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Drug Action IV > Intro to Med Micro (Pathophys) - Block 1 > Flashcards

Intro to Med Micro (Pathophys) - Block 1 Flashcards

1
Q

What is pathogenicity?

A

Potential to cause disease

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2
Q

What is virulence?

A

Degree of pathogen’s ability to cause harm to the host and overcome host’s defence

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3
Q

List some of the characteristics of prokaryotes?

A
  1. No membrane enclosed organelles
  2. dsDNA -> nucleoid
  3. No histones
  4. Haploid
  5. Smaller 70s ribosomes
  6. Peptidoglycan cell wall
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4
Q

List some of the characteristics of eukaryotes?

A
  1. Membrane bound organelles
  2. DNA -> chromosomes
  3. Histones
  4. Diploid
  5. Large 80s ribosomes
  6. Cell membrane contains sterols
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5
Q

What are the basic shapes of bacteria?

A

Cocci, bacilli, spirochetes

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6
Q

What is the difference between spirillium and spirochetes?

A

Spirillium: rigid
Spirochete: flexible

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7
Q

What is the structural differenc ebetween strep and staph?

A

Strep: chains
Staph: clusters

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8
Q

What is the purpose for simple staining? Types?

A

Analyzing size, shape, and aggregation of bacteria:
1. Methylene blue
2. Safranin
3. Crystal violet

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9
Q

What is the purpose of ddifferential staining? Types?

A

2 or more dyes used to distinguish between types of cell wall structures of the same organism:
1. Gram stain
2. Ziehl Neelsen acid fast
3. Negative
4. Flagella (silver)
5. Endospore

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10
Q

Describe the composition of the cell wall?

A
  1. Composed of peptidoglycan
  2. Polymer of repeating disaccharide units cross-linked by short polypeptides
  3. Overall negative surface charge
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11
Q

Describe the composition of peptidoglycan?

A

Murein:
1. NAG and NAM sugar derivatives
2. Small group of aa (glycine, L-alanine, D-alanine, D-glutamic acid, L-lysine, DAP)
3. Transpeptidase makes the peptide crosslinks between glycan sheets

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12
Q

What enzyme do penicillins bind to?

A

Transpeptidase

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13
Q

Describe how peptidoglycan is assembled?

A

Cytoplasmic phase: NAG and NAM are encoded by murA-F genes in cytoplasm
Membraine-associated phase: Enzymes link NAG and NAM to lipids on plasma membrane
Extracytoplasmic phase: Cell wall units move from the inner cell membrane to the outer lipid layer of the membrane

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14
Q

What are the basic dyes used for Gram staining?

A

Crystal violet, safranin

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15
Q

What the differentiation of Gram staining?

A

G(-): pinkish red
G(+): purple

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16
Q

How is gram stain useful?

A
  1. ID bacteria by morphology and color
  2. Determines choice of ABX
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17
Q

Describe the components of G(+) cell walls?

A
  1. Thick peptidoglycan outside of the cytoplasmic membrane
  2. Teichoic acid that gives surfec a negative charge
  3. Lipoteichoic acid (PAMP) is an amphiphitic glycophosphates witha lipophilic glycolipid portion
  4. Inner cell membrane only
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18
Q

Describe the components of G(-) cell walls?

A
  1. Thin peptidoglycan layer sandwiched between innner and outer phospholipid membranes
  2. Periplasm that contains hydrolytic enzymes (b-lactamases)
  3. Porins that allow the passage of small molecules and ions
  4. Lipopolysaccharides
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19
Q

`

What is an endotoxin?

A

Contributes to dx sx (e.g. fever, shock)
* lipid portion of lipopolysaccharides on the outer surface of G(-) bacteria

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20
Q

What is the endotoxin component of LPS?

A

Lipid A

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21
Q

What is used to identify species in a clinical lab?

A

O antigen

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22
Q

What are the ABX targets that are within the cell wall?

A
  1. Plasma membrane
  2. Cytoplasm
  3. Ribosomes
  4. Endospores
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23
Q

What bacteria types commonly have endospores?

