Introduction Flashcards
1
Q
What is another name for the human micro biome?
A
Normal Flora
2
Q
What is the human micro biome? Functions?
A
- Normal population of organisms that populate our body, mostly bacteria, some yeast and fungi
- educates immune system, local and systemic
- helps digestion of food and synthesis of vitamins
- protects against harmful microbes
- inhibit establishment of pathogens (colonization of resistance)
3
Q
Where do bacteria accumulate on our bodies? What part of our bodies is sterile? What happens if normal body b bacteria gain access to sterile sites?
A
- nasopharynx (nasal, oral)- S aureus
- skin- S aureus
- gastrointestinal tract- E coli
- urogenital tract
- vagina- strep, fragillis
- inner organs are sterile
- can become pathogens if gain access to sterile sites, or become immunocompromised
4
Q
Definition of infection? Example?
A
- a microbe colonizes and grows in or on a host where it isn’t normally found
- ex. streptococcus pneumonia colonizes the nasopharynx or from another infected individual can gain access to the lung
5
Q
What is an infectious disease? characteristics?
A
- an illness caused by the presence of a pathogenic microorganism growing in or on an infected host
- communicable
- can cause mortality, morbidity
6
Q
How is a particular disease defined?
A
- signs
- symptoms
- syndrome
7
Q
Signs?
A
- objective evidence
- something that can be detected or measured by someone else, what the doctor sees
- fever, heart rate, respiratory rate
8
Q
Symptoms?
A
- subjective evidence
- something that must be described be the one suffering with the disease
- what the patient experiences
9
Q
Syndrome?
A
the complete signs and symptoms associated with a specific disease
10
Q
Signs and symptoms of pneumonia?
A
- chest pain with difficulty breathing
- high fever, shaking, chills
- excessive sweating
- fatigue
- cough with phlegm that persists or gets worse
11
Q
Pathogen?
A
an organism that has the capacity to cause disease
12
Q
Etiology?
A
the cause of a disease or condition (virus, prion, bacteria, fungi, parasite)
13
Q
T/F Viruses and prions are not cells. Why?
A
True
- cannot grow on their own, have to infect a cell
- prions-infectious proteins
14
Q
What type of cells are fungi and parasites (protozoa and helminths)?
A
eukaryotic cells- have membrane bound organelles
15
Q
Why are fungi and parasites harder to treat?
A
they are eukaryotic cells, so they are similar to human cells
16
Q
What type of cells are bacteria?
A
prokaryotic
17
Q
Why are bacteria easier to treat?
A
they are different from human cells, they do not have membrane organelles, so antibiotics can destroy them and not hurt our cells
18
Q
Points about microbes and disease?
A
- a single microbe may cause many diseases (MRSA)
- multiple microbes may cause the same disease (pneumonia)
- many microbes cause a range of illness, asymptomatic to severe disease, host factors play a role in determining severity
- infections can be endogenous or exogenous
19
Q
Infections can be endogenous or exogenous. What is the difference?
A
- endogenous- already found in person, inside source
- exogenous- caused by another person or thing, outside source
20
Q
What is the host objective when a pathogen invades? The pathogen causing a disease depends in part on what?
A
- clear the pathogen
- prevent dissemination- deeper level
- prevent future infections
- adaptive, innate immunity
- how rapidly the immune response can eliminate the microbe
21
Q
What is the goal of the immune response to a pathogen?
A
- create a defense against pathogens
- preserve a symbiotic relationship with resident microbes (microbiota)
22
Q
What is the pathogen objective when it invades a host? How does the pathogen avoid the immune response?
A
- avoid the host immune response long enough to be transmitted to a new host
- pathogens constantly evolve to escape immune response
- ganarea- keeps evolving, body can’t attack
23
Q
How do pathogens enter and leave a host?
A
- exposure to environment
- skin
- respiratory tract
- gastrointestinal tract
- urogenital tract
24
Q
How does a host protect innately at sites where bacteria can enter?
A
- physical barrier
- mucus/mucociliary transport
- acid, mucus, enzymes, peristalsis -voiding
25
What are the modes of transmission of a disease? How are they controlled?
