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Host and Defense > EXAM 1 Basics of Bacteriology > Flashcards

EXAM 1 Basics of Bacteriology Flashcards

1
Q

what are two reasons bacterial infections are on the rise?

A
  • advancements in medicine
    • created large populations of immunocompromised people
  • increasing spread of antibiotic resistant bacteria, facilitated by international travel and the misuse of available antibiotics
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2
Q

what are the oldest, most prevalent forms of life on earth?

A

bacteria

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3
Q

relationships among bacteria can be surmised by comparing ____

A

16S rRNA sequences

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4
Q

list and describe the 4 basic shapes of bacteria

A
  • cocci
    • spherical
  • bacilli
    • rods
    • short bacilli are called coccobacilli
  • spiral forms
    • comma-shaped, S-shaped, spiral-shaped
  • pleomorphic
    • lacking a distinct shape
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5
Q

name 7 key unique features of bacteria

A
  • usually single, circular chromosome
    • haploid, no histones
  • may have plasmids
  • no internal organelles, no nucleus
  • cell wall components
  • 70S ribosomes
  • unique metabolic pathways
  • mode of replication (binary fission)
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6
Q

how do bacteria replicate?

A

binary fission

  1. DNA replication
  2. chromosome segregation
  3. cytokinesis
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7
Q

bacteria are often associated with ___ rather than free swimming

A

biofilms

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8
Q

what do biofilms promote?

A

bacterial colonization and persistence

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9
Q

where can biofilms form?

A
  • in the environment
  • on medical devices
  • on body surfaces
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10
Q

what forms the basis for recognition of bacteria by innate and adaptive immunity and for antibiotic-based therapies?

A

the unique features of bacteria

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11
Q

what shape do neisseria sp. and moraxella catarrhalis have?

A

diplococci

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12
Q

what is the shape of streptococci sp?

A

streptococci

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13
Q

what is the shape of micrococcus luteus?

A

tetrad

located in soil and on the skin

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14
Q

what is the shape of sacina sp.?

A

sarcinae

found on skin and in intestines

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15
Q

what is the shape of staphylococcus aureus?

A

staphylococci

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16
Q

what is the shape of bacillus sp., escherichia sp, mycobacterium sp, salmonella sp, klebsiella sp, pseudomonas sp, yersinia sp, and porphyromonas gingivalis?

A

single bacillus and diplobacilli

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17
Q

what is the shape of bacillus anthracis and bacillus megaterium?

A

streptobacilli

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18
Q

what is the shape of haemophilus influenzae, chlamydia trachomatis, and bordetella pertussis (whooping cough)?

A

coccobacillus

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19
Q

what is the shape of vibrio cholerae?

A

vibrio

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20
Q

what is the shape of spirillum sp?

A

spirillum

rat bite fever agent

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21
Q

what is the shape of borellia, brachyspira, and treponemonas, and leptospira sp?

A

spirochete

lyme disease, relapsing fever, syphilis, leptospirosis

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22
Q

bacteria in biofilms are often refractory to ___ treatments and protected from ___

A
  • antibiotics
  • host defenses
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23
Q

bacteria within biofilms can persist for ___, but can break off and do what?

A
  • long periods
  • cause systemic or distant infections
24
Q

biofilm development is often regulated by what?

A

quorum sensing

25
Q

describe the gram positive cell wall

A

thick peptidoglycan layer

contains a plasma membrane

26
Q

describe the gram negative cell wall

A

thin peptidoglycan layer with an outer membrane

contains a plasma membrane

27
Q

which bacteria do not have cell walls?

A

mycoplasma and ureaplasma sp.

no cell wall, so no peptidoglycan

28
Q

what is the function of bacterial cell walls?

A

maintains cell shape, controls influx and efflux of materials, protects against osmotic lysis

29
Q

bacterial cell walls are the site for what 3 things?

A
  • respiratory chains
  • secretion systems
  • adhesins
30
Q

bacterial cell walls are the target of what?

