Classification and epidemiology Flashcards

1
Q

Bacteria

A
  • Prokaryotes (no nucleus or membrane bound organelle)
  • Control centre = single circular bacterial chromosome of DNA
    • Some bacteria also contain plasmids - small extracellular DNA that contain genese for various functions (i.e. antibiotic resistance).
  • Classified via Gram stain, morphology, and oxygen requriements
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2
Q

Streptococcus

A

Gram positive cocci, grows in chains

  • Alpha hemolytic
    • S. pneumonia
    • S. viridans
  • Beta hemolytic
    • Group A strep
    • Group B Step
  • Gamma hemolytic
    • S. gallolyticus
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3
Q

Staphlyococcus

A

Gram positive cocci, grows in clusters/groups

  • Coagulase positive
    • S. aureus
      • Methicillin Susceptible (MSSA)
      • Methicillin Resistant (MRSA)
  • Coagulase negative
    • S. epidermidis
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4
Q

C. difficile

A
  • Anaerobic, spore forming, gram positive bacilli
  • Normal colonizer of the human intestine via fecal oral route
  • However, toxin producing strains can cause severe diarrhea - binds to receptors on intestinal epithelial walls leading to inflammation and diarrhea
  • Biggest risk factor for infection is antibiotic use
    • Alteration of bowel flora
    • Development of antibiotic resistant strains
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5
Q

Common Gram negative bacilli

A
  • Salmonella
  • Shigella
  • Enterotoxigenic E. coli
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6
Q

Viruses

A
  • Small obligate intracellular parasites
  • Can multiple only on living cells
  • Viruses infect all types of life forms (including bacteria)
  • Made up of genetic material (DNA or RNA), a protein coat, and in some cases an outer envelope
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7
Q

Antigenic Shift vs. Antigenic Drift

A

Mutations in viruses

  • Shift - reassortment with an virus to make a completely different strain (can lead to emergence of pandemic strain)
  • Drift - point mutation
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8
Q

Fungi

A
  • Eukaryotic organisms characterized by cell walls containing chitn
  • Medically important fungi are chracterized as yeasts, molds, or dimorphics
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9
Q

Incidence

A

I = # of new events in a specifed period/

of persons exposed to risk during this period

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10
Q

Prevalence

A

P = # of events during a particular time /

Population at risk

(all events - new and old)

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11
Q

Attack Rate

A

AR =# of new cases of disease after a specific exposure /

of people in the population exposed

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12
Q

Relative Risk

A

RR = Risk of disease among exposed/

Risk of disease among unexposed

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13
Q

Case fatality Rate

A

CFR = # of deaths from disease in a given period /

of diagnose cases of that disease in the same period

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14
Q

Surveillance

A
  • Ongoing, systematic collection, analysis and interpretation of health data essential to the planning, implementation and evaluation of public health practice, closely integrated with the timely dissemination of these date to those who need to know
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15
Q

Types of surveillance

A
  • Passive - relying on physicians, labs, etc. to report disease using standardize forms
  • Active - involves actively searching for cases
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16
Q

How are disease selected for surveillance

A
  • Frequency - incidence, prevalence, mortality
  • Severity - case-fatality ration, hospitalization ratio
  • Costs
  • Preventability
  • Communicability
  • Public interest
17
Q

What makes a good surveillance system

A
  • Simplicity, flexibility, data quality, accepatbility, sensitivity, positive predictive value, representativeness, timeliness, stability
18
Q

Reportable disease

A
  • One for which regular, frequent, and timely information about the individual cases is needed in order to prevent and/or control the disease
19
Q

Criteria used for determining reportable communicable disease

A
  • Disease/agent - severity, incidence, trends, communicability, socioeconomic impact, pulbic perception
  • Interventions - preventability, need for rapid public health response
  • System - reporting requried by others, feasibility, monitoring of existing controls
20
Q

Endemic

A
  • Constant presence of disease within geographic area or popluation group maintained over time
21
Q

Epidemic

A
  • Sharpe increase in disease incidence over expected level in a particular area of group in a given peruod
22
Q

Pandemic

A
  • Epidermic occuring throughout much of the world
23
Q

Outbreak

A
  • An excessive number of cases beyond that usually expected, thought to be linked in time and place. A sudden epidemic