Evaluating the presence of human bacterial pathogens in Lubbock area playa lakes
Hamilton, Lynne Ann
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Waterbome bacterial pathogens are causative agents for many human diseases, and their presence in water bodies poses a potential threat to the human population. Because of the risk of public outbreaks of disease, it is of utmost importance that communities be aware of potential risks associated with water contact, including the presence of frankly pathogenic bacteria. The goal of my research was to determine if the playa lakes of the South Plains are reservoirs of transmissible bacterial pathogens, and if these pathogens could be recovered using standard hospital methods, employing selective and enrichment culture techniques to recover viable, cultivable bacteria. The pathogens in question included Salmonella .Shigella, Campylobacter, Yersinia, Escherichia coli 0157:H7, Vibrio, Aeromonas hydrophila, Plesiomonas shigelloides, and Pasteurella multocida. Recovery thresholds were established to determine the concentration of each pathogen that must be present in the playa water to detect using the established techniques. Organisms isolated from the playa lake water included: Aeromonas hydrophila, Plesiomonas shigelloides, a rare Yersinia enterocolitica, presumptive Salmonella species, and a rare presumptive Vibrio cholerae. Review of current epidemiologic reports of the city of Lubbock indicated that Salmonella, Shigella, and Campylobacter were most frequently isolated as the causative agents of water-borne disease in the Lubbock area during the course of the experimentation. Survivability experiments demonstrated how long the pathogen Salmonella enterica serovar Typhimurium could survive in the playa water. Results indicated that this pathogen does not survive for long periods of time in the playa lake water with the competing normal playa bacterial flora, and survival may be temperature-dependent. Evaluation of the experimental results and epidemiologic information should provide insight regarding the biological safety of the playa lakes in Lubbock, Texas, and pave the road for future environmental studies of other water resources. These results may also initiate management practices of water sources to ensure safety to the human and wildlife populations.