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Pathogenesis Of Microbial Infections Flashcards

1
Q

Definition of symbiosis

A

Close and often long term interaction between 2 biological species

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2
Q

Definition of commensalism

A

1 organism benefits and the other derives neither benefit nor harm

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3
Q

Definition of mutualism

A

Association which is beneficial to both organisms involved

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4
Q

Definition of parasitism

A

1 organism, the parasite benefits at the expense of the other

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5
Q

Definition of obligate intracellular parasites

A

Can only reproduce within host cells

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6
Q

Definition of facultative parasites

A

Do not rely on its host to continue their life cycle

Can live and reproduce inside and outside cells

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7
Q

Definition of normal flora

A

Population of microorganisms that live in the skin, mucus membranes and GI tract of a healthy human body

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8
Q

Definition of human micribiome

A

Collection of all genes of all the microbes in normal flora

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9
Q

Definition of opportunistic infections

A

Caused by non pathogenic microbes that act pathogenic in certain circumstances

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10
Q

Definition of infection

A

Prescience of microbes in the body that are causing harm

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11
Q

Definition of colonisation

A

Describes when new microbes grow on superficial body sites (skin, mucus membranes, GI) without invading the body

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12
Q

Definition of carrier

A

Someone who harbours a microbe, a source of infection for others

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13
Q

Definition of pathogen

A

Microbe that can cause disease

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14
Q

Definition of microbial pathogenesis

A

Process by which infection => disease

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15
Q

Definition of immunopathogenesis

A

Primary cause of cell death in many infections, due to killing of infected cells by host immune systems

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16
Q

Definition of symptoms

A

Subjective features of a disease experienced only by the patient
Can be a symptomatic (subclinical) or symptomatic

