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Tag: Ynes Ortega

Survival of Salmonella and Shiga Toxin-producing Escherichia coli and Changes in Indigenous Microbiota During Fermentation of Kombucha Made from Home-brewing Kits

Survival and growth of Salmonella and Shiga toxin-producing Escherichia coli (STEC) in kombucha prepared from four brands of commercially available kombucha kits intended for use by home brewers were investigated. Changes in microbiota responsible for fermentation were also determined. An initial population of Salmonella (6.77 log CFU/mL) decreased to below the detection limit (0.30 log CFU/mL) within 10 d in kombucha prepared from two of the four test brands. Populations of 1.85 and 1.20 log CFU/mL were detected in two brands fermented for 14 d. An initial population of STEC (7.02 log CFU/mL) decreased to <0.30 log CFU/mL in two of the four brands within 14 d; 0.20 and 0.87 log CFU/mL were detected in kombucha prepared from the other two brands. Salmonella and STEC increased in populations within 1 d in three brands of base tea used to prepare kombucha, and were stable throughout 14 d of incubation. Both pathogens steadily declined in base tea prepared from one brand of kombucha kit. Inactivation of the pathogens occurred as the pH of kombuchas decreased, but a clear correlation between rates of inactivation and decrease in pH was not evident when comparing kombuchas prepared from the four kits. Growth and peak populations of mesophilic aerobic microorganisms, yeasts, lactic acid bacteria, and acetic acid bacteria varied, depending on the kombucha kit brand. There was not strong evidence to correlate the behavior of Salmonella and STEC with any of these groups of indigenous microbiota. Results of this study show that the ability of Salmonella and STEC to survive in kombucha and base tea used to prepare kombucha is dependent on inherent differences in commercially available kombucha kits intended for use in home settings. Strict application of hygienic practices with the goal of preventing contamination with Salmonella or STEC is essential for reducing the risk of illness associated the consumption of kombucha.

Sheridan S. Brewer, Courtney A. Lowe, Larry R. Beuchat, Ynes R. Ortega; Survival of Salmonella and Shiga Toxin-producing Escherichia coli and Changes in Indigenous Microbiota During Fermentation of Kombucha Made from Home-brewing Kits. J Food Prot 2021; doi:

Ynes Ortega receives grant to study Cyclospora presence in the U.S.

Historically, Cyclospora infection in the United States has been associated with imported fresh produce. However, in 2018, the U.S. saw two significant outbreaks associated with vegetables grown in the United States.

“We had more than 2,000 non-travel associates cyclosporiasis cases,” said Ynes Ortega, member of the Center for Tropical and Emerging Global Diseases and associate professor in the Department of Food Science and Technology’s Center for Food Safety.

Fresh produce vegetable trays containing broccoli, cauliflower, carrots, and dill dip, which are not often associated with Cyclospora outbreaks, were implicated in the first outbreak affecting 250 people and lettuce from a salad mix used by a fast food chain was the source of the second outbreak with 511 cases.

“Cyclospora has previously been detected in salad greens produced in the US and lettuce implicated in the second outbreak was produced in the U.S.,” said Ortega. “Clearly, we need to determine if Cyclospora is not only a parasite present in other countries but also in the U.S.”

cyclospora factsCyclospora cayetanensis, the single-cell parasite that causes cyclosporiasis, was first described by Ortega in the 1990s. A person becomes infected with the parasite by consuming contaminated food, mostly fresh fruits and vegetables, and water. Infection results in gastrointestinal illness characterized primarily by diarrhea. Cyclosporiasis is treated with sulfa drugs, fluids, and rest. If left untreated, the symptoms can persist for up to a month and can be recurring. Prevention of infection is accomplished by frequent hand washing by those who process fruits and vegetables, thoroughly rinsing fruits and vegetables with water prior to consumption, and avoiding potentially contaminated water while traveling in countries where C. cayetanensis is endemic.

Ortega has been awarded a 2-year grant from the Center for Produce Safety, a non-profit organization committed to addressing issues faced by the produce industry, to investigate C. cayetanensis presence in the United States.

“We will be testing surface water for the presence of Cyclospora cayetanensis, improving sample collection methods, and genotyping of the parasite,” said Ortega.

Up until 2018, it was believed that Cyclospora was not present in the United States. Therefore, one of the main goals of this grant is to determine how widely distributed this parasite is within the United States. To aid in this determination, a simpler and more sensitive method of detection is needed which Ortega’s laboratory is already working on.

“These two objectives are critical to implement monitoring and intervention strategies not only in the U.S. but also in endemic locations, with the ultimate goal of reducing the number of domestic cases of cyclosporiasis,” said Ortega.

Mitochondrial genome sequence variation as a useful marker for assessing genetic heterogeneity among Cyclospora cayetanensis isolates and source-tracking


BACKGROUND: Cyclospora cayetanensis is an important enteric pathogen, causing diarrhea and food-borne cyclosporiasis outbreaks. For effective outbreak identification and investigation, it is essential to rapidly assess the genetic heterogeneity of C. cayetanensis specimens from cluster cases and identify the likely occurrence of outbreaks.

METHODS: In this study, we developed a quantitative PCR (qPCR) targeting the polymorphic link region between copies of the mitochondrial genome of C. cayetanensis, and evaluated the genetic heterogeneity among 36 specimens from six countries using melt curve, gel electrophoresis, and sequence analyses of the qPCR products.

RESULTS: All specimens were amplified successfully in the qPCR and produced melt peaks with different Tm values in the melt curve analysis. In gel electrophoresis of the qPCR products, the specimens yielded bands of variable sizes. Nine genotypes were identified by DNA sequencing of the qPCR products. Geographical segregation of genotypes was observed among specimens analyzed, which could be useful in geographical source-tracking.

CONCLUSIONS: The length and nucleotide sequence variations in the mitochondrial genome marker allow rapid assessment of the genetic heterogeneity among C. cayetanensis specimens by melt curve, gel electrophoresis, or DNA sequence analysis of qPCR products. The sequence data generated could be helpful in the initial source-tracking of the pathogen.

KEYWORDS: Cyclospora cayetanensis; Genotyping; Mitochondrion; Source-tracking; qPCR

Yaqiong Guo, Yuanfei Wang, Xiaolan Wang, Longxian Zhang, Ynes Ortega, and Yaoyu Feng. Parasite Vectors 2019 Jan 21; 12(1):47. doi.1186/s13071-019-3294-1

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