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Microbiology > EXAM 2 > Flashcards

EXAM 2 Flashcards

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Biology 101 flashcards
1
Q

study of bacteria

A

bacteriology

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2
Q

study of fungi

A

mycology

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3
Q

study of parasites

A

parasitology

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4
Q

study of viruses

A

virology

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5
Q

prokaryote characterisitcs

A
  • unicellular
  • lack a membrane-bound nucleus
  • lack membrane-bound organelles
  • simpler genetic makeup
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6
Q

archaea

A
  • cell wall lacks peptidoglycan
  • dont cause human disease
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7
Q

size of bacteria

A

0.2 micrometers to 750 micrometers

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8
Q

micrometer

A

1x10^-6 meter

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9
Q

coccus

A

sphereical shaped

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10
Q

spirochete

A

spiral shaped

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11
Q

bacillus

A

rod shaped

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12
Q

strep

A

grows in a chain

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13
Q

staph

A

grows in grape-like clusters

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14
Q

diplo

A

grows in pairs

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15
Q

phospholipid head

A

polar-hydrophillic

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16
Q

phospholipid tail

A

nonpolar-hydrophobic

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17
Q

peptidoglycan

A

rigid, net-like lattice comprised of sugars (glycans/polysaccharides) and amino acids

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18
Q

how are peptidoglycans linked

A

2 repeating diasaccahrides crosslinked by short tetrapeptides

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19
Q

gram negative stain technique

A

allows classification of bacteria based on cell wall structure

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20
Q

gram negative bacteria

A
  • stain pink
  • THIN peptidoglycan layer in the cell wall
  • contains periplasm between inner and outer membranes
  • outer membrane present
  • LPS present
  • NO teichoic acid
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21
Q

gram positive bacteria

A
  • stain dark purple
  • THICK peptidoglycan layer in cell wall
  • NO outer membrane
  • MINO periplasm
  • NO LPS
  • contain teichoic acids
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22
Q

acid fast bacteria

A

cell walls contain waxy lipid called mycolic acid
- stain weakly as gram positive

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23
Q

flagellum

A

a thread-like appendage made up of multiple subunits of the protein flagellin *used for motility

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24
Q

chemotaxis

A

movement of an organism in response to chemical stimuli

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25
Q

phototaxis

A

movement in response to light stimuli

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26
Q

areotaxis

A

movement in response to presence or absence of oxygen

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27
Q

pilus

A

hair-like appendage, comprised of the protein pilin, that is found on the surface of many bacteria
*stick to surfaces

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28
Q

conjugative pili (sex pili)

A

used during conjugation to transfer DNA from one bacteria to another

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29
Q

conjugative pili steps

A
  1. pilus makes initial contact with recipient bacteria
  2. pilus draws in recipient bacteria
  3. DNA (mobilized plasmid) transferred from donor to recipient
  4. both bacteria now contain DNA in question
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30
Q

type IV pili - twitching motility

A
  • movement along a solid surface
  • crawling action
  • only found at poles of cells
  • important host colonization factor in certain pathogens
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31
Q

fimbriae

A

short structures used for attachment to surfaces

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32
Q

glycocalyx

A

viscous, gummy layer surrounding certain bacterial species
- typically polysaccharides, but can be polypeptides
- composition and thickness vary

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33
Q

slime layer

A

loose coating that does not exclude small particles

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34
Q

capsule

A

tight coating that does exclude small particles

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35
Q

functions of glycocalyx

A
  • protection from environment
  • protection from immune system
  • attachment to surfaces
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36
Q

cytoplasm

A

gelatinous solution comprised of water, protein, carbohydrates, lipids, inorganic ions, and low-molecular weight compounds
*also contains nucleoid, plasmids, ribososmes, and inclusion bodies

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37
Q

what do prokaryotes lack

A
  • cytoskeleton
  • endoplasmic reticulum
  • mitochondria
  • microsomes
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38
Q

nucleoid

A
  • single circular segment of double stranded deoxyribonucleic acid (DNA)
  • encodes genetic information for cell function and structure
  • smaller than most genomes
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39
Q

how many million base pairs is the human genome (haploid)

