Somerset Times

Flesh-Eating Bacteria in Year 7 Science




Somerset Times Edition

Week 10,
Term Two, 2016

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On 1 June, Year 7 was fortunate enough to be visited by Dr John Gerrard, a biologist who investigated an uncommon disease that occurred in parts of Australia and the United States of America. For around a decade, Dr Gerrard passionately examined this unknown disease, until he found the cause of this flesh-eating bacteria.

Throughout the talk, Dr Gerrard explained to us how he first heard of the disease and his journey of uncovering the mystery of it. He said that a man (named MB) was first discovered when he checked into a Gold Coast hospital. This man suffered from various red lumps along his lower limbs, upper limbs and trunk, as well as a high fever. Similar cases had been popping up around Australia and the US.

Dr Gerrard told us that he searched the land the man was working on, but found no further evidence. They did, however, take blood and tissue samples to a lab, where they found a strange bacterium growing over the plates. Using DNA sequencing, they were able to discover that the bacterium was Photorhabdus, meaning ‘light rod’ in Greek, given its name for its ability to glow in the dark. After doing some more research, they found that Photorhabdus was normally found in a small worm. This worm penetrates the skin of insects, whereupon it vomits up the Photorhabdus, killing the insect, but at the same time preserving the body. Once inside the insect, the worm starts multiplying, until thousands of them appear.

After doing extensive research over the course of a decade, Dr Gerrard was eventually able to find evidence supporting the idea that these worms were attacking humans, hence the flesh starting to erode from the body. Throughout his talk, Dr Gerrard displayed a PowerPoint he created that guided his talk. A couple of slides showed the detrimental effects of the bacterium at the infection sites, to which most of the Year 7s recoiled in horror at the sight of nasty, peeling flesh!

On one of the occasions, a man had been renovating the outside part of his house. He had been digging deep holes in the dirt to make room for the fence poles that he would eventually install. He was using his right hand to scoop up handfuls of the soils at a time. Sometime afterwards, he began to develop a nasty, deep infectious area on the back of his right hand. The wound was so deep, his tendons could be seen from the outside. Soon, Dr Gerrard arrived back at his house and began to look for any signs of a worm, but they were nowhere to be seen.

Dr Gerrard then decided to use live mealworms as a bait, hoping to entice the infectious worms from the soil. A week later, when Dr Gerrard went to check on his soil samples, he found all the mealworms dead. Curiously, Dr Gerrard placed one of the mealworms under a microscope and there, he saw, one by one, tiny worms escaping the body of the mealworm. Then came tens, hundreds and thousands of them. He had found the answer and the culprit to the origins of this unknown disease! As a result of his amazing discovery, he managed to have the new species of bacteria carried by the worm named after him, Photorabdus gerradi.

On behalf of Year 7, we would like to thank Dr Gerrard for taking time out of his day to talk about his amazing discovery, as well as Mrs Walker for organising the talk. We all enjoyed having Dr Gerrard talk to us, even if it involved some unpleasant images of worms and rotting flesh.

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