Food Research Institute

Goncuoglu, M. – Ayaz, N. D. – Cufaoglu, G. – Cengiz, G.
Escherichia coli O157:H7 and Listeria monocytogenes in raw meatballs and phage control of L. monocytogenes
Journal of Food and Nutrition Research, 60, 2021, No. 2, s. 124-130

Muammer Goncuoglu, Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ankara University, Sht. Omer Halisdemir Boulevard No. 40, 06110 Ankara, Turkey. Tel.: +90 312 317 03 15 / 4267, e-mail: goncu@veterinary.ankara.edu.tr

Received 12 January 2021; 1st revised 16 March 2021; 2nd revised 1 April 2021; accepted 14 April 2021; published online 25 May 2021.

Summary: Raw meatball (cig kofte, CK) is a traditional ready-to-eat product that is commonly consumed in Turkey. This appetizer poses a great risk in terms of containing foodborne pathogens due to the ingredients contained, such as ground beef. In this study, Escherichia coli O157:H7 and Listeria monocytogenes strains previously isolated from CK were characterized. Out of 27 E. coli O157 isolates, 13 were identified as E. coli O157:H7. In all of E. coli O157:H7 isolates, eaeA, hly, fliCh7, espA, lpfA_1-3 and stx genes were detected. All L. monocytogenes isolates (n = 4) were identified as serotype 1/2a or 3a. In addition to strain characterization, efficacy of a cocktail of lytic bacteriophages on L. monocytogenes in CK food model was investigated in order to demonstrate an alternative method to combat this pathogen. Samples contaminated with 2.30 log CFU·g^-1 in the phage-applied group, L. monocytogenes was not detected from the very first hour of incubation. The highest reduction was observed as 2.35 log CFU·g^-1 after incubation of 3 h when the multiplicities of infection was 4.14 log PFU·CFU^-1g^-1. This study showed that L. monocytogenes counts could be reduced to acceptable levels by bacteriophage application in a complex food like CK.

Keywords: bacteriophage; biocontrol; Escherichia coli O157:H7; Listeria monocytogenes; raw meatball; ready-to-eat

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