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Microbiology > Lecture 11: Interactions between microbes and humans > Flashcards

Lecture 11: Interactions between microbes and humans Flashcards

1
Q

What is an infectious disease?

A

When the tissue or organism is disrupted by microbes or their products

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2
Q

How does an infectious disease come about?

A

contact –> colonization–> infection –> disease

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3
Q

Does contact always lead to colonization then infection then disease?

A

NO

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4
Q

What are 2 other names for resident flora?

A

Indigenous flora or normal flora

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5
Q

What are examples of resident flora?

A 
bacteria
fungi
protozoa
viruses
arthropods
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6
Q

Where is resident biota acquired?

A

most areas of the body that have contact with the outside world

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7
Q

What areas of the body are sterile?

A

internal organs, tissues, and their fluids

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8
Q

Are most microbes destroyed by the immune system before they are able to colonize?

A

YES

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9
Q

What sites of the body are known to harbor normal biota?

A 
Skin
Upper Respiratory Tract
Gastrointestinal Tract
Outer opening of urethra
external genitalia
vagina
external ear canal
external eye
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10
Q

How much of your weight is made up by skin?

A

15%

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11
Q

Compared to the geographic regions of the earth what is the forearm compared to?

A

the desert

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12
Q

Compared to the geographic regions of the earth what is the scalp compared to?

A

the cool woods

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13
Q

Compared to the geographic regions of the earth what is the armpit compared to?

A

the tropical forest

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14
Q

What things are found on the skin?

A

Fatty acids, lysozymes, and salt

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15
Q

Where are lysozymes found ?

A

sweat, tears, and saliva

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16
Q

What prevents overgrowth of bacterial population?

A

Sloughing (the shedding of the skin)

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17
Q

What specific bacteria make up the normal flora of the skin?

A

s. epi
s. aureus
pro acnes (Diptheroids)
yeast (Fungi)
canidida albicans (Fungi)
dermidex folliculorum (arachnid)

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18
Q

What is used to remove nonresident bacteria?

A

soap with hexachlorophene or other disinfectants

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19
Q

What factors affect the normal flora of the skin?

A

weather, age, and hygiene

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20
Q

What is the conjunctiva?

A

mucous membrane that covers the exposed surface of the eyelid

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21
Q

What does the microbial environment of conjunctiva consist of?

A

an impenetrable surface and is flushed by tears which contain lysozymes. Many normal flora are not found due to the constant flushing, but staphylcoccus and diptheroids are found.

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22
Q

When are the bacteria of the nasal cavity and nasopharynx colonized?

A

4 to 12 hours after birth

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23
Q

How many organisms are inhaled daily?

A

10,000

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24
Q

What is the microbial environment of the nasal cavity and nasopharynx like?

A

Its warm and moist and has a mucociliary system

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25
Q

What can affect the mucocilliary system be affected?

A

cystic fibrosis and smoking

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26
Q

What is the main flora found in the nasal cavity and nasopharynx?

A

s. aureus

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27
Q

What bacteria causes middle ear infections?

A

moraxella catarrhalis

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28
Q

When is the bacteria of the mouth colonized?

A

at birth when passing through the birth canal

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29
Q

What is the microbial environment of the mouth like?

A

warm and moist and it contains saliva and lysozymes

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30
Q

How many different species of bacteria are found in the mouth?

A

80

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31
Q

What bacteria causes tooth decay?

A

streptococcus mutans

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32
Q

Where do bacteria in the intestinal tract come from?

A

from the mouth and through the GI tract

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33
Q

What can affect the flora present in the intestinal tract?

A

your diet

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34
Q

What is the microbial environment of the intestinal tract like?

A

very few microbes survive upper GI, peristalis is less in the large intestine, and 100 billion to 100 trillion are eliminated per day

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35
Q

What are most of the bacteria of the intestinal tract?

A

anaerobes

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36
Q

What complicated interactions occur in the intestinal tract?

