There seems to be a rising fear of sickness around the world. With ever increasing populations in regions of poor hygiene, international access to transportation, and an abundance of antibiotic resistant outbreaks, its no wonder movies like Contagion can find an audience.
CC by SilentFrenzy
While people realize that restricting access to medical treatment or travel would be inconvenient, most promote awareness of proper antibiotic use and limiting the use of antibacterial soaps. Despite these interventions, the rise of the superbug still remains a problem on our horizon. It would seem pathogens are still developing immunity to our arsenal and that the vast majority are appearing out of nature. Or are they?
While Antibiotic Resistant Genes (ARG) have been evolving in an arms race with toxins and biocides for millenia, there is evidence that human activity may be partially responsible for selective pressures even when these ARGs seem to appear out of nature. Here are two human induced sources that have been until recently overlooked:
CC, by Karen V Bryan
Domestic rearing of animals has long had implications of giving rise to ARGs in bacteria, however the relationship between these pathogens and their aquatic vector to us remains largely unstudied. While practices like composting manure can help eliminate ARG carrying pathogens, bacteria can still survive through animal production wastewater and seep into surface and ground water. Such wastewater derived ARGs have been found making their way through sewage and treatment plants and to our local tap. If this is not enough to worry about, bacteriophages can transmit ARGs to bacteria without selective pressures, and they are even more robust than their hosts in aqueous environments.
NRCS photo gallery (Sarah Minor)
A way to diminish this vector may lie with riparian buffer zones and grassed waterways which reduce the turbidity of water, significantly reducing the viability of bacteria in treatment plants.
CC by Maria S
Another potential vector is metal. People have long known of the biocidic effects of various metals due to jewellery. The reaction, colloquially called metal allergy, can influence a person’s choice of earrings as much the look itself.
While many have taken advantage of this, think hospitals and plumbing, recent experiments suggest that metal concentration may have an impact on ARGs. Areas of past mining or industrial application have been cited as having higher ARG levels correlated with various metal concentrations. While some researchers maintain that metal resistance does not correlate with antibiotic resistance, proponents of metal derived resistance maintain that it is not the metal itself that creates the resistance but that it increases the frequency of gene transfer which may increase the incidence of ARGs over time. To add credence to their argument, a strong correlation of copper with ampicilin resistance was found in the wild, and further examination is currently underway.
Altogether, we are finding more vectors of ARGs everyday, and that they often have simple causes and occasionally practical solutions. And while we may still fear what we don’t know, it is science that enlightens us with what we do. There is no doubt that with time and the application of science, the rising fears of sickness will dissipate, and some thriller films will be a little less infectious.
