TB Flashcards
1
Q
how did we double the human life expectancy
A
conquering infectious disease
2
Q
what are the 3 big components of conquering infectious disease
A
1) knowledge of the true method of transmission of disease = Germ Theory (for some disease we can take action - cholera - clean water supplies)
2) development of antibiotics (treat bacterial disease)
3) development of an effective vaccine (prevent disease from spreading
3
Q
what did John Snow do
A
1850-1900 transmission of Miasma Theory - Germ Theory
4
Q
name the bacteria that cause Tb
A
Mycobacterium tuberculosis
5
Q
before antibiotics for Tb
A
millions of people died, no treatment or cure for tb
6
Q
after antibiotics
A
the disease could be cured
7
Q
last few years what has happened to Tb
A
increase in the prevalence of drug-resistant Tb = hard to treat >inurable Tb
8
Q
how many people infected with Tb in the world
A
1/4 of the population infected 1.8 billion people
9
Q
incidence
A
new cases of Tb = active cases
10
Q
what countries are most likely to have TB
A
India and China = vast populations
11
Q
mode of transmission for Tb
A
DIRECT CONTACT = person with active case of Tb: coughs, spits, sneezes, expels droplets with bacteria
12
Q
what was an attempt to stop the spread of Tb in the past
A
stop people from spitting/coughing in public
13
Q
if exposed to someone with Tb will you get Tb
A
probably not 1/5 chance
14
Q
why will you be unlikely to get infected by someone who has Tb
A
of those infected 90% = do not develop active case of tb - still, have Tb bacteria, not multiplying, low number, dormant, not infectious, not symptomatic
15
Q
what happens to 10% of the population infected
A
immediately develop an active case of Tb = no of bacteria increase and cause problems
16
Q
what happens to 90% Asymptomatic/latent Tb cases
A
immune system fought bacteria but some still survive = if something changes > later develop Tb
17
Q
a difference between cholera and Tb
A
Tb = slow disease
18
Q
changes that cause latent Tb to become active
A
- age (older immune system changes)
- general welfare (nutrition)
- other diseases (AIDS/Cancers)
- immunosuppression for cancer therapy
- immunosuppression for transplants
- stress
19
Q
if untreated active cases of Tb have a death rate of
A
50% within 2 years
20
Q
how does Tb affect you
A
inhaling droplets > respiratory system > lung function lost
21
Q
if you’re vaccinated against Tb what will be the result of a skin test
A
postive skin test - detects if the immune system has mounted response
22
Q
what are 3 reasons why you can get a positive result for a standard Tb test
A
- active case
- latent case
- had vaccine
23
Q
1815 how many people died of Tb in England
A
1/4
24
Q
who did Tb affect
A
rich and poor equally
25
what kind of disease is Tb, contrast to cholera
endemic (cholera = epidemic)
26
where is Tb more likely and what age group were mostly affected
crowded urban cities - prime age of life
27
can Tb be caused by other species
yes in cattle = can affect humans and vice versa
28
what causes Tb in cattle
Mycobacterium Bovis (slow-growing)
29
what causes Tb in humans
Mycobacterium tuberculosis (slow-growing)
30
a way in which Tb can be transmitted
via milk
31
how do you kill microbes - Louis Pasteur
boil them
32
what happens if you boil milk
changes chemistry
33
what did Louis Pasteur realize
raise temp - reach point where you kill microbes before boiling = repeat several times = kill most of microbes (low level = decreases chances of infection)
34
what years did Louis Pasteur carry out relevant work
The 1860s, 1870s, 1880s
35
vaccine
a preparation of killed microorganisms, living attenuated organisms or living fully virulent organisms administered to produce or artificially increase immunity to a particular disease
36
vaccination
administering weakened or dead pathogens to a healthy person or animal, with the intent of conferring immunity against a targeted form of a related disease agent
37
BCG
is a vaccine against Tb that is prepared from a strain of the attenuated (weakened) live Mycobacterium Bovis
38
attenuated
reducing the virulence of an organism, usually a virus whilst keeping it viable (can infect a person but the immune system can fight it)
39
what countries use BCG
countries with Tb
40
The US and Western European countries do not use BCG, how do they then detect Tb
simple test: Tb Skin Test
use a purified protein from Tb (not infectious/bacteria) - recognized by immune system
measure size of the raised area
never seen before = small reaction
41
why do the US and Western European countries do not use BCG
because of the low risk of infection
42
how did we develop 2 strains of Tb
early human history: single disease only affected cattle, then evolved to affect humans, humans became more abundant - evolutionary event = two different strains
43
asymptomatic
individuals affected by the disease but do not show any of the typical symptoms
44
Tb
a chronic infectious disease usually caused by mycobacterium tuberculosis in humans
45
how did strain specialized in humans spread
human density increased, as people moved to cities
46
where was a common site of breeding for Tb in Victorian England
in Debtor's prison
47
how was Tb exported to different countries
people moved from England to colonies > returned back brought Tb with them
48
why did people not think Tb was infectious
slow disease - thought it ran in the family
49
when did Robert Koch find a causative agent for Tb
1982
50
when did we find out Tb was infectious
The 1860s
51
when were antibiotics discovered and by who and what was the first antibiotic
1928, Alexander Flemming, penicillin
52
what did we do to treat Tb without antibiotics and why, did it help
place people in sanitoriums, get fresh air
| 50% of people died within 5 years
53
how did Alexander Flemming discover antibiotics
knew that bacteria grown in different conditions = show different results
Staphylococcus aureus -grow well in the human body and not room temperature
