Microbiology > Ch. 13 Microbes > Flashcards

Ch. 13 Microbes Flashcards

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1
Q

What is the approximate number of microbes that occupy the human body?

A

100 trillion microbes

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2
Q

What is the importance of balanced coexistence between humans and microbes?

A

It is important for dynamic equilibrium.

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3
Q

What protective effect do microbes provide on body surfaces?

A

They establish themselves as normal residents.

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4
Q

How do microbes contribute to the immune system?

A

They are involved in maturation of host defenses.

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5
Q

What results when a microbe penetrates host defenses and invades sterile tissue?

A

Infection

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6
Q

What is an infectious agent?

A

A microbe that can invade and multiply in sterile tissue.

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7
Q

What is the term for damage caused by an infection to tissues or organs?

A

Disease

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8
Q

What are normal resident microbiota also referred to as?

A

Indigenous microflora

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9
Q

What characterizes transients in microbiota?

A

Microbes that occupy the body for only short periods.

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10
Q

What defines residents in microbiota?

A

Microbes that become established.

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11
Q

What is microbial antagonism?

A

Beneficial microbes help prevent the overgrowth of harmful microorganisms.

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12
Q

What is the state of the uterus and its contents before birth?

A

Sterile

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13
Q

What type of bacteria begins colonization of a newborn within hours of birth?

A

Streptococci, staphylococci, and lactobacilli

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14
Q

How does breast milk influence microbial composition in infants?

A

Promotes the growth of beneficial microbes.

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15
Q

What are the major anatomical sites that harbor microbiota?

A

Skin, GI tract, oral cavity, upper respiratory tract, genital tract

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16
Q

What type of bacteria predominantly inhabit the large intestine?

A

Strict anaerobes

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17
Q

What beneficial contributions do intestinal bacteria make to the host?

A
  • Fermentation of waste produces vitamins (B12, K) and acids (acetic, butyric)
  • Aid in carbohydrate digestion
  • Contribute to intestinal odor
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18
Q

What is the primary role of normal flora in human health?

A

Prevent infections and enhance host defenses.

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19
Q

What are probiotics?

A

Introducing known microbes back into the body.

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20
Q

What is the infectious dose (ID)?

A

The quantity of microbial cells or particles that enter the portal of entry.

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21
Q

What is the typical infectious dose for measles?

A

1 virus

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22
Q

What are exogenous sources of infectious agents?

A

Sources originating from outside the body.

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23
Q

What is an endogenous source of infectious agents?

A

Microbiota or latent infections existing in the body.

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24
Q

What are the portals of entry for microbes?

