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Microbiology > Chapter 11: Interactions between Humans and Microbes > Flashcards

Chapter 11: Interactions between Humans and Microbes Flashcards

1
Q

Infectious Disease

A

the disruption of a tissue or organism caused by microbes or their products

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2
Q

Do all contacts lead to colonization and then to infection and then to disease?

A

Not all contacts lead to colonization; Not all colonizations lead to infection and Not all infections lead to disease

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3
Q

Normal (Resident) Biota

A

microbes that live peacefully and symbiotically in the human body; include an array of bacteria, fungi, protozoa, viruses, and arthropods

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4
Q

Human Microbiome Project

A

will identify genetic sequences to determine which microbes are inside and on humans, even though they can’t be cultured in the laboratory; will determine what the normal biota play in human health and disease; uses metagenomics

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5
Q

These general parts of the body are microbe free:

A

Internal organs, tissue, and their fluids

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6
Q

Sites that harbor normal biota (8)

A

(1) Skin and its adjacent mucous membranes; (2) Respiratory tract; (3) GI Tract (various parts); (4) Outer opening of the urethra; (5) External genitalia; (6) Vagina; (7) External ear canal; (8) External eye

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7
Q

Factors that weaken host defenses and increase susceptibility to infection (4)

A

(1) Old age and extreme youth; (2) Genetic and acquired defects in immunity; (3) surgery and organ transplants; (4) Underlying disease

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8
Q

Why are normal biota unlikely to be displaced by other microbes?

A

(1) Limited number of attachment sites; (2) Chemical and physiological environment created by normal biota is hostile to others

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9
Q

Vaginally delivered baby has been colonized by these microbes (3)

A

streptococci, staphylococci, and lactobacilli

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10
Q

These bacteria colonize the large intestine of bottle-fed infants:

A

coliforms, lactobacilli, enteric streptococci, staphylococci

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11
Q

Bifidobacterium

A

Breast-fed infants receive this bacterium because it favors the growth factor in milk; metabolizes sugars into acids to protect the infant from intestinal pathogens

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12
Q

Which of the following body sites is not colonized by known normal biota?

A. skin and mucous membranes
B. external genitalia
C. gastrointestinal tract
D. kidneys and bladder
E. respiratory tract
A

D. Kidneys and bladder (internal organ)

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13
Q

Pathogenicity

A

an organism’s potential to cause infection or disease

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14
Q

A true pathogen is capable of…

A

causing disease in a healthy person with normal immune defenses

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15
Q

Opportunistic Pathogen

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; Not pathogenic to a normal, healthy person

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16
Q

Examples of opportunistic pathogens (2)

A

Pseudomonas species; Candida albicans

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17
Q

Virulence

A

determined by its ability to establish itself in a host & cause damage (not the same as pathogenicity)

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18
Q

Virulence Factor

A

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

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19
Q

Portal of Entry

A

the route that a microbe takes to enter the tissues of the body to initiate an infection

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20
Q

Exogenous

A

microbe originating from a source outside the body from the environment or another person or animal

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21
Q

Endogenous

A

microbe already existing on or in the body – normal biota or a previously silent infection

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22
Q

Infectious agents that can enter through more than one portal of entry (3)

A

(1) Mycobacterium tuberculosis can enter through both the respiratory and gastrointestinal tracts; (2) Streptococcus and (3) Staphylococcus can enter through the skin, urogenital tract, and the respiratory tract

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23
Q

Infectious Dose (ID)

A

the minimum number of microbes necessary to cause an infection to proceed; smaller ID = higher virulence

