Browsing by Subject "Enterococcus"
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Item Effects of Wet and Dry Weather Events on Bacteria (Enterococci) and the Public Health Threat from the Re-Suspension of Sediment Sequestered Enterococci(2014-06-04) Bare, Ryan MichaelApproximately 66% of Texas surface waters are impaired with bacteria from fecal waste, including several tributaries and segments within the Galveston Bay system. This study was conducted in the waters of the Marina Del Sol marina on Clear Lake in Kemah, Galveston County, Texas, USA. A series of hypothesis were tested; 1) rainfall and subsequent runoff from stormwater is the primary cause of elevated Enterococcus levels in the waters in Marina Del Sol, 2) hotspots of Enterococcus will be present in the waters in Marina Del Sol and 3) the concentration of Enterococcus will increase from the marina entrance to the rear of the marina. Sampling was conducted at 10 stations between 0800 and 1100 every Monday, Thursday, and Saturday over five weeks in June and July 2013. Enterococci concentrations were quantified using the IDEXX Enterolert method for detection and enumeration estimation, Fluorogenic Substrate Enterococcus Test, Multi-well procedure and three-day rainfall accumulation prior to sampling was recorded from NOAA?s Climate Data Online. Eleven dry weather and four wet weather events occurred during the sampling period with the largest rainfall accumulation at 1.39 inches. The geometric means of wet versus dry weather samples were not significantly different (Mann Whitney). Two hotspots were found yielding geometric means of 42.98 and 41.25 MPN, which exceed the U.S. EPA primary contact recreation limit of 35 MPN. Additionally, the EPA single sample maximums (104 CFU/100 mL) were exceeded at nine out of ten sampling stations at least once, including a spike of 1,445 MPN and 1,198 MPN. A low to high gradient of Enterococci, from the entrance to the back portion of the marina, was evident. The results from the initial summer study indicated that the stormwater retention pond to the west of the marina could be a possible source of Enterococci. The fourth hypothesis, states that sediments are a source of elevated Enterococcus concentrations in the water at the Marina Del Sol marina, was tested during a follow up study. Sediment and water samples were collected on the 13th of November, 2013 between the hours of 0900 and 1400. Six stations in the stormwater retention pond were sampled. In addition, three of the original sampling stations in the marina were sampled. A stormwater outfall was found to be a concentrated source of Enterococci into the retention pond (12,098 MPN/100 mL). Data from these two studies indicate that there are numerous sources that contribute to the concentrations of Enterococci in the marina. A gateway effect is occurring between the increasingly built environment of the Galveston Bay marinas and the natural environment.Item Microbial Indicators in Restaurant Salads: Correlation Between Salad Type, Restaurant Ownership Format, and Customer Business Volumes(2013-12-12) Prince, David WarrenFoodborne illness outbreaks associated with fresh produce have increased over the past decade. Food workers employed at full-service restaurants are found to perform risky food practices more often than food workers employed in other segments of the foodservice industry. The goal of this study was to determine if differences in restaurant ownership format, business volume, and salad type influenced the level of indicator organisms present in restaurant salads. Overall levels of heterotrophic bacteria, total coliforms, Escherichia coli, Enterococcus, male-specific coliphages, and somatic coliphages were determined by aerobic plate counts (APC), Colilert?, Enterolert?, and U.S. EPA (Method 1601 and 1602), respectively. Molecular methods including automated rep-PCR DiversiLab? system and reverse transcriptase-PCR were used for the DNA fingerprinting of E. coli and the genotyping of male-specific coliphages, respectively. All of the above mentioned indicator organisms were present in the restaurant salads. Comparisons between restaurant types found that levels of APC, Enterococcus, and male-specific coliphages were significantly higher in locally owned restaurants and levels of total coliforms and somatic coliphages were significantly higher in corporate restaurants. The levels for all indicator organisms were significantly higher in specialty salads compared to leafy greens salads. Comparisons between business volumes suggested that indicator organism counts were higher during low customer traffic sampling periods. These results suggested that there were differences in safe food handling practices between locally owned and corporate restaurants. Staffing and labor issues as a result of low customer traffic and the need for additional handling and preparation of specialty salads seemed to increase the risk of cross-contamination issues for fresh produce. DNA fingerprinting for E. coli revealed that the same organism was found at multiple restaurants. These results indicate that there was a common source of contamination somewhere between field production and distribution. Genotyping results for male-specific coliphages found that some of the produce had been exposed to human and animal sources of contamination. Overall, the monitoring for indicator organisms in restaurant salads found that there is still a need for improved education-based programs in the area of safe food handling practice associated with fresh produce for food workers in restaurants.