Bicarbonate turns bacteria virulent

Findings in Bacillus anthracis may provide basis for new drug development
Scientists from the Scripps Research Institute have discovered that bicarbonate is the key chemical that signals Bacillus anthracis, the aerobic sporulate bacterium that causes anthrax, to become lethal. This finding opens up new avenues of exploration for the development of treatments for bacterial infections.
The scientists identified bicarbonate, a chemical found in all body fluids and organs that plays a major role in maintaining pH balance in cells, as providing the signal for Bacillus anthracis to unleash virulence factors. Without the presence of the bicarbonate transporter in the bloodstream, the scientists found, the bacteria do not become virulent.
Scientists have known for some time that bicarbonate is implicated in many diseases, but controversy has existed about whether bicarbonate, carbon dioxide, or some combination of these two molecules are responsible for triggering bacterial pathogenesis. This study confirms, for the first time, that it is indeed bicarbonate, rather than carbon dioxide, that signals the gram-positive B. anthracis to become virulent. This finding also is significant because other pathogenic bacteria such as Streptococcus pyogenes, Escherichia coli, Borrelia burgdorferi, and Vibrio cholerae have bicarbonate transport pathways similar to B. anthracis and thus are likely to have similar virulence triggering mechanisms.
Gram-positive bacteria are the major culprits driving the increase of community and hospital acquired bacterial infections. The Centers for Disease Control and Prevention estimates that as many as 10 percent of all patients, or about 2 million people, contract hospital acquired infections each year. These bacteria are often resistant to multiple antibiotics, making the problem a growing public health concern and the need for new antibacterial treatment more urgent. Now, the bicarbonate transporter pathway may be investigated as a potential new target for drug intervention.
The best medium for toxin production was one that people believed mimicked conditions found in the blood of a human or animal host, where anthrax bacteria would find both carbon dioxide and bicarbonate. But it is not known which of these two molecules was the more important for bacterial pathogenesis, according to these results bicarbonate is the molecule that triggers the growth by mimicking the host growth conditions.
Source: PLoS Pathogens Nov 2008
Aporte: Guillermo Figueroa