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Microbial growth and antibiotics[XA BY02] > Microbial Diseases > Flashcards

Microbial Diseases Flashcards

1
Q

What means Phathogenic?

A

Disease causing

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2
Q

What is phathogenicity?

A

Ability of bacterium to cause diseases

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3
Q

What is 2 ways pathogens cause diseases?

A

Damaging host tissues - By reproducing

Toxins

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4
Q

What are main factor affecting pathogenicity?

A

Features of cell wall and capsule that affects attachment and entry to host cells

Types of toxin(exo or endo)

Infectivity - measure of number bacteria required to cause infection

Invasiveness - ability to spread within host

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5
Q

What use bacteria to attach to protein receptor of host cell?

A

Ligands and Glycocalyx on cell wall with specific tertiary structure

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6
Q

What is ways bacteria enter host cell?

A

Attaching to cell membrane receptor

Production of enzymes damaging cell membrane

Endocytosis - bacteria are engulfed by host cell

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7
Q

What is 2 main type of toxin?

A

Exotoxins - proteins secreated from bacteria, cayses many symptoms of a disease e.g. tetanus and food poisoning

Endotoxins - Lipopolysaccharides present in cell walls, they can be released when cell wall of bacterium breaks up after death

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8
Q

What is Infectivity?

A

Number of bacteria required to cause infection

Varies between spicies

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9
Q

What is invasiveness?

A

Ability of the bacteria to spread

Usually in hosts blood and lymph system as its where it enters other places

It has to be able to avoid body immunity and get through fibers, connective tissues and intercellular cement

Toxins can also spread through the body and cause damage to unrelated tissues

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10
Q

Give 2 examples of invasive diseases?

A

Bubonic plague and anthrax

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11
Q

Give method of trasmission of diseases?

A

Airborne/droplets

Food-borne

Water-borne

Contact

Sexual intercourse

Vector-borne

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12
Q

How does cholera spread?

A

Water-borne

Transmission by ingesting water or sometimes food contaminated by faecal material having bacteria

This can happens as:

-Drinking water is not properly purified
-Untreated sewage leaks into water courses
-Food is eated which is contaminated by those preparing or serving

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13
Q

Name bacteria causing cholera?

A

Vibrio cholerae

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14
Q

What is cholera bacterium structure?

A

Common prokaryotic structure

Flagellum

Plasmid

Capsule

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15
Q

How is cholera caused by bacteria?

A

Endotoxin bind to specifically complementary receptors on small intestine epithelial cells

This causes change in cell permeability as ion channel open

Chloride ion diffuse into lumen from cell

This lowers water potential in lumen and increase water potential in cell

So water diffuse via osmosis into lumen from cell

This causes diarrhea and dehydration as blood and cell lose water

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16
Q

What is sympthoms of chloera?

A

Diarrhoea

Dehydration

Other including stomach cramps, vomiting and fever

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17
Q

What is treatment for chloera?

A

Restoring water and ions lost through oral rehydration solution(ORS)

Bacteria don’t affect co-transport in epithlial cells

So sodium ions and glucose are taken up as normal

Water potential of epithelial cell is reduced and is lower than the water potential of lume

Water taken by ORS movens from lumen into cell as normal

So water would move into blood, rehydrating patients

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18
Q

What does ORS contain?

A

Water, sodium ions, chloride ions and glucose

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19
Q

What is ineffective and effective ORS and how it was discovered?

A

ORS production is long process done using scientific experiments

Mixture with more glucose caused lower water potential in lumen causing more dehydration

Using instead starch was is good

Starch is insoluble so osmotically inactive

But it hydrolyse into maltase and then glucose

As this is slow, its same rate as co-transport taking it up

So can’t affect water potential in lumen

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20
Q

What is ideal scientific trial?

A

Large number of subjects

Subjects randomly split into 2 groups

One group treated, another group is control

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21
Q

What is real scientific trial condition of ORS testing?

A

Subjects with dehydration and diarrhoea required

Frequently thse subjects are children in danger of deth

So ideal scientifc trial cannot be conducted as ethically unacceptable

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22
Q

What is virus?

A

Intracellular parasites reproducing inside their living host cwlla

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23
Q

How does virus cause diseases?

A

Damage to host cells following entry and replication of viruses

Toxin produced in the process of replication

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24
Q

What structure does virus usually have?

