Spread of antibiotic resistance in water: a public health and environmental issue
Résumé
Genes encoding antibiotic resistance have been found in DNA present in 30,000-year-old permafrost sediment and in areas without human activity. Antibiotics belong to a class of small bioactive molecules secreted by environmental microorganisms. Since 1950, intensive use of antibiotics in human and veterinary medicine has been accompanied by an unprecedented increase in bacterial resistance in clinical settings, and a contamination of the environment, mainly surface water, by antibiotics and by antibiotic-resistant (ATBr) bacteria. To further illustrate this problem, we study here the fate of both antibiotic and antibiotic-resistant fecal bacteria in the Seine estuary in France, highly impacted by humans. Thus, ATBr Escherichia coli and ATBr Enterococcus spp. were investigated along a medical center-wastewater treatment plant-river continuum and along a rural hydrological continuum, in relation to antibiotic prescription and contamination of surface water. To date, notwithstanding the spread of ATBr bacteria in aquatic environments, it remains difficult to estimate their risk to human health. Environmental contamination by ATBr bacteria could be linked to the transfer of clinical integrons and antibiotic resistance genes to (i) environmental strains that are opportunistic pathogens in humans, or (ii) environmental organisms that may secondarily transfer such genes to strains that are pathogenic in humans. One of the major scientific challenges of the decades to come will be the evaluation of the vulnerability and resilience of the aquatic environment to contamination by ATBr bacteria and their genes. For this purpose, collaborative research should be conducted, supported by environmental observatories and in accordance with the DPSIR (Driving forces-Pressure-State-Impact-Response) concept.