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Survival of Escherichia coli O157:H7 in Galotyri cheese stored at 4 and 12 degrees C.
Food Microbiol. 2006 May; 23(3):268-76.FM

Abstract

Post-process contamination of fresh acid-curd cheeses with Escherichia coli O157:H7 may pose a risk considering the low infectious dose and the ability of the pathogen to survive in acidic foods. To evaluate its survival in Galotyri, a traditional Greek acid-curd cheese, portions (0.5 kg) of two commercial fresh products, one artisan (pH 3.9+/-0.1) and the other industrial (pH 3.7+/-0.1), were inoculated with approximately 3.0 or 6.5 log cfu g(-1) of a five-strain cocktail of E. coli O157:H7, including rifampicin-resistant derivatives of the strains ATCC 43895 and ATCC 51657, and stored aerobically at 4 and 12 degrees C. Survival was monitored for 28 days by plating cheese samples on tryptic soy agar with 100 mg l(-1) rifampicin (TSA+Rif), SMAC and Fluorocult E. coli O157:H7 agar media. The pathogen declined much faster (P<0.05) in the industrial as compared to the artisan cheeses at both temperatures. Thus, while E. coli O157:H7 became undetectable by culture enrichment after 14 days at 4 degrees C in industrial samples, irrespective of the inoculation level, populations of 1.4-1.9 and 4.2-5.1 log cfu g(-1) survived after 28 days in the corresponding artisan cheeses with the low and high inocula, respectively. Survival was longer and greater (P<0.05) on TSA+Rif than on SMAC and Fluorocult, indicating the presence of acid-injured cells. Interestingly, survival of E. coli O157:H7 after 14-28 days in cheeses was better at 12 degrees C than at 4 degrees C, probably due to yeasts which grew on the surface of temperature-abused cheeses. The large difference in the pathogen's inactivation between the industrial and artisan cheeses at 4 degrees C could not be associated with major differences in pH or type/concentration of organic acids, suggesting another anti-E. coli O157:H7 activity by the industrial starter. The high survival of the pathogen in artisan Galotyri under conditions simulating commercial storage should be of concern.

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Authors+Show Affiliations

Lekkas C
National Agricultural Research Foundation, Dairy Research Institute, Katsikas, Ioannina 45221, Greece.
Kakouri A
No affiliation info available
Paleologos E
No affiliation info available
Voutsinas LP
No affiliation info available
Kontominas MG
No affiliation info available
Samelis J
No affiliation info available

MeSH

CheeseColony Count, MicrobialConsumer Product SafetyEscherichia coli O157Food ContaminationFood HandlingHumansHydrogen-Ion ConcentrationTemperatureTime Factors

Pub Type(s)

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

Language

eng

PubMed ID

16943013

Citation

Lekkas, Charidimos, et al. "Survival of Escherichia Coli O157:H7 in Galotyri Cheese Stored at 4 and 12 Degrees C." Food Microbiology, vol. 23, no. 3, 2006, pp. 268-76.
Lekkas C, Kakouri A, Paleologos E, et al. Survival of Escherichia coli O157:H7 in Galotyri cheese stored at 4 and 12 degrees C. Food Microbiol. 2006;23(3):268-76.
Lekkas, C., Kakouri, A., Paleologos, E., Voutsinas, L. P., Kontominas, M. G., & Samelis, J. (2006). Survival of Escherichia coli O157:H7 in Galotyri cheese stored at 4 and 12 degrees C. Food Microbiology, 23(3), 268-76.
Lekkas C, et al. Survival of Escherichia Coli O157:H7 in Galotyri Cheese Stored at 4 and 12 Degrees C. Food Microbiol. 2006;23(3):268-76. PubMed PMID: 16943013.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Survival of Escherichia coli O157:H7 in Galotyri cheese stored at 4 and 12 degrees C. AU - Lekkas,Charidimos, AU - Kakouri,Athanasia, AU - Paleologos,Evaggelos, AU - Voutsinas,Leandros P, AU - Kontominas,Michael G, AU - Samelis,John, Y1 - 2005/06/08/ PY - 2004/11/04/received PY - 2005/03/14/revised PY - 2005/03/29/accepted PY - 2006/9/1/pubmed PY - 2006/9/26/medline PY - 2006/9/1/entrez SP - 268 EP - 76 JF - Food microbiology JO - Food Microbiol VL - 23 IS - 3 N2 - Post-process contamination of fresh acid-curd cheeses with Escherichia coli O157:H7 may pose a risk considering the low infectious dose and the ability of the pathogen to survive in acidic foods. To evaluate its survival in Galotyri, a traditional Greek acid-curd cheese, portions (0.5 kg) of two commercial fresh products, one artisan (pH 3.9+/-0.1) and the other industrial (pH 3.7+/-0.1), were inoculated with approximately 3.0 or 6.5 log cfu g(-1) of a five-strain cocktail of E. coli O157:H7, including rifampicin-resistant derivatives of the strains ATCC 43895 and ATCC 51657, and stored aerobically at 4 and 12 degrees C. Survival was monitored for 28 days by plating cheese samples on tryptic soy agar with 100 mg l(-1) rifampicin (TSA+Rif), SMAC and Fluorocult E. coli O157:H7 agar media. The pathogen declined much faster (P<0.05) in the industrial as compared to the artisan cheeses at both temperatures. Thus, while E. coli O157:H7 became undetectable by culture enrichment after 14 days at 4 degrees C in industrial samples, irrespective of the inoculation level, populations of 1.4-1.9 and 4.2-5.1 log cfu g(-1) survived after 28 days in the corresponding artisan cheeses with the low and high inocula, respectively. Survival was longer and greater (P<0.05) on TSA+Rif than on SMAC and Fluorocult, indicating the presence of acid-injured cells. Interestingly, survival of E. coli O157:H7 after 14-28 days in cheeses was better at 12 degrees C than at 4 degrees C, probably due to yeasts which grew on the surface of temperature-abused cheeses. The large difference in the pathogen's inactivation between the industrial and artisan cheeses at 4 degrees C could not be associated with major differences in pH or type/concentration of organic acids, suggesting another anti-E. coli O157:H7 activity by the industrial starter. The high survival of the pathogen in artisan Galotyri under conditions simulating commercial storage should be of concern. SN - 0740-0020 UR - https://www.unboundmedicine.com/medline/citation/16943013/Survival_of_Escherichia_coli_O157:H7_in_Galotyri_cheese_stored_at_4_and_12_degrees_C_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0740-0020(05)00051-1 DB - PRIME DP - Unbound Medicine ER -