AUTHOR=Burris Kellie P. , Simmons Otto D. , Webb Hannah M. , Deese Lauren M. , Moore Robin Grant , Jaykus Lee-Ann , Zheng Jie , Reed Elizabeth , Ferreira Christina M. , Brown Eric W. , Bell Rebecca L. 

TITLE=Colonization and Internalization of Salmonella enterica and Its Prevalence in Cucumber Plants

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01135

DOI=10.3389/fmicb.2020.01135

ISSN=1664-302X

ABSTRACT=<p>Consumption of cucumbers (<italic>Cucumis sativus</italic> var. <italic>sativus</italic>) has been linked to several foodborne outbreaks involving <italic>Salmonella enterica</italic>. The purpose of this work was to investigate the efficiency of colonization and internalization of <italic>S. enterica</italic> into cucumber plants by various routes of contamination. Produce-associated outbreak strains of <italic>Salmonella</italic> (a cocktail of serovars Javiana, Montevideo, Newport, Poona, and Typhimurium) were introduced to three cultivars of cucumber plants (two slicing cultivars and one pickling) via blossoms (ca. 6.4 log<sub>10</sub> CFU/blossom, 4.5 log<sub>10</sub> CFU/blossom, or 2.5 log<sub>10</sub> CFU/blossom) or soil (ca. 8.3 log<sub>10</sub> CFU/root zone) and were analyzed for prevalence of <italic>Salmonella</italic> contamination (internal and external) and serovar predominance in fruit and stems. Of the total slicing fruit harvested from <italic>Salmonella</italic>-inoculated blossoms (ca. 6.4, 4.5, or 2.5 log<sub>10</sub> CFU/blossom), 83.9% (47/56), 81.4% (48/59) or 71.2% (84/118) were found colonized and 67.9% (38/56), 35.6% (21/59) or 22.0% (26/118) had <italic>Salmonella</italic> internalized into the fruit, respectively. <italic>S.</italic> Poona was the most prevalent serovar isolated on or in cucumber fruits at all inoculation levels. When soil was inoculated at 1 day post-transplant (dpt), 8% (10/120) of the plants were shown to translocate <italic>Salmonella</italic> to the lower stem 7 days post-inoculation (dpi). Results identified blossoms as an important route by which <italic>Salmonella</italic> internalized at a high percentage into cucumbers, and <italic>S.</italic> Poona, the same strain isolated from the 2015 outbreak of cucumbers imported from Mexico, was shown to be well-adapted to the blossom niche.</p>