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Some Salmonella enterica subsp. enterica serovars, the majority of which are adapted to animals, have virulence plasmids allowing strains to cause systemic infections in mice. Fierer et al. (1992) assumes that virulence plasmids contribute to bacteremia occurrence in humans. Chiu et al. (1999) has shown that virulence plasmids can play a role in primary bacteremia occurrence. However insufficiency of the clinical data in these studies demonstrate no connection between clinical manifestation of infection with biological and plasmid characteristics of the pathogen, nor a conclusion of the importance of virulence plasmids in clinic of Salmonella infection in humans. The purpose of this study was to analyze the epidemiological features and variabilities of clinical manifestation of Salmonella infection caused by Salmonella enterica subsp. enterica serovar Enteritidis (further S. Enteritidis) that do not contain virulence plasmids.
For this, we used a group selected of 41 patients isolated S. Enteritidis without virulence plasmids with the molecular weight of 38 MDa. The investigation reveals 48 strains of microbe. It is caused by the strains of microbe without virulence plasmid with weight 38 MDa have made in 1995-2001 of only 3.6% (91 persons) whereas the others - contained it.
The proof of absence virulence plasmid genes studying presence of a spvC-gene in polymerase chain reaction where primers have been picked up to a fragment of a spvC-gene has been carried out. Electrophoresis of PCR-products carried out in 2% of agarose gel. The studied strains did not contain a spvC-gene whereas control strains with plasmid of 38 MDa did.
The group of patients (41 persons) isolated S. enteritidis without virulence plasmid of 38 MDa (group I) was compared by to group of 147 persons isolated the pathogen with plasmid of 38 MDa (group II). Carriers in the first group made 12.1%, as compared to the second group – with only 4.6% (p less than 0.05). Easy transmission of disease in the first group is revealed at 19.5% of patients and in the second group of persons 6.8% (p less than 0.05).
Hence, at the patients with Salmonella infection isolated pathogen without virulence plasmid disease frequently proceeds in the simple form and is characterized by high frequency of carrier state.

Principal and presenting author (Alexey Vladimirovich Rakov MD PhD) e-mail: vokar@mailru.com
Principal and presenting author (Alexey Vladimirovich Rakov MD PhD) fax: +7 (4232) 441438

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