Persistence of a wild-type virulent aeromonas hydrophila isolate in pond sediments from commercial catfish ponds: a laboratory study

Authors: TUTTLE, JAMES - Auburn University; BRUCE, TIMOTHY - Auburn University; ABDELRAHMAN, HISHAM - Auburn University; ROY, LUKE - Auburn University; BUTTS, IAN - Auburn University; Beck, Benjamin; KELLY, ANITA - Auburn University

Submitted to: Veterinary Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2023
Publication Date: 3/22/2023
Citation: Tuttle, J., Bruce, T., Abdelrahman, H., Roy, L., Butts, I., Beck, B.H., Kelly, A. 2023. Persistence of a wild-type virulent aeromonas hydrophila isolate in pond sediments from commercial catfish ponds: a laboratory study. Veterinary Sciences. 10(3):236. https://doi.org/10.3390/vetsci10030236.
DOI: https://doi.org/10.3390/vetsci10030236

Interpretive Summary: Virulent Aeromonas hydrophila (vAh) is a major bacterial pathogen in the U.S. catfish industry and is responsible for large-scale losses within commercial ponds. One of the main avenues of treatment for this pathogen is antibiotic feeds, but it is imperative to develop new approaches and better understand the mechanics of infection for this bacterium. As such, the persistence of vAh in pond sediments was determined by conducting laboratory trials using sediment from four commercial catfish ponds. Twelve chambers contained sterilized sediment, vAh, and 8 L of water maintained at 28 degrees C and aerated daily. At 1, 2, 4, 6, 8 days, and every 7th day post-inoculation for 28 d, a sample of sediment was removed, and vAh colonies were quantified. Viable vAh colonies were present in all sediments at all sampling periods. The vAh growth curve peaked at 96 h post-inoculation. Population plateauing began by 14 d, with no differences between 21 and 28 d. No correlation occurred between CFU g-1 and physiochemical sediment variables. This study validated vAh’s ability to persist within pond sediments in a laboratory setting. Further research on environmental factors influencing vAh survivability and population dynamics in ponds is needed.

Technical Abstract: Virulent Aeromonas hydrophila (vAh) is a major bacterial pathogen in the U.S. catfish industry and is responsible for large-scale losses within commercial ponds. One of the main avenues of treatment for this pathogen is antibiotic feeds, but it is imperative to discern new approaches and better understand the mechanics of infection for this bacterium. As such, the persistence of vAh in pond sediments was determined by conducting laboratory trials using sediment from four commercial catfish ponds. Twelve chambers contained sterilized sediment, vAh isolate ML-09-119, and 8 L of water maintained at 28 'C and aerated daily. At 1, 2, 4, 6, 8 days, and every 7th day post-inoculation for 28 d, one gram of sediment was removed, and vAh colonies were enumerated on ampicillin dextrin agar. Viable vAh colonies were present in all sediments at all sampling periods. The vAh growth curve peaked (1.33 ± 0.26 x 109 CFU g-1) at 96 h post-inoculation. Population plateauing began by 14 d, with no differences between 21 and 28 d. No correlation occurred between CFU g-1 and physiochemical sediment variables. This study validated vAh’s ability to persist within pond sediments in a laboratory setting. Further research on environmental factors influencing vAh survivability and population dynamics in ponds is needed.