- respiratory or salivary spread- not readily controlled
- fecal oral spread- controllable by public health measures
- venereal spread- difficult to control due to social factors
- vector- bite(malaria, sandfly fever, typhus)
- vertebrate reservoir- brucellosis, rabies, Q fever, salmonellosis
- vector vertebrate reservoir- plague, trypanosomiasis, yellow fever
26
How do pathogens cause disease?
- direct damage at site of microbial replication(induce cell death)
- express toxins with local or systemic effects
- indirect damage due to activation of the immune response (immune mediated pathology-sepsis)
- induce autoimmune response (disrupt host tolerance to self)
- immunosuppress host-susceptible to opportunistic pathogens -trigger oncogenesis
27
How does the host combat pathogens?
- innate immunity
- physical barrier, complement pathway, inflammation
- adaptive immunity
- humoral, cell mediated
28
How do pathogens get around host defense mechanism?
- evolve
- avoid the immune response
- hide from it
- escape it
- neutralize it
- manipulate it
- microbes have evolved many ways
29
Factors that influence the manifestation of disease?
- transmission determines site of entry
- inoculum size influences severity
- tissue tropism determines site of pathology
- microbial virulence factors influence the severity of the illness, pathology, ability of immune response to limit infection
- age, susceptibility
30
Host factors influencing disease?
- immune status- prior immunity, compromised or non compromised immune system
- general health of person
- nutrition status, comorbidities
- age
- genetics
31
Kochs postulates (4)?
1. microorganism is present in all cases of the disease, but not in healthy organisms
2. microorganism must be isolated from a diseased organism and grown in pure culture
3. cultured microorganism should cause disease when introduced to naive host
4. same microorganism must be re-isolated from inoculated, diseased experimental host
32
Exceptions to Kochs postulates?
- asymptomatic carriers
- some organisms can't be isolated and grown in pure culture
- can be identified by molecular methods, immunohistochemistry, serology
- not all infected hosts will develop disease
33
Revised postulates (7)?
1. a nucleic acid sequence belonging to a putative pathogen should be present in most cases of an infectious disease
2. fewer or no copies of pathogen associated nucleic acid sequences should occur in hosts or tissues without disease
3. with resolution of disease, the copy number of pathogen associated nucleic acid sequences should decrease or become undetectable- clinical relapse the opposite should occur
4. when sequence copy number correlates with severity of disease, the sequence disease association is stronger
5. the nature of the microorganism inferred from the available sequence should be consistent with the known biological characteristics of that group of organisms
6. microbial sequences should be demonstrated, at a cellular level, in areas of tissue pathology and where microorganisms are known or presumed to be located
7. sequence based evidence for microbial causation should be reproducible
34
How many new diseases have been recognized since 1940? How many are from zoonotic origin? Most have been recognized since when?
- 400 new infectious diseases
- 60% zoo
- most since 1980
35
What is the driving forces behind new discoveries in pathology?
- the need to look beyond genetics and other environmental factors (stress, diet, smoking)
- development of polymerase chain reaction (amplify small genes, identify disease)
- revolutionary findings of warren and marshall in 1983 (helicobacter pylori associated with gastric ulcers)
- inflammation and its triggers as key components to pathogenesis
36
What causes chronic neurological conditions? How long does it take?
- caused by viruses, virus like agents, intracellular bacteria, fungi, protozoa
- long incubation period followed by slow development of symptoms and a progressive fatal course
37
Why is the central nervous system more susceptible with aging?
1. diminished functioning of the blood brain barrier and cellular immune mechanisms - infectious agents enter and hide from detection
2. transfer can occur from peripheral nerves into CNS (HSV1)
3. neurons become damaged by oxidative stress and impaired energy production
4. pathways by which neurotrophic factors protect nerve cells may function less efficiently -innate immune- strong whole life -adaptive immune- diminishes over time
38
What are the possible outcomes of disease?
see picture
39
Explain how the delayed immune response could affect disease outcomes?
explain picture
40
explain the different courses of infection?
see picture
