Saturday, 11 July 2009

Erm, does anyone have any new antibitoics?

The golden age of antibiotics is drawing gradually but definitively to an end.

Since Alexander Flemming revoloutionised the way we view diseases with his discovery of penicillin in 1928, we have stopped worryingabout ailments like whooping cough and tuberculosis. It's worth remembering though that pre-1920s these kind of bacterial infections were rife, and wiped out large numbers of people, regularly. Plague epidemics, for example, have occurred several times in the last ten thousand years, with notably widespread outbreaks in the mid 1300s, 1665 ('the great plague of London') and again just before the beginning of the 20th century. There were also localised bouts constantly happening all over the world up until Flemmings' breakthrough.

So we've seemed to have the upper hand on bacteria for the last 100 years or so - but bugs that we can't beat are coming back. For instance, MRSA [1] has been thwarting the efforts of hospital staff to disinfect-it-out-of-existence for a number of years now. Although they're not bactrial (but rather viral) in nature, the SARS [2] and swine flu epidemics are two other examples - rather more immediate and frightening ones - of why we need to sit up and start thinking about whether we are too comfortable with the ways we treat disease.

The problem is that bacteria are very quick to develop resistance to antibiotics. Drugs like penicillin, great 40 or so years ago, quickly became no good at treating a whole host of bacterial infections. So called wide-spectrum antibiotics have been a big problem; they act upon just about any bacteria they meet, so even if all the bacteria which are the source of the problem are destroyed, lots of others will inevitably remain which have had a chance to build up resistance. Up until now we've had reserve drugs, which we only use in emegencies, so bacteria don't have a chnace to develop resistence. Even these though, are beginning to become less effective. It may only be a matter of decades before we no longer have a last line of antibiotic defence. We need new drugs, and quickly.

In science, researchers often look to nature for inspiration, and for this reason it turns out that the majority of the antibiotics in clinical use today are what are called 'natural products'. These are complicated chemicals which float around in all living organisms. Especially interesting ones can be found in single-celled organisms. Typically scientists take one of these cells, (a type known as streptomyces is very popular) and extract some of its bodily fluids and try and identify the various compounds contained in them. This kind of process led to the identification of some of the most powerful antibiotics we know of, such as Vancomycin and Chloramphenicol.

Now its getting progressively more difficult to identify new, useful antibiotics. One way some scientists think we should move forward is to, again, take a quick look at nature and see what we can learn. But this time we need to look in new places.

Recently sceintists have begun to explore in depth a fact which we have known in essence for many years. That is that many species of insect actually use docile bacteria as a protection against the more vicious ones [3]. Storing the organisms in their skin or intestines, or even farming them in the open, insects appear to grow the good bacteria as a protection against the bad. The question is, what compounds are responsible for keeping the bad guys at bay?

Take for example the european Beewolf. Not a bee at all, but an insect which paralyses bees and transports them back, alive, to their sand-burrow nests. There, the imobilised bees are a welcome food source for little beewolf larvae.

The Beewolf - not a bee

The hot sandy burrows are warm and moist - perfect conditions for all types of life, including bacteria. So how is it that the beewolf larvae do so well, apparently immune to the presence of the microorganisms? Researchers have now found that the mature Beewolves smear a sticky white broth containing a previously unencountered type of Streptomyces bacteria all over the cocoons of the developing larvae [4]. The insects and the streptomyces live in a symbiant relationship - the bacteria keep the larvae safe by fighting off infections with their antibiotics, and in return they live off a diet of nice, juicy Bee. Scientists don't yet know what the active compounds the bacteria produce are, but they could prove to be potent antibacterials for human use, too.

Another symbiant partnership exists between leafcutter ants and the common fungus they feed on. The ants carefully farm the fungus, which they use as food. In many parts of the world a highly competitive fungus called Escovopsis out-competes it's fungal enemies. This never happens in ant-farmed funus patches though - why? Again, scientists have been on the trail and have found the ants have been growing bacteria alongside the fungus.

When these new-to-science bacteria were grown in a laboratory, scientists identified a new compound - dentigerumycin - and sure enough, when applied to some Escovopsis it was a potent fungicide.

