Enhancing effect of 50 Hz rotating magnetic field on induction of Shiga toxin-converting lambdoid prophages.

Studies aimed at investigating factors and mechanism of induction of prophages, a major pathogenesis factor of Shiga toxin-producing Escherichia coli (STEC), are considered important to develop an effective treatment for STEC infections. In this study, we demonstrated the synergistic effect of the rotating magnetic field (RMF) of induction B = 34 mT and frequency ƒ = 50 Hz at a constant temperature of 37 °C and