A

Bacillus (B. anthracis) and Clostridium (C. botulinum causes botulism)

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24
Q

What are endospores?

A

Thick keratin like coat contianing DNA and cellular components -> highly resistant to heat, dehydration, UV, chemicals, and ABX -> germinates in the presence of nutrients and water

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25
Q

What is the outcome of sporulation?

A

Release of spores when nutrients deplete due to environmental stress

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26
Q

What is the differential staining used to identify endospores?

A

Malachite green

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27
Q

What is gycocalyx?

A

Viscous and sticky polysaccharide and polypeptide that encases bacterium

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28
Q

What are the types of glycocalyx?

A

Capsule: neat, firmly attached to cell wall
Slime layer: covers surface like a film and loosely attached to cell wal

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29
Q

What is the function for glycocalyx?

A
  1. Protects cell from drying out
  2. Provides adherence of bacteria to human tissue
  3. Prevents phagocytosis (virulence)
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30
Q

Capsular polysaccharides can be recognized by ___?

A

Adaptive humoral response

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31
Q

What provides flagella energy source?

A

ATP

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32
Q

How is flagella visualized?

A

Silver stain

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33
Q

What is the function of the flagella?

A

Whiplike structures and provide movement to the bacterium

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34
Q

Bacteria species that contains flagella?

A

E. coli, H. pylori

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35
Q

What is a fimbriae?

A

Hairlike filaments extending from the cell surface that contributes to virleuce

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36
Q

What is the role of the fimbraie?

A
  1. Mediates the attachemnt of bacteria to host
  2. Has specificity for certain hosts
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37
Q

What is the role of the pilus?

A
  1. Provides contact between bacteria
  2. Allows for the transfer of DNA (toxin genes, abx reistance genes)
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38
Q

Reduced antibody effectiveness is caused by ___ through pilus horizontal gene transfer?

A

Antigenic variation

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39
Q

What is a mesophiles?

A

Infectious agents in humans

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40
Q

How does bacteria reproduce?

A

Binary fission (vertical genetransfer)

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41
Q

What is growth?

A

Increase in cell number

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42
Q

What is binary fission?

A

Cell division following enlargemtn of a cell to twice its minimum size

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43
Q

What is generation time?

A

Time required for microbial cells to double in number

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44
Q

Describe the growth rate of bcteria?

A

Exponential (logarithmic) growth: growth of a microbial population in which cell numbers double within a specific time interval

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45
Q

Describe the 4 phases of bacterial growth?

A

Lag phase: interval between inoculation and with growth begins where bacteria undergoes vigorous metabolic activity without division
Log phase: exponential growth where cells undergo rapid cell division
Stationary phase: No net increase or decrease in cell number, growth rate stops, spores form
Death: decline in the number of viable cells due to a buildup of waste

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46
Q

What phase of growth do B-lactam drugs act on?

A

Log phase

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47
Q

O2 is an ____ in cellular respiration

A

Electron acceptor

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48
Q

What ROS are generated by O2?

A

H2O2, O-2

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49
Q

What enzymes are used to protect against ROS?

A

Superoxide dioxide, catalase

Respnse to O2 is an important criteria for classifying bacteria

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50
Q

Requres O2 to grow?

A

Obligate areobes

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51
Q

Can utilize O2 for respiration if present or can use ferementation processess?

A

Facultative anaerobe

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52
Q

Grows the same with or without O2?

A

Aerotolerant anaerobes

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53
Q

Can’t survive in the presence of O2?

A

Obligate anaerobe

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54
Q

Aerobes that grow in reduced O2 environments (<2-10% o2)

A

Microaerophiles

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55
Q

What enzyme tests are used to ID bacteria?

A

Catalase and oxdase

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56
Q

What is the catalase test? What typical tests positive and negative?

A

Catalase is an enzyme that degrades H2O2 into water and O2 -> producing bubbles when exposed to hydorgen peroxide

USed to distinguish G(+) organisms:
C(+): Staph
C(-): Strep and Entero

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57
Q

What species do not make catalase?

A

Obligawte and aerotolerant anaerobes

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58
Q

How does an oxidase test work? What typical tests positive and negative?