A

3,234 Mbp

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40
Q

plasmids

A

circular, extrachromosomal DNA found in many (but not all) bacteria
- replicate independently

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41
Q

5 classes of plasmids

A
  • fertility F plasmids
  • resistance R plasmids
  • col plasmids
  • degradative plasmids
  • virulence plasmids
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42
Q

inclusion bodies

A

amorphous particles in cytoplasm used as reverse nutrients stored during periods of nutrient abundance

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43
Q

endospores

A
  • metabolically inactive structures that preserve the cells genetic information, allowing the cell to survive during times of extreme stress
  • highly resistant to environmental stress
  • can germinate back into vegetative cell
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44
Q

sporulation

A

bacteria storing genetic information in a pod during times of environmental stress

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45
Q

what kind of bacteria produce most endospores

A

gram negative bacteria

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46
Q

how do bacteria grow

A

binary fission

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47
Q

what elements are required in large amounts for bacteria to grow

A

N2, H2, CO2, Carbon, PO4, Iron, Sulfur, Potassium, Calcium, Magnesium and energy

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48
Q

what elements are required in trace amounts for bacteria to grow

A

Mn, Zn, Cobalt, Molybdenum, Nickel, Copper, Selenium

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49
Q

prototroph

A

a microorganism that can derive all nutritional requirements for growth from the micronutrients and macronutrients supplied

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50
Q

fastidious

A

microorganisms that have complex and special nutrient requirements
- might require special vitamins or amino acids to grow

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51
Q

obligate aerobe

A

absolute requirement for O2

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52
Q

facultative aerobe/anaerobe

A

grow either aerobically or anaerobically

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53
Q

obligate anaerobe

A

ideal growth in absence of O2

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54
Q

4 phases of bacterial growth

A
  1. lag phase
  2. exponential (logarithmic) phase
  3. stationary phase
  4. death
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55
Q

lag phase

A

initial or beginning of growth

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56
Q

exponential phase

A

great increase in numbers

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57
Q

stationary phase

A

no increase in number of bacteria

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58
Q

heterotrophic bacteria

A
  • essentially all pathogenic bacteria
  • obtain energy from organic compounds
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59
Q

photosynthetic bacteria

A
  • synthesize their own glucose
  • less apt to be pathogenic
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60
Q

autotrophic bacteria

A
  • no sunlight
  • no organic compounds
  • use inorganic compounds
  • less apt to be pathogenic
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61
Q

what are the ways bacteria can generate energy

A
  • aerobic respiration
  • anaerobic respiration
  • fermentation
  • photosynthesis
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62
Q

bacteria producing energy through aerobic respiration

A
  • major energy producing mechanism for aerobes
  • consists of 3 major pathways: glycolysis, krebs cycle, and electron transport chain
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63
Q

how much ATP does 1 molecule of glucose yield

A

38 molecules

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64
Q

what is the primary substrate in the glycolytic pathway

A

glucose

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65
Q

what is the primary end product of the glycolytic pathway

A

pyruvate

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66
Q

what happens in the investment phase of glycolysis

A

2 ATPs are spent

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67
Q

what happens in the payoff phase of glycolysis

A

4 ATPs and 2 NADHs are gained

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68
Q

summary of glycolytic pathway

A
  • 1 glucose –> 2 pyruvates
  • net gain of 2 ATPs
  • NADH generated (converted to ~3 more ATP)
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69
Q

initial step of krebs cycle

A

2 NADH are produced for energy

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70
Q

krebs cycle overview

A
  • net gain of 2 ATPs
  • 6 more NADH produced
  • 2 FADH2 produced
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71
Q

what is electron transport + oxidative phosphorylation

A
  • a series of electron transfers within the cytoplasmic membrane
  • generate ADP and ATP from NADH and FADH2
  • accomplished with cytochromes and enzymes
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72
Q

bacteria producing energy through anaerobic respiration

A
  • utilizes the same three pathways as aerobic respiration
  • but O2 is not the terminal electron acceptor (NO3, SO4, CO3, and Fe3+ are instead)
  • produce energy by reducing substrate
  • LESS ATP is generated **
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73
Q

