تعيين طرح پلاسميدي سالمونلاهاي جدا شده از مواد غذايي

Plasmid profile analysis of Salmenella strains isolated from food products

Among the gram negative bacteria causing food born enteritis, the most important organisms belong to the members of Salmonella genus. In this investigation, three methods of Serotyping, Resistotyping and Plasmid Profile Analysis were used to study the Salmonella strains isolated from food products. A total of 50 Salmonella strains isolated from food products and sent to the Veterinary Organization of Tehran Province and pasteur Veterinary Laboratory were studied from April to August 2005. Serotyping was performed using the Mast Diagnostic Kit. Resistotyping was performed by Kirby and Bauer disk diffusion method according to the NCCLS criteria. Plasmids were extracted using Takara kit (Takara company, Japan) and electrophoresed on a 1% Agarose gel. Fifty Salmonella strains belonged to 11 serotypes. S. Durban was the most common serotype followed by S. Nigeria and S. Thompson. All 50 Salmonella strains were resistant to Ampicillin and Streptomycin. Resistance to three or more antibiotics (MDR) was detected for 58% of the studied strains. Strains showed 6 different resistance patterns. The most common resistance pattern was S. Am. Gm. Cz. Te. All fifty Salmonella strains contained one to four plasmids and showed 4 different plasmid profiles. All the strains had a 3.036 MD plasmid and all these serotypes were resistant to Ampicillin and Streptomycin. Serotyping distinguished more strains than did the two other methods. Since our strains contained very few plasmids, this method could distinguish few strains. However, the method of Plasmid Profile Analysis showed that all the strains contained a 3.036 MD plasmid that can be considered as a common characteristic of Salmonella strains isolated from food products.