A

Either DNA or RNA

Enzymes

Outer protein coat or capsid made of capsomeres

Some has lipid envelope which helps entry

Some had glycoprotein spikes on capsid or envelope for attachment, it is also antigens

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25
Q

How does virus usually reproduce?

A

Viral nucleic acid is replicated

new capsid and other structures are produced and assambled

They are released when cell burst during lytic cycle and these virus particles would infect other cells

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26
Q

What is type of viruses?

A

Polyhedral(Adenovirus)

Spherical(Influenza)

Helical(Tabacco mosaic virus)

Complex(Bacteriophage)

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27
Q

What virus cause influenza and explain them?

A

Influenza virus

Contains RNA and RNA polymerase

There are 3 types, A, B and C

Only A causes serious epidemics

Rapid mutation therefore various strains can occur and this antigenic can lead to re-inffection

Influenza is endemic, regularly epidemic and sometimes pandemic

28
Q

What is influenza viral replication?

A

Virus enter epithelial cells of nose, throat and sometimes bronchi

Molecules in the outer coat of the virus bind to receptor molecules in the cell membrane of epithelial cells

Inside the cell the viral coat is removed releasing the viral RNA and the enzyme RNA polymerase

Viral RNA enters the host nucleus and controls protein synthesis in the cell

RNA polymerase is activated and sythesises viral mRNA strands

Viral proteins and lipids are formed in the cytoplasm and are assembled into viral coats

Viral RNA and viral coats are assembled into new virus particles

Lysis of the cell occurs and the released virus particles infect other cells

29
Q

How does influenza transmission happen?

A

Trasmitted via droplet infection during coughing and sneezing

Overcrouding and poor ventilation enchnce spreading

30
Q

What is influenza symptoms?

A

Incubation peridod of 2 days

Headache, sore throat, backache and joint pain, fever, shivering, sweating and dry cough

Usually last up to 7 days

Coughing may continue due too epithelial damage to trachea and bronchi

Depression may presist for some time

Rarely longer than 6 days

The virus attach is usually localised, but can allow secondary invasion of bacteria due to tissue damage on respiratory leading to bronchitis and pneumonia

31
Q

What is treatment for influenza?

A

Viruses are intracellular infections

So very difficult to treat since drugs may not penetrate cells, and if they do, they are as likely to damage the host cells as the virus

For the most part we must rely on the body’s own defences

Rest, aspirin to reduce temperature and plenty of fluids, can relieve the symptoms and help the body recover

As with all viral diseases antibiotics are ineffective, however they may be given to treat or prevent secondary infections

32
Q

What is way of reducing influenza?

A

Vaccines are available from variety of strains of the virus, annually given to maintain antibody level

However only about 70% effective as antigenic variation in new strains

Vaccination helps to protect particularly susceptible to reduce reseirvoir of infection

Nasal sprays containing a live weakened strain for 2 to 7 years old and 2 to 17 years old at high risk

Affected people should stay isolated to prevent spreading

Also tissues should be used to cut the spread of droplets

Ventilation and less overcrowding help also

33
Q

What is coronavirus?

A

Large family of virus with crown-like glycoprotein spikes

They contain RNA and cause respiratory tract infection in mammals and birds

Common diseases caused is usual cold, SARS, MERS and Covid-19

34
Q

How is coronavirus transmitted?

A

Coronaviruses are zoonotic(spread between animals with different spicies)

Coronaviruses spread through close contact with people who have the virus through droplets

You can catch these viruses if you breathe in these droplets or touch surfaces covered with droplets

The risk of transmission is highest indoors and in crowded places

35
Q

How does virus replicate in humans?

A

It attaches to epithelial cells of respiratory tract using complementary glycoproteins on cell receptor

Once attached it releases RNA genome into host cell cytoplasm

Coronavirus RNA genome allows it to act like a mRNA and be translated by cells ribosome to generate new viral particles

Then viral particles are released from host cell by exocytosis through secretory vesicles and go to infect other cells

36
Q

What is symptoms of coronavirus in respiratory tract?

A

Continuous cough

High temperature, fever or chills

Loss of or change in, your normal sense of taste or smell

Shortness of breath

Unexplained tiredness, lack of energy

Muscle aches or pains that are not due to exercise

Not wanting to eat or not feeling hungry

Headache that is unusual or longer lasting than usual

Sore throat, stuffy or runny nose

Diarrhoea

Feeling sick or being sick

37
Q

What is called when no symptoms exhibited?