A

Cytochrome c oxidase is a part of nitrate metabolism -> an indicator aerobic respiration

  • Produced by non-enteric G(-)
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59
Q

What dye is used for oxidase test?

A

methyl blue

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60
Q

What is fermentation?

A

BReak down of sugar -> pyruvate -> lactic acid + ATP in the absence of O2

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61
Q

What is the test to id fermentation?

A

MacConkey agar contains pH sensitive dyes that change color in the presence of acid

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62
Q

What species are used for fermentation tests using MacConkey agar?

A

G(-): supported to grow
G(-): inhibited to grow (fecal coliforms - faculitative agar) due to bile salts

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63
Q

What is the result of MacConkey agar?

A

Lactose fermenters turn to red or pink as pH becomes more cidic

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64
Q

What is the difference between selective media?

A

Selective: contains ingredients that inhibits gorwth of specifc organisms
Differential: Provides visualization and diffent bacterial colonies

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65
Q

Describe the genetic distinctions of prokaryotes?

A
  1. SIngle circular DNA
  2. Haploid
  3. No introns for mRNA
  4. 1 gene specifies more than 1 protein
  5. If a gene is mutated then it is not expressed or the protein is nonfunctional
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66
Q

What is the key metabolite for proliferating bacteria?

A

Folate

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67
Q

How is folate synthesized by bacteria?

A

Dihydropteroate synthase (DHPS), Dihydrofolate reductase (DHFR)

Enzymes are targeted by antifolate ABX

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68
Q

Describe bacterial DNA replication?

A
  1. Bidirectional replication forks form a theta structure
  2. DNA is unwound by helicase whil polymerases replicate DNA on leading and lagging strands
  3. DNA ligase seals DNA
  4. Topisomerases regulate supercoils
  5. DNA separates into 2 daughter cell
69
Q

WHat enzyme manages supercoiling?

A

DNA gyrase (topoisomerase II) introduces negative supercoils -> Circular DNA is twisted, then a break occurs where the 2 chains come together and then the broken DNA helix is resealed on the opposite side if the intact strand

70
Q

How does bacterial transcription occur?

A
  1. Transcription is the conversion of DNA to mRNA, tRNA, and rRNA
  2. Carried out by a single bacterial RNA polymerase
71
Q

What occurs during bacterial translation?

A
  1. Production of bacterial ribosomes (30S and 50S)
  2. Initiation, elongation, and termination
  3. The initiation tRNA is different between eukaryotes (Met) and prokaryotes (fMet = N-formyl-methionine)
72
Q

What is horizontal gene transfer and what are the types?

A

Transfer of geneic info from 1 cell to another post-maturation
1. Conjugation
2. Transduction
3. Transformation

73
Q

What is conjugation?

A

Mating using pilus to transfer plasmids and transposons unidirectionally

74
Q

What is transduction?

A

Transfer of DNA by bacteriophage

75
Q

What is transformation?

A

Naked DNA is taken up by another bacteria
* A Bacteria that is able todo so is considered competent

76
Q

What are the typical genetic targets of ABX?

A
  1. Folate synthesis
  2. DNA replication (e.g. DNA gyrase)
  3. DNA transcription
  4. DNA translation
77
Q

What is a plasmid?

A

Extrachromosomal double stranded circular DNA capable of replicated independently of the bacterial chromosome -> can be integrated into bacterial chromosome or remain in cytoplasm

78
Q

What is an F plasmid?

A

Allows for formation of the pilli to transfer DNA (via. conjugation)

79
Q

What is a dissimilation plasmid?

A

Contain genetic info to allow bacteria to become more resistant to antiseptics and disinfectants

80
Q

What are R plasmids?

A

Carry genes that code for resistance to ABX and heavy metals, and genes for pili (F factor) via conjugation

81
Q

What are transposons?

A

Jumping genes: pieces of DNA that can readily move from one site to another (DNA of plasmids, bacteria, and bacteriophages)
* Code for resistance
* Cause mutations

82
Q

What are the domains of transposons?

