Bacteriological and Molecular Characterization of Salmonella Species Isolated from Humans and Chickens in Sharkia Governorate, Egypt

Heba Ahmed,Rasha M Gharieb,Mohamed E.M Mohamed,Rehab E Mohamed,Magda A Amin

doi:10.21608/zvjz.2017.29240

Abstract

This study was carried out to investigate the occurrence of Salmonella species in 690 different samples collected from Sharkia Governorate, Egypt. The samples comprised of chicken meat, organs, eggs, cloacal swabs and wooden surface swabs from pluck shop outlets and hand swabs from workers. In addition, stool swabs from patients with gastroenteritis attending the Outpatient Clinics at Zagazig and Abo-Hammad cities. Salmonella spp. were detected in 5.9%, 2.6%, 4.2%, 10.4%, 10% and 10% of chicken meat, organs, egg shell, cloacal swabs, surface swabs and hand swabs, respectively. The isolation rate from stool swabs was 0.8%. Biochemical Identification revealed that Salmonella spp. were identified in 129 out of 690 examined samples (18.7%). Meanwhile, molecular identification using invA gene revealed that only 29 Salmonella isolates were detected (4.2%). S. Typhimurium and S. Enteritidis were identified from different samples with the percentages of 1.2 and 1.01, respectively. The other identified Salmonella serovars were S. Newport (0.9%), S. Kentucky (0.7%), and S. Infantis (0.4%). Virulence associated genes including avrA, hilA and pef were identified in 100, 91.3 and 10.3% of the examined isolates. In conclusion, a proportion of chicken carcasses and giblets sold in Sharkia Governorate, Egypt was contaminated with Salmonella spp. including potentially virulent S. Typhimurium and S. Enteritidis, posing risk for human consumers.

Highlights

Salmonella is an important foodborne pathogen with an estimated 1.3 billion incidences of nontyphoidal salmonellosis worldwide annually [1]
The plasmid encoded fimbriae gene plays an important role in the pathogenicity of Salmonella spp. because the fimbriae promote their attachment to epithelial cells [13]
De Freitas et al [22] have reported that increased uncertainty in morphological and biochemical testing is attributed to variations among Salmonella strains

Summary

Introduction

Salmonella is an important foodborne pathogen with an estimated 1.3 billion incidences of nontyphoidal salmonellosis worldwide annually [1]. Traditional identification methods including phenotyping and serotyping are time consuming and labor intensive. For these reasons, the use of PCR for identification of Salmonella serovars is an attractive alternative to the most traditional techniques. The invA gene encodes a protein in the inner membrane of bacteria, which is necessary for invasion of epithelial cells of the host [5]. The hyper invasive locus A (hilA) gene is one of the important virulence determinants which is necessary for the expression of the TTSS components required to invade epithelial cells [11, 12]. The plasmid encoded fimbriae (pefA) gene plays an important role in the pathogenicity of Salmonella spp. because the fimbriae promote their attachment to epithelial cells [13].

Material and Methods

Results and Discussion

Conclusion