A

Assymptomatic

38
Q

What is CFR?

A

Measure of severity of disease

39
Q

What is equation of CFR?

A

CFR = Number of deaths from diseases/ Number of deaths from disease + Number of recovered from disease * 100

40
Q

What is treatment for coronavirus?

A

Vaccinations

Antiviral medicines

Neutralising monoclonal (nMAb) treatment

Treatment of symptoms by using rehydration treatments and painkillers to tackle dehydratation, pain and fever

41
Q

What is AIDS?

A

Disease caused by HIV

HIV is a retrovirus containing RNA and enzyme reverse transcriptase

RNA and enzymes are surrounded by inner protein coat and outer protein capsid forming nucleocapsid

Nucleocapsid is surrounded by a lipid envelope which contains glycoprotein spikes

This enables them to attach on Helper T cells using gp120(glycoprotein)

42
Q

How is HIV transmitted?

A

Secual transmission

Blood products/transfusion

Sharing of needles

Mother to baby via placenta, labor, breast milk

43
Q

How is HIV replicated in body?

A

Virus attaches to CD4 in helper T cells by gp120 on receptor site

Viral RNA and the reverse transcriptase are released into helper T cell

In helper T cell viral DNA is formed using reverse trancriptase using viral RNA as template

Viral DNA enters the nucleus and attaches to host DNA

Viral DNA gets replicated with host DNA

Viral DNA may remain inactive for up to 10 years

When activaated viral DNA controls synthesis of viral protein and RNA

HIV particles are assembled and helper T cell is destroyed as particles is released

Virus infects other helper T cell

So helper T cell decrease

Immune system breaks and opportunistic infection or tumours that leads to death

Common diseases are kaposi’s sacroma and pneumonia

44
Q

What is symptoms of HIV infection?

A

During first phase after infection, body produces HIV antibodies and short flu-like ilness, skin rash and swollen glands

The second phase(antibody-positive phase/HIV positive phase) where no symptoms shown, may last from few weeks to 13 or more years

The third phase is AIDS-related complex, variety of opportunistic diseases appear, not life threating, loss of weight and reduction of T helper cell occurs

The fourth phase involves opportunistic infection organs and development of cancer and HIV wasting symptoms(dramatic weight loss)

Most AIDS patients eventually die from pneumonia as immune system collapses

45
Q

What is treatment for HIV?

A

Antiretroviral therapy(ART) is used to treat

HIV positive individuals on ART take a combination of HIV medicines every day

ART cannot cure HIV but reduce the level of HIV in blood allowing immune system to repair to prevent HIV related diseases

This will increase chances for long and healthier life

Also these reduce risk of HIV trasmission as level kept low in blood

HIV medicines prevents HIV from multiplying reduing amount of HIV

46
Q

What is ART?

A

Can be classified in 4 ways:
- Reverse transcription inhibitors
-Protein inhibitors
-Fusion and entry inhibitors
-Integrase inhibitors

Taking 2 or more ART is called combination therapy

Combination of three or more anti-HIV drug is called Highly active antiretroviral therapy(HAART)

Choice of drug to take depends on a number of factors including availability and price of drug, no of pills, side effects and other medical condition

Most people living with HIV in developing world still have very limited access to drug and gets treated for opportunistic diseases and not effective for long term

47
Q

How can be HIV infection be prevented?

A

Reduce promiscuity and safe sex by using condoms

Blood screening

Tissue screening

Provision of clean needles for drug users to prevent sharing

Caesarean section

Blottle feed of babies instead of breast feed

48
Q

What is post-exprosure prophylaxis(PEP)?

A

Anti-HIV medication that can be taken if individual think they have been exposed to HIV

For effectiveness, it should be started within 72 hours, it is only recommended to be taken if high risk explosure

The quicker PEP is started the better

PEP is a month-long treatment with serious side effects and not guaranteed to work

This also involves taking same drugs prescribed to people who have tested positive

49
Q

What is pre-exprosure prophylaxis(PrEP)?

A

Course of HIV drugs for HIV negative indivuals at risk of being infecter

Drugs are taken before sex to reduce the risk of getting HIV

Results form trials are promising reducing risk of becoming positive without major side effects

Available on US since 2012 and by NHS since 2016

50
Q

How is ebola transmitted?

A

By giving care and thouching victim body or fluid

Handling unsterilised needles or medical equipment used

Having sex with infected victims

51
Q

How does ebola replicate in host cell?

