Temporal shifts in antibiotic resistance elements govern phage-pathogen conflicts

Back to the future phage The interrelationships that prevail between bacteria and their phage parasites are subtle and evolutionarily dynamic. In Bangladesh, cholera remains endemic, and natural, clinically relevant infections have been monitored for decades. LeGault et al . investigated the relationship between antiphage defenses and phage counterresponses in human Vibrio cholerae cases. These bacteria have integrative and conjugative elements called SXT ICEs, which are notorious for carrying antibiotic resistance genes but also contain genes that defend bacteria from phage. Phage have their own counterdefense mechanisms. One constitutes a 44–amino acid peptide product in a phage lineage that inhibits the bacterium’s SXT ICE defenses. In a further complication, SXT-ICEs also inhibit the lysogenic phage that transmit Vibrio virulence factors, including cholera toxin. Therefore, this process drives bacterial diversity as well as antibiotic resistance. —CA