Escherichia coli O157:H7 and Listeria monocytogenes in raw meatballs and phage control of L. monocytogenes
2021
Goncuoglu, Muammer | Ayaz, Naim Deniz | Cufaoglu, Gizem | Cengiz, Gorkem
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, lpfA1-3 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.
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