The Evolution of Multidrug Resistance in an Isolated Pseudomonas Strain

Abstract

As an unintentional result of the extensive use of antibiotics in healthcare and agriculture, antibiotics have become an increasingly prevalent selective pressure on bacteria. This forces bacteria to evolve and acquire antibiotic-resistant genes or mutations in order to survive. Suppose a bacterial strain acquires resistance to three or more antibiotics. In that case, it is deemed multidrug-resistant (MDR), and it becomes a potentially more serious problem to solve in the context of healthcare. This study aims to evaluate the acquisition of resistance to multiple antibiotic drugs by an initially susceptible isolated bacterium from a Minnesota forest environment. The bacterium was found to be Pseudomonas by 16s rRNA gene sequencing. Three antibiotics, neomycin, ciprofloxacin, and imipenem, each from a different drug class, were selected to see if this isolate could become resistant over time and exposure. The bacterial strain developed resistance to the selected antibiotics through a series of sequential exposures to increasing concentrations of each drug in this order. As determined by a disc susceptibility test, the initial isolate acquired resistance to all three selected antibiotics. Single nucleotide polymorphisms (SNPs) between the original isolate and the final resistant strain were identified. These SNPs suggest that mutations to efflux transporters and antibiotic protein targets play a role in acquiring and maintaining antibiotic resistance. KEYWORDS: Multidrug Resistance; Antibiotics; Neomycin; Ciprofloxacin; Imipenem; Pseudomonas; Evolution; MDR; Minnesota Environment