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POM Exam 1 > L5: Principles of Microbiology > Flashcards

L5: Principles of Microbiology Flashcards

1
Q

acellular microbes

A
  • need host cells to propagate
    • viruses
    • prions
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2
Q

viruses

A
  • nucleic acid packaged in protein coat
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3
Q

prions

A
  • pure protein
  • pathogenesis arises from accumulation in CNS of abnormal isoforms
  • Mad Cow
  • CJD
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4
Q

Cellular organisms

A
  • prokaryotes

- eukaryotes

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5
Q

prokaryotes

A
  • include archaea & bacteria
  • do not have a nucleus
  • very little intracellular organization
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6
Q

eukaryotes

A
  • include Eukarya
  • contain a nucleus
  • visible subcellular organelles (mitochondria, chloroplasts)
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7
Q

archaea

A
  • more primitive

- currently no known human pathogens among the archaea

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8
Q

membrane of bacteria

A
  • peptidoglycan in the cell call
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9
Q

why don’t we have uncontrolled growth of microbes?

A
  • circumstances are not ideal
  • nutrients are limited
  • host defenses protect us
  • even microbes get infections
  • carrying capacity!
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10
Q

bacteria central dogma

A
  • single circular bacterial chromosome
  • DdRp translates genes into RNA
  • ribosomes translate to protein
  • structural proteins and enzymes do most of the work
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11
Q

plasmids

A
  • extrachromosomal genetic elements
  • usually circular
  • autonomously replicating
  • may encode virulence factors or antibiotic resistance genes
  • source of mobile genetic information that can be transferred from one cell to another
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12
Q

vertical gene transmission

A
  • from parent to progeny

- through cell division

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13
Q

horizontal gene transfer

A
  • lateral
  • foreign donor gives DNA to recipient
  • three mechanisms
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14
Q

transduction

A
  • done by phage
  • phage lands on bacteria and shoots DNA into cell
  • phage DNA integrates into bacterial DNA
  • new phages form with some bacterial DNA packaged
  • donor cell lysis
  • phage lands on new donor cell and inserts the newly hybridized DNA
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15
Q

transformation

A
  • uptake of naked DNA by the cell

- different mechanism for gram negatives versus gram positives

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16
Q

conjugation

A
  • structure forms between two bacterial cells
  • DNA is transferred
  • slightly different in gram positives versus gram negatives
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17
Q

what can mobile genetic elements encode?

A
  • antibiotics resistance
  • toxins
  • other virulence factors
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18
Q

microbe reproduction

A
  • microbes reproduce rapidly

- mutations continually arise from replication errors

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19
Q

health consequences

A
  • drug resistance

- emergency infectious diseases

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20
Q

what are viruses made out of?

A
  • protein
  • nucleic acids (DNA or RNA)
  • lipids
  • sugars
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21
Q

is a virus that infects the fecal-oral route more likely to be enveloped or not?

A
  • not

- envelope contains important information that would be degraded by stomach acid

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22
Q

generic virus life cycle

A
  • attachment to cell - based on viral receptor on the host surface
  • entry into the cell
  • uncoating - once it gets into the cell, it falls apart
  • host cell machinery takes over and synthesizes new protein and nucleic acids of the virus
  • all the proteins and nucleic acids come together in assembly and the virus exits the cell
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23
Q

functions of the viral genome

A
  • genome replication
  • genome assembly and packaging
  • regulation of replication cycle
  • modulation of host defenses
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24
Q

what is not in the viral genome

A
  • genes that code for protein synthesis machinery, energy metabolism, or membrane biosynthesis
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25
Q

viral genome replication

A
  • in many cases the virus uses the host cell polymerases
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26
Q

modulation of host cell defenses

A
  • some viruses make proteins that tell the host cell to turn down the host cell response
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27
Q

what do human cells lack the ability to do?

A
  • replicate RNA or make DNA from RNA
  • no RdR/Dp
  • viruses that need these enzymes must encode them in their own genome
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28
Q

positive sense RNA

A
  • mRNA
  • can be directly translated into protein
  • also must be replicated to make new virus
  • requires viral RdRp
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29
Q

negative sense RNA

A
  • must first be copied to positive sense
  • negative polarity not recognized by the ribosome
  • intact virus must include viral RdRp
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30
Q

coating and packaging of viruses

A
  • happens inside the host cell and not in the viral particle
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31
Q

viruses classification

A
  • obligate intracellular parasites
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32
Q

viral outside structure

A
  • may be enveloped or naked
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33
Q

viral genomes

A
  • can be DNA or RNA
34
Q

different steps in the viral life cycle may provide

A
  • targets for antiviral therapy
35
Q

encounter

A
  • infectious agent meets host
36
Q

entry

A
  • agent enters host
37
Q

spread

A
  • agent spreads from site of entry
38
Q

multiplication

A
  • agent multiplies within host
39
Q

damage

A
  • agent, host response, or both cause tissue damage
40
Q

outcome

A
  • agent or host wins or they learn to coexist
41
Q

what is the most common type of infection?