A
  1. Inverted repeat on each short DNA sequence
  2. Gene for transposase
  3. Repressor gene
  4. Enzyme mediating antibiotic resistance
83
Q

What are the outcomes of antimicrobial resistance?

A
  1. Non-sensitive and non-persister cells will die
  2. Resistant cells will survive and daughter cells will also be resistant (via, HGT)
  3. Persistent cells will survive while dormant but new cells will be sensitive to ABX
    * Persister cells that aren’t actively growing or dividing
84
Q

What are the mechanisms of ABX resistance?

A
  1. Modification of drug targets: DNA gyrase, beta-lactamase, penicillin binding proteins
  2. Reduction of drug uptake: porin permeability
  3. Activation or overexpression of efflux mechanisms: specifc and brad spec efflux pumps
  4. Alterations of metabolic pathways: alt. in methylation in ribosomes
85
Q

What is commensal microbes?

A

Provides mutualistic benefits to host, however, can become opportunisitc

86
Q

What is a primary (true) pathogen?

A

Cn cause dx in healthy hosts and does normally reside in a host

87
Q

What is an opportunistic pathogen?

A

When commensal microbes become pathogenic in a host -> only when microbe moves to another site in the body

88
Q

What is a virulence factor?

A

Traits that enhance pathogenicity and allow bacteria to establish and replicate in host

89
Q

What are the tasks a pathogen is required to do to cause a disease?

A
  1. Portals of entry to get into the host
  2. Penetration or envasion of host defense
  3. Damage the host increasing the spread of infection
  4. Portals of exit to infect another host
90
Q

List portals of entry?

A
  1. Skin/mucous membranes through ingestion, sex, inhalation (via respiratory, GI, GU)
  2. Parenteral through trauma, needles, bites (skin)
91
Q

What are the adhesins that allow bacteria to stay in the body?

A
  1. Lipoteichoic acid
  2. M protein
  3. Fimbriae
  4. Flagella
92
Q

What are MSCRAMMS?

A

Proteins secreted by bacteria that binds to host’s EC matrix

93
Q

What are the host receptors that recognize lectins called?

A

Complements

94
Q

What is ID50?

A

Infectious dose: number of organisms needed to cause infection in half the hosts

95
Q

What is LD50?

A

Number of organisms needed to kill half the hosts

96
Q

How can we express the range of virulence?

A

More: low ID50 and LD50
Less: high ID50 and LD50

97
Q

What is the first line of defense of the innate immune response? How can bacteria bypass this?

A

Phagocytosis; capsules, cell wall, mycolic acid

98
Q

How does the cell wall increase virulence?

A
  1. Increase adherence to host cells
  2. Help pathogen become resistant to heat and acidic environments
  3. Help block phagocytosis
  4. Strep pyogenes use M protein for cell wall
99
Q

What is the function of mycolic acid?

A

Waxy lipid that protects against digestion in phagolysosome by allowing bacteris to expand inside phagocyte

100
Q

Distinguish the toxins produced by bacteria in order to increase virulence?

A

Membrane disrupting enzymes:
1. Leukocidins: kill WBC
2. Hemolysins: damage read and white blood cells
3. Hyaluronidase/collagenase
4. Coagulase

101
Q

Distinguish the different types of hemolysins?

A

ALpha: produce incomplete lysis and have a green pigment surrounding colony
Beta: produce total hemolysis and breakdown Hb creating a clear area around the colony
Gamma: produce no hemolysis

102
Q

What enzymes allow infections to spread by breaking down host’s connective tissue and collagen -> boils or necrotizing fasciitis?

A

Hyaluronidase and collagenase

103
Q

What is the function of coagulase?

A

Causes fibrin clots in the host preventing the spread of the pathogen

Fibrinogen -> fibrin -> clotted plasma

104
Q

What bacteria produces coagulase?

A

Staph aureus

105
Q

What is the purpose for the coagulase test?

A
  1. Diffentiate S. aureus from negative Staph species
  2. Clumping indicates coagulase of human plasma
106
Q

Describe the results and purpose for the urease test?

A

Used to ID species of Proteus, Corynebacterium, E.coli, Salmonella, Shigella, Klebsiella, Enterobacter, and Helicobacter pylori that produce ammonia when basic pH changes from yellow to pink

107
Q

What is urease?