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17
Q

Definition of a sign

A

Objective manifestation of disease that can be observed and measured by others

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18
Q

Definition of syndrome

A

Group of symptoms and signs characteristic of a disease

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19
Q

Definition of communicable

A

Infection spreads from host => host either directly or indirectly

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20
Q

Definition of contagious

A

Highly communicable disease spread by contact

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21
Q

Definition of non communicable

A

Infection non transmissible between humans

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22
Q

Definition of sporadic

A

Only occurs occasionally

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23
Q

Definition of endemic

A

Always present in a population, community, country

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24
Q

Definition of epidemic

A

Has greater no of cases than normal in an area within a short timeframe

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25
Definition of pandemic
Epidemic disease that has a worldwide distribution
26
Definition of outcome
Balance between microbial replication and spread of hosts ability to respond/resist
27
Definition of acute infection
Rapid onset of disease, relatively brief period of symptoms | Pathogen cleared within days
28
Definition of a persistent infection
Pathogen not cleared from the host following the primary infection but stays in tissues of infected individuals
29
Definition of latent
Microbes persist after initial clearance, may have asymptomatic reactivation
30
Definition of chronic
Continued production of infectious organism and immune evasion Are carriers
31
Definition of nosocomial infections
Any infection acquired in a hospital or medical facility Can affect patients, health care workers and are common because -Easily moved around by staff, patients, visitors -Not always prevented by hand washing
32
Definition of host range
Different species of hosts a given pathogen can infect | Determined by interactions of viral proteins with cognate cellular receptors
33
Definition of tissue tropism
Different tissues within a given host that are infected by the pathogen
34
Definition of permissive cells
Allows pathogen to replicate | Has required receptors, lacks defences against pathogen/pathogen has evolved mechanism to overcome defences
35
Definition of pathogenicity
Ability of a microbe to cause disease
36
Definition of virulence
Degree of pathogenicity in a microbe
37
Definition of endotoxins
LPS in G-ve bacteria | Can induce inflammation and fever as an immune response
38
Definition of exotoxins
Secreted proteins by G+ve and -ve | Many mechanisms, targets => many diseases
39
Definition of superantigens
Toxins that stimulate the immune system without MHC II
40
What are the 4 types of host microbe associations
Symbiosis, close long term interaction between 2 species Commensalism, 1 benefits, other not harmed or benefits Mutualism, benefits both Parasitism, 1 benefits, other harmed
41
What are the 2 ways for parasites to reproduce
Obligate intracellular -only reproduce in hosts Facultative parasites -reproduce in and out of cells
42
What are the 3 functions of normal flora When can they cause problems
Mucosal immunity dev Protection against pathogenic colonisation Digestion aid Bacteria found outside reservoir Changes in flora due to -exogenous infection -invasive technique, AB
43
What are the 3 properties of resident flora | What is the most common type
Can reestablish population Not removed by handwashing Not associated with infection spread Staph epidermidis
44
What are the 3 properties of transient flora
Can't reestablish population Removed by handwashing Associated with infection spread Staph aureus
45
When can opportunistic infections occur
Normal flora found outside resevoirs Host defenses weakened Lack of normal flora competition
46
What is immunopathogenesis What 2 réponses are possible?
The damage that occurs as a result of the immune response - CD8 attack - AB attack - Complement attack Local vs systemic
47
What 2 conditions lead to a syndrome
Symptoms,-subjective EXP of patient Sign -objective manifestation, can be observed/measured
48
What are the 4 steps needed for an infectious organism to thrive
Enter body Evade immune system Rapid growth Transmission into next host
49
What are the 3/4 stages of disease progression What factors affect the first stage
Incubation Prodrome (not always present) Illness Recovery Factors affecting incubation - Virulence, dose - Patient immunity - Site - Generation time
50
What are the 4 methods of infection classification
Transmission - Communicable - Non communicable (not spread between people) Site - Superficial - Systemic Occurence - sporadic - endemic - epidemic - pandemic Outcome - acute - persistent => latent/chronic
51
How can we get nosocomial and iatrogenic infections
Infection acquired in HC environment Disrupted mechanical barriers to infection - foreign bodies easier to colonize - injury associated with therapy => normally sterile areas are vulnerable
52
What 3 factors lead to AB resistance
Mutation -transfer resistance genes via plasmids Transmission -via surfaces/hands of staff AB -incorrect, inappropriate use
53
Describe bacterial attachment methods Describe viral attachment methods
Bacteria -adhesins (glycolipid, capsule, pilo, proteins, polysaccharides) bind to receptors Virus - viral surface proteins bind to receptor => membrane fusion/penetration - attachment factors concentrate viral particles at surface
54
What do these invasins do - Collagensase/hyaluronidase - coagulase - leukocidin - haemolysin
Collagenase/hyaluronidase -BM degradation => spread via tissues Coagulase -fibrin forms => surrounds s aureus, protection from phagocytosis Leukocidin -WBC degradation Haemolysin -RBC degredation
55
What does the LD50, ID50 tell you about the virulence of a pathogen
LD50 -no of pathogens that kill 50% of hosts ID50 -no of pathogens that infect 50% of hosts
56
What are the 2 main types of virulence factors in bacteria
Endotoxins | Exotoxins
57
What are the properties of endotoxins - source - secreted? - molecule - gene location - toxicity - clinical effects - antigenicity - heat stability
Source -G-ve Secreted? -No Molecule -Lipopolysaccharide Gene location -chromosome Toxicity -low Clinical effects -fever, shock Antigenicity -poor Heat stability -stable at 100C
58
What are the properties of exotoxins - source - secreted? - molecule - gene location - toxicity - clinical effects - antigenicity - heat stability
Source -G+-ve Secreted? -Yes Molecule -Polypeptide Gene location -plasmid Toxicity -high Clinical effects -variable Antigenicity -high Heat stability -destroyed rapidly at 60C
59
What 4 things do viral virulence factors do
Alter viral replication abilities Modify host defences Enable viral spread Act as toxic proteins
60
What are super antigens | What do they do
Stimulate immune system, bind directly to MHC2 non specifically => many T cell stimulated Example, E2 spike protein in coronavirus

Immunity and Infection (9 decks)

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