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Quantitation of viable Coxiella burnetii in milk using an integrated cell culture-polymerase chain reaction (ICC-PCR) assay.
J Dairy Res 2015; 82(4):478-84JD

Abstract

The obligate intracellular pathogen Coxiella burnetii has long been considered the most heat resistant pathogen in raw milk, making it the reference pathogen for determining pasteurisation conditions for milk products. New milk formulations and novel non-thermal processes require validation of effectiveness which requires a more practical method for analysis than using the currently used animal model for assessing Coxiella survival. Also, there is an interest in better characterising thermal inactivation of Coxiella in various milk formulations. To avoid the use of the guinea pig model for evaluating Coxiella survival, an Integrated Cell Culture-PCR (ICC-PCR) method was developed for determining Coxiella viability in milk. Vero cell cultures were directly infected from Coxiella-contaminated milk in duplicate 24-well plates. Viability of the Coxiella in milk was shown by a ≥ 0.5 log genome equivalent (ge)/ml increase in the quantity of IS111a gene from the baseline post-infection (day 0) level after 9-11 d propagation. Coxiella in skim, 2%, and whole milk, and half and half successfully infected Vero cells and increased in number by at least 2 logs using a 48-h infection period followed by 9-d propagation time. As few as 125 Coxiella ge/ml in whole milk was shown to infect and propagate at least 2 logs in the optimised ICC-PCR assay, though variable confirmation of propagation was shown for as low as 25 Coxiella ge/ml. Applicability of the ICC-PCR method was further proven in an MPN format to quantitate the number of viable Coxiella remaining in whole milk after 60 °C thermal treatment at 0, 20, 40, 60 and 90 min.

Authors+Show Affiliations

US Food and Drug Administration,Division of Food Processing Science & Technology,Bedford Park,IL 60501,USA.US Food and Drug Administration,Division of Food Processing Science & Technology,Bedford Park,IL 60501,USA.US Food and Drug Administration,Division of Food Processing Science & Technology,Bedford Park,IL 60501,USA.Illinois Institute of Technology, Institute for Food Science & Health,Bedford Park,IL 60501,USA.US Food and Drug Administration,Division of Food Processing Science & Technology,Bedford Park,IL 60501,USA.US Food and Drug Administration,Division of Food Processing Science & Technology,Bedford Park,IL 60501,USA.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

26143937

Citation

Stewart, Diana, et al. "Quantitation of Viable Coxiella Burnetii in Milk Using an Integrated Cell Culture-polymerase Chain Reaction (ICC-PCR) Assay." The Journal of Dairy Research, vol. 82, no. 4, 2015, pp. 478-84.
Stewart D, Shieh YC, Tortorello M, et al. Quantitation of viable Coxiella burnetii in milk using an integrated cell culture-polymerase chain reaction (ICC-PCR) assay. J Dairy Res. 2015;82(4):478-84.
Stewart, D., Shieh, Y. C., Tortorello, M., Kukreja, A., Shazer, A., & Schlesser, J. (2015). Quantitation of viable Coxiella burnetii in milk using an integrated cell culture-polymerase chain reaction (ICC-PCR) assay. The Journal of Dairy Research, 82(4), pp. 478-84. doi:10.1017/S0022029915000400.
Stewart D, et al. Quantitation of Viable Coxiella Burnetii in Milk Using an Integrated Cell Culture-polymerase Chain Reaction (ICC-PCR) Assay. J Dairy Res. 2015;82(4):478-84. PubMed PMID: 26143937.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Quantitation of viable Coxiella burnetii in milk using an integrated cell culture-polymerase chain reaction (ICC-PCR) assay. AU - Stewart,Diana, AU - Shieh,Y-Carol, AU - Tortorello,Mary, AU - Kukreja,Ankush, AU - Shazer,Arlette, AU - Schlesser,Joseph, Y1 - 2015/07/06/ PY - 2015/7/7/entrez PY - 2015/7/7/pubmed PY - 2016/8/18/medline KW - Coxiella burnetii KW - ICC-PCR KW - milk KW - quantitation SP - 478 EP - 84 JF - The Journal of dairy research JO - J. Dairy Res. VL - 82 IS - 4 N2 - The obligate intracellular pathogen Coxiella burnetii has long been considered the most heat resistant pathogen in raw milk, making it the reference pathogen for determining pasteurisation conditions for milk products. New milk formulations and novel non-thermal processes require validation of effectiveness which requires a more practical method for analysis than using the currently used animal model for assessing Coxiella survival. Also, there is an interest in better characterising thermal inactivation of Coxiella in various milk formulations. To avoid the use of the guinea pig model for evaluating Coxiella survival, an Integrated Cell Culture-PCR (ICC-PCR) method was developed for determining Coxiella viability in milk. Vero cell cultures were directly infected from Coxiella-contaminated milk in duplicate 24-well plates. Viability of the Coxiella in milk was shown by a ≥ 0.5 log genome equivalent (ge)/ml increase in the quantity of IS111a gene from the baseline post-infection (day 0) level after 9-11 d propagation. Coxiella in skim, 2%, and whole milk, and half and half successfully infected Vero cells and increased in number by at least 2 logs using a 48-h infection period followed by 9-d propagation time. As few as 125 Coxiella ge/ml in whole milk was shown to infect and propagate at least 2 logs in the optimised ICC-PCR assay, though variable confirmation of propagation was shown for as low as 25 Coxiella ge/ml. Applicability of the ICC-PCR method was further proven in an MPN format to quantitate the number of viable Coxiella remaining in whole milk after 60 °C thermal treatment at 0, 20, 40, 60 and 90 min. SN - 1469-7629 UR - https://www.unboundmedicine.com/medline/citation/26143937/Quantitation_of_viable_Coxiella_burnetii_in_milk_using_an_integrated_cell_culture_polymerase_chain_reaction__ICC_PCR__assay_ L2 - https://www.cambridge.org/core/product/identifier/S0022029915000400/type/journal_article DB - PRIME DP - Unbound Medicine ER -