A

lysozyme and many antibiotics

31
Q

bacterial cell walls are the basis for ____ pathogens

A
  • serotyping
    • using antibodies to distinguish between bacteria
    • antigens: O (LPS), K (capsule), H (flagellin)
32
Q

the bacterial cell wall contains ___ that are recognized by innate and adaptive immune systems

A

ligands

33
Q

the gram positive envelope contains ___ and ___ in the peptidoglycan layer

A
  • lipoteichoic acid
    • anchors to plasma membrane
  • teichoic acid

they anchor the peptidoglycan layer to the plasma membrane

34
Q

describe the peptidoglycan structure of both gram positive and gram negative cell walls

A
  • binding of peptidoglycan by the pattern recognition receptor (PRR) toll-like receptor 2 (TLR2) can stimulate inflammatory responses
  • cleaved by lysozyme
  • biosynthesis is inhibited by various antibiotics, including beta-lactams like penicillin
35
Q

what is contained in the gram negative envelope?

A
  • lipoproteins
    • anchor outer membrane to the peptidoglycan layer
  • lipopolysaccharides (LPS)
  • porins
  • O-specific side chains of LPS
  • phospho lipid and integral proteins on plasma membrane
36
Q

what do bacteria that have no cell wall require to stabilize its cell membrane?

A
  • sterols
    • cholesterol from host
37
Q

bacteria that lack a cell wall are linked with what pathogenic conditions?

A
  • pelvic inflammatory disease, pneumoniae, meningitis, abortions, urethritis, infertility, premature birth, and some cancers
38
Q

how does the unique cell wall of mycoplasma affect the susceptibility of these bacteria to antibiotics?

A

they will be resistant because they lack a peptidoglycan layer, so the antibiotics don’t have anything to attack

39
Q

what factors are associated with bacterial cell walls?

A
  • electron transport chains
    • aerobic bacteria and facultative anaerobes versus anaerobes
  • protein secretion systems
  • flagella
  • adhesins
  • capsules
  • spores
40
Q

what is used by many bacteria to break down glucose to pyruvate, thus creating ATP?

A

fermentation

41
Q

what are 4 types of facultative anaerobes, and how do they produce energy?

A
  • phototrophs
    • use light to generate energy
  • autotrophs
    • use chemicals to generate energy
  • heterotrophs
    • use organic sources
  • chemoheterotrophs are the most medically important bacteria
42
Q

what does superoxide dismutase do?

A

converts seperoxide to hydrogen peroxide and oxygen

43
Q

what does catalase or peroxidase do?

A

converts peroxide to hydrogen and oxygen

44
Q

describe gram negative secretion systems

A
  • type I, II, and V secretion systems deliver proteins like toxins, siderophores to the extracellular environment
  • type III, IV, VI, and VII secretion systems can inject factors (effector proteins or toxins) directly into target host cells
45
Q

the structure of bacterial flagella promotes what?

A

bacteria dissemination within host environments, and facilitates chemotaxis towards or away from specific stimuli

46
Q

highly antigenic (H antigen) and some bacteria can do what to escape immune detection?

A

swap (phase vary) different flagellin proteins

47
Q

how can the expression of flagellin be down regulated within a host to avoid triggering innate immune responses?

A

by stimulating TLR5 or NLRC4

48
Q

what are axial filaments?

A

flagella present within the periplasmic space

49
Q

describe how axial filaments aid in movement

A

the rotation of the axial filament relative to the cell body causes the entire bacterium (spirochete) to move forward in a corkscrew-like motion, even through material viscous enough to prevent the passage of normally flagellated bacteria

50
Q

what is the function of bacterial adhesins?

A
  • mediate contact with other bacteria, inanimate surfaces, host cells, and ECM
  • associate with different pili and can have unique receptor specificity, thereby affecting tissue tropism
51
Q

what are anti-adhesins used for?

A

being developed as anti-bacterial therapeutics

52
Q

what is the function of type IV pili?

A
  • conjugation (bacterial mating)
  • DNA binding/uptake (competence)
  • motility
53
Q

what are capsules?

A
  • layers of polysaccharide (or polypeptide) associated with the bacterial surface
54
Q

what is the function of capsules?

A
  • provides protection against desiccation, phage, detergents, and antimicrobial peptides
  • protects bacteria from phagocytes
55
Q

antibodies against specific capsule (K antigen) are ___, and for this reason capsular antigens are a main component in some vaccines

A

opsonic (generate antibodies to recognize specific antigens, which can then be recognized by receptors on macrophages)

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