Antimicrobial resistance: an indicator of humanity’s growing ecological footprint

Antimicrobial resistance is a global problem that affects not only humans but also animals and the environment. In an effort to better understand the dynamics at play, researchers sought to quantify the impact of human activity on the spread of resistance genes in wild animal populations, specifically those of the Galápagos giant tortoises.   Antibiotic resistance or antimicrobial resistance has become one of the main threats to global public health. It results from the repeated or inappropriate administration of antibiotics in humans or animals, which creates conditions that favor the spread of microbial strains capable of resisting these molecules. Today, new drugs capable of combating pathogens are scarce, and it is sometimes difficult—if not impossible—to treat certain infections. Antimicrobial resistance has gradually developed and now affects all pathogenic bacteria. Understanding and combating the spread of these resistances has become a top priority for global health authorities. It is, in particular, one of the main objectives of the “One Health” initiative. In their research, scientists assess the prevalence of antimicrobial resistance genes in wild animal populations. They have focused in particular on one of the planet’s most iconic species: the Galápagos giant tortoises (Chelonoidis spp.). Found throughout the archipelago, these tortoises are ideal candidates for assessing the role of human activities in the transmission of resistance genes for antimicrobial resistance among wild species. The researchers therefore sampled a total of 200 wild tortoises on Santa Cruz Island—the most populous in the archipelago—and 70 tortoises around the isolated Alcedo Volcano on Isabela Island, a natural area with minimal human presence. According to the results of quantitative PCR analyses performed on fecal samples, resistance genes for several classes of antibiotics were isolated in both turtle populations. However, those living on Santa Cruz, in a human-altered environment, had much higher loads. Furthermore, the Santa Cruz tortoises sampled in these human-altered areas (farmland and urban areas) had a higher number of resistance genes, multidrug-resistant microbiomes, and resistance to more classes of antimicrobials than those from less human-impacted areas of the same island. Human activity therefore has a proven negative impact on the health of ecosystems in the Galápagos through the spread of antimicrobial resistance genes. These findings reveal a new threat to the conservation of the archipelago’s unique and endemic wildlife, which is listed as a World Heritage Site. But this alarming finding is likely not limited to these isolated islands in the Pacific Ocean. Antimicrobial resistance is a global phenomenon, linked to human activities around the world that contribute to the spread of resistance genes. To effectively address this global problem, researchers are calling for better control and reduction of antibiotic use in both human and animal health, particularly through stricter enforcement of existing regulations.