Journal of Consumer Protection and Food Safety

, Volume 14, Issue 4, pp 399–407 | Cite as

Prevalence of Salmonella spp. in Egyptian dairy products: molecular, antimicrobial profiles and a reduction trial using d-tryptophan

  • Mahmoud Elafify
  • Wageh Sobhy DarwishEmail author
  • Maha Al-Ashmawy
  • Mohammed Elsherbini
  • Shige Koseki
  • Shuso Kawamura
  • Adel Abdelkhalek
Research Article


The study aims to determine the prevalence and serotypes of Salmonella spp. in milk and dairy products sold on Egyptian markets, characterize their virulence-associated genes, and assess their antimicrobial profile. Furthermore, d-tryptophan was used as a new approach for controlling the growth of Salmonella in combination with heat stress. A total of 125 samples (raw market milk, bulk tank milk, Kareish cheese, white soft cheese, and small scale ice cream, 25 each) were used for assessing the prevalence of Salmonella spp. Nine Salmonella isolates with different serotypes were recovered from bulk tank milk (4/9; 44.44%) and Kariesh cheese (5/9; 55.55%), respectively. Antimicrobial susceptibility testing indicated that all isolates were resistant to streptomycin and erythromycin. PCR analysis revealed that 100%, 66.67% and 88.89% of the obtained isolates possessed invA, avrA and stn genes, respectively. d-Tryptophan (40 mM) in combination with heat stress had a significant inhibitory effect on Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) added to control milk samples. The results indicate insufficient hygienic measures adopted during handling by dairies in Egypt. Therefore, strict hygienic approaches are recommended during milking, processing and distribution of dairy products in Egypt. A synergistic effect of d-tryptophan and heat stress is considered as a promising tool for controlling growth of Salmonella in milk.


Antimicrobial profile Dairy products d-Tryptophan Heat stress Salmonella spp. 



This work was supported by Egypt–Japan Education Partnership “EJEP.


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Copyright information

© Bundesamt für Verbraucherschutz und Lebensmittelsicherheit (BVL) 2019

Authors and Affiliations

  1. 1.Department of Food Hygiene and Control, Faculty of Veterinary MedicineMansoura UniversityMansouraEgypt
  2. 2.Graduate School of Agricultural ScienceHokkaido UniversitySapporoJapan
  3. 3.Food Control Department, Faculty of Veterinary MedicineZagazig UniversityZagazigEgypt

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