A

competition, genetic changes (antibiotic resistance) and peristalsis (contraction to move things through)

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37
Q

What is the microbial environment of the urethra like?

A

the movement of urine can remove the bacteria of the tightly joined cells and the normal flora

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38
Q

What are the 2 bacteria of the urethra?

A

enterococci and s. epi

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39
Q

When is the vagina bacteria colonized?s

A

soon after birth

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40
Q

What is the microbial environment of the vagina like?

A

It has very few nutrients and low pH then becomes normal before puberty then drops again

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41
Q

What bacteria is present in 25% of women?

A

Group B streptococcus

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42
Q

After a vaginally delivered baby how long until its been colonized and by what?

A

8 to 12 hours and streptococci, staphylococci, and lactobacilli

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43
Q

How are c section babies colonized?

A

by adult skin bacteria

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44
Q

What are formula fed babies large intestines colonized with?

A

mixed population of coliforms, lactobacilli, enteric streptococci, staphylococci

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45
Q

What are breast-fed babies large intestines colonized with?

A

Bifidobacterium whose growth is favored by a growth factor in milk; metabolizes sugars into acids to protect the infant from intestinal pathogens

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46
Q

What is a pathogen?

A

a microbe whose relationship with its host is parasitic and results in infection and disease

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47
Q

What does the severity of an infection depend on?

A

pathogenicity of the organism

condition of the host

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48
Q

What is pathogenicity?

A

an organism’s potential to cause infection or disease

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49
Q

What are true pathogens?

A

capable of causing disease in healthy persons with normal immune defenses

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50
Q

What are examples of true pathogens?

A

examples include the influenza virus, plague bacillus, and malarial protozoan

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51
Q

What are opportunistic pathogens?

A

cause disease when the host’s defenses are compromised or when they become established in a part of the body that is not natural to them

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52
Q

What are examples of opportunistic pathogens?

A

examples include Pseudomonas species and Candida albicans

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53
Q

What is virulence?

A

The ability of a microbe to establish itself in a host and cause damage

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54
Q

What is the virulence factor?

A

any characteristic or structure of the microbe contributes to its ability to establish itself in the host and cause damage

55
Q

What are the steps of a microbe causing disease?

A
  1. find a portal of entry
  2. attach firmly
  3. survive host defenses
  4. cause damage (disease)
  5. exit the host
56
Q

Do pathogens have specific portal of entries?

A

Yes and if they enter the wrong one they wont be infectious

57
Q

What 2 diseases can enter multiple places and still causes disease?

A

Mycobacterium tuberculosis can enter through both the respiratory and gastrointestinal tracts

Streptococcus and Staphylococcus can enter through the skin, urogenital tract, and the respiratory tract

58
Q

What are the direct modes of transmission?

A

horizontal- person to person

vertical- mom to baby

59
Q

What are the indirect modes of transmission?

A

fomites from objects
droplets from sneeze/cough
aerosols from air

60
Q

What are the parenteral modes of transmission?

A

Directly into the blood from the skin such as from a bite or piercing

61
Q

What are the fecal-oral modes of transmission?

A

Infected feces into mouth

Can occur by direct body contact or water, food, fomites, vectors

62
Q

What is the infectious dose (ID)?

A

the minimum number of microbes necessary to cause an infection to proceed

63
Q

What is the ID for rickettsia?

A

1 cell

64
Q

What is the ID for tuberculosis ?

A

10 cells

65
Q

What is the ID for gonorrhea?

A

1,000 cells

66
Q

What is the ID for typhoid fever?

A

10,000 cells

67
Q

What is the ID for chlorea?

A

1,000,000,000 cells

68
Q

What are the resevoirs of pathogens?

A

primary habitat in the natural world from which a pathogen originates

often a human or animal carrier

also soil, water, and plants

69
Q

Where do many infections that affect humans have their resevoirs?

