Antibiotic resistance is one of the nastier problems we’ve got on the horizon. But why is it happening? Why is it getting worse, and what causes it? Most importantly, what can we do to stop it?

There are a lot of diseases that we don’t really worry about at the moment, and it’s all thanks to antibiotics. About 90 years ago, biologist Alexander Fleming discovered penicillin, the first antibiotic. He had a petri dish with bacteria growing on it, and accidentally left it too long. He later noticed that there was some mould growing on part of the dish, and around it, there was a clear area where the bacteria weren’t growing. He investigated, and it turned out that the mould was producing a substance that killed bacteria, in order to compete with them for resources. That substance was penicillin. If you read my previous blog about Louis Pasteur, you might recall that he had some bacteria left too long which failed to make some chickens sick, and led to some of the first vaccines. Biology Badger really loves that two of the best weapons against infectious diseases, vaccines and antibiotics, came of accidentally leaving things out and having them “go off”!

Image: A petri-dish with some mould on it. The clear area around the colony in the top right is caused by an antibiotic.

Penicillin was eventually heavily used in people to fight a variety of bacteria, and other antibiotics soon followed. Some very bad diseases were caused by bacteria and used to be extremely common! In particular, tuberculosis, a common lung infection, used to kill huge numbers of people (and in fact still does in parts of the world). Getting an infected wound used to be incredibly dangerous, bacteria causing gangrene and effectively rotting the wound from the inside! Others, like leprosy, plague (that caused the black death), salmonella, cholera, and many others, harm vastly fewer people now then they did historically.

Antibiotics work because bacteria cells are different from animal cells. Separated from multicellular animals and plants by a billion years of evolution, there are quite a few of these differences. An important one is that unlike animal cells, bacteria have a cell wall. They also have different “machinery” in them for keeping them alive and making the bits and pieces for living, like proteins. An antibiotic usually breaks one of these bits of machinery and the bacteria then dies or can’t grow! Penicillin stops the bacteria from making it walls, and other antibiotics knock holes in them so all the innards leak out and kill the bacteria! Our cells, lacking the machinery or a cell wall, are just fine and happily continue along.

Image: Bacteria hanging out. They look pleased with themselves.

Unfortunately, bacteria are extremely adaptive little devils, and some of them have been gaining resistance to different kinds of antibiotics. Imagine a situation where there’s a cluster of thousands of bad bacteria, just hanging out doing what they do, causing a sickness in the person they’re living in. There are so many of them, some of them, just by the nature of chance and mutation, are slightly different from the others. Along comes an antibiotic, killing most of the bacteria by getting inside and breaking some of its machinery. But a couple of bacteria cells don’t die with the rest! Maybe the bit of the machinery that the antibiotic targets is slightly differently shaped so the antibiotic can’t break it. Maybe the bacteria has a pump in its wall that grabs the antibiotic and shoves it out of the cell so that it’s machinery is safe, or it makes little chemicals that break the antibiotic before it can work – these are all ways in which bacteria have adapted to different antibiotics.

Image: Most of the bacteria aren’t so happy now. In fact, the antibiotic yellow lightning has killed them all but one! He has an umbrella!

However the bacteria does it, it doesn’t die. And now it’s all alone and ready to start growing without any competition, so makes thousands and thousands of new friends, and all of them inherit the resistance to the antibiotic. Now the disease can get worse, and even spread to other places and people.

Image: He probably gets hailed as the chosen one.

Worst of all, this can happen over and over with bacteria becoming resistant to multiple antibiotics in turn.

This has been going on for a long time now, and it’s beginning to get really serious. MRSA is an antibiotic resistant disease that’s causing illness in hospitals, and there are others, like C difficile, syphilis, some types of E coli, and tuberculosis, which have become really difficult to treat as they don’t get killed by most antibiotics. These will only get worse in time.

Scientists and Doctors are very much aware of the problem and are working hard on it. New antibiotics are being developed that the bacteria aren’t resistant to. Changes in procedures in hospitals are making it less likely for antibiotic resistant diseases to be passed on. New approaches, like giving patients a virus that kills bacteria (known as a phage) are being tried. However, it seems like it will be awhile before our efforts to stop the problems will take effect, and in the meantime, resistance to drugs is becoming more widespread and potentially deadly. It could make a really big difference to our culture if old infectious diseases come back as we look for ways to stop it, and for that reason, and it’s seeming inevitability, Biology Badger gives antibiotic resistance a Doomwatch rating of “foreboding”.

IMAGE: Don’t worry son, you can’t get an antibiotic-resistant infection. Because there aren’t any antibiotics yet. Also, we’ll have to remove your arm.

Bacteria aren’t the only thing that gets resistant to drugs. Take a look at this post on fungal drug resistance at Jeez, Disease!

Images: Title image from Wikipedia commons, petri dish from Forbes.com, Crudely drawn diagrams by Biology Badger