English subtitrări

← What if we could diagnose infections in minutes, not days? | Dr Neciah Dorh | TEDxBristol

Obține codul încorporat
13 Languages

Showing Revision 17 created 04/02/2020 by Leonardo Silva.

  1. Every year,
  2. 700,000 people are killed by superbugs
  3. To put that in perspective,
  4. that's more than the combined populations
    of the cities of Bristol and Bath.
  5. What's more is that in about thirty years
  6. that number is expected to rise
    to 10 million people a year,
  7. which would mean that superbugs
    would have killed more people than cancer.
  8. Now, many of us may have heard
    the term 'superbug'
  9. thrown around at some point in our lives.
  10. But lets take some time to think about
    what it is we're really referring to,
  11. how we got here,
  12. and most importantly,
  13. how do we get ourselves
    out of this crisis?
  14. So what is a superbug?
  15. 'Superbug' is a name given
    to a particular group of bacteria,
  16. otherwise known as a strain,
  17. that cannot be treated
    with most of the antibiotics
  18. available or in use today.
  19. They're a formidable enemy
    when you consider the fact
  20. that many people would not have lived
    to see their sixtieth birthday
  21. prior to the discovery of penicillin
    and other classes of antibiotics.
  22. Raise your hand if you've ever had
    an antibiotic prescribed to you.
  23. OK.
  24. Well, you'll be familiar with the process
    I'm about to describe next.
  25. It probably all started
    when you weren't feeling very well:
  26. a persistent cough, a fever,
  27. or perhaps that burning sensation
    when you'd go for a wee.
  28. (Laughter)
  29. Having put up with it all weekend,
  30. you finally mustered up that courage
    to go out and speak to your doctor.
  31. After reviewing your symptoms,
  32. you're given a prescription
    for antibiotics and told:
  33. 'Come back after the third dose
    if your symptoms persist'.
  34. Now, I'm an engineer,
    so I love my flowcharts.
  35. And they really help me
    get my head around what's going on.
  36. So I took the liberty of putting
    this little schematic together.
  37. So step one: bacterial infection starts.
  38. Step two: signs and symptoms develop.
  39. Step three: person goes out
    to get medical attention.
  40. Step four: antibiotic
    prescription is given.
  41. And step five: after three doses,
  42. check whether symptoms are getting better.
  43. If yes, carry on.
  44. If no, order a diagnostic test
    to determine what is making you sick,
  45. and then return to step three.
  46. Now, I've got the utmost respect
    for our friends in the medical profession,
  47. but this system is fundamentally flawed,
    for a couple of reasons.
  48. Firstly, it encourages your doctor
    to start treatment
  49. before having all the information.
  50. Secondly,
  51. each time we go around that loop,
  52. what we're actually doing
    is killing off all the bacteria
  53. that cannot defend themselves
    against a given antibiotic,
  54. leaving behind a monolithic group
    of bacteria that can.
  55. In effect, we're helping the enemy
    sift out unfit soldiers.
  56. Now, we're in this predicament
    because, still today,
  57. one of the most commonly used methods
    for identifying bacteria
  58. involves taking a sample of urine,
    of mucus, of blood,
  59. and growing it under varying conditions
    to help us piece together the identity.
  60. Think of it like a process of elimination
    carried out in the lab.
  61. Once the bacteria is identified,
  62. we then use another process
  63. to determine which antibiotic
    most likely will work.
  64. The problem is that that takes time,
  65. two days or more,
  66. and in some extreme cases,
  67. people have actually died
    before their doctors got the answers.
  68. Nevertheless, this is our system;
    treatment first, diagnostic second.
  69. So how do we get ourselves out of this?
  70. Actually, it would be a lot better
  71. if we could first work out
    what's making you sick,
  72. and then selecting
    the most appropriate antibiotic.
  73. Not only would you get better days sooner,
    but we'd also curb the rise of superbugs.
  74. But to do that,
    we'd need a test that's fast.
  75. I mean, like, really, really fast;
  76. fast enough to meet the 20 minutes or less
  77. that you have with your doctor
    or your pharmacist.
  78. But also, it'd also need to be affordable;
  79. affordable enough
    that developing countries
  80. could make that transition.
  81. And finally, it would need to be
    easy enough to use
  82. that it's as effortless
    as checking your temperature.
  83. And that is exactly what my team and I
    have been working towards
  84. over the last two years.
  85. We've been developing a technique
    based on receptor-mediated sensing.
  86. We've quoted it GMS for short,
    and it's a lot simpler than it sounds.
  87. For many bacteria,
    the first step of infecting you
  88. involves sticking themselves
    to the cells in your body
  89. using a hook and loop system
  90. that's quite similar
    to what we've come to love in Velcro.
  91. (Laughter)
  92. The hooks in this case
