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Unit 9 > Week 1: Infection as a Mechanism of Disease > Flashcards

Week 1: Infection as a Mechanism of Disease Flashcards

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1
Q

Why are infections still a major global concern despite advances in medicine?

A

Vaccine hesitancy
AMR (antimicrobial resistance)
Poor Healthcare
High threat pathogens (MDR-TB)

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2
Q

What are the key features of the bubonic plague?

A

Spread by bite from infected flea off rodent (vector borne)
Can be fatal within 24 hours
Causes painful swollen lymph nodes in groin and armpit
Can cause gangrene (lack of blood flow from narrowed/blocked/hardened arteries blackens tissue)
Highest rates in DRC, Madagascar and Peru

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3
Q

What pathogen causes bubonic plague?

A

Yersinia Pestis - zoonotic microbe with fleas as a vector

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4
Q

What are the key features of cholera?

A

Acute diarrhoeal disease
Fatal within hours
Endemic in many countries
Spread by contaminated food/water

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5
Q

What pathogen causes cholera?

A

Vibrio cholerae - bacteria

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6
Q

What is the pathogen responsible for the Spanish flu?

A

Influenza A virus
Common fever, sore throat and headache
Often developed pneumonia and died

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7
Q

What are the different types of microbes that can cause infection?

A

Bacteria
Viruses
Prions
Viroids
Fungi
Parasites
Helmiths

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8
Q

What are prions?
Give examples of diseases they cause

A

normal prion proteins to become abnormal and clump together causing brain damage
E.g CJD (mad cow disease), Kuru and FFI

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9
Q

What are viroids?
Examples?

A

Free RNA molecules (no viral coat)
Hepatitis D - which requires hepatitis B virus in order to replicate

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10
Q

What type of infection does Staphylococcus aureus cause?

A

Skin infections

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11
Q

What type of infection does E.Coli cause?

A

UTIs
Diahorreal
Neonatal meningitis
Pneumonia

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12
Q

What bacteria typically causes tonsilitis?

A

Streptococcus pyrogenes

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13
Q

What pathogen is normally responsible for a yeast infection?

A

Candida albicans - a fungi

Often caused by overuse of penicillin

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14
Q

What is a common parasite?

A

Malaria

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15
Q

What is a parasite?

A

Lives on or in a host, gets food at the expense of the host

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16
Q

What is a helminth?
What is a common example?

A

Cysticercosis - tape warm
Are a subset of intestinal macroparasites, typically cause abdominal pain, bloating and bloody stool

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17
Q

Define disease from a microbiology perspective

A

Suboptimal functioning of an organism due to infection or other causes

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18
Q

Define infection

A

When a foreign microbe invades and replicates in a host

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19
Q

What is an endogenously acquired infection?

A

Caused by microbes on or in us.
- alteration of microbiome by antibiotics
- commensal on skin enters by wound

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20
Q

What is an exogenously acquired infection?

A

Caused by pathogens in the external environment
- Food, air, water, objects, animal or insect bites

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21
Q

What are commensals?

A

A microorganisms that lives on/in a host, replicates. but does not interact with the host so rarely causes disease

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22
Q

What are some common examples of commensals?

A

Staphylococcus epidermis on the skin
Lactobacillus in the gut
Streptococcus salvarius - oral microbiome

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23
Q

What are opportunistic pathogens?

A

When microorganisms commonly found in the microbiome with causing disease, exploit compromised immunity to cause disease

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24
Q

What are some common opportunistic pathogens?

A

S, aureus if enters blood stream
Candida albicans - thrush in penicillin use
P.aeruginosa - serious infection in immunocompromised such as CF patients