There are lots more symbiotic insect-microorganism relationships out there which we haven't yet discovered. I'm not suggesting we start coating our young in sticky bacterial broths, but if we continue studying these relationships closely it is easy to imagine a whole host of potential new drugs waiting to be harvested. Then we can keep one step ahead of those pesky mutating bacteria.

Notes and references

[1] MRSA = Methicllin-resistant staphylococcus aureus
[2] SARS = Severe, acute respiratory syndrome
[3] H. B. Bode, Angew. Chem. Int. Ed., 2009, 48, 2 - 5.
[4] M. Kaltenpoth, W. Gttler, G. Herzner, E. Strohm, Curr. Biol. 2005, 15, 475 – 479

Sunday, 5 July 2009


Last week it was climate change, this week alternative medicines threatening developing countries. Is it me, or is benchtwentyone developing a sentimental side?

I sincerely hope not. None the less I think it's important people know a little bit about homeopathy and how dangerous it can be if approached from a naive standpoint. Homeopathy is a form of alternative medicine which claims to be able to treat various illness by presenting the patient with highly dilute 'preparations'. Sometimes the disease-causing item itself is used in the preparation, sometimes not. The important criterion for homeopathic preparations is that the substance used in them causes the symptoms the patient presents - whether it is the real cause or not is irrelevant. For example to treat a runny nose (caused by a virus, say) a homeopath might employ onion essence, as this induces the same symptoms.

And what do I mean by highly dilute? Well, for a patient suffering from hayfever, the homeopathic practitioner might take
a grain of pollen and dilute it in 100 ml of water. He would then take a drop of this and dilute it again with a further 100 ml of water. If he repeats this action 30 times he ends up with what homeopaths call a 30C preparation, which would be administered to the patient. The general idea is that by presenting the sufferer with an extremely small amount of a substance which causes their symptoms, they will some how become acclimatised to it.

You might be thinking this seems a little rubbish. Would onion extract really cure me of my cold? Well, benchtwentyone (and many others around the globe) is here to point out that these astute individuals are 100% right. Once you have carried out dilution to that extent, you end up with essentially a jar of water. In point of fact, the chance of there being even a single molecule of the active ingredient in a 30C preparation is less than the chance of winning the lottery five weeks in a row [1].

When charged with this fact, homeopaths sometimes respond by stating that water has a 'memory' which somehow transfers an impression of the active ingredient (what little there is of it) to the body.
I don't want to skirt the issue on benchtwentyone, so let's be frank - this is utterly unsubstantiated nonsense. Water doesn't have a memory, and once a substance is taken out of it there is no impression left on the water molecules. No serious scientist has ever presented a shred of evidence that anything like this is possible

So homeopathy is scientifically on very dodgy ground. If we are rating this treatment by how sure we are that it works based on pharmacological trials and scientific proof it scores a rather fat zero. In a recent report by premier medical journal
The Lancet, researchers found that there is absolutely no evidence that homeopathy works at all on a biological basis [2].

It seems clear that in cases where homeopathy appears to do some good in patients (and believe it or not there are some patients who claim it does) it is merely a placebo effect. That is, the patient believes that they have been given a cure or treatment and thus something in their mentality makes them feel better even though there is no physiological change.

I was disturbed to learn this week then, that Homeopathy, while at least not life-threatening in developed countries, is now being advertised in the developing world as an alternative therapy for conditions such as HIV/AIDS, TB and diarrhoea. Homeopathic clinics offer pricey treatments for vunerable people - and are making fairly big sums of money off the back of it. This is serious stuff, as people are being given false hope in the face of life-threatening conditions. What is more there are perfectly safe and - importantly - scientifically proven treatments which can treat and help control the spread of these conditions.

A group of scientists from the VoYS (Voice of young science) wrote to the World Health Organisation last week calling for them to issue a strong statement to condemn homeopathy as the fraudulent and dangerous thing it really is. You can read the letter, which was reported on in the guardian, here. Hopefully this will signify the begining of the end for homeopathy clinics in the developing world.


[1] Sense about Homeopathy, a briefing document from Sense about science, published online here.

[2] A. Shang et al., The Lancet, 2005, 366, 726 - 732.