bacteria producing energy through fermentation

A
  • generates energy primarily using the glycolytic pathway
  • simple organic end-products formed from anaerobic dissimilation or metabolism of glucose
  • LESS ATP generated**
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74
Q

bacteria producing energy through photosynthesis

A
  • converts light to ATP
  • not a feature of pathogenic bacteria
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75
Q

final electron acceptor in aerobic respiration

A

oxygen

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76
Q

what determines phenotype

A

genotype

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77
Q

genome

A

entire collection of genetic material in a cell or virus

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78
Q

gene

A

heritable unit of genetic material that define a particular trait

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79
Q

genotype

A

genetic makeup

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80
Q

phenotype

A

physiological or physical traits

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81
Q

chromosomes

A
  • genome organized into packaged strands of DNA
  • number does not influence organism complexity
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82
Q

prokaryotic chromosomes

A
  • 1-3 chromosomes
  • circular
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83
Q

eukaryotic chromosomes

A
  • numerous linear chromosomes
  • histones to package
  • mitochondria and chloroplasts
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84
Q

plasmids

A

circular and extracheomosomal

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85
Q

nucleic acids

A
  • built from nucleotides
  • phosphate
  • sugar (deoxy or ribose)
  • nitrogen base (purine or pyrmidine)
  • in RNA: ribonucleotides
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86
Q

structure of DNA

A

antiparallel

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87
Q

central dogma

A

DNA–>RNA–>proteins

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88
Q

DNA replication

A
  • process by which a cell copies its genome before division
  • Bidirectional
  • typically very fast and accurate
  • few mutations
  • proofreading mechanisms
  • enzymes
  • unwind DNA, copy DNA, rewind parent and new DNA
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89
Q

leading strand

A
  • continuous replication by DNA polymerase III (5’ to 3’)
  • DNA polymerase I replaces RNA primer with DNA
  • ligase
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90
Q

lagging strand

A
  • discontinuous replication by DNA polymerase III
  • okazaki fragments
  • DNA polymerase I and ligase remove and replace primers
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91
Q

eukaryotic DNA replication

A
  • takes longer, involves more protein factors
  • multiple replication initiation sites
  • slower: amount of DNA and packaging
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92
Q

how are genes expressed

A

proteins

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93
Q

transcription

A

DNA–> RNA

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94
Q

translation

A

RNA–> proteins

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95
Q

steps of transcription

A
  • initiation
  • elongation
  • termination
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96
Q

RNA polymerase

A
  • binds to promoter
  • complementary ribonucleotides (U-A)
  • continues until it has its terminator sequence
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97
Q

where does protein synthesis take plase

A
  • prokaryotes: cytoplasm
  • eukaryotes: nucleus
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98
Q

transcription initiation

A

RNA polymerase binds to the promoter and DNA unwinds, revealing the template strand

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99
Q

transcription elongation

A

RNA polymerase travels down the DNA. The RNA strand is built from 5’–>3’ as complementary ribonucleotides are paired with the template strand

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100
Q

transcription termination

A

a terminator sequence at the end of the translated gene signals the RNA polymerase to fall off ther DNA and release the new RNA

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101
Q

mRNA

A

carries genetic messages in triplet codes and is translated to build a protein

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102
Q

tRNA

A

cloverleaf structure shaped molecule serves as an adaptor molecule to usher amino acids into the ribosome during translation

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103
Q

rRNA

A

takes on complex stem and loop structures and combines with proteins to build structures

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104
Q

splicing mRNA

A
  1. mRNA contains non-protein coding regions (introns)
  2. introns are removed by splicosome creating a coherent protein-encoding mRNA strand
  3. processed mRNA with joined exons is ready to be exported to the cytoplasm to be translated
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105
Q

translation steps

A
  • initiation
  • elongation
  • termination
106
Q

location of translation

A

cytoplasm in both prokaryotes and eukaryotes

107
Q

what carries out translation

A

ribosomes
- rRNA and proteins
- APE sites
- large and small subunits

108
Q

translation initiation

A
  • ribosome attaches to mRNA and scans until it reaches a start codon (AUG)
  • initiator tRNA carrying amino acid methionine then enters the ribosomes P site
  • the start codon on the mRNA base pairs with the anticodon on the initiator tRNA
109
Q