A
  • asymptomatic
42
Q

spectrum of relationship between microbes and hosts?

A
  • Essential and mutually beneficial
  • Colonization
  • Infection (active or latent)
  • Disease
43
Q

active infection

A
  • active and growing inside the patient

- asymptomatic versus symptomatic

44
Q

latent infection

A
  • asymptomatic with pathogen present, but little or no replication
  • pathogen can re-activate if immune responses wane
45
Q

variety of host susceptibility

A
  • Host genetics
  • Immune status
  • Microbiota
  • Co-infections
46
Q

transmission of microbial agents

A
  • person to person (communicable)
    • horizontal or vertical
  • animal to person (zoonoses)
  • insect to person (vector borne)
  • environmental (nosocomial, fomite)
47
Q

Routes of transmission

A
  • entry via epithelial surfaces (inhalation/ingestion/sexual contact)
  • deeper tissue penetration (insect bites, cuts/wounds, organ transplants and blood transfusions)
48
Q

entry via epithelial surfaces

A
  • inhalation
  • ingestion
  • sexual contact
49
Q

deeper tissue penetration

A
  • spread from epithelia
  • insect bites
  • cuts and wounds
  • organ transplants and blood transfusions
50
Q

spread of infections

A
  • Efficiency of transmission
  • Duration of infectiousness
  • Number of people exposed
51
Q

how might we change the duration of infectiousness

A
  • antimicrobial therapy
  • immunomodulatory therapy
  • some vaccines don’t prevent infection, but reduce duration or severity
  • screening for important symptomatic infection
    • important for immunocompromised
52
Q

how might we change the number of exposed, susceptible individuals?

A
  • vaccination
  • chemoprophy
  • environmental/structural control
  • public health policies
53
Q

environmental/structural controls?

A
  • quarantine

- PPE

54
Q

public health policies

A
  • contact tracing
  • partner treatment
  • DOT
55
Q

population level factors that influence infectious diseases

A
  • time

- place

56
Q

time

A
  • time of year

- incubation period

57
Q

place

A
  • geographic distribution of some infectious agents (vectors and/or pathogens)
  • occupation related exposures
  • travel
58
Q

prevention strategies

A
  • education and public health awareness
  • hygiene
  • limit exposure
  • improve host defenses (vaccines)
59
Q

education and public health awareness

A
  • scientific literacy

- reporting and surveillance

60
Q

hygiene

A
  • handwashing

- sanitation

61
Q

limit exposure

A
  • insecticide-treated bed nests

- PPE

62
Q

improve host defenses

A
  • vaccines
63
Q

obligate versus facultative

A
  • obligate always does

- facultative may or may not

64
Q

asymptomatic infection

A
  • also called subclinical infection
  • without subjective symptoms
    • patient decides symptoms
  • often used to also include without objective signs
65
Q

prodromal infection

A
  • early signs and symptoms that appear before full-blown disease
66
Q

symptomatic infection

A
  • accompanied by signs and/or symptoms of disease
67
Q

are asymptomatic diseases medically irrelevant?

A
  • no!
  • asymptomatic infections are frequently transmissible
  • the next host may not experience asymptomatic infection
68
Q

What are 4 major pathogen categories?

A
  1. Bacteria
  2. Viruses
  3. Fungi
  4. Parasites
69
Q

Name 3 modes of transmission of infectious diseases.

A
  1. Person to person (communicable); horizontal or vertical
  2. Anima to person (zoonoses)
  3. Insect to person (vector borne diseases)
  4. Environmental (nosocomial, fomite)
70
Q

Why is understanding infection important?

A

Infection can affect every body system.

71
Q

What is AMR?

A

Antimicrobial resistance,

72
Q

What do drugs target in bacteria?

A

Prokaryotic ribosomes and cell wall.

Bacteria have unique ribosomes (e.g. 70s) and a peptidoglycan cell wall.

73
Q

What are the 3 phylogenetic domains?

A

Bacteria, Archaea and Eukarya

74
Q

Examples of Eukarya

A

Fungi, protozoa and helminths

75
Q

Obligate human parasites

A

Found only in humans (no animal or environmental reservoirs)

76
Q

Obligate aerobe

A

must use oxygen for growth

77
Q

Obligate anaerobe

A

must avoid oxygen for growth

78
Q

Obligate intracellular pathogen

A

only replicates inside eukaryotic cells (may be human or animal)

79
Q

Name 3 microbiological stains

A
  1. Gram’s stain
  2. Acid-fast stains
  3. Silver stain (GMS)
80
Q

Gram’s stain

A

Results determined by bacterial cell wall structure (bacteria either gram-positive or gram-negative)

81
Q

Acid-fast stains

A
  • Include Ziehl-Neelsen & Auramine-Rhodamine

- Used for Mycobacterium species

82
Q

Silver stain

A

Used for many fungi, protozoa and some bacteria

POM Exam 1 (16 decks)

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