Posts Tagged ‘uk’

Toothbrushes and breath testers for tuberculosis

// January 15th, 2013 // Comments Off on Toothbrushes and breath testers for tuberculosis // Recent Research

Far-advanced tuberculosis diagnosed by x-ray. Image from the CDC, accessed on Wikipedia.

Tuberculosis is a major health issue, with around a third of the world’s population infected with the bacteria mycobacterium tuberculosis. Not all these people actually have signs of illness, only 10% will go on to have any symptoms during their life. For the rest it remains latent, the bacteria is present but not causing any problems.

As tuberculosis is only contagious and dangerous when it’s active, that’s usually what people test for. Chest x-rays can check whether TB has affected the lungs, and are required for people travelling from high-TB countries to low-TB countries including Australia and the United Kingdom. The other avenue for diagnoses is the slightly grosser method of analysing the gunk people cough up, to see if there’s bacteria in it. For  mycobacterium tuberculosis, growing a sample in agar takes weeks.

A breath test would be a much safer and faster way to see if bacteria are present in the lungs, and that’s what our first paper is looking at. Researchers from the University of Vermont are finding out whether bacteria can be identified by their “chemical fingerprint,” a cocktail of chemicals that makes its way from the lungs to the breath. Their research is published in the Journal of Breath Research.

Now, it’s some time before police can pull you over for a quick TB test when you’ve been swerving off the road from a coughing fit. “Honestly, it’s just the flu!” But it’s got to be a cheaper option for many countries with low health care budgets.

TB poster, image from Wikipedia.

It is early research. They studied the tiny puffs from mice, rather than humans, and looked at two different bacteria that cause lung infections Pseudomonas aeruginosa and Staphylococcus aureus (Golden staph), neither of which are the TB bacteria. Clearly there is more research to be done, but it’s a promising start.

Read more about it here.

TB can be cured with a course of antibiotics, or more specifically a combination of several antibiotics that have to be taken for six months. Like Golden Staph, the bacteria that causes tuberculosis is becoming increasingly drug resistant. Drug resistant strains need different antibiotics and take 18 months or more to cure.

In Papua New Guinea, extensively drug resistant TB is a problem. A recent outbreak there and movement of patients to better health facilities in Queensland and the Torres Strait Islands has triggered alarm and, frankly, scaremongering media reports and political backlash. You can read about it on the Conversation, because I’ve been out of Aus too long to be in on the goss (but I’m back in a month, yay!)

The next weapon against drug resistant TB may come in the unlikely form of a traditional toothbrush. The South African toothbrush tree contains a compound called diospyrin, which inactivates an enzyme critical for bacteria reproduction (but does not affect the similar enzyme found in human cells.) The enzyme is a DNA gyrase… would you care to know how it works?

When DNA is replicated, the two strands normally joined in a double helix are broken apart, and you can imagine it’s like putting your fingers into a rope and pulling apart the strands. If this imaginary rope is a circle (as DNA in bacteria is) then it can’t just unwind itself at the ends. Instead, things will get messy, and the DNA will coil and twist up on itself. These “positive supercoils” are a bit like like twisting a shoelace until it bunches up, and is bad for the DNA. Gyrases relax the positive supercoils by cutting the DNA and moving one strand to the other side, then joining them up again.

Circular DNA supercoiling. Image by Richard Wheeler.

Circular DNA supercoiling. Image by Richard Wheeler.[/caption]

By stopping gyrase activity, the bacteria can’t replicate its DNA. The research by a team from the UK and South Africa described how this compound from the toothbrush tree interferes with gyrase, and importantly, that it acts in a different way to existing antibiotics. This will hopefully be a chink to exploit in the armour of drug resistant bacteria.

Here’s the paper from the Journal of Biological Chemistry and the press release.






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