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24
Q

ID for Rickettsia

A

single cell

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25
ID for tuberculosis, giardiasis, and coccidioidomycosis
10 cells
26
ID for gonorrhea
1,000 cells
27
ID for typhoid fever
10,000 cells
28
ID for cholera
1,000,000,000 cells
29
Adhesion
process by which microbes gain a more stable foothold on host tissues; firm attachment is imperative for causing infection
30
Adhesion Mechanisms (4)
(1) fimbriae (pili), (2) surface proteins, (3) adhesive slimes or capsules, (4) specialized receptors
31
Phagocytes
cells that engulf and destroy host pathogens by means of enzymes and antimicrobial chemicals
32
Slime or Capsule
makes it difficult for the phagocyte to engulf the pathogen
33
Bacteria with slime or capsule (4)
(1) Streptococcus pneumoniae, (2) Salmonella typhi, (3) Neisseria meningitidis, and (4) Cryptococcus neoformans
34
Bacteria that can survive inside the phagocyte (3)
(1) Legionella, (2) Mycobacterium, and (3) many rickettsias
35
3 ways microorganisms cause damage to their hosts
(1) directly through the action of ENZYMES; (2) directly through the action of TOXINS; (3) indirectly by inducing the HOST'S DEFENSES to respond excessively or inappropriately
36
Exoenzyme
enzymes secreted by microbes that break down and inflict damage on tissues & dissolve the host’s defense barriers to promote the spread of disease to other tissues
37
Mucinase
exoenzyme that digests the protective coating on mucous membranes
38
Toxin
a specific chemical product of microbes, plants, and some animals that is poisonous to other organisms
39
Neurotoxins act on...
the nervous system
40
Enterotoxins act on...
the intestines
41
Hemotoxins...
lyse red blood cells
42
Nephrotoxins...
damage the kidneys
43
Exotoxins
toxins that affect the cell by damaging the cell membrane and initiating lysis and disrupting intracellular function
44
Hemolysins
toxins that disrupt the membrane of red blood cells to release hemoglobin
45
Streptococcus pyogenes produces
streptolysins (a hemolysins)
46
Staphylococcus aureus produces
alpha and beta toxins (hemolysins)
47
Lipopolysaccharide (exotoxin)
part of the outer membrane of gram-negative cell walls; causes fever, inflammation, hemorrhage, and diarrhea
48
Blood infections by these 4 bacteria are particularly dangerous
(1) Salmonella, (2) Shigella, (3) Neisseria meningitidis, and (4) Escherichia coli
49
Steps Involved When a Microbe Causes Disease in a Host-summary
(1) Find portal of entry; (2) Attaching firmly; (3) Surviving host defenses; (4) causing damage; (5) exiting host
50
Necrosis
accumulated damage due to pathogens leading to cell and tissue death
51
Sign
objective evidence of disease as noted by an observer
52
Edema
the accumulation of fluid in afflicted tissue (sign)
53
Lymphadenitis
swollen lymph nodes (sign)
54
Symptom
subjective evidence of disease as sensed by the patient
55
Syndrome
a disease identified by a certain complex of signs and symptoms
56
Leukocytosis
increase in white blood cell levels
57
Leukopenia
decrease in white blood cell levels
58
Septicemia
a general state in which microorganisms are multiplying in the blood and are present in large numbers
59
Bacteremia/Viremia
bacteria or viruses are present in the blood but not multiplying
60
Portal of Exit
Usually the same as the portal of entry; shed through secretion, excretion, discharge, or sloughed tissue
61
Latency
a dormant state of microbes in certain chronic infectious diseases
62
Viral Latency (5)
(1) herpes simplex, (2) herpes zoster, (3) hepatitis B, (4) AIDS, (5) Epstein-Barr
63
Bacterial/Protozoan Latency (4)
(1) syphilis, (2) typhoid fever, (3) tuberculosis, (4) malaria.
64
Sequelae
long-term or permanent damage to tissues or organs caused by infectious disease
65
Sequelae of meningitis
Deafness
66
Sequelae of strep throat
rheumatic heart disease
67
Sequelae of lyme disease
arthritis
68
Sequelae of polio
paralysis
69
Incubation Period
the time from initial contact with the infectious agent to the appearance of symptoms & ranges from several hours to several years; majority of infections range from 2 and 30 days
70
Prodromal Stage
1 – 2 day period when the earliest notable symptoms of infection appear
71
Period of Invasion
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
72
Convalescent Period
patient begins to respond to the infection and symptoms decline
73
Reservoir
primary habitat in the natural world from which a pathogen originates; often a human or animal carrier; also soil, water, and plants
74
Transmitter
individual or object from which an infection is acquired
75
Carrier
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
76
Majority of animal reservoir agents
arthropods such as fleas, mosquitoes, flies, and ticks
77
Biological Vector
INFECTED; actively participates in a pathogen’s life cycle, serving as a site in which it can multiply or complete its life cycle; Mosquitoes and malaria
78
Mechanical Vector
NOT INFECTED; carries the microbe more or less accidentally on its body parts
79
Zoonosis
an infection indigenous to animals but naturally transmissible to humans
80
Nonliving Reservoirs
natural habitats important in diagnosis of disease and epidemiological studies
81
Communicable Disease
host can transmit the infectious agent to another host; synonymous to infectious
82
Contagious
a disease that is highly communicable, especially through direct contact; influenza and measles
83
Horizontal Transfer
disease is spread through a population from one infected individual to another (most common)
84
Vertical Transfer
From parent to offspring
85
Direct Contact
Coughing and sneezing and touching, etc.
86
Indirect Transmission
vehicle is involved; injecting infected saliva into blood (mosquito)
87
Nosocomial Infections
infections acquired or developed during a hospital stay
88
Koch's Postulates
a series of proofs that became the standard for determining causation of infectious disease
89
Postulate 1
Find evidence of a particular microbe in every case of disease
90
Postulate 2
Isolate and cultivate microbe in lab; perform full characterization
91
Postulate 3
Inoculate susceptible healthy subject with lab culture (poor mice) and observe same result
92
Postulate 4
Reisolate the same agent from new subject
93
Epidemiology
study of frequency and distribution of disease and other health-related factors in defined populations
94
Techniques of Epidemiology (3)
(1) Track Behaviors; (2) Uses clues on the causative agent; (3) tracks the numbers and distribution of cases
95
Prevalence
the total number of existing cases with respect to the entire population; reported as a percentage
96
Incidence (case or morbidity rate)
measures the number of new cases over a certain time period (rate and risk of infection)
97
Mortality Rate
total number of deaths due to a disease
98
Point-Source Epidemic
infectious agent came from a single source, and all of its “victims” were exposed to it from that source (a type of common-source epidemic)
99
Common-Source Epidemic
result from common exposure to a single source of infection over a period of time (general term)
100
Propagated Epidemic
results from an infectious agent that is communicable from person to person and is sustained over time in a population
101
Index Case
the first patient found in an epidemiological investigation (does not have to be the first person infected)
102
Endemic
an infectious disease that exhibits a relatively steady frequency over a long time period in a particular geographic location
103
Sporadic
occasional cases are reported at irregular intervals at random locales
104
Epidemic
when statistics indicate that the prevalence of an endemic or sporadic disease is increasing beyond what is expected for a population (measured in hours to years)
105
Pandemic
Spread of epidemic across continents

Microbiology (14 decks)

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