( Antibiotic doses could be reduced by up...)New approach could lower antibiotic requirements by 50 times

Steven Hagens, previously at the University of Vienna, told Chemistry & Industry, the magazine of the SCI, that certain bacteriophages, a type of virus that infects bacteria, can boost the effectiveness of antibiotics gentamicin, gramacidin or tetracycline.

It is the phages' ability to channel through bacterial cell membranes that boosts antibiotic effectiveness. 'Pseudomonas bacteria for example are particularly multi-resistant to antibiotics because they have efflux pump mechanisms that enable them to throw out antibiotics. A pore in the cell wall would obviously cancel the efflux effect,' Hagens explains.

Pseudomonas bacteria cause pneumonia and are a common cause of hospital-acquired infections.

Experiments in mice revealed that 75% of those infected with a lethal dose of Pseudomonas survived if the antibiotic gentamicin was administered in the presence of bacteriophages. None survived without the phages (Microb. Drug Resist., 2006, 12 (3), 164).

The bacteriophage approach would also be particularly useful for treating cases of food poisoning, because the lower doses of antibiotic needed would not disrupt the friendly bacteria in the gut - a big problem with conventional antibiotic treatments.

'The prospect of using such treatments to prolong the life of existing agents and delay the onset of widespread resistance is to be welcomed,' said Jim Spencer a lecturer in microbial pathogenesis at the University of Bristol.

The overuse of antibiotics since the 1940s had slowly created a host of infections that are resistant to antibiotics. MRSA (Methicillin-resistant Staphylococcus aureus) for example is rapidly spreading through hospitals, affecting more than 8,000 people in the UK every year. MRSA infection can lead to septic shock and death.