genetic code redundancy

A
  • protects versus mutations
  • wobble 3rd position
110
Q

translation elongation

A
  • ribosome constructs the protein
  • incoming tRNA;s codon pairs with codon in ribosomes A site
  • peptide bond forms between amino acids, transferring the growing protein chain to tRNA in A site
  • ribosomes translocates down mRNA; tRNA in the A site shifts to the P site
  • the tRNA in the P site shifts to the E site, exiting the ribosome
111
Q

translation termination

A
  • ribosome encounters stop codon
  • termination factor enters the ribosome
  • ribosome releases the protein and detaches from the mRNA
112
Q

translation in eukaryotic cells

A

most mRNA encodes a single protein

113
Q

translation in prokaryotic cells

A
  • mRNA is commonly polycistronic
  • polysome formation
114
Q

post translational modification

A
  • addition of organic and/or inorganic factors
  • trimming of AA sequence
  • often required for proper protein function
  • way to regulate how often mRNA is made into protein
115
Q

regulating protein synthesis

A

~20% of a cells genes are expressed at any given time
- need mechanisms to turn certain proteins on or off according to cells needs

116
Q

constitutive genes

A

housekeeping genes; always on

117
Q

facultative genes

A

not always on

118
Q

pre transcriptional regulation

A

controlled by operons

119
Q

operons

A

collection of genes controlled by shared regulatory elements
- promoter
- genes
- repressor
- operator

120
Q

inducible operon

A

OFF by default; can be turned on

121
Q

repressible operon

A

ON by default; can be turned off

122
Q

lac operon when glucose is present but lactose is NOT

A
  • no transcription
  • repressor is bound
123
Q

lac operon when glucose is NOT present but lactose IS present

A
  • high transcription
  • allolactose inactivates repressor; not allowing it to bind
124
Q

arg operon when arginine is low

A
  • insufficient amount of arginine cannot activate the repressor
  • repressor cannot bind to operator because it is not associated with arginine
  • transcription occurs
125
Q

arg operon when arginine is high

A
  • abundant arginine activates repressor
  • activated repressor binds to operator
  • transcription is blocked
126
Q

lac operon

A

inducible operon

127
Q

arg operon

A

repressible operon

128
Q

mutation

A

a change in genetic material of a cell or virus

129
Q

substitution mutation

A

an incorrect nucleotide is added

130
Q

insertion mutation

A

addition of one or more nucleotides

131
Q

deletion mutation

A

removal of one or more nucleotides

132
Q

silent mutation

A

no change in the amino acid sequence
**degeneracy

133
Q

missense mutation

A

single change in amino acid sequence

134
Q

nonsense mutation

A

single change in the amino acid sequence that results in a stop codon

135
Q

reversion mutation

A

restores to the wild type gene sequence

136
Q

frameshift mutation

A

mutations that result in a shift of the reading fame, changing the way the mRNA transcript is read

137
Q

spontaneous mutation

A

naturally occurring due to errors in DNA replication; creates evolutionary diversity

138
Q

mutagens

A

agents that increase rate of mutations

139
Q

carsiongens

A

mutagens that promotes development of cancers

140
Q

chemical mutagens

A
  • organic or inorganic agents
  • arsenic, asbestos, compounds in tobacco
141
Q

physical mutagens

A

UV light, X rays, radioactive gamma rays

142
Q

biological mutagens

A
  • RECOMBINATION
  • viruses, transposons
143
Q

excision repair

A
  • damaged DNA clipped and removed
  • DNA polymerase I lays down new nucleotides
  • ligase seals
144
Q

vertical gene transfer

A

cells passing genetic information from parent cell to offspring

145
Q

horizontal gene transfer

A

passing genetic information between cells independent of cell division

146
Q

examples of horizontal gene transfer

A
  • conjugation
  • transformation
  • transduction
  • transposons
147
Q

conjugation

A
  • bacteria use a cytoplasmic bridge called a pili to copy and transfer a special plasmid known as the F plasmid (fertility factor)
148
Q