Fungi - optimum at room temperature
Halo around fungus - fungus producing something killing bacteria - isolated fungi and identified it, substance it produced = penicillin
54
how was penicillin obtained
solely from fungal growth
55
how was penicillin develop
find fungi that produced most penicillin - need huge culture, stabilize it - go to markets and collect mouldy fruits
56
how did Howard Florey and Ernst Chain contribute to antibiotics and when
1930s/1940s
1. increased productivity by 4 orders of magnitude
2. developed submerged cultures
57
what do bacteria do and how are they able to
grow and divide - continually make cell wall - defence against the extracellular environment/organisms
58
how is bacterial cell wall made
PEPTIDOGLYCAN - numerous glycan backbones connected by peptides
59
gram-positive
thick wall of peptidoglycan
60
gram-negative
peptidoglycan between membranes = defend better, substance don't reach it easily (outer membrane)
61
how do beta-lactam antibiotics work (include penicillin and derivatives)
bacteria make glycan backbones then move to surface - enzyme allows peptide bonding - part of penicillin structure that enzyme recognizes = enzyme binds to penicillin = irreversible
62
effect of penicillin on bacteria
```
gram-positive = enough kills them
gram-negative = variable, far less effective
```
63
did we conquer all infectious diseases with antibiotics
no, gram-negative bacteria diseases are not treated
64
bacteria causing infections (wound/following surgery)
all gram-positive
65
some gram-positive bacteria form spores which are very resistant, how did Flemming detect this
took swatches from soldiers uniform, put them on cultures = clostridium
66
antiseptics
kill bacteria
67
how did Flemming show antiseptics don't work on battlefield wounds
1. two sterile tubes: smooth.cracked
2. pollute with bacteria
3. disinfect tubes
4. apply a culture medium to tubes
= disinfectant work on smooth surfaces (reach all bacteria) not on rough edges
68
was evolution to antibiotic resistance expected
| and how do multicellular/eukaryotic organisms get new info
expected but didn't know the different ways bacteria could acquire new info - bacteria evolve resistance to one antibiotic, may develop for everything that has the same mode of action - (humans only get new genetic info by mutation)
69
different antibiotics have
MODES OF ACTION
70
how does natural selection work (penicillin)
1. original population = variation of bacteria
2. change the environment by adding penicillin - ones that die fist = make least cell wall making enzyme
3. some bacteria resistant to antibiotic = natural selection population favours this bacteria
(changing env = favours surviving bacteria)
71
why do antibiotics have trouble reaching mycobacteria
thick waxy coat outside layer
72
what year did we antibiotics against all bacteria
1950s
73
how do genes for resistance appear
```
bacteria can acquire new info by
1. transformation
2.transduction
3. conjugation
AND MUTATION
```
74
transformation
some bacteria can take up DNA from the environment and incorporate into own genetic sequence
75
competence (for bacteria)
the ability of a cell to take up extracellular DNA from its environment
76
transduction
the process by which bacterial DNA is moved from one bacterium to another by a virus
77
conjugation
transfer of genetic information between bacteria through direct cell-to-cell direct
. plasmids replicate and pass info
. can occur between different species
78
what are some resistance mechanisms of bacteria
1. degrade antibiotics (penicillinase)
2. make more product
3. alter antibiotic
pump out antibiotic
79
where do antibiotics come from
not invented, come from the natural world - pencilin came from a fungus
bacteria competing in soil (grow and divide)
80
types of antibiotic misuse
1. inappropriate prescription (antibiotics only kill bacteria, not viruses)
2. use of broad-spectrum antibiotics - affect range of bacteria (patient, doctor, company = happy ) * all bacteria get affected - some resistant - selected in that population
3. agricultural use (pigs grew 50% faster)
4. incorrect use (incomplete course/Tb thicky waxy layer = harder to reach)
5. water contamination (urinate antibiotics - water sources not regulated)
81
why are we 'back in the nineteenth century'
Tb - strains we can't deal with > back to sanitariums/accept the transmission of an incurable disease
82
MDR-TB
multi-drug-resistant Tb - any strain of Tb that is resistant to both of the two main first-line antibiotic drugs
83
how many antibiotics do you get prescribed for Tb and why
cocktail of antibiotics - mutation can develop resistance
84
problems between the first and second-line drugs
cost and severe side effects
85
XDR-TB
extreme drug-resistant Tb - any strain of Tb that is resistant to both of the two main first-line antibiotic drugs AND two more of the second-line drugs
86
antibiotic resistance strains are a big problem before antibiotics resistant to everything why
1. drugs of last resort - more expensive
2. inconvenience - drugs may need to be given intravenously and over longer period
3. side effects - much more severe
87
why are we still heading in the wrong direction
no new antibiotics being made
88
antibiotics
chemical substance that kills/suppresses the growth of microorganisms
89
antibiotic resistance
ability of a microorganism to withstand the effects of an antibiotic
90
latent/dormant infection
asymptomatic infection only capable of manifesting symptoms if activated
91
Describe the work of Fleming, and Florey and Chain, and how this work was important
Fleming isolated penicillin from a fungus that was killing bacteria, the first antibiotic
Florey and Chain found more productive strains of penicillin to increase productivity
This work allowed widespread use of ABs, reducing mortality from infection in WWII and paving the way for widespread use of ABs throughout the world