A

Enzyme produced by bacteria in acidic environments to neutral acid producing ammonia and CO2

108
Q

What is in the reagent of a urease test?

A

Urea and phenol red

109
Q

What are the enzyme tests?

A
  1. Coagulase
  2. Urease
110
Q

What is the function of C5apeptidase?

A

Degrades the anaphylatoxin C5a

111
Q

What is O polysaccaride?

A

Found on G- bacteria can bind complement prevent it from inserting in or binding to the cell membrane

112
Q

What is the enzyme that degrades IgA?

A

IgA protease

113
Q

What is the function of antigenic variation?

A

Bacteria alter surface antigens slowing host’s ability to make antibodies against bacteria

114
Q

How can bacteria mimick host molecules?

A

Bacteria coat their surface with molecules found on host cell such as hyaluronic acid

115
Q

What is an invasin?

A

Promotes entry in the host cell’s actin filaments of cytoskeleton

116
Q

What is an cadherins?

A

Provides adhesion to host cell without being exposed to the immune system

117
Q

What is quorum sensing?

A

Proteins in the bacteria that provide info to the cell about its environment

118
Q

What is a biofilm?

A

Protein film that coats the surface of a med device
* bacteria adheres and accumulates
* bacteria secrete polysaccharide that surrounds bacterial aggregate

119
Q

How is biofilm advantageous for bacteria and fungi?

A
  1. Prevents or impede entry of antimicrobial agents
  2. Helps bacteria avoid the host’s immune response
120
Q

What is direct damage?

A
  1. Host cells are damaged when pathogens metabolize and multiply inside the host cell
  2. Localized infection
  3. Disruption of host cell function
  4. Production of toxins
121
Q

What is indirect damage?

A
  1. Immune responses leads to damage
  2. Inflammation
  3. Production of toxins
  4. Toxins move through the blood and lymph away from the original site of infection
  5. Systemic infections
  6. Leads to shock, fever, diarrhea, trauma
122
Q

What is an exotoxin?

A

Toxins secreted by bacteria

123
Q

Describe the subunits of exotoxins?

A

A (active): processes toxic activity usually an enzyme
B (binding): binding to the host membrane that dictates the cell type to be infected

124
Q

What is a neurotoxin?

A

Damage to the nervous system by interfering with neurological signal transmission
Ex: Clostridium botulinum

125
Q

What is enterotoxin?

A

Causes intestinal disturbances by affecting the lining of the GIT -> diarrhea, hypersecretion, cramping
Ex: Shiga, cholera

126
Q

What is a cytotoxin?

A

Kill or damage host cells by altering the host membrane
Ex: Diptheria toxin inhibits protein synthesis

127
Q

What are toxins that can lyse host cell?

A
  1. Leukocidins
  2. Hemolysins
  3. Streptolysins
128
Q

What is a fastidious bacteria?

A

Has complicated nutritional requirements:
1. Require iron but are not hemolytic
2. Must be grown of special chocolate agar that contains lysed RBCs
3. Used to grow Haemophilius influenzae and Neisseria gonorrhoeae and meningitidis

129
Q

What is a siderophores?

A

Secreted by bacteria to capture iron from the host:
* Small, high affinity iron chelating compounds
* Remove iron from iron-binding proteins
* Helps with growth and colonization

130
Q

What are superantigens?

A

Bacterial toxin that can override the specificity of T cell action leading to the overstimulation of T cells and the production of cytokines from the host T cells
* Cytokine storm, TSS, scralet fever

131
Q

What is the toxin portion of LPS?

A

Lipid A

132
Q

What cytokines cause fever?

A

IL1 and TNF

133
Q

How do endotoxins contribute to shock?

A
  1. TNF increases vascular permeability -> fluid leakage and hypotension
  2. NO production -> hypotension
134
Q

How can endotoxins cause DIC?

A

Endotoxin activates the clotting cascade leads to minor clotting occuring throughout the body -> MOD

135
Q
A
136
Q

How can bacteria exit the host?

