Němečková I., Havlíková Š., Gelbíčová T., Pospíšilová L., Hromádková E., Lindauerová J., Baráková A., Karpíšková R. (2020): Heat-resistance of suspect persistent strains of Escherichia coli from cheesemaking plants. Czech J. Food Sci., 38: 323–329.
Besides its health and spoilage hazards, Escherichia coli is a process hygiene indicator for cheeses made from milk that has undergone heat treatment. Hence, its ability to persist in cheesemaking plant environment and equipment is important. In total, 120 samples from two producing plants were analysed and 72 E. coli isolates were obtained. The target was to find out whether there is a difference in heat-resistance between persistent and non-persistent E. coli strains. The strains were selected using macrorestriction analysis and recurrent detection in cheesemaking plants hereby: one strain persisting in brine for blue-veined cheeses, two strains persisting in brine for hard cheeses and one non-persistent strain from raw material. Their D(50)-values were 196; 417; 370 and 182 min, respectively, D(59)-values ranged from 20 to 32 min and z-values were 7.5; 6.6; 8.1 and 9.0 °C, respectively. The non-persistent strain was the least resistant to heating to 50 °C but it was not the least resistant generally. All tested strains were highly heat-resistant and carried genes of the heat resistance locus LHR1 and/or LHR2. Our results emphasise the need to screen for the presence of LHR genes and the occurrence of heat-resistant E. coli in cheese production where they could survive sub-pasteurisation temperatures and contaminate the manufacturing environment and finished products.
Blackburn C.W., Curtis L.M., Humpheson L., Billon C., McClure P.J. (1997): Development of thermal inactivation models for Salmonella enteritidis and Escherichia coli O157:H7 with temperature, pH and NaCl as controlling factors. International Journal of Food Microbiology, 38: 31–44. https://doi.org/10.1016/S0168-1605(97)00085-8
Boll E.J., Marti R., Hasman H., Overballe-Petersen S., Stegger M., Ng K., Knøchel S., Krogfelt K.A., Hummerjohann J., Struve C. (2017): Turn up the heat-food and clinical Escherichia coli isolates feature two transferrable loci of heat resistance. Frontiers in Microbiology, 8: 579. https://doi.org/10.3389/fmicb.2017.00579
Dlusskaya E.A., McMullen L.M., Gänzle M.G. (2011): Characterization of an extremely heat-resistant Escherichia coli obtained from a beef processing facility. Journal of Applied Microbiology, 110: 840–849. https://doi.org/10.1111/j.1365-2672.2011.04943.x
Glatz B.A., Brudvig S.A. (1980): Survey of commercially available cheese for enterotoxigenic Escherichia coli. Journal of Food Protection, 43: 395–398. https://doi.org/10.4315/0362-028X-43.5.395
Gonthier A., Guérin-Faublée V., Tilly B., Delignette-Müller M.L. (2001): Optimal growth temperature of O157 and non-O157 Escherichia coli strains. Letters in Applied Microbiology, 33: 352–356. https://doi.org/10.1046/j.1472-765X.2001.01010.x
Johnson M.E. (2001): Cheese products. In: Marth E.H., Steel J.L. (eds.): Applied Dairy Microbiology (2nd Ed.), Marcel Dekker, Inc., New York, USA: 345–384.
Kaper J.B., Nataro J.P., Mobley H.L. (2004): Pathogenic Escherichia coli. Nature Reviews. Microbiology, 2: 123–140.
Kuhtyn M., Berhilevych O., Kravcheniuk K., Horiuk Y., Semaniuk N. (2017): Formation of biofilms on dairy equipment and the influence of disinfectants on them. Eastern-European Journal of Enterprise Technologies, 89: 28–33.
Li R., Shi Y., Ling B., Cheng T., Huang Z., Wang S. (2017): Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method. Emirates Journal of Food and Agriculture, 29: 91–97. https://doi.org/10.9755/ejfa.2016-07-978
Marti R., Muniesa M., Schmid M., Ahrens C.H., Naskova J., Hummerjohann J. (2016): Heat-resistant Escherichia coli as potential persistent reservoir of extended-spectrum β-lactamases and shiga toxin-encoding phages in dairy. Journal of Dairy Sciences, 99: 8622–8632. https://doi.org/10.3168/jds.2016-11076
Mercer R.G., Zheng J., Garcia-Hernandez R., Ruan L., Gänzle M.G., McMullen L.M. (2015): Genetic determinants of heat resistance in Escherichia coli. Frontiers in Microbiology, 6: 932. https://doi.org/10.3389/fmicb.2015.00932
Murano E.A., Pierson M.D. (1992): Effect of heat shock and growth atmosphere on the heat resistance of Escherichia coli O157:H7. Journal of Food Protection, 55: 171–175. https://doi.org/10.4315/0362-028X-55.3.171
Nazarowec-White M., Farber J.M. (1997): Thermal resistance of Enterobacter sakazakii in reconstituted dried-infant formula. Letters of Applied Microbiology, 24: 9–13. https://doi.org/10.1046/j.1472-765X.1997.00328.x
Peng S., Hummerjohann J., Stephan R., Hammer P. (2013): Heat resistance of Escherichia coli strains in raw milk at different subpasteurisation conditions. Journal of Dairy Science, 96: 3543–3546.
PulseNet Europe (2013): Standard Operating Procedure for PulseNet PFGE of Escherichia coli O157:H7, Escherichia coli non-O157 (STEC), Salmonella serotypes, Shigella sonnei and Shigella flexneri: 1–16.
Rosso L., Lobry J.R., Flandoris J.P. (1993): An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model. Journal of Theoretical Biology, 162: 447–463. https://doi.org/10.1006/jtbi.1993.1099
Singh R.S., Ranganathan B. (1980): Heat resistance of Escherichia coli in cow and buffalo milk. Journal of Food Protection, 43: 376–380. https://doi.org/10.4315/0362-028X-43.5.376