ISOLATION AND IDENTIFICATION OF SALMONELLA ENTERITIDIS AND SALMONELLA TYPHIMURIUM FROM THE EGGS OF RETAIL STORES IN MASHHAD, IRAN USING CONVENTIONAL CULTURE METHOD AND MULTIPLEX PCR ASSAY

Abstract

In this study, a total of 250 eggs were collected randomly from 50 retail stores in Mashhad city over a period of 3 months in the summer of 2008. Five samples from each store were collected, and transferred to the laboratory. In order to isolate Salmonella spp., conventional culture method – including pre‐enrichment, enrichment, selective plating and differential plating – were performed. To confirm the identification of isolated colonies as Salmonella spp. and determining serovars as Typhimurium and Enteritidis serovars, a multiplex polymerase chain reaction assay using three pairs of primers were employed: S141 and S139 for the invA gene, specific for the genus of Salmonella; Fli15 and Tym for the fliC gene, specific for Typhimurium serovar; and Prot6e‐5 and Prot6e‐6 for Prot6E gene, specific for Enteritidis serovar. Four out of 250 samples (1.6%) from eggshells were determined as contaminated with Salmonella spp. Isolated colonies were confirmed as Salmonella, and their serovar was determined as Typhimurium. Salmonella spp. was not isolated from the eggs' contents. PRACTICAL APPLICATIONS It seems that Salmonella Typhimurium is the most prevalent serotype of egg contaminant in the Mashhad area of Iran, and the multiplex polymerase chain reaction method based on amplification from conserved genes could be a reliable alternative for conventional culture methods.

DETECÇÃO DE Salmonella spp E Listeria monocytogenes ATRAVÉS DE TÉCNICA DE PCR

“…Em acordo com os resultados obtidos neste estudo, um grande número de relatos na literatura tem demonstrado que a PCR apresenta uma sensibilidade igual ou maior que métodos de culturas tradicionais, e permite a detecção mais rápida de patógenos em amostras alimentares e fecais (GÖKSOY; KIRKAN;KAYA, 2006;FRATAMICO, 2003;SCHRANK et al, 2001;BOLTON et al, 2002;JAMSHIDI;KALIDARI;HEDAYATI, 2010).…”

Development of a Polymerase Chain Reaction-Temporal Temperature Gradient Gel Electrophoresis Assay for Identification of Salmonella enterica Subspecies enterica Using a Hypothetical Non-specific Endonucleas S. entericae Gene Sequence

“…Several studies, including multiplex PCR and real-time multiplex PCR, have been conducted to identify some serotypes of S. enterica, simultaneously (10,20,21). Multiplex tests identify only a limited number of species in each reaction.…”

Prevalence and genetic characteristics of Salmonella strains in wild Mallard ducks (Anas platyrhynchos) in Semnan suburb, Iran

“…Despite several studies showing the prevalence and serotypes of S. enterica isolated from various hosts (Tizard, 2004;Coburn et al, 2007;Pennycott et al, 2010), serotyping presents no information about the phyletic relationships inside the different S. enterica subspecies for epidemiological investigations and for such purposes, the use of methods that can reveal the genotype of causative strains at a taxonomic level far more particular than that obtained by serotyping, is needed (Wattiau et al, 2011). By the PCR method, in vitro DNA amplification is a powerful tool in microbiological diagnostics and several markers such as virulence chromosomal genes and genes involved in the synthesis of flagellin have been used to detect Salmonella in environmental and natural samples as well as food and faecal samples (Malorny et al, 2003;Jamshidi et al, 2010). All of our Salmonella isolates were positive for invA gene which contains sequences unique to this genus, encoding a protein in the inner membrane of bacteria responsible for invasion to the epithelial cells of the host (Shanmugasamy et al, 2011).…”