    would be specific proteins, or receptors,
  93. on the surface of the bacteria,
  94. and the loops would be specific molecules
    on the surface of the cells in your body.
  95. What we've done is created a low-cost,
    light-emitting material
  96. and coated it in loops;
  97. let's call them probes.
  98. When we mix our probes with a sample -
    for example, urine -
  99. they stick to bacteria like Velcro.
  100. And by measuring the light
    coming off of them,
  101. we can then calculate the number
    of bacteria present in that sample.
  102. The final process itself
    will be quite simple.
  103. Take a bit of urine,
    add it to a special cartridge.
  104. Then place that cartridge
    in our very own bug detector.
  105. The cartridge would mix
    the urine with our probes
  106. before separating out the bacteria
    and measuring the light coming off.
  107. That final step will allow us to determine
    whether bacteria is present,
  108. which one, and how many,
  109. all within 15 minutes.
  110. From two days, to 15 minutes.
  111. Now, as with most scientific developments,
  112. the journey is fraught with challenges
    and sometimes disappointments, frankly.
  113. And I'll share a couple of them with you.
  114. One of our first challenges was:
    how do you develop a probe
  115. that effectively mimics
    the cells in your body?
  116. It took a team of researchers at the
    University of Bristol
  117. months of experimenting
  118. to get the recipe just right
  119. to have the right type and balance
    of loops to mimic the cell.
  120. I mean, this is not like bashing out
    bad pancakes on a Sunday morning.
  121. This is the kind of effort
    you put into winning Masterchef.
  122. (Chuckling)
  123. The second challenge for us was actually
    finding a detection method
  124. that was low-cost, yet powerful enough
    to detect the probes
  125. once attached to the bacteria.
  126. For that, we turned to a well-established
    technique based on fluorescence.
  127. Fluorescence is a phenomenon
  128. where a material stimulated with light
    absorbs some of it,
  129. and re-emits a different colour.
  130. As a detection technique,
  131. we'd effectively take
    a specific colour of light,
  132. shine it at that material,
    and observe the colour coming back,
  133. and that helps us tell what's present.
  134. So, we've got probes,
    they stick to the right bacteria,
  135. and we can detect them.
  136. Job done, right?
  137. Actually, not quite.
  138. Most of the foods that we eat
    actually get broken down
  139. into light-emitting materials
    that end up in your wee.
  140. And so, these are things like
    energy drinks, vitamin supplements,
  141. pregnancy supplements,
  142. and all of these together
    could lead to false positives.
  143. In other words, they make it really hard
    for us to determine the difference
  144. between friend or foe.
  145. And so, differentiating our probes from
    the remnants of your last energy drink
  146. is absolutely important
  147. for ensuring that we do not report
    that bacteria is present
  148. even when there aren't any.
  149. This is where the research
    took a really interesting turn,
  150. because getting around this
    meant getting familiar with our probes,
  151. but also getting
    really familiar with urine.
  152. We carried out several experiments
    observing how our probes behaved
  153. when stimulated with
    different colours of light.
  154. Particularly, we're interested
    in how much green light is emitted
  155. for every colour of light
    that we stimulated them with.
  156. This is the profile of our probes,
  157. and it does not change.
  158. So any deviation from that
    would then tell us
  159. that there's other stuff
    mixed in with the sample,
  160. and it would look a little bit like
    when it's mixed with urine, for example.
  161. By measuring that change,
    we can actively correct for interference
  162. from anything else
    that's present in the urine.
  163. So pulling it all together,
    the probes help us find the bacteria
  164. and fluorescence helps us find the probes.
  165. We're still at the
    early stages of our journey,
  166. but we were able to take
    our first prototype into a hospital lab
  167. where we tested for E. coli
    in human urine.
  168. GMS was able to detect the presence
    of urine without any false positives,
  169. and it correctly reported the absence
    of E. coli in the urine in 63% of cases.
  170. Finally,
  171. by placing three measurements in parallel,
  172. we were able to achieve an average time
    per test of just four minutes.
  173. This is certainly not
    the end of the story for us.
  174. We're now developing other forms of loops
    to address other harmful bacteria,
  175. and we aim to test and improve
    the system a few more times
  176. before it gets to your GP.
  177. But once we do this,
  178. combining our faster, accurate diagnostics
  179. with better antibiotic usage
    and continued public engagement,
  180. we could finally tip this war
    back in our favour
  181. and overcome superbugs once and for all.
  182. Thank you.
  183. (Applause)