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. 2019 Oct 1;8(3):8291.
doi: 10.4081/ijfs.2019.8291. eCollection 2019 Sep 30.

Molecular characterization of Escherichia coli isolated from cheese and biocontrol of Shiga toxigenic E. coli with essential oils

Heba Hussien  1 , Ayman Elbehiry  2   3 , Marwa Saad  4 , Ghada Hadad  5 , Ihab Moussa  6   7 , Turki Dawoud  6 , Ayman Mubarak  6 , Eman Marzouk  3
Affiliations

Molecular characterization of Escherichia coli isolated from cheese and biocontrol of Shiga toxigenic E. coli with essential oils

Heba Hussien et al. Ital J Food Saf. .

Abstract

The current research was carried out to study the incidence of Escherichia coli (E. coli) in Egyptian cheese (Kariesh and Ras) and molecular characterization of certain E. coli virulence genes (stx1, stx2, eaeA, hlyA and fimH) using multiplex PCR technique. Biocontrol of E. coli with essential oils (clove and thyme oil) was also studied. A total of 150 random samples of Kariesh and Ras cheese (75 each) were collected from various areas in Governorate of Menoufia. According to our results, the frequency of E. coli isolated from Kariesh and Ras cheese was 16% and 5.3%, respectively. Serological identification classified the E. coli strains into two groups, enterohemorrhagic E. coli (EHEC) serogroup (O26: H11, O91: H21, O111: H2 and O103: H2). While the enterotoxigenic E. coli (ETEC) serogroup were detected as O125: H21 which is the most prevalent strain. O171: H2, O86 and O119: H6 belonging to enteropathogenic E. coli (EPEC). The most prevalent gene detected in E. coli strains was stx1 (87.5%) followed by stx2 (86%), fimH (75%), hlyA (50%) and eaeA (25%) genes. Concerning the antimicrobial activity with essential oils, thyme oil (1%) is considered as the bactericidal effect against E. coli (ATCC35150) with improved the sensory evaluation than clove oil (1%). In conclusion, Kariesh and Ras cheese are extremely tainted with pathogenic E. coli strains, which represent a strong hazard on the human health.

Keywords: Biocontrol; Cheese; Escherichia coli; Essential oils; Virulence genes.

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Conflict of interest statement

Conflict of interest: the authors declare no potential conflict of interest.

Figures

Figure 1.
Figure 1.
Agarose gel electrophoresis of multiplex PCR of stx1 (614 bp), stx2 (779 bp), eaeA (890 bp) and hlyA (165 bp). Lane M: 100 bp ladder as molecular size DNA marker; lane C+: Control positive E. coli for stx1, stx2, eaeA and hlyA genes; lane C-: negative control; lanes 1, 2, 4 (O26) and 9 (O111): positive E. coli for stx1, stx2, eaeA and hlyA genes; lanes 6 (O91), 8 (O103) and 10 (O111): positive E. coli for stx1, stx2 and hlyA genes; lanes 3 (O26) and 11 (O119): positive E. coli for stx1 and stx2 genes; lanes 7 (O91): positive E. coli for stx1 and hlyA genes; lanes 12, 13, 14 (O125) and 16 (O171): positive E. coli for stx1 gene; lanes 5 (O86) and 15 (O156): positive E. coli for stx2 gene.
Figure 2.
Figure 2.
Agarose gel electrophoresis of PCR of fimH (508 bp). Lane M: 100 bp ladder as molecular size DNA marker; lane C+: control positive E. coli for fimH gene; lane C-: control negative; lanes 1, 2, 4 (O26); 6, 7 (O91); 8 (O103); 9, 10 (O111); 11 (O119); 13, 14 (O125) and 15 (O156): positive E. coli for fimH gene. Lanes 3(O26); 5 (O86); 12 (O125) & 16 (O127): negative E. coli for fimH gene.
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