A

in other humans

70
Q

What is a carrier?

A

an individual who inconspicuously shelters a pathogen, spreads it to others without any notice, and who may not have experienced disease due to the microbe

71
Q

What are biological vectors?

A

actively participates in a pathogen’s life cycle, serving as a site in which it can multiply or complete its life cycle

72
Q

What are mechanical vectors?

A

carries the microbe more or less accidentally on its body parts

73
Q

What do mammals spread?

A

rabies

74
Q

What do birds spread?

A

psittacosis

75
Q

What do lizards spread?

A

salmonellosis

76
Q

What is zoonosis?

A

an infection indigenous to animals but naturally transmissible to humans

77
Q

How is zonotic spread of disease promoted?

A

by close associations between humans and animals

78
Q

How much of all new emerging diseases are zoonosis?

A

70%

79
Q

What is a communicable/infectious disease?

A

a disease in which an infected host can transmit the infectious agent to another host and establish infection in that host

80
Q

What is a noncommunicable disease?

A

an infectious disease that does not arise through transmission of the infectious agent from host to host

81
Q

What is herd immunity?

A

Indirect protection from infection of susceptible members of a population and the protection of the population as a whole

82
Q

What are the mechanisms of adhesion?

A
  • fimbriae (pili)
  • surface proteins
  • adhesive slimes or capsules
  • viruses attach by specialized receptors
  • parasitic worms fastened by suckers, hooks, and barbs
83
Q

What are phagocytes?

A

cells that engulf and destroy host pathogens by means of enzymes and antimicrobial chemicals

84
Q

What is another name for virulence factors?

A

antiphagocytic factors

85
Q

What are leukocidins?

A

kill phagocytes outright; Streptococcus and Staphylococcus

86
Q

What are the 3 ways a microorganism can cause damage to a host?

A

directly through the action of enzymes

directly through the action of toxins (both endotoxins and exotoxins)

indirectly by inducing the host’s defenses to respond excessively or inappropriately

87
Q

What are exoenzymes?

A

enzymes secreted by microbes that break down and inflict damage on tissues by dissolving the host’s defense barriers to promote the spread of disease to other tissues

88
Q

What is mucinase?

A

digests the protective coating on mucous membranes

89
Q

What is hyaludronidase?

A

digests the ground substance that cements animal cells together

90
Q

What is coagulase?

A

causes clotting of blood or plasma

91
Q

What is Kinase?

A

dissolves fibrin clots

92
Q

What are exotoxins?

A

proteins with a strong specificity for a target cell and extremely powerful, sometimes deadly effects that affect cells by damaging the cell membrane and initiating lysis and disrupting intracellular function

93
Q

What are hemolysins?

A

disrupt the membrane of red blood cells to release hemoglobin

94
Q

What is an endotoxin?

A

lipopolysaccharide (LPS), part of the outer membrane of gram-negative cell walls that has a variety of systemic effects on tissues and organs and can causes fever, inflammation, hemorrhage, and diarrhea

95
Q

What are the 6 patterns of infection?

A
  1. localized infection
  2. systemic infection
  3. focal infection
  4. mixed infection
  5. primary infection
  6. secondary infection
96
Q

What is a localized infection?

A

microbes stay in one area

97
Q

What is a systemic infection?

A

infection spreads to many places via blood

98
Q

What is a focal infection?

A

infection spreads to other tissues

99
Q

What is a mixed infection?

A

many agents at one infection site

100
Q

What is a primary infection?

A

the initial infection

101
Q

What is a secondary infection?

A

the second infection caused by another microbe

102
Q

What is a syndrome?

A

a disease identified by a certain complex of signs and symptoms

103
Q

What is leukocytosis?

A

increase in white blood cells

104
Q

What is leukopenia?

A

decrease in white blood cells

105
Q

What is septicemia?

A

when microbes are multiplying in the blood in large numbers

106
Q

What is bactermia or viremia?