A
  • Skin
  • GI tract
  • Respiratory tract
  • Urogenital tract
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25
What factors can compromise host defenses and increase susceptibility to infection?
* Old age and extreme youth * Genetic defects in immunity * Organic disease (cancer, diabetes)
26
What are the two types of cutaneous populations on the skin?
* Transients * Residents
27
What is the primary microbial inhabitant of the GI tract?
Anaerobic bacteria
28
What is the primary role of vaginal flora in females?
Respond to hormonal changes during life.
29
What is a characteristic of the respiratory tract microbiota?
No flora in bronchi and lungs
30
What can be a cause of yeast infections in the genital tract?
Candida
31
What is the significance of maintaining normal microbiota?
Essential for health and prevention of infections.
32
True or False: The internal reproductive organs are kept sterile.
True
33
What is the significance of the microbiota in relation to stress and cognition?
Germ-free mice show abnormal stress, anxiety, sociability, and cognition.
34
What is the main role of the microbiota in the development of intestines?
Normal development
35
What is a characteristic of opportunistic pathogens?
Cause disease when host defenses are compromised.
36
What does the term virulence refer to?
The organism's potential to cause infection or disease.
37
What is the effect of antibiotics on normal flora?
They may alter flora.
38
What are some examples of exogenous pathogens?
* Influenza virus * Meningococcus
39
What does STORCH stand for in the context of transplacental infections?
* Syphilis * Toxoplasmosis * Other diseases (Hepatitis B, AIDS, Chlamydia) * Rubella * Cytomegalovirus * Herpes simplex virus
40
What is the estimated infectious dose for Salmonellosis?
10,000 cells
41
What is the causative agent of measles?
Virus
42
What type of pathogen causes shigellosis?
Bacteria
43
How many viruses are typically needed to cause infection?
1 to 10 viruses
44
What is the primary mode of transmission for tuberculosis?
Respiratory
45
What type of contact is associated with gonorrhea transmission?
Sexual contact
46
Fill in the blank: A pathogen must establish a stable association with the host in the phase of _______.
[Attaching to the host]
47
What is the term for the properties that help pathogens invade and evade host defenses?
Virulence
48
What are factors that help in virulence called?
Virulence factors
49
True or False: Exotoxins are secreted by living bacterial cells.
True
50
What are the structures used by bacteria to adhere to host cells?
*Flagella *Fimbriae *Pili *Adhesive slimes *Capsules
51
What type of bacterial toxin is released after the host cell is damaged?
Endotoxin
52
What is the role of exoenzymes in bacterial virulence?
Dissolve barriers and penetrate through or between cells to invade underlying tissues
53
What happens to cells when toxins secreted by bacteria damage them?
Cells die and begin to slough off
54
Fill in the blank: Bacteria can evade phagocytosis by producing _______.
[Antiphagocytic factors]
55
What is the primary function of leukocidins produced by Staphylococcus and Streptococcus?
Toxic to white blood cells (WBCs)
56
What is the effect of hyaluronidase produced by bacteria?
Breaks down hyaluronic acid, allowing bacteria to spread through tissues
57
What type of toxin affects the gastrointestinal tract causing vomiting and diarrhea?
Enterotoxins
58
What is the difference between toxinoses and toxemias?
*Toxinoses: adverse effects of toxins *Toxemias: when the toxin is spread by the blood from the site of infection
59
What is the chemical composition of endotoxins?
Lipopolysaccharide of cell wall
60
What is the primary source of exotoxins?
A few gram-positive and gram-negative bacteria
61
Fill in the blank: An _______ is an antibody that reacts specifically with a toxin.
[Antitoxin]
62
What are the signs of a disease?
Changes in body function that are observable by an observer
63
What term describes the invasion of the body by a pathogen?
Infection
64
What are permanent or semi-permanent changes to health seen after the pathogen is gone called?
Sequelae
65
What is the scientific name of the causal agent of disease referred to as?
Etiological Agent
66
What are the four distinct stages of clinical infections?
* Incubation period * Prodromal stage * Period of invasion * Convalescent period
67
Define the incubation period.
Time from initial contact with the infectious agent to the appearance of first symptoms; agent is multiplying but damage is insufficient to cause symptoms.
68
What occurs during the prodromal stage?
Initial symptoms are vague feelings of discomfort and nonspecific complaints.
69
What characterizes the period of invasion?
Infectious agent multiplies at high levels and becomes well-established in target organs or tissues, with more specific signs and symptoms.
70
What happens during the convalescent period?
As the person begins to respond to the infection, symptoms decline and the immune system clears the infectious agent.
71
What is a localized infection?
Microbes enter the body and remain confined to a specific tissue.
72
Define systemic infection.
Infection spreads to several sites and tissue fluids, usually in the bloodstream.
73
What is a focal infection?
When the infectious agent breaks loose from a local infection and is carried to other tissues.
74
What does toxemia refer to?
Infection remains localized at the portal of entry, but toxins produced by the pathogens are carried by blood to actual target tissues.
75
What is a mixed infection?
When several microbes grow simultaneously at the infection site.
76
Define secondary infection.
When a primary infection is complicated by another infection by a different microbe.
77
What is an acute infection?
An infection that comes on rapidly, with severe but short-lived effects.
78
What characterizes chronic infections?
Infections that progress and persist over a long period of time.
79
Define sign in the context of disease.
Objective evidence of disease as noted by an observer.
80
What is a symptom?
Subjective evidence of disease as sensed by the patient.
81
What is a syndrome?
A disease identified or described by a collection of signs and symptoms.
82
List the earliest symptoms of disease as a result of the activation of body defenses.
* Fever * Pain * Swelling
83
What is leukocytosis?
Increase in white blood cells.
84
Define leukopenia.
Decrease in white blood cells.
85
What is septicemia?
Microorganisms are multiplying in the blood and present in large numbers.
