Photo of and provided by Rideeta Islam Aishy
By Alaina Dismukes
The aquaculture industry supplies over half of the fish consumed globally and plays a crucial role in addressing food insecurity and nutritional deficiencies in impoverished countries. However, the industry frequently encounters disease outbreaks due to various factors that elevate bacterial survival rates under selective pressure from environmental conditions. One of the most significant selective pressures is the use of antibiotics, which are used to control these outbreaks but if misused can lead to antimicrobial resistance (AMR).
“The selective pressure created by these drugs establishes an environment known as a genetic hotspot for the emergence of resistant bacterial strains,” said Rideeta Islam Aishy, a graduate research assistant at the Mississippi State University College of Veterinary Medicine. “The widespread distribution of these resistant strains poses a significant threat, as resistance is not confined to its original contamination source; it can spread. This can result in bacterial pathogens developing resistance to multiple antibiotics. Therefore, understanding the mechanisms that drive rapid bacterial adaptation and resistance is essential to prevent the dissemination of resistance genes.”
Aishy earned her undergraduate degree in microbiology from Brac University in Bangladesh and is now pursuing a Master of Science in Veterinary and Biomedical Science with an Infectious Diseases concentration at MSU’s Department of Comparative Biomedical Sciences, driven by her interest in AMR. In the fall of 2024, she won the top prize for her master’s poster presentation on the antimicrobial resistance of Edwardsiella ictalurid, a key pathogen in channel catfish, at the American Society for Microbiology meeting for the South Central and Kentucky-Tennessee branches.
“As I studied more about the growing global threat of AMR, I became increasingly interested in understanding how resistance develops and spreads in the environment,” she said. “The impact of AMR on both human and animal health—where antibiotic overuse is a concern—made me realize the issue's urgency. While looking for an opportunity to dive further into this field of research, I met Dr. Hasan Tekedar, assistant research professor at the Department of Comparative Biomedical Sciences, who conducts research on AMR. His expertise in infectious diseases, computational biology, bacterial and viral genomics, and bacterial pathogenesis aligned perfectly with my research interests, particularly in understanding AMR.”
From there, Aishy began research focused on how different environmental stress factors, such as antibiotics, drive the rapid adaptation of bacterial populations in aquaculture, utilizing the combination of adaptive laboratory evolution (ALE) and genomics.
“While ALE will allow us to observe real-time bacterial evolution under selective pressure in a controlled laboratory environment mimicking the natural environment, genomics will allow us to identify key mutations and evolutionary pathways that contribute to the development and spread of AMR,” Aishy said.
“My research shows that antibiotic pressure drives genetic alterations in bacteria, such as single nucleotide polymorphisms or inversions and deletions, leading to AMR. These selective pressures ensure the persistence of resistant pathogens, highlighting the complexity of AMR mechanisms. This suggests that antibiotics may lose efficacy over time, leading to the emergence of multidrug-resistant pathogens.”
AMR in aquaculture is not just a matter of bacterial survival; however, it directly impacts global food security. As antibiotic resistance increases, traditional treatments become ineffective and lead to higher mortality rates and economic losses. Addressing these issues is crucial for safeguarding both public health and the long-term sustainability of aquaculture.
“The FAO Reference Center helps MSU researchers achieve important work in AMR by strengthening capacity development in this field of research,” said Stephen Reichley, head of the FAO Reference Center on Antimicrobial Resistance and Aquaculture Biosecurity, associate director of the Global Center for Aquatic Health and Food Security, and CVM faculty member. “Dr. Tekedar and Aishy’s work demonstrates how the university is attracting exceptional experts and students who are making a world of difference through their research and, moreover, their dedication to fighting a global issue.”
To learn more about the FAO Reference Center on Antimicrobial Resistance and Aquaculture Biosecurity, visit www.gcahfs.msstate.edu/projects/fao-reference-center-antimicrobial-resistance-and-aquaculture-biosecurity.