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microbio 3810 > 12. pathogenesis II > Flashcards

12. pathogenesis II Flashcards

1
Q

the quantitative ability of an agent to cause disease. these agents cause disease when introduced into the host in small numbers. involves adherence, persistence, invasion and toxigenicity

A

virulence

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2
Q

the process by which bacteria stick to the surfaces of host cells. after bacteria have entered the body, this is a major initial step in the infection process

A

adherence

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3
Q

the process by which bacteria, parasites and fungi and viruses enter host cells or tissues and spread in the body

A

invasion

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4
Q

the ability of a microorganism to produce a toxin that contributes to the development of disease

A

toxigenicity

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5
Q

these are the objective changes in the body, such as fever, rash, that can be directly observed

A

signs

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6
Q

these are subjective changes, such as pain and loss of appetite, that are experienced by the patient

A

symptoms

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7
Q

what are the four stages of the infectious process?

A
  1. the incubation period
  2. the prodromal stage
  3. the illness period
  4. the convalescence (recovery) period
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8
Q

this period of the infectious process is the time between pathogen entry and development of signs and symptoms. the pathogen is reproducing but has not reached a sufficient level to cause clinical manifestation. this periods length varies with the pathogen

A

the incubation period

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9
Q

this period of the infectious process occurs with an onset of signs and symptoms that are not yet specific enough to make a clear diagnosis. however, the patient is often contagious

A

the prodromal period

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10
Q

this period of the infectious process occurs when the disease is the most severe and displays characteristic signs and symptoms. the host immune response is typically triggered at this stage

A

the illness period

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11
Q

this period of the infectious process is the period of decline, the signs and symptoms begin to disappear

A

the convalescence (recovery) period

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12
Q

pathogens adhere with a ______ degree of specificity to particular tissues

A

high

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13
Q

the cell surfaces of both bacteria and host cells are ________

A

hydrophobic

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14
Q

in general, the more hydrophobic the bacterial cell surface the ________ the adherence to the host cell

A

greater

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15
Q

is gram positive or gram negative bacteria more hydrophobic?

A

gram neg

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16
Q

examples of this are pili and fimbrae, membrane and capsular materials (glycocalyx, capsule or S layer), and specialized adhesion molecules on the surface of the invading microbe

A

adherence factors/adhesions

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17
Q

these are the main adherence virulence factors that mediate ligand-receptor mechanisms to adhere to host cell surfaces

A

pili (or fimbrae)

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18
Q

______ strains have type 1 pili, which adhere to epithelial cell receptors

A

E.coli

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19
Q

E.coli organisms that cause urinary tract infections commonly have _____

A

P-pili

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20
Q

these have fimbrae that consist partly of protein F, and M protein and are covered by lipoteichoic acids (LTA)

A

group A streptococci e.g. Streptococcus pyogenes

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21
Q

_____ and ________ cause adherence of the Streptococci to buccal epithelial cells (e.g. cause sore throat)

A

LTA and protein F

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22
Q

during this step of a pathogen infecting a host, the bacterial pathogens actively penetrate the hosts mucous membranes and epithelium. this is accomplished by secreting lytic substances or enzymes such as coagulase, collagenase, hemolysins

A

invasion

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23
Q

how do hyaluronidase and collagenase work?

A

1, attacking the extracellular matrix and basement membranes of body surfaces (integuments) and intestinal linings
2. degrading carbohydrate-protein complexes between cells or on the cell surface
- some pathogens may penetrate to deeper tissue and continues disseminating through the body of the host

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24
Q

in this type of pathogen, after adherence occurs, conformational changes in the cytoskeleton of the host cell allow the uptake of the bacteria

A

intracellular pathogen

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25
Q

these three bacteria induce the polymerization of the host cell actin which induces the formation of pseudopods by the host cells and engulfing of the pathogen (invasion); they also activate the assembly of an actin tail and other cytoskeleton proteins, which propel the bacteria within the host cell and from one cell to another

A
  1. Listeria monocytogenes
  2. Shigella spp.
  3. Rickettsia spp.
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26
Q

invasiveness varies greatly among pathogens. for some pathogens, a ______ infection is sufficient to cause disease. however, many pathogens invade other tissues

A

localized

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27
Q

_______, the cause of tetanus, is considered noninvasive because it does not spread from one tissue to another, but its toxin becomes blood-borne, thereby causing disease

A

Clostridium tetani

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28
Q

______ the cause of anthrax and ______ the cause of plague also produce toxins and they are highly invasive

A

Bacillus anthraces and Yersinia pestis

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29
Q

how do pathogens get access to all organs and systems of the host?

A

some pathogens may enter the small terminal lymphatic capillaries that surround epithelial cells. these capillaries merge into large lymphatic vessels that eventually drain into the circulatory system.