A

when bacteria or viruses are in the blood, but not multiplying

107
Q

What are infections that go unnoticed called?

A

asymptomatic, subclinical, or inapparent

108
Q

Is the portal of exit the same as portal of entry?

A

Most of the time, but not always

109
Q

Does recovery mean the microbe has been removed or destroyed?

A

NO!!!

110
Q

What is latency?

A

a dormant state of microbes in certain chronic infectious diseases

111
Q

What is sequelae?

A

long-term or permanent damage to tissues or organs caused by infectious disease

112
Q

What is the sequelae of menigitis?

A

deafness

113
Q

What is the sequelae of strep throat?

A

rheumatic heart disease

114
Q

What is the sequelae of lyme disease?

A

arthritis

115
Q

What is the sequelae of polio?

A

paralysis

116
Q

What is the incubation period of a disease?

A

the time from initial contact with the infectious agent to the appearance of symptoms. During this time the agent is multiplying at the portal of entry but has not caused enough damage to elicit symptoms

117
Q

What does the incubation period range from?

A

several hours to several years, but majority are 2 to 30 days

118
Q

What is the prodromal stage?

A

1 – 2 day period when the earliest notable symptoms of infection appear

vague feeling of discomfort: head and muscle aches, fatigue, upset stomach, general malaise

119
Q

What is the period of invasion?

A

infectious agent multiplies at high levels, exhibits greatest toxicity, becomes well established in host tissue

marked by fever and other prominent and specific signs and symptoms

extremely variable in length of period

120
Q

What is the convalescent period?

A

patient begins to respond to the infection and symptoms decline

patient’s strength and health gradually return due to the healing nature of the immune response

many patients stop taking antibiotics during this period, even though pathogens are still in their system leading to antibiotic resistance

121
Q

When can measles be passed on>

A

incubation period

122
Q

When can shigella be passed on?

A

Invasive period

123
Q

When can hep b be passed on?

A

all periods

124
Q

What are nosocomial infections?

A

infections acquired or developed during a hospital stay

125
Q

How many nosocomial infections could be avoided by infection control methods

A

1/3

126
Q

What are Koch’s postulates?

A
  1. a series of proofs that became the standard for determining causation of infectious disease
  2. continue to play an essential role in modern epidemiology
  3. reliable for many diseases, but cannot be completely fulfilled in certain situations
127
Q

What are exceptions to koch’s postulates?

A

some infectious agents cannot be readily isolated or grown in the laboratory

some infections cannot be elicited in animals; viruses have a limited host range, human viruses will only cause disease in humans, etc.

not possible to determine causation in polymicrobial diseases

128
Q

What did florence nightingale do?

A

laid the foundations of modern epidemiology

before the discovery of the germ theory, she understood that filth contributed to disease

instituted revolutionary methods in military field hospitals, including separate linens and towels for each patient, cleaning of floors, and unclogging of sewage pipes

kept meticulous notes and demonstrated that more men died of disease than traumatic injuries

129
Q

What is the prevelance of a disease?

A

the total number of existing cases with respect to the entire population reported as the percentage of the population having a particular disease at a given time

130
Q

What is the incidence of a disease?

A

measures the number of new cases over a certain time period

also called the case or morbidity rate; indicates both the rate and risk of infection

131
Q

What is an endemic?

A

an infectious disease that exhibits a relatively steady frequency over a long time period in a particular geographic locale

132
Q

What is a sporadic disease?

A

occasional cases are reported at irregular intervals at random locales

133
Q

What is an epidemic?

A

when statistics indicate that the prevalence of an endemic or sporadic disease is increasing beyond what is expected for a population

time period is not defined; can be measured in hours to years

exact percentage of increase needed before an outbreak qualified as an epidemic is also not defined

134
Q

What is a pandemic?

A

spread of an epidemic across continents

Microbiology (12 decks)

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