Association of antibiotics and heavy metal arsenic to horizontal gene transfer from multidrug-resistant clinical strains to antibiotic-sensitive environmental strains

Abstract

The emergence of multidrug-resistant bacteria is currently posing a significant threat to global public health. By testing for resistance to different antibiotic classes, we discovered that the majority of clinical bacteria are multidrug-resistant. These clinical multidrug-resistant species have antibiotic resistance genes on their plasmids that can be horizontally transferred to various antibiotic susceptible environmental bacterial species, resulting in antibiotic-resistant transconjugates. Furthermore, we discovered that the presence of an optimal concentration of antibiotics or heavy metal (arsenic) facilitates horizontal gene transfer through the formation of transconjugants. Notably, the addition of a conjugation inhibitor (2-hexadecynoic acid, a synthetic fatty acid) completely blocked the formation of antibiotic or arsenic-induced transconjugants. We discovered a high level of arsenic in water from the Shukratal region, Uttarakhand, India, which corresponded to a high serum level of arsenic in clinically infected individuals from the Shukratal region compared to other locations in Uttarakhand. Importantly, bacterial strains isolated from infected people who drink water from the Shukratal region with high arsenic levels were found to be more antibiotic-resistant than strains isolated from other sites. We discovered that bacterial strains isolated from individuals with high serum arsenic levels are significantly more resistant to antibiotics than individuals with low serum arsenic levels within the Shurkratal. This research sheds light on imminent threats to global health in which improper clinical, industrial, and other waste disposal, increased antibiotic concentrations in the environment, and increased human interference can easily transform commensal and pathogenic bacteria found in environmental niches into life-threatening multidrug-resistant superbugs.

Keywords: Antibiotic resistance genes; Arsenic heavy metals; Conjugation; Horizontal gene transfer; Multidrug resistance.