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25
Define apparent infection
An infection that causes symptoms
26
What is an acute infection?
Symptoms within 4 weeks (rapid) e.g Influenza
27
What is a subacute infection?
Slower onset of symptoms within4-12 weeks e.g endocarditis
28
What is a chronic infection?
Long duration before symptoms >12 weeks e.g TB
29
What is a recurrent infection?
Repeated episodes of infection e.g UTI, thursh
30
What is a local infection?
Affects only one body part/ara (tonsilitis)
31
What is a systemic infection?
Affects entire body system (sepsis)
32
What is an active infection?
When pathogen is replicating so able to spread to new hosts
33
What is a subclinical infection?
Active infection with no symptoms (asymptomatic or inapparent)
34
What is a latent infection?
Inactive or dormat - pathogen not replicating so unable to spread.
35
With reference to the host pathogen interaction explain how a pathogen can spread between individuals?
Microbe infects one host Leaves host and enters another susceptible host
36
What are the three stages of the host-pathogen interaction?
Transmission Spread Infection
37
What are the different ways an infection can be transmitted?
Direct or indirect contact respiratory Contaminated food/water Faecal oral route Sexual transmission Vertical transmission Vectors
38
In the host pathogen interaction what is meant by the spread of the pathogen?
Pathogen infected host Pathogen proliferates locally at site of infection Invades other sites directly Spreads indirectly by lymphatics, blood or nerves
39
How can a pathogen establish infection? (reference to the host pathogen interaction)
Pathogen expresses virulence factors to overcome host defences Host defences are compromised
40
What is the circular link between evolution of hosts and pathogens?
Pathogen evolves to better invade host and escape immune defences Host evolves more methods to detect the pathogen and defend against it
41
What are the different mechanisms a pathogen may evolve to exploit host resources and cause damage?
1. Adhesion molecules 2. Invasion methods 3. Colonisation methods 4. Immune evasion
42
How can pathogens exploit host resources to adhere to host? Example
Express cell membrane Adhesion molecules allow initial contact to host cell receptors Example: Shigella spp produces molecules to attract dendritic cells and spread within them
43
How can pathogens exploit host resources to better invade the host tissue? Example
Evolved methods to cross host barriers such as mucus membranes and skin N.meningitidis down regulates capsule to adhere to host and invade, then upregulates capsule to avoid phagocytosis once in the blood stream
44
How can pathogens exploit host resources to better colonise the host? Example
Pathogens can multiply and form colonies within the host. Staphylococcus Aureus, produces Staphyloccus protein A which binds to the constant regions of antibodies, prevents recognition of antibodies, so antibodies struggle to mediate the killing of S.aureus
45
How can pathogens exploit host resources to avoid immune detection? Example
Pathogens may deploy stratergies to evade the host immune system or damage components of the system M.Tuberculosis, hides in alveolar macrophages and secretes tyrosin phosphatase to prevent phagolyosomal fusion.
46
What are the host defence mechanisms against infection?
Barrier defenses Innate Immunity Adaptive Immunity
47
What pathogens are typically spread by needlesticks?
HIV and Hepatitis
48
What pathogens are typically spread by bites?
Lyme disease Malaria Rabies
49
What pathogens typically cause ciliary paralysis?
H.Influenza
50
What pathogens typically have acid resistant eggs?
Parasites
51
What pathogens are typically spread by local trauma?
STIs HPV
52
What does the chain of infection show? What are the different stages in the chain?
Chain of infection shows six points to how a pathogen spreads from person to person, hence six point where spread can be stopped. Infectious microbe Reservoir of infection Portal of exit Mechanism of transmission portal of entry Susceptible host
53
What is the most effective way to break to chain of infection?
Wash hands - stops mode of transmission
54
Define latency period
Time from initial contact of a pathogen and a host till pathogen starts replicating, hence becomes infectious.
55
What is the incubation period?
The time from initial contact of pathogen with a host to when symptoms start
56
What is the infectious period?
The time in which a pathogen can replicate within host hence can spread to a new host.
57
Specific incubation period of diseases
Table from pp.
58
Where is the human microbiota typicallt found?
Skin Upper respiratory tract Oral cavity Intestine Vaginal tract
59
Where is the human microbiota noticably reduced/absent?
Lower respiratory tract Muscle tissue Blood and tissue fluid CSF Meninges Peritoneum Pericardium
60
What problems can the human mictobiota cause if invade wrong location or become unbalanced?
Disease (opportunistic pathogens) Allergies inflammation
61
What are the benefits of the human microbiota?
Nutrient producing (E.coli and Vit K) Competition for pathogens Digestion of soluble fibre complex carbohydrates Produce short chain fatty acids for energy Educate immune system to detect harmless and pathogenic microbes Produces enzymes humans do not make
62
How can E.coli found normally in the gut become pathogenic?
Exchange genes with other strains or E.coli to other types of bacteria Gains virulence genes
63
What is symbiosis?
The interaction between two different species in close proximity to each other over a long period of time
64
What are the three types of symbiosis? How are they different
Mutalism - both species benefit - E.coli Commensalism - one benefits, other neutral - S epidermis Parasitism - one benefits, other harmed - N meningitidis
65
What does -emia mean
Prescense of something Bacteremia Septecemia
66
What is the difference between a communicable and contagious disease?
Communicable disease spreads between individuals Contagious disease - spreads easily between two individuals
67
What are fomites?
Inanimate objects capable of being intermediate in the indirect transition of an infectious disease
68
What is the difference between a biological animal vector and a mechanical animal vector?
Both cases the pathogen lives on the animal, and uses it to transfer to a susceptible host Biological - infectious agent incubates in animal (replicates) as part of life cycle Mechanical - does not incubate or grow on the vector only travels by it

Unit 9 (15 decks)

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