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Micro / Immuno > Leys Exam II > Flashcards

Leys Exam II Flashcards

1
Q

biofilm definition

A

A biofilm is a mixture of microbes and a matrix made up of extracellular polymers.

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2
Q

What do bacteria form?

A

Bacteria form complex structures within a biofilm.

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3
Q

How are biofilm and microbes related?

A

Most biofilms are mixtures of different species of bacteria.

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4
Q

Biofilms can include…

A

Biofilms can include other micro-organisms than bacteria.

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5
Q

Describe the structure of biofilms.

A

Biofilms have complex structures that give accessibility to nutrients and removal of waste products.

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6
Q

Describe the bacteria in a biofilm, and their relationship to antibiotics.

A

Bacteria in a biofilm are more resistant to antibiotics and host attacks.

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7
Q

In what type of environment do biofilms form?

A

Most bacteria form biofilms in an environment where there is liquid flowing.

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8
Q

What makes wild bacteria unique?

A

Wild bacteria have extracellular polymers attached to their surface that allow them to bind to surfaces or other bacteria.

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9
Q

What are biofilms associated with?

A

Biofilms are associated with many diseases including periodontal disease and caries.

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10
Q

What species are involved in bacterial diseases?

A

Many bacterial diseases (including oral infections) are polymicrobial where several species are involved.

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11
Q

quorum sensing defintion

A

Quorum sensing is the communication between bacteria.

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12
Q

Describe the two general mechanisms for quorum sensing.

A

One recognizes similar bacteria (same species).

One recognizes all bacteria.

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13
Q

Which bacteria have mechanisms for quorum sensing?

A

Essentially all bacteria have mechanisms for quorum sensing.

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14
Q

When do quorum sensing mechanisms produce a response?

A

Quorum sensing mechanisms produce a response when a certain threshold concentration of secreted molecules in reached.

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15
Q

Relationship between quorum sensing and biofilm formation?

A

Quorum sensing is an essential process in biofilm formation.

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16
Q

Name and define the three types of aerobes.

A

Strict aerobes must have oxygen to grow.

Obligate anaerobes cannot tolerate oxygen. Facultative anaerobes can grow with or without oxygen.

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17
Q

Name the three “destinies” of DNA that enters a bacteria cell.

A

1DNA that enters a bacterial cell can be:

  1. degraded,
  2. integrated into the host chromosome or
  3. integrated into a plasmid (extrachromosomal element).
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18
Q

What do bacteria use to degrade foreign DNA?

A

Restriction endonucleases, or restriction enzymes, are used by bacteria to degrade foreign DNA.

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19
Q

Define transformation.

A

Transformation is the uptake of naked DNA by “competent cells.”

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20
Q

Define transduction.

A

Transduction is the transfer of DNA between bacteria through a virus.

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21
Q

Define conjunction.

A

Conjugation is transfer of DNA through cell to cell contact using a sex pilus.

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22
Q

Where do mutations come from?

A

Mutations can be the result of base changes, deletions, insertions, duplications or rearrangements. Deletions are less likely to cause antibiotic resistance.

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23
Q

What do DNA mutations cause?

A

Mutations in DNA can cause antibiotic resistance.

Deletions are less likely to cause antibiotic resistance.

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24
Q

How do bacteria remove oxygen radicals from the cell?

A

Bacteria remove oxygen radicals from the cell by converting them to hydrogen peroxide with superoxide dismutase. Hydrogen peroxide is converted to water and oxygen with catalase.

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25
Q

What kinds of bacteria will not tolerate oxygen?

A

Bacteria that do not have superoxide dismutase and catalase will not tolerate oxygen; they are anaerobic.

26
Q

What are the most numerous members of the normal flora of the colon?

A

Bacteroides are the most numerous members of the normal flora of the human colon.

27
Q

What causes biphasic disease?

A

Spillage of intestinal material into the peritoneal cavity typically results in a biphasic disease: acute inflammation followed by localized abcesses.

28
Q

What results after spillage of intestinal material into the peritoneal cavity?

A

Spillage of intestinal material into the peritoneal cavity typically results in a biphasic disease: acute inflammation followed by localized abcesses.

29
Q

Compare acute phase and abcesses.

A

Large number of bacterial species present during the acute phase. Only a few species that predominate in abcesses.

30
Q

Bacteriodes fragilis

A

Bacteriodes fragilis is the most common isolate from intra-abdominal abscesses.

31
Q

LPS on surface of B. fragilis

A

The LPS on the surface of B. fragilis is not toxic unlike other gram negative bacteria.

32
Q

Which bacteria survive phagocytosis by the host?

A

Of the hundreds of species that are introduced into the peritoneal cavity by spillage from the colon, those (including B. fragilis) that have a polysaccharide capsule survive phagocytosis by the host.

33
Q

What do intra-abdominal abcesses lead to?

A

Intra-abdonimal abcesses cause by B. fragilis or other bacteria can lead to bacteremia and septic shock.

34
Q

Define bacteremia.

A

Bacteremia is the presence of bacteria in the blood, with or without the presence of an illness.

35
Q

Define sepsis.

A

Sepsis is a severe systemic illness marked by hemodynamic derangement and organ malfunction.

36
Q

Discuss treatment of sepsis with antibiotics.

A

Treatment of sepsis with antibiotics is important but can be difficult because the dead bacteria can release toxins that initially cause more damage.

37
Q

Where are spirochetes found?

A

Spirochetes are widespread in nature, but few cause disease.

38
Q

Describe the corkscrew-like movement of spirochetes.

A

The corkscrew-like movement of spirochetes is facilitated by a periplasmic flagella.

39
Q

What is the causative agent of syphilis, and why is it difficult to study?

A

Treponema pallidum, the causative agent of syphilis, has been difficult to study because in cannot be grown in the laboratory.

40
Q

What happens to T. pallidum after it enters the body?

A

When T. pallidum enters the body it becomes systemic almost immediately, by traveling through the lymphatic channels to the systemic circulation.

41
Q

Characterize the infection caused by T. pallidum.

A

The primary chancre formed by T. pallidum heals spontaneously, but the infection is already systemic.

42
Q

How many patients enter secondary stage of syphilis?

A

About 50% of patients who do not receive treatment enter the secondary stage of syphilis.

43
Q

Syphilis rash is often mistaken for…

A

The rash produced by secondary syphilis is often mistaken for other problems.

44
Q

What happens if tertiary syphilis is left untreated?

A

Tertiary syphilis, if left untreated, can progress to the CNS, causing ataxic gait, paresis, blindness, dementia and death.

45
Q

Is syphilis easy to control?

A

Syphilis is one of the easiest STDs to control. There are good diagnostic tests and treatment is available and inexpensive.

46
Q

Caustive agent of Lyme’s disease?

A

Borrelia burgdorferi is the causative agent of Lyme’s disease.

47
Q

Describe the progression of Lyme’s disease.

A

Like syphilis, Lyme’s disease progresses in stages from an acute and local skin infection to a chronic disease of the CNS and joints.

48
Q

What is transmitted by ticks?

A

B. burgdorferi is transmitted by ticks.

49
Q

How many species found in oral cavity?

A

There are 500 – 1000 bacterial species found in the oral cavity, from a wide variety of phyla.

50
Q

Describe the environmental niches of sub/supragingival bacteria.

A

Different bacteria occupy different environmental niches.
Subgingival bacteria are generally proteolitic.
Supragingival bacteria are generally saccrolitic.

51
Q

Which factors promote colonization in the oral cavity?

A

Factors that promote colonization in the oral cavity include: adherence properties, synergistic bacteria, nutritional substrates and temperature and moisture content.

52
Q

Which factors inhibit colonization in the oral cavity?

A

Factors that inhibit colonization in the oral cavity include antimicrobial properties of saliva, mechanical shearing, antagonistic bacteria.

53
Q

Numbers of species associated with periodontitis and periodontal health.

A

Many bacterial species that are associated with periodontitis. Fewer species are associated with periodontal health.

54
Q

Describe the microbial composition in periodontitis.

A

Shifts in microbial composition occur in periodontitis, however no bacterium is found in all patients with periodontitis and never found in healthy subjects.

55
Q

What is the source o tissue destruction during periodontitis?

A

The tissue destruction that occurs during periodontitis is mainly the result of a host response.

56
Q

There is a small shift from gram ____ to gram ____ during ____.

A

There is a small shift from gram POSITIVE to gram NEGATIVE during PERIODONTITIS.

57
Q

What happens to the complexity of the microbial community during periodontal disease?

A

The complexity of the microbial community INCREASES during periodontal disease.

58
Q

There is a slight shift to ___ ___ bacteria in ____.

A

There is a slight shift to more uncultivated bacteria in periodontitis.

59
Q

Microbial diversity ____ in caries.

A

Microbial diversity declines in caries.

60
Q

What happens as caries progress?

A

There is a progression of dominant species as caries progresses.

61
Q

Describe the location in the oral cavity.

A

Each location in the oral cavity has its own associated microbial composition. However there is overlap of species.

Micro / Immuno (2 decks)

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