Just before Christmas last year, a 60-year-old patient at Westmead Hospital got some good news. The woman was suffering from a chronic infection that nothing could shift.

Pseudomonas aeruginosa had taken up residence in her bladder and all of the available antibiotics proved useless. She was facing a decision: radical surgery or a new therapy that has been rarely tested in a western hospital.

She opted for the latter. Over five days just before Christmas 2007, she was infused with a cocktail of bacteriophages through a catheter. Bacteriophages are viruses that infect bacteria and represent the most prolific organism on the planet.

Phages are natural born bacteria killers and are nature’s solution to keeping bacteria in check. They are ancient, they are everywhere and there are an estimated 1031 of them in existence.

The patient began to feel better within a couple of days and was home for Christmas. Six months after her treatment, she remains infection-free.

Not only was this good news for the patient, but good news for the private Sydney company that is developing bacteriophage therapy, Special Phage Holdings(SPH), run by Dr Tony Smithyman.

Phage therapy is nothing new of course, having been used extensively in the countries of the former Soviet Union for close to a century. It is most definitely coming back into fashion in the west, however, as it represents a radically different – and safe - alternative to antibiotics.

Smithyman and his team at SPH have been investigating phage therapy for the last five years. They have managed to refine their technology for collecting, screening and growing phages, and now have a library of several hundred, all specific to particular bacteria and even specific to strains of bacteria.

“They are commonly found in soil, water, plants, sewage, mud – anywhere there is bacteria that they can go and eat,” Smithyman says.

“The question is, how do you get them? You’ve got to go looking for them in the most appropriate places, which means a lot of interesting times. For instance, we go looking in Manly lagoon and Hubert (SPH’s marketing manager, Hubert Mazure) has been on a sewage mission.

“However, you have to have the right systems to extract the phages. There is quite a lot of skill involved. It’s a bit like looking for monoclonal antibodies – you have a target and then you screen. And the longer you go the better you get.”

Bacteriophages come in two forms: lytic and lysogenic. Lytic phages have evolved purely to destroy bacteria, Smithyman says. “There is no messing around with them. They go straight in and destroy the bacteria, and because of that they have fairly small genomes.

“The lysogenic phages have evolved to live with the bacteria, so they have larger genomes and have a different lifecycle. They can transfer toxin genes to the bacteria, so one of the things we have to do in phage therapy is have a system for screening to make sure you don’t have the lysogenic ones.”

Smithyman recently returned from a phage conference in Edinburgh with tales of some of the fascinating research being done with phages throughout the world. Surprisingly, it was the business sector rather than academics that first took the idea of phage therapy and decided to run with it, but Smithyman says the universities are quickly catching up.

“They are looking at using phages for delivering vaccines, a lot of work on using phages for purification and more genetic work coming through to help understand the molecular biology. And then there is the clinical work. A lot of that is very interesting. It is an intrinsically fascinating topic.”