A

Secretion: nasal, saliva, sputum, resp drolets, vaginal discharge, semen
Excretion: urine, feces
Blood/broken skin

137
Q

What are the types of contact transmission?

A
  1. Direct
  2. Indirect
  3. Droplet
  4. Vehicle
  5. Vector
138
Q

What is direct transmission?

A

No intermediary between an infected person and uninfected person
Ex: bites, touching

139
Q

What is indirect transmission?

A

Organism is passed from infected person to another person through a fomite (non-living agent of transmission)

140
Q

What is droplet transmission?

A

Pathogen is transmitted through respiratory droplets

141
Q

What are the types of reservoirs of pathogens?

A
  1. Human
  2. Zoonotic (animal)
  3. Nonliving
142
Q

What is vehicle transmission?

A

Pathogens transferred from supposedly clean components (can be diret or indirect)

143
Q

What is vector transmission?

A

infectious organism that requires another organism (vector) to transmit disease to a healthy person

144
Q

What are vectors?

A

Arthropods that transfer pathogens mechanical or biological

145
Q

What is the difference between mechanical and bioliogical transfer?

A

Mechanical: pathogens are transferred passively from contaminated vectors to an object
Bioligcal: transmission through a bite

146
Q

What is the difference between vertical and horizontal transmission?

A

Vertical: mother to baby via placenta, birth canal, breast milk
Horizontal: person to person via body fluids and excretion

147
Q

What are factors that affect transmission?

A
  1. Immunocompromised
  2. Vents, cath, cannulas
  3. Age
  4. Lifestyle
  5. Day care
  6. Crowds
  7. Trauma
148
Q

What are the Kochs postulates?

A
  1. Pathogen must be present in every case of the disease, but not in healthy individuals.
  2. Pathogen must be isolated from the sick host and grown in a pure culture.
  3. The pure pathogen must cause the same disease when given to uninfected hosts.
  4. Pathogen must be re-isolated from these newly infected hosts and shown to be the same organism as isolated initially.
149
Q

What are the limitations of Koch postulates?

A
  1. Not always possible to satisfy all postulates
  2. Not all microorganisms can be grown in culture
  3. Animal models are not available for all organisms
150
Q

What are the phases of infection?

A
  1. Incubation
  2. Prodromal
  3. Illness
  4. Decline
  5. Convalescence
151
Q

What occurs during the incubation period?

A

Time between initial infection and onset of symptoms
* Subjective sx

152
Q

What is the prodromal period?

A

phase where nonspecific symptoms occur
* Fever, malaise, n, loss of appetite

153
Q

What occurs in the illness phase?

A

Signs and symptoms specific to disease appear
* Signs are objective and measurable

154
Q

What occurs during the decline phase?

A

signs and symptoms decrease and pathogen number decrease

155
Q

What occurs during convalescence period?

A

Recuperation and recovery from a dx

156
Q

pathologic changes that occur quickly and last for a short period of time

A

Acute infection

157
Q

infection characterized by delayed onset, pathologic changes that can occur over a longer time span (last months, years, even a lifetime)

A

Chronic infection

158
Q

pathogen remains in host after initial signs and symptoms disappear and can be reactivated after long periods of time

A

Latent infection

159
Q

infection that persists through host immune response?

A

Persistant infections

160
Q

symptoms of the infection do not appear even with ongoing infection?

A

Subclinical infetion

161
Q

initial acute onset of symptoms in an infection

A

Primary infection

162
Q

another infection by a different microbe due to suppression of the immune system due to a primary infection

A

Secondary infection

163
Q

microbe remains confined to a specific area

A

Localized infection

164
Q

pathogen spreads to several sites and usually spreads through the circulatory system

A

Systemic infection

165
Q

May harbor and spread the infectious agent in the absence of signs and symptoms?

A

Carriers

166
Q

Bacteria circulating through the blood?

A

Bacteremia

167
Q

Toxins circulating in the blood

A

Toxemia

168
Q

acute, life-threatening illness caused by infectious agents or their products (e.g. toxins) in the blood?

A

Septicemia

Drug Action IV (28 decks)

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