A

The glycoproteins on the Ebola virus bind to receptors on a host cell membrane

Virus then enters the cell by endocytosis

On entry into the cell, the protein coat is removed and the viral RNA and RNA polymerase is released

The viral RNA is replicated, transcribed and translated to produce viral RNA and proteins

These are assembled to form new viruses and bud out of the cell to go on to infect other cells

52
Q

What is symptoms of ebola?

A

Fever, headache, jont and muscle pain, sore throat and intense muscle weakness between 2 to 21 days after infected first

Then diarrhoea, vomitting, rash, stomach pain and impared kidney and liver

Bleeding internally, and maybe from ears, eyes, nose or mouth

Fatal in 50 to 90 pecent of cases depending on quality of care

53
Q

What cell gets infected by ebola?

A

Liver cells, immune system cells, endothelial cell in blood vessels

54
Q

How is ebola diagnosed?

A

Difficult to know in early stages as conventional symptoms

If ebola is considered, bodily fluid would be sent to lab to be tested

Suspect would be isolated to minimise contact and spreading

If test is positive, patients are sent to hospital high-level isolation unit

If negative, doctors will test for disease such as malaria, typhoid fever or cholera

55
Q

What is treatment for ebola?

A

Vaccines

Intravenous fluids and balancing electrolytes

Maintenance of oxygen status and blood pressure

Treatment of other infections if happens

If one cases confirmed, area should be quarantined

56
Q

What method use virulent phages?

A

Lytic pathway resulting in lysis of prokaryotic cells

57
Q

What methods use temperate phages?

A

Enter lysogeny

Here, viral DNA is incorporated into host DNA and remain dormant as not expressed

Viral genome is replicated everytime host cell divides

This virus is referred as provious as inactive and host cell is said to be lysogenic and capable of lysis when become active

58
Q

What happens in lytic cycle?

A

Host DNA gets digested

Using nucleotides from host DNA, viral DNA formed and increase in number

Host cell synthesise viral phage protein from viral DNA

New phages is assembled and phage enzymes causes lysis

59
Q

What is life cycle of malaria?

A

Mosquito gets plasmodium from infected humans

Virus reproduce in gut of female mosquito that would move into salivary glands

When this feeds on humans, it would be passed into blood with anticoagulant

This would multiply in liver cells

They then gest into red blood cells where multiply again

This causes burst releasing more

60
Q

What is symptoms of malaria?

A

Fever, headache, nausea, sweating, vomiting, diarrhoea, general aches and pains

Complications can occur such as severe anaemia

In some cases (more severe species) the malarial parasite can accumulate in the blood vessels of the kidney causing kidney failure, or in the brain causing seizures, brain damage and coma

61
Q

What is prevention and treatment of malaria?

A

Vaccination

Avoid being bitten by covering arms and legs, using insect repellent and mosquito nets

Use of insecticides (spraying mosquito breeding sites and also in the production of insecticide treated bed nets)

Use of antimalarial drugs, prior to and after travel, such as Atovaquone plus proguanil mefloquine (Larium) and Doxycycline

62
Q

How can eradication of malaria be done?

A

This is difficult due to an increase in numbers of Plasmodium resistant to drugs (e.g. chloroquine) and an increase in numbers of mosquitoes that are resistant to insecticides

Previously it was difficult to produce a vaccine due to the plasmodium occupying the liver and red blood cells

However, first malaria vaccine was licensed in 2021 and second roll out in 2023

The larval stages of the mosquito live in stagnant water, so draining can remove breeding sites

63
Q

How can eradication of malaria be done?

A

This is difficult due to an increase in numbers of Plasmodium resistant to drugs (e.g. chloroquine) and an increase in numbers of mosquitoes that are resistant to insecticides

Previously it was difficult to produce a vaccine due to the plasmodium occupying the liver and red blood cells

However, first malaria vaccine was licensed in 2021 and second roll out in 2023

The larval stages of the mosquito live in stagnant water, so draining can remove breeding sites

64
Q

What is parasite?

A

Feeds on another organism and causes harm

65
Q

Why is malaria not detected by immune system?

A

Lives inside host cells so avoids attack by host

Antigens not exposed
So production of antibodies slowed

Rapidly changing surface antigens
So antibodies no longer effective

Hides. in red blood cells/liver
So antigens cannot be detected

Microbial growth and antibiotics[XA BY02] (5 decks)

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