86
Define bacteremia.
Small numbers of bacteria present in blood not necessarily multiplying.
87
What does viremia refer to?
Small number of viruses present not necessarily multiplying.
88
What does the suffix --itis indicate?
Inflammation.
89
What does the suffix --emia refer to?
Associated with the blood.
90
What does the suffix --osis mean?
Morbid process or disease.
91
What is an asymptomatic infection?
Infection where the host doesn’t show any signs of disease.
92
Define latency in the context of infections.
After initial symptoms, the microbe can periodically become active and produce recurrent disease.
93
What is a chronic carrier?
A person with a latent infection who sheds the infectious agent.
94
What is epidemiology?
Study of the frequency and distribution of disease and other health-related factors in defined human populations.
95
What is a reservoir in the context of infectious disease?
Primary habitat of pathogen in the natural world.
96
Define a carrier.
An individual who inconspicuously shelters a pathogen and spreads it to others.
97
What is a vector?
A live animal (other than human) that transmits an infectious agent from one host to another.
98
What are zoonoses?
Infections indigenous to animals naturally transmissible to humans.
99
What is the mode of infection for rabies?
Bite from infected animals.
100
What is a communicable disease?
When an infected host can transmit the infectious agent to another host.
101
Define non-communicable infectious disease.
Does not arise through transmission from host to host.
102
What is direct contact transmission?
Physical contact or fine aerosol droplets.
103
What is airborne transmission?
Droplet nuclei or aerosols containing live pathogens.
104
What is the role of an epidemiologist?
To collect clues on causative agents, pathology, sources, and modes of transmission.
105
What does prevalence refer to?
Total number of existing cases with respect to the entire population.
106
Define incidence.
Measures the number of new cases over a certain time period.
107
What is the mortality rate?
Total number of deaths in a population due to a certain disease.
108
What is an endemic occurrence?
Disease that exhibits a relatively steady frequency over a long period of time in a particular geographic locale.
109
Define sporadic occurrence.
When occasional cases are reported at irregular intervals.
110
What is an epidemic occurrence?
When prevalence of a disease is increasing beyond what is expected.
111
What is a pandemic occurrence?
An epidemic across continents.
112
Define nosocomial infections.
Diseases acquired or developed during a hospital stay.
113
What are common sources of nosocomial infections?
* Surgical procedures * Equipment * Personnel * Exposure to drug-resistant microorganisms
114
What are the most common types of surgical incisions that lead to infections?
Respiratory tract, GI tract, skin, urinary tract, and blood (sepsis) ## Footnote These are common areas where nosocomial infections can occur.
115
Name three examples of Gram-negative intestinal flora.
* Escherichia coli * Klebsiella * Pseudomonas ## Footnote These bacteria are significant contributors to nosocomial infections.
116
What is the annual prevalence of nosocomial infections in the U.S.?
1 to 2 million cases/year with approximately 72,000 deaths ## Footnote This statistic highlights the severity of nosocomial infections.
117
What type of precautions are required for enteric diseases?
Gowns and gloves must be worn by all persons having direct contact with the patient. Masks are not required. Special precautions are taken for disposing of feces and urine. ## Footnote Enteric precautions include diseases like E. coli and Clostridioides difficile.
118
What is required in strict isolation?
Private room with closed door; gowns, masks, and gloves must be worn; contaminated items must be wrapped and decontaminated. ## Footnote Strict isolation is used for highly virulent or contagious microbes.
119
What is reverse isolation also known as?
Protective Isolation ## Footnote This type of isolation is used to protect immunocompromised patients.
120
What is the assumption behind universal blood and body fluid precautions?
All patient specimens could harbor infectious agents and must be treated with the same degree of care. ## Footnote This is critical for preventing the spread of infections.
121
Fill in the blank: The first step in the disease cycle is _______.
Survival outside the host (reservoir) ## Footnote This is essential for understanding how diseases spread.
122
What does the infectious dose 50 (ID50) refer to?
The dose or number of organisms that will infect 50% of an experimental group of hosts within a specified time. ## Footnote This metric is used to measure virulence.
123
What is the lethal dose 50 (LD50)?
The dose or number of organisms that will kill 50% of an experimental group of hosts within a specified time. ## Footnote This is another important measure of virulence.
124
What is antigenic variation?
A mechanism used by pathogens to evade host defenses by presenting many variants that act as moving targets for the immune system. ## Footnote This allows pathogens to persist in the host.
125
What are exotoxins?
Proteins synthesized by bacteria and secreted outside the cells. ## Footnote They can cause damage to host tissues.
126
List some examples of exotoxins.
* Diphtheria exotoxin * Erythrotoxin * Enterotoxin * Neurotoxins ## Footnote Each of these has specific effects on the host.
127
What is the role of endotoxin in infections?
It is a component of all Gram-negative cells and can trigger serious effects such as fever and septic shock. ## Footnote Endotoxins are released when the bacteria die.
128
True or False: Exotoxins are heat labile.
False ## Footnote Exotoxins can be heat sensitive, while endotoxins are not.
129
Fill in the blank: The portal of _______ is a crucial step in the disease cycle.
Entry ## Footnote This is essential for understanding how pathogens infect a host.
130
What are the protective measures for respiratory precautions?
Private room with closed door; gowns and gloves are not required; masks are usually indicated. ## Footnote Contaminated items must be disinfected.
131
What is the significance of the term 'opportunistic pathogens'?
Pathogens that exploit a host's weakened immune system, such as those found in patients with cancer or AIDS. ## Footnote This underscores the importance of protective isolation.
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