Is Our Use of Antibiotics Creating More Resistant, Virulent Bacterial Strains?

By: Alexandra Ortiz 

Human Gut and Environmental Metagenomic Comparison. Schematic overview of the comparative study of the human gut and environmental metagenomes. Researchers mined in the genes of the human gut and environmental bacterial communities to understand the relationship between antibiotic resistance genes and virulence factors (VFs). Their efforts were able to show that there is a link between the dissemination of VFs and antibiotic resistance. 

Over the years, our excessive use of antibiotics in both medicine and agriculture has selected for antibiotic-resistant bacterial strains in human and environmental communities. Although pathogenic bacteria are the targets of antibiotics, nonpathogenic bacteria are affected in antibiotic contaminated environments. Pathogenic bacteria use virulence factors for parasitizing hosts that include proteins for adhesion and invasion of tissues, secretion of toxins and iron acquisition systems. Interestingly, environmental bacteria use these virulence factors (VFs) to adhere and colonize different surfaces, compete with other bacteria, and access resources such as iron. Escudiero et al. (2019) conducted a comparative study between environmental and human gut microbial communities from different human populations across the world to identify differences between and among the sampled communities. They were able to find a higher diversity of antibiotic resistance (AR) and VFs in environmental samples when compared to human gut samples. However, human fecal microbiomes had a higher accumulation of AR than environmental communities. This research was also able to catch a glimpse of what the pre-antibiotic era of the human resistome looks like in uncontacted Ameridian gut microbiome samples. Lastly, the correlation found between AR and VF diversity in both human and environmental samples suggests that as our use of antibiotics continues, we may be selecting for more virulent, resistant bacteria.