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Updated: Jun 27, 2026
An Allelotyping PCR for Identifying Salmonella enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium
Published on: July 22, 2011
Molecular study of Salmonella enteritidis in poultry samples by PCR, plasmid curing, antibiotic resistance and
M H Mirmomeni1, A Hosseinzadeh Colagar, S Ghazaey
1Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran.
Abstract:
In this study two control isolates of Salmonella enteritidis, RTCC1623 and RTCC1624, were obtained from the institute ofRazi (Karaj-Iran) and 14 strains were isolated from poultry samples in Kermanshah province of Iran, according to a standard protocol. These isolates were confirmed by PCR amplification of SefA gene fragments. Results showed that, 6 isolates of 14 isolates of Salmonella which their biochemical tests were positive contain 511 bp amplified fragments of the SefA gene. In other purpose, to correlating the presence of plasmids with antibiotic resistance and protein pattern, plasmid DNA was isolated before and after plasmid curing by using the alkaline lysis method. Strains of S. enteritidis contain seven different plasmid profiles (P1-P7) which were characterized by antibiotic resistance and protein pattern. Our observed showed, there was a high molecular weight plasmid with Rf 0.17 in all strains and the frequency of other plasmids was low. The plasmid with Rf about 0.2 is responsible for resistance to Cephalothin and the isolates that lost it were susceptible to this antibiotic. All strains, 100%, were resistant to ampicillin before and after curing of strains. According to present findings, PCR is a rapid and sensitive method for typing of S. enteritidis and plasmid profiling; antibiotic resistance and protein pattern are suitable methods for subtyping of S. enteritidis isolates. No direct correlation was found between plasmid contents, antibiotic resistance patterns and protein profiles of local S. enteritidis isolates.
Insights
This study identified Salmonella enteritidis in Iranian poultry using PCR and plasmid analysis. While PCR confirmed the SefA gene, plasmid profiling and antibiotic resistance showed no direct correlation with protein patterns in these Salmonella enteritidis isolates.
Area of Science:
- Microbiology
- Molecular Biology
- Food Safety
Background:
- Salmonella enteritidis is a significant foodborne pathogen.
- Understanding its genetic diversity and resistance mechanisms is crucial for public health.
- Local surveillance of Salmonella enteritidis in Iran is essential.
Purpose of the Study:
- To isolate and identify Salmonella enteritidis from poultry samples in Iran.
- To characterize the isolates using PCR, plasmid profiling, and antibiotic resistance testing.
- To investigate the correlation between plasmid content, antibiotic resistance, and protein patterns.
Main Methods:
- Isolation of Salmonella enteritidis from poultry samples.
- Confirmation using Polymerase Chain Reaction (PCR) for the SefA gene.
- Plasmid DNA isolation, curing, and profiling using alkaline lysis.
- Antibiotic susceptibility testing and protein pattern analysis.
Main Results:
- Six out of 14 Salmonella isolates tested positive for the 511 bp SefA gene fragment via PCR.
- Seven distinct plasmid profiles (P1-P7) were identified among the S. enteritidis strains.
- A high molecular weight plasmid (Rf 0.17) was present in all strains; a plasmid with Rf ~0.2 conferred Cephalothin resistance.
- All strains exhibited 100% resistance to ampicillin, irrespective of plasmid content.
Conclusions:
- PCR is a rapid and sensitive method for Salmonella enteritidis typing.
- Plasmid profiling, antibiotic resistance, and protein patterns are useful for subtyping S. enteritidis.
- No direct correlation was found between plasmid profiles, antibiotic resistance, and protein patterns in the studied local isolates.