high frequency recombination

A

a bacteria with the F factor integrated into its chromosomal DNA

149
Q

transformation

A

bacteria take up extracellular DNA

150
Q

Griffiths experiment

A

conversion of a non-pathogenic pneumococcal bacteria to a virulent strain

151
Q

transduction

A

viruses transfer bacterial DNA between different bacterial hosts

152
Q

generalized transduction

A
  1. bacteriophage infects a bacterial cell
  2. phage replicates in the host. Most phages contain only phage DNA, but occasionally a phage will package a piece of the hosts DNA
  3. the transducing phage injects DNA from prior host
153
Q

specialized transduction

A
  1. bacteriophage injects a bacterial cell
  2. the bacteriophage’s DNA recombines into the host chromosome
  3. at some point the bacteriophage DNA excises from the host chromosomes and may take neighboring host genes with it
  4. all of the manufactured phage particles will contain phage DNA and the host genes that were excised with the phage DNA
  5. the bacteriophage injects its DNA into a new host
  6. the bacteriophage integrates into the chromosomal DNA of the new host, which endows the new host with genes from the phages prior host as well as phage DNA
154
Q

antimicrobials

A
  • drugs against microbes
  • therapeutic compounds that kill microbes or inhibit their growth to prevent pathogenic action
  • categorized based on the type of pathogen they target
155
Q

alexander fleming

A
  • unable to grow staphylococcus aureus near mold at the zone of inhibition
  • called the moled penicillin: first antibiotic
156
Q

basic criteria for drugs used as chemo-therapeutic agents in the treatment of infectious disease

A
  1. effective against microbes
  2. sufficiently nontoxic to the host
  3. able to be purified in high amounts
157
Q

broad spectrum antimicrobial agent

A

drug is effective agains a broad range of microbes

158
Q

narrow spectrum antimicrobial agent

A

antimicrobial targets a limited range of microbes
- effective aginst one group or subgroup
- present less disruption to normal microbiota

159
Q

limited spectrum antimicrobial agent

A

drug is effective against a single organism/disease

160
Q

empiric therapy

A

a medical treatment with a broad spectrum drug initiation while waiting for culture/ID results

161
Q

criteria of antimicrobial drugs

A
  1. nontoxic to the host and without undesirable side effects
  2. nonallergenic to the host
  3. not eliminates normal microbiota
  4. able to reach the infected part of the body
  5. inexpensive and easy to produce
  6. chemically stable
  7. resistance is unlikely to develop
162
Q

naturally occurring antimicrobials

A

substances produced by microorganisms that inhibit other living microorganisms

163
Q

synthetic antimicrobials

A

manufactured by chemical processes

164
Q

semisynthetic antimicrobials

A

chemical modification of naturally occurring antibiotics

165
Q

modifying antimicrobial drugs

A
  • antimicrobial compounds can be modified by chemical means
  • drugs in later generations have expanded capabilities over their predecessors
166
Q

next generation drugs

A

result from each successive round of chemical modification

167
Q

selective toxicity

A

goal is to inhibit or kill the pathogen with little or no toxic effect on the patient

168
Q

how is selective toxicity achieved

A

exploiting vulnerable targets

169
Q

hepatotoxic

A

toxic to liver

170
Q

nephrotoxic

A

toxic to kidneys

171
Q

oral administration

A
  • preferred antimicrobial route
  • convenient and cost effective
172
Q

parenteral administration

A
  • any route not involving the GI tract
  • usually an injection or infusion
  • faster onset of drug
173
Q

half life of drug

A

time it takes for half of a dose to be eliminated or deactivated by the body; determines frequency of adminstration

174
Q

bacteriostatic drugs

A
  • prevent/inhibit bacteria from growing
  • target bacterial protein synthesis and metabolic pathways
  • patients own immune system eventually kills off latent bacteria
175
Q

batericidal

A
  • kills bacteria
  • targets bacterial cell walls, cell membranes, or nucleic acids
  • does NOT rely on patients immune system to eliminate bacteria
  • kill normal microbiota
176
Q

antiviral drugs

A
  • do not destroy their target pathogen but inhibit viral development
  • viruses use the host cell to replicate to antiviral drugs are difficult to make
  • aim to target and disable essential virus-specific proteins
  • effective when viruses are actively replicating
177
Q

