Ever since the infamous US anthrax attacks of 2001, where envelopes containing anthrax spores were mailed to a number of media outlets and two US Senators, there has been a push to develop new ways of determining the severity of anthrax infections.

John Barr, of the US Centers for Disease Control and Prevention (CDC), has developed a new, more sensitive way of monitoring the level of infection in a victim. This is keenly important as the symptoms for anthrax infection start off looking much like a cold or the flu, but can then lead to a subject deteriorating rapidly – often leading to death, even after treatment. According to Barr some 40 per cent of the victims of the 2001 anthrax letters died.

The Bacillus anthracis bacterium produces two different t toxins, the oedema factor and the lethal factor. Barr has developed a way of detecting both of these using a liquid chromatography – mass spectrometry (LC-MS) approach that can provide earlier diagnosis than any other technique. This is particularly important as providing antibiotics at an early stage in the infection can increase the odds of survival.

His method, which uses an antibody purification step to extract the toxins, can detect the toxins at concentrations as low as 25pg/ml in about two hours. If the antibody extraction step is left for around 16 hours, that detection limit can fall as low as 5 pg/ml.

The progression of the infection tends to go through a brief remission, and the changes in lethal factor levels correlate with the clinical symptoms – and during remission other methods that rely on detecting the bacteria themselves often fail during this stage.

Barr believes his results should enable clinicians to predict the clinical outcome of an infection, which could prove immensely important as there have recently been a number of anthrax poisoning cases in Scotland, after heroin addicts injected themselves with anthrax-contaminated spores.

Matt Wilkinson