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Studying the growth boundary and subsequent time to growth of pathogenic Escherichia coli serotypes by turbidity measurements.
Food Microbiol. 2010 Sep; 27(6):819-28.FM

Abstract

The presence of Escherichia coli in contaminated food products is commonly attributed to faecal contamination when they are improperly handled and/or when inactivation treatments fail. Adaptation of E. coli at low pH and a(w) levels can vary at different temperatures depending on the serotype, thus more detailed studies are needed. In this work, a screening to assess the growth of four pathogenic serotypes of E. coli (O55:H6; O59:H21; O158:H23 and O157:H7) was performed. Subsequently, boundary models were elaborated with the fastest serotype selected at different temperatures (8, 12 and 16 degrees C), and inoculum levels (2, 3 and 4log cfu/mL) as function of pH (7.00-5.00) and a(w) (0.999-0.960). Finally, the growth kinetics of E. coli was described in the conditions that allowed growth. Results obtained showed that the serotypes O157:H7 and O59:H21 did not grow at more stringent conditions (8 degrees C; pH 5.50), while the E. coli O158:H23 was the best adapted, resulting in faster growth. The logistic regression models presented a good adjustment to data observed since more than 96.7% of cases were correctly classified. The growth interface was shifted to more limited conditions as the inoculum size was higher. Detection times (t(d), h) and their variability were higher at low levels of the environmental factors studied. This work provides insight on the growth kinetics of E. coli at various environmental conditions.

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Authors+Show Affiliations

Valero A
Department of Food Science and Technology, University of Cordoba, Campus de Rabanales, Edificio Darwin, 14014 Córdoba, Spain. bt2vadia@uco.es
Rodríguez M
No affiliation info available
Carrasco E
No affiliation info available
Pérez-Rodríguez F
No affiliation info available
García-Gimeno RM
No affiliation info available
Zurera G
No affiliation info available

MeSH

Adaptation, PhysiologicalColony Count, MicrobialEscherichia coliEscherichia coli O157Food ContaminationFood MicrobiologyHydrogen-Ion ConcentrationKineticsLogistic ModelsModels, BiologicalSerotypingSpecies SpecificityTemperatureWater

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

20630325

Citation

Valero, A, et al. "Studying the Growth Boundary and Subsequent Time to Growth of Pathogenic Escherichia Coli Serotypes By Turbidity Measurements." Food Microbiology, vol. 27, no. 6, 2010, pp. 819-28.
Valero A, Rodríguez M, Carrasco E, et al. Studying the growth boundary and subsequent time to growth of pathogenic Escherichia coli serotypes by turbidity measurements. Food Microbiol. 2010;27(6):819-28.
Valero, A., Rodríguez, M., Carrasco, E., Pérez-Rodríguez, F., García-Gimeno, R. M., & Zurera, G. (2010). Studying the growth boundary and subsequent time to growth of pathogenic Escherichia coli serotypes by turbidity measurements. Food Microbiology, 27(6), 819-28. https://doi.org/10.1016/j.fm.2010.04.016
Valero A, et al. Studying the Growth Boundary and Subsequent Time to Growth of Pathogenic Escherichia Coli Serotypes By Turbidity Measurements. Food Microbiol. 2010;27(6):819-28. PubMed PMID: 20630325.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Studying the growth boundary and subsequent time to growth of pathogenic Escherichia coli serotypes by turbidity measurements. AU - Valero,A, AU - Rodríguez,M, AU - Carrasco,E, AU - Pérez-Rodríguez,F, AU - García-Gimeno,R M, AU - Zurera,G, Y1 - 2010/05/05/ PY - 2010/01/12/received PY - 2010/04/26/revised PY - 2010/04/27/accepted PY - 2010/7/16/entrez PY - 2010/7/16/pubmed PY - 2010/10/13/medline SP - 819 EP - 28 JF - Food microbiology JO - Food Microbiol VL - 27 IS - 6 N2 - The presence of Escherichia coli in contaminated food products is commonly attributed to faecal contamination when they are improperly handled and/or when inactivation treatments fail. Adaptation of E. coli at low pH and a(w) levels can vary at different temperatures depending on the serotype, thus more detailed studies are needed. In this work, a screening to assess the growth of four pathogenic serotypes of E. coli (O55:H6; O59:H21; O158:H23 and O157:H7) was performed. Subsequently, boundary models were elaborated with the fastest serotype selected at different temperatures (8, 12 and 16 degrees C), and inoculum levels (2, 3 and 4log cfu/mL) as function of pH (7.00-5.00) and a(w) (0.999-0.960). Finally, the growth kinetics of E. coli was described in the conditions that allowed growth. Results obtained showed that the serotypes O157:H7 and O59:H21 did not grow at more stringent conditions (8 degrees C; pH 5.50), while the E. coli O158:H23 was the best adapted, resulting in faster growth. The logistic regression models presented a good adjustment to data observed since more than 96.7% of cases were correctly classified. The growth interface was shifted to more limited conditions as the inoculum size was higher. Detection times (t(d), h) and their variability were higher at low levels of the environmental factors studied. This work provides insight on the growth kinetics of E. coli at various environmental conditions. SN - 1095-9998 UR - https://www.unboundmedicine.com/medline/citation/20630325/Studying_the_growth_boundary_and_subsequent_time_to_growth_of_pathogenic_Escherichia_coli_serotypes_by_turbidity_measurements_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0740-0020(10)00090-0 DB - PRIME DP - Unbound Medicine ER -