1st category of antiviral drug targets

A

target viral replication cycle

178
Q

2nd category of antiviral drug targets

A

stimulate the hosts anti-viral immune responses

179
Q

what is the most effective way to reduce significant viral infection

A

vaccination

180
Q

anti-fungal drug targets

A
  • target fungal-specific compounds not in host cells
  • interfere with cell wall synthesis –> lysis
  • interfere with cell membrane stability and structure causing death
  • interfere with nucleic acid synthesis
181
Q

anti-parasitic drug

A
  • target intracellular components
  • difficult to develop
  • limited by their toxicity
182
Q

assessing susceptibility to antibiotics (AST)

A

determine the organism causing the specific infection and which antimicrobials will inhibit the growth of the infecting microbe; will identify and report drug resistance in pathogens

183
Q

aga diffusion tests

A
  • determine a basic antimicrobial susceptibility profile
  • relatively inexpensive and can be used to determine pathogen susceptibility
184
Q

kirby-bauer disk diffusion test

A
  • agar diffusion test
  • determines susceptibility only
185
Q

epsilometer test (E-test)

A
  • agar diffusion test
  • determines susceptibility and minimum inhibitory concentration assays
186
Q

minimum inhibitory concentration (MIC) assays

A

determine the lowest concentration of an antimicrobial agent that inhibits growth

187
Q

minimum bactericidal concentration (MBC) assays

A

determine the lowest concentration of an antimicrobial agent required to kill the organism

188
Q

antimicrobial resistance (AMR)

A

occurs when a microbe is not affected by a drug therapy that is intended to inhibit or eliminate the pathogen

189
Q

intrinsic antimicrobial resistance

A
  • natural resistance to microbial drugs based on inherent microbial structure/function
  • makes certain pathogens/infections harder to treat/eliminate
190
Q

acquired resistance

A
  • acquired by genetic mutation or acquisition of resistance genes
  • resistance occurs when drug concentration levels within the cell are kept below the MIC
191
Q

types of acquired resistance

A
  1. alter drug’s target
  2. inactivate drug
  3. reduce drug concentrations inside the cell
192
Q

superbugs

A

strains of bacteria, viruses, parasites and fungi that are resistant to the antimicrobials commonly used to treat the infections they cause

193
Q

superinfections

A

result when superbugs emerge from the initial infection resistant to the treatment and become the primary cause of a second infection

194
Q

emergence of drug resistance

A
  • antibiotic resistance is fueled by natural selection
  • noncomplicance with prescribed dosing parameters
  • antimicrobial misuse
195
Q

antimicrobial stewardship

A

coordinated program that promotes the appropriate use of antimicrobials to promote patient outcomes, reduce and combat microbial resistance and decrease the spread of infections caused by multidrug resistant organisms

196
Q

staphylococcus characteristics

A
  • gram positive
  • cocci
  • form irregular clusters
  • non-spore formers
  • non-motile
  • typically lack a capsule
197
Q

where is staphylococcus found?

A
  • everywhere in nature
  • part of normal human microbiota
  • typically an opportunistic pathogen
198
Q

how are staphylococcus infections transmitted

A
  • direct transmission (skin, hands, sputum, pus)
  • enter through respiratory route, hair follicles, or breaks in the skin
199
Q

how are staphylococcus different from other gram positive cocci

A
  • they are facultative anaerobes
  • grow in the presence of bile salts
  • produce catalyase; breaks H2O2 into H2O and O2
200
Q

how to tell difference between different staphylococcus species

A
  • coagulase test: production of coagulase
  • genomic/DNA based ID
  • culture media: mannitol salt agar, blood agar
201
Q

coagulase test with S.aureus

A

coagulase +

202
Q

coagulase negative staphylococcous

A

S.epidermidis and S. saprophyticus

203
Q

how to tell the difference between the coagulase negative staphylococcous

A

susceptibility to antibiotic novobiocin

204
Q

S. aureus

A
  • major pathogen of staphylococcus genus
  • coagulase positive
  • most common causes of bacteremia and infective endocarditis
  • spreads through direct contact
  • significant cause of chronic BIOFILM infections
205
Q

