The Association of Virulent Vibrio Spp. Bacteria on Gafftopsail and Hardhead Catfish in Galveston Bay
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Vibrio vulnificus (Vv) and V. parahaemolyticus (Vp) are gram negative, halophilic bacteria that occur naturally in estuarine waters of Galveston Bay. Both bacteria have the potential to cause infections in humans either via consumption or direct contact. Finfish are a potential vector for these bacteria. Previous work by Brinkmeyer determined that these bacteria are present on the benthic dwelling catfish, Ariopsis felis and Bagre marinus, using a conventional microbial method. The present work focused on using Quantitative Polymerase Chain Reaction (QPCR) and Terminal Restriction Fragment Length Polymorphism (T-RFLP) to not only determine presence of these bacteria, but also to quantify them and look at community structure. QPCR was able to detect bacteria presence in 34 percent, 31.6 percent, and 0 percent for V.vulnificus, V.parahaemolyticus. thermolabile hemolysin (tlh) and thermostable direct hemolysin (tdh) genes, respectively. Statistical analysis of the QPCR results found that there was no significant difference between the length of fish, location of catch or species of fish in relation to the abundance of bacteria. T-RFLP was able to detect the presence of bacteria in approximately 70 percent of the samples surveyed. Bands produced from T-RFLP were able to be grouped into five different ranges. The most frequently occurring band fell in the range of 213-219 base pairs, and the most common number of bands per sample was 1 band. This study found that both QPCR and T-RFLP were better assays than conventional microbial methods for detecting the presence of V. vulnificus and V. parahaemolyticus on catfish fins. QPCR proved to be the most rapid detection method. Based on this study, it was determined that these Vibrio spp. bacteria have some type of relationship with A. felis and B. marinus. This information may be useful to the medical community for determining when there is a greater risk of infection via catfish puncture wounds.
Gilbert, Leslie Deanne (2010). The Association of Virulent Vibrio Spp. Bacteria on Gafftopsail and Hardhead Catfish in Galveston Bay. Master's thesis, Texas A&M University. Available electronically from