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Host and Defense > EXAM 1 Basics of Bacteriology > Flashcards

EXAM 1 Basics of Bacteriology Flashcards

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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?

Study These Flashcards
A
  • long periods
  • cause systemic or distant infections
24
Q

biofilm development is often regulated by what?

Study These Flashcards
A

quorum sensing

25
describe the gram positive cell wall
thick peptidoglycan layer contains a plasma membrane
26
describe the gram negative cell wall
thin peptidoglycan layer with an outer membrane contains a plasma membrane
27
which bacteria do not have cell walls?
mycoplasma and ureaplasma sp. no cell wall, so no peptidoglycan
28
what is the function of bacterial cell walls?
maintains cell shape, controls influx and efflux of materials, protects against osmotic lysis
29
bacterial cell walls are the site for what 3 things?
* respiratory chains * secretion systems * adhesins
30
bacterial cell walls are the target of what?
lysozyme and many antibiotics
31
bacterial cell walls are the basis for ____ pathogens
* serotyping * using antibodies to distinguish between bacteria * antigens: O (LPS), K (capsule), H (flagellin)
32
the bacterial cell wall contains ___ that are recognized by innate and adaptive immune systems
ligands
33
the gram positive envelope contains ___ and ___ in the peptidoglycan layer
* lipoteichoic acid * anchors to plasma membrane * teichoic acid they anchor the peptidoglycan layer to the plasma membrane
34
describe the peptidoglycan structure of both gram positive and gram negative cell walls
* 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
what is contained in the gram negative envelope?
* 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
what do bacteria that have no cell wall require to stabilize its cell membrane?
* sterols * cholesterol from host
37
bacteria that lack a cell wall are linked with what pathogenic conditions?
* pelvic inflammatory disease, pneumoniae, meningitis, abortions, urethritis, infertility, premature birth, and some cancers
38
how does the unique cell wall of mycoplasma affect the susceptibility of these bacteria to antibiotics?
they will be resistant because they lack a peptidoglycan layer, so the antibiotics don't have anything to attack
39
what factors are associated with bacterial cell walls?
* electron transport chains * aerobic bacteria and facultative anaerobes versus anaerobes * protein secretion systems * flagella * adhesins * capsules * spores
40
what is used by many bacteria to break down glucose to pyruvate, thus creating ATP?
fermentation
41
what are 4 types of facultative anaerobes, and how do they produce energy?
* phototrophs * use light to generate energy * autotrophs * use chemicals to generate energy * heterotrophs * use organic sources * chemoheterotrophs are the most medically important bacteria
42
what does superoxide dismutase do?
converts seperoxide to hydrogen peroxide and oxygen
43
what does catalase or peroxidase do?
converts peroxide to hydrogen and oxygen
44
describe gram negative secretion systems
* 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
the structure of bacterial flagella promotes what?
bacteria dissemination within host environments, and facilitates chemotaxis towards or away from specific stimuli
46
highly antigenic (H antigen) and some bacteria can do what to escape immune detection?
swap (phase vary) different flagellin proteins
47
how can the expression of flagellin be down regulated within a host to avoid triggering innate immune responses?
by stimulating TLR5 or NLRC4
48
what are axial filaments?
flagella present within the periplasmic space
49
describe how axial filaments aid in movement
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
what is the function of bacterial adhesins?
* 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
what are anti-adhesins used for?
being developed as anti-bacterial therapeutics
52
what is the function of type IV pili?
* conjugation (bacterial mating) * DNA binding/uptake (competence) * motility
53
what are capsules?
* layers of polysaccharide (or polypeptide) associated with the bacterial surface
54
what is the function of capsules?
* provides protection against desiccation, phage, detergents, and antimicrobial peptides * protects bacteria from phagocytes
55
antibodies against specific capsule (K antigen) are \_\_\_, and for this reason capsular antigens are a main component in some vaccines
opsonic (generate antibodies to recognize specific antigens, which can then be recognized by receptors on macrophages)

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