cell wall associated virulence factors

A
  • peptidoglycan
  • teichoic acid
  • capsule (microcapsule)
  • clumping factor
  • protein A
206
Q

protein A

A
  • binds to host antibodies (IgG) at the Fc region
  • blocks opsonization
207
Q

extracellular enzymes virulence factors

A
  • coagulase
  • staphylokinase
  • hyaluronidase
  • lipase
  • thermonuclease
  • catalase
  • proteases
  • beta-lactamase
208
Q

coagulase

A
  • plasma clotting protein
  • converts fibrinogen to fibrin
  • detected by tube free coagulase test
209
Q

staphylokinase

A
  • activates plasminogen to form plasmin (digests fibrin)
  • cleaves IgG and particular complement proteins
210
Q

hyluronidase

A
  • spreading factor
  • digests hyaluronic acid
211
Q

beta-lactamase

A

resistance to beta-lactam class of antibiotics

212
Q

toxin virulence factors

A
  • hemolysin
  • leukocidin
  • enterotoxin
  • toxic shock syndrome toxin
  • exfoliative toxin
213
Q

hemolysin

A
  • lyse host red blood cells
  • alpha hemolysin: causes beta hemolysis on blood agar plates
214
Q

leukocidin

A

lyse white blood cells

215
Q

super antigens

A
  • binds to TCR outside of normal region
  • nonspecific activation of T cells
  • activates 20-30% of T cells
  • excessive activation of T cells
  • massive cytokine release–> inflammatory response in entire body
216
Q

toxic shock syndrome

A
  • toxigenic infection
  • inflammation in entire body; full body cytokine response
  • in menstruating or postpartum women
  • treatment: replacement of fluids, ICU, antibiotics
217
Q

enterotoxin

A
  • superantigen
  • food poisioning
  • ingestion of preformed toxin
  • heat stable
  • increased intestinal peristalsis
218
Q

toxic shock syndrom toxin-1

A

stimulates production of interleukin by macrophages

219
Q

exfoliative (epidermolytic) toxin

A
  • protease that causes peeling of superficial skin layers
  • dissolves intracellular bridges
220
Q

infections caused by S.aureus

A
  1. superficial infections
  2. toxigenic infections
  3. systemic infections
221
Q

superficial infections

A
  • cutaneous infections-pyodermic
  • pus formation
  • sebaceous glands, hair follicles, wounds
  • self resolve or topical antibiotics to treat
222
Q

staphyloccoal scalded skin syndrom (SSSS)

A
  • toxigenic infection
  • neonatal disease
  • exposure to exfoliative toxin A and B (separates epidermal layer from dermis)
  • starts as an erythema around mouth and neck
  • treatments: antibiotics, rehydration of skin
223
Q

gastrointestinal disease

A
  • toxigenic infection
  • food poisoning - gastroenteritis
  • **enterotoxin: disrupts gastrointestinal lining
  • route of infection: food handlers, lesions on skin, unrefrigerated foods
224
Q

systemic infections

A
  • septicemia (sepsis)
  • pyaemia (pyemia)
  • osteomyelitis
  • pneumonia
  • endocarditis
  • meningitis
225
Q

septicemia (sepsis)

A
  • bacteremia: bacteria in the blood
  • infection of multiple sites within the body
  • bacteria spread from initial site of infection
226
Q

pyaemia

A
  • type of sepsis caused by staphylococcus
  • widespread, distinctive abscesses
227
Q

nosocomial infections

A
  • infections acquired from a hospital
  • S.aureus is leading cause of HAI
  • there is an increase in antibiotic resistance resistant strains of S. aureus
228
Q

MRSA (methicillin-resistance staphylococcus aureus)

A

acquisition of resistance genes via horizontal gene transfer

229
Q

methicillin

A
  • narrow spectrum beta-lactam antibiotic
  • binds to penicillin-binding proteins causes cell death
230
Q

streptococci

A
  • gram positive cocci
  • grow in pairs or chains
  • catalase negative (no bubbles)
  • fastidious: require complex media for growth
  • faculative aerobes
  • large heterogenous group of bacteria
231
Q

most common strptococcal pathogens

A
  • streptococcus pneumoniae
  • streptococcus pyogenes
  • streptococcus agalactiae
232
Q

lancefield group

A

a serologic system based on the reaction of specific antisera with surface carbohydrate antigens

