February 2018
Multi-antibiotic resistance in pathogenic microbes is a serious, and increasingly common, occurrence. It complicates the treatment of infectious diseases, makes health care more expensive, and can be a death-sentence for the patient.
We know that, once a pathogen evolves a mutant gene for antibiotic resistance, this can be passed to other microbes by horizontal gene transfer. Long ago, concerns were raised that the artificial antibiotic resistance genes often added to GM crop plants as markers during their development could fuel the emergence of antibiotic resistant pathogens. No one seems to be tracking whether this is a reality, but bugs can make themselves resistant to toxic medicines by other means, and counter-intuitively these 'other means' can be fuelled by herbicide-tolerant GM crops.
When bacteria are exposed to a toxin, their first line of defence is to switch on their own pumps to rid themselves of it. If this physiological mechanism can kick in fast enough (before the toxin kills it), the bug can make itself resistant to an antibiotic for as long as necessary.
The link to GM crops is that herbicidal chemicals and their spray co-formulants are also toxic to bacteria. Tests on the glyphosate-based herbicide used on most current GM crops, and on dicamba and 2,4-D which are up-and-coming replacements for glyphosate, plus the 'surfactants' added to all three to aid penetration into the weeds, showed they all trigger the toxin-pump mechanism in three commonly pathogenic bacteria. 'Surfactants' are detergents, classed as 'inerts' by US Environmental Protection Agency (EPA), and are ignored in safety assessments. However, the bacteria clearly don't find them 'inert'.
