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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #206634
Title: Mixed culture enrichment of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Yersinia enterocolitica

Author
item Gehring, Andrew
item Albin, David
item BHUNIA, ARUN - PURDUE UNIV.
item KIM, HYOCHIN - PURDUE UNIV.
item Reed, Sue
item Tu, Shu I

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2012
Publication Date: 8/12/2012
Citation: Gehring, A.G., Albin, D.M., Bhunia, A.K., Kim, H., Reed, S.A., Tu, S. 2012. Mixed culture enrichment of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Yersinia enterocolitica. Food Control. 26:269-273.

Interpretive Summary: Rapid methods for the testing of foods for the presence of harmful bacteria typically suffer from poor sensitivity and therefore require a large amount of the bacteria to be present. Since foods are often contaminated with little or no harmful bacteria, the need exists to increase the number of potentially harmful bacteria through growth in an appropriate culture medium. Furthermore, simultaneous testing for the presence of different bacteria in food samples necessitates the ability to increase, through growth/culture, the numbers of multiple species of bacteria to detectable levels. We have evaluated several commercially available and in-house media preparations for their ability to support the simultaneous growth of the following bacteria: Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, and Yersinia enterocolitica O:8. Conditions (primarily incubation temperature and time of growth) that resulted in growth of all bacteria to at least 10 e6 cells per milliliter were reported and were deemed suitable for use and further testing in a challenging food matrix (ground pork). Additional results in ground pork indicated that several of the growth media tested appear to be suitable for the growth of the selected bacteria prior to testing with rapid methods. Several of the tested growth media may be used by regulatory agencies as well as food producers for increasing numbers of tested bacteria immediately prior to rapid testing for the presence of multiple, harmful bacteria in numerous food samples.

Technical Abstract: Rapid methods for the testing of foods for the presence of pathogenic bacteria typically suffer from poor sensitivity and therefore require large concentrations of the bacteria to be present. Since foods are often contaminated with little or no pathogens, the need exists to increase the number of potentially present pathogenic bacteria through growth in an appropriate culture medium. Furthermore, multiplexed testing for the presence of different bacteria in food samples necessitates the ability to increase, through growth/culture, the concentration of multiple bacterial species to detectable levels. We have evaluated several commercially available and in-house media preparations for their ability to support the simultaneous growth of the following bacteria: Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica Serovar Typhimurium, and Yersinia enterocolitica O:8. Conditions (primarily incubation temperature and time) that resulted in growth of all bacteria to at least 10 e6 cells/mL were reported and considered suitable for use prior to testing with a rapid method. Additional mixed culture results in ground pork indicated that several of the growth media tested appear to be suitable for the growth of the selected bacteria prior to testing with rapid methods as well.