233
Q

hemolytic pattern

A

RBC lysis on blood agar plates

234
Q

phenotypic trains

A

biochemical reactions and antibiotic senstivities

235
Q

molecular studies

A

designating species and sub-species genetically

236
Q

alpha hemolytic

A

colonies surrounded by green

237
Q

beta hemolytic

A

clear transparent

238
Q

gamma hemolytic

A

no notable sones around the colonies

239
Q

S. pneumoniae

A
  • alpha hemolytic
  • encapsulated, found in pairs
  • commonly colonizes the human nasopharynx
  • significant global cause of illness and death
240
Q

pneumococcal transmission

A

transmitted from person to person via infected respiratory secretions/droplets

241
Q

pneumococcal colonization

A
  • inhabit the healthy human nasopharynx
  • strains are typically carried asymptomatically for weeks to months
  • nasopharyngeal colonization does not usually result in disease
  • NP colonization is a necessary step for the development of pneumococcal disease
242
Q

pneumolysin

A

a secreted cytotoxin that lyses cells and damages tissues
**pneumococcal virulence factor

243
Q

polysaccharide (pneumococcal) capsule

A

a protective, antigenic, carbohydrate layer anchored to the external surface of the cell
**pneumococcal virulence factor
- most important determinant of virulence
- protects agains phagocytosis, antibiotics, and environmental stressors
- basis of pneumococcal vaccines

244
Q

invasive pneumococcal disease (IDP)

A

infection of a normally sterile body fluid or organ

245
Q

otitis media

A
  • non-invasive pneumococcal disease
  • middle ear disease
246
Q

sinusitis

A
  • non-invasive pneumococcal disease
  • inflammation of the facial sinus cavity
247
Q

pneumonia

A
  • non-invasive pneumococcal disease
  • serious lung infection that inflames the alveoli
248
Q

bacteremia

A
  • invasive pneumococcal disease
  • bacteria in the blood stream
249
Q

meningitis

A
  • invasive pneumococcal disease
  • inflammation of the meninges, the membranes that cover the brain and the spinal cord
250
Q

S. pyogenes

A
  • group A strep GAS
  • beta hemolytic
  • bacitracin sensitive
  • colonization is infrequent
  • pathogenic
  • infections begin in throat or skin
251
Q

s. pyogenes transmission and pathogenesis

A
  • person to person contact
  • mild to life threatening
  • large # of virulence factors
252
Q

M protein s. pyogenes virulence factor

A
  • major protein coating the cell surface
  • contributes to phagocytosis evasion
253
Q

hyaluronic acid capsule s. pyogenes virulence factor

A
  • protects against phagocytosis
  • not produced by all strains
  • weak immunogen
254
Q

streptolysins s. pyrogenes virulence factor

A

damage cell membranes, cause beta hemolysis phenotype

255
Q

streptococcal pyrogenic exotoxins s. pyrogenes virulence factor

A

linked to rash, TSS, and severe invasive infections

256
Q

s. pyrogenes GAS pharyngitis

A
  • sterp throat
  • scarlet fever
257
Q

s. pyrogenes GAS skin and soft tissue infections

A
  • superficial skin and progressively deeper tissue infections occur following breach in protective skin layer
  • impetigo
    -erysipelas and cellulitis
  • necrotizing faciitis
258
Q

s. pyrogenes GAS infection complication: non-supportive sequelae

A
  • rheumatic fever
  • glomerulonephritis
  • PANDAS
259
Q

S. agalactiae

A
  • group B strep: GBS
  • beta hemolytic
  • part of normal human GI and GU tract microbiota
  • major cause of potentially fatal sepsis, pneumonia, and meningitis in newborns
260
Q

S. agalactiae virulence factors

A

capsule and beta hemolysin

261
Q

S. agalactiae GBS treatment

A

prompt diagnosis and intiation of antimircobial therapy

Microbiology (10 decks)

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