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30
Q

the presence of viable bacteria in the bloodstream is called

A

bacteremia

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31
Q

this is a substance that disrupts the normal metabolism of host cells with deleterious effects on the host

32
Q

these are disease that result from the entrance of a specific preformed toxin into the body of a host

A

intoxications

33
Q

true or false: intoxications require the presence of the actively growing pathogen

A

false - just its toxin

34
Q

toxins are classified into two main groups which are:

A
  1. exotoxins
  2. endotoxins
35
Q

these are toxins that are secreted outside the cell

36
Q

these are toxins that are part of the outer membrane of gram negative bacteria

A

endotoxins

37
Q

endotoxin or exotoxin? is excreted by a living cell

38
Q

endotoxin or exotoxin? is an integral part of the cell wall of gram negative bacteria; released on bacterial death and in part during cell division

39
Q

endotoxin or exotoxin? found only in gram negative bacteria

40
Q

endotoxin or exotoxin? produced by both gram negative and gram positive bacteria

41
Q

endotoxin or exotoxin? a polypeptide

42
Q

endotoxin or exotoxin? lipopolysaccharide complexes; lipid A portion probably responsible for toxicity

43
Q

endotoxin or exotoxin? relatively unstable; toxicity often destroyed rapidly by heating at temperature above 60 degrees cels

44
Q

endotoxin or exotoxin? relatively stable. withstand heating at temps above 60 degrees cels for hours without loss of toxicity

45
Q

endotoxin or exotoxin? weakly immunogenic `

46
Q

endotoxin or exotoxin? highly antigenic; stimulate formation of high titer antitoxin

47
Q

endotoxin or exotoxin? highly toxic; fatal to animals in microgram quantities or less

48
Q

endotoxin or exotoxin? moderately toxic; fatal to animals in tens to hundred of micrograms

49
Q

endotoxin or exotoxin? usually do not produce fever in the host

50
Q

endotoxin or exotoxin? usually produce fever in the host

51
Q

endotoxin or exotoxin? frequently controlled by extrachromosomal genes (e.g. plasmids)

52
Q

endotoxin or exotoxin? synthesis directed by chromosomal genes

53
Q

exotoxins can be divided into three groups which are

A
  1. AB exotoxins
  2. specific host site exotoxins
  3. membrane-disrupting exotoxins
54
Q

this group of exotoxins consists of A and B subunits (often referred to as binary toxins or type III toxins).

A

AB exotoxins

55
Q

this subunit of the AB exotoxins provides the toxic activity

56
Q

this subunit of the AB exotoxins is used for the adherence and entry of the toxin complex to a host cell

57
Q

an example of an AB exotoxin is ______________ produced by Corynebacterium diphtheriae and causes diphtheria disease (swollen neck or throat)

A

diphtheria toxin

58
Q

an example of a specific host site exotoxin is ________

A

neurotoxins - specifically affects nervous tissue

59
Q

an example of a specific host tissue exotoxin is ______ produced by Clostridium bootulinum and causes botulism; it is one of the most lethal toxins known

A

botulinum toxin

60
Q

what is the toxin that is produced by C. tetani that causes tetanus

A

Tetanospasmin toxin

61
Q

this is an example of a specific host tissue exotoxin that is an enterotoxin, thus it affects the intestinal mucosa and causes toxic shock syndrome

A

staphylococcal enterotoxin

62
Q

this is a type of specific host tissue exotoxin that has a specific toxic action upon cells/tissues of a special organ

A

cytotoxins e.g. nephrotoxin, hepatotoxin

63
Q

this is a type of exotoxin that disrupts th integrity of the plasma membrane. e.g. leukocidins toxins that kill phagocytic leukocytes

A

membrane disrupting exotoxins

64
Q

vaccines have been developed for some of the exotoxin-mediated disease and continue to be important in the prevention of disease. these vaccines are called _____ and are made from modified exotoxins that are no longer toxic

65
Q

regarding endotoxins, if _________ gets in the bloodstream, it interacts with receptors on macrophages and neutrophils which causes the release of pro inflammatory cytokines. the following can be observed: fever, diarrhea, hypoglycaemia, hypotension, shock resulting in impaired perfusion of essential organs (e.g brain, heart, kidney) and death from massive organ dysfunction

A

lipopolysaccharide (LPS)

66
Q

this is a tissue degrading enzyme which degrades collagen in connective tissue, and is produced by Clostridium perfringens and promotes the spread of infection in the tissue

A

collagenase

67
Q

this is a tissue degrading enzyme that hydrolyze hyaluronic acid, a substance of connective tissue. they are produced by many bacteria and aid in their spread through tissues

A

hyaluronidases

68
Q

this is a tissue degrading enzyme produced by Staphylococcus aureus and works with blood factors to coagulate plasma. it contributes to the formation of fibrin walls around staphylococcal lesions which help them persist in tissues

69
Q

some pathogens evaded phagocytosis by absorbing normal host components to their surfaces. an example of this is ______________ (bacteria) has surface protein A which binds to the Fc portion of IgG

70
Q

what are some pathogens that impede phagocytosis?

A
  • polysaccharide capsules
  • S. pyrogens: has M protein
  • N. gonorrhoeae has pili
71
Q

_____ of pathogenic bacteria encode for pathogenic agents or virulence factors that could be found in chromosomes (as PAIs), plasmids, or as transposons or phage encoded

72
Q

these are large groups of evens that are associated with pathogenicity and are located on the bacterial chromosome, they have one or more virulence genes. they have a different G+C content than the rest of the bacterial genome and they are commonly associated with tRNA genes

A

pathogenicity islands

73
Q

what is the PAI name and virulence characteristics of E.coli?

A

PAI I536, II536
alpha hemolysin, fimbriae, adhesions, in UTI

74
Q

what is the PAI name and virulence characteristics of Salmonella serotype Typhimurium?

A

SPI-1
invasion and damage of host cells, diarrhea

75
Q

what is the PAI name and virulence characteristics of Staphylococcus aureus?

A

SCC mec/SaPl1
methicillin and other antibiotic resistance/toxic shock syndrome toxin-1, enterotoxin

microbio 3810 (16 decks)

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