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7
Q

What is the importance of differential staining of bacteria?

A

Antimicrobial therapy = the most effective when it is narrow-spectrum targeted. The type of bacteria determines the drug type (i.e., how the cell wall can be degraded)

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8
Q

What shape of bacteria is shown?

A

Coccus

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9
Q

What shape of bacteria is shown?

A

Rod (or Bacillus)

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10
Q

What shape of bacteria is shown?

A

Sprillum/Spirochete

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11
Q

What shape of bacteria is shown?

A

Mycobacteria

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12
Q

What shape/arrangement of bacteria is shown?

A

Corynebacteria (palisades arrangement)

“Coryne” = rod-like shaped
Palisades = fenced arrangement

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13
Q

What shape of bacteria is shown?

A

Coccobaccilli

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14
Q

What arrangement of bacteria is shown?

A

Streptococci (cocci in chains)

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15
Q

What arrangement of bacteria is shown?

A

Staphylococci (large cocci in irregular clusters)

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16
Q

What arrangement of bacteria is shown?

A

Spore-forming rods

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17
Q

What arrangement of bacteria is shown?

A

Streptomycetes (mold-like, filamentous)

-mycete = mushroom, fungus

18
Q

What are the features of the “capsule” that encloses some bacteria?

A

Amorphous, gelatinous material enclosing around the cell wall; has pili attached to it; comprised of carbohydrates; antigenically diverse; anti-phagocytic!

19
Q

Can you see capsules in a gram stain?

A

No

20
Q

What is the importance of determining if a bacterium is enclosed in a capsule or not?

A

Determines type of antimicrobial needed (i.e., for cell-wall penetration/degradation)

21
Q

Describe the gram stain protocol.

A
  1. Heat-fix
  2. Stain with crystal violet
  3. Stain with iodine treatment
  4. Stain with de-colorizer
  5. Counter-stain with safranin
  6. Will be either purple or pink
22
Q

What is the purpose of pili?

A

Adherence

23
Q

What is the purpose of flagella?

A

Motility

24
Q

What is the importance of bacterial spores?

A

Dormant form of bacteria that are resistant to harsh conditions (extreme temperatures/pH; antibiotic exposure; lack of nutrition)

25
Q

What forms a single colony on an agar plate?

A

A single bacterium that has undergone clonal expansion

26
Q

If the # of colonies increases, then the # of bacteria ___.

A

increases

27
Q

What are the two states bacteria can exist in?

A

Planktonic (free) or sessile (attached)

28
Q

What forms a biofilm, and what state of bacterium is it?

A

Biofilm: sessile

Formed when a bacterial population becomes adherent to each other and/or a surface, and then becomes enclosed within a biopolymer matrix = “goop”

29
Q

What is quorum sensing?

A

A communication mechanism used by bacteria within a biofilm that allows them to function as one/an “organism”

30
Q

How do biofilms aid in the pathogenesis (development) of bacterial infections? (3)

A
  1. Aid in colonization
  2. Aid in avoiding phagocytosis
  3. Aid in avoiding antibiotics
31
Q

Which type of bacteria requires O2 for growth (respiratory catabolism)?

A

(Strict or obligate) aerobes

32
Q

Which type of bacteria is killed by O2 (fermentative pathways)?

A

(Strict or obligate) anaerobes

33
Q

Which type of bacteria can grow either aerobically or anaerobically?

A

Facultative Anaerobes

34
Q

Which type of bacteria require reduced O2?

A

Microaerophiles

35
Q

What type of infection can you rule out anaerobic bacteria from your differential dx?

A

Surface-skin infection

36
Q

What is the importance of knowing the atmospheric requirements of bacteria?

A

Influences your dx approach, which influences your tx plan

37
Q

Where do anaerobic bacteria live in the body?

A

Epithelial surfaces of: G.I. tract lumen, gums, vagina

Lumen of G.I.T.
38
Q

Describe the bacterial genome.

A

Haploid; circular chromosome with dsDNA

39
Q

What is the significance of the plasmid molecule in bacteria?

A

carries genes for antibiotic resistance

40
Q

What are 3 ways bacteria can undergo genetic variation?

A
  1. Mutation (change in nucleotide seq)
  2. Recombination (exchange of DNA b/w two separate bacteria; transduction, conjugation, transformation)
  3. Transposition (transposons “jumping genes”/integrons move locations within the genome, or integrate into plasmid –> jump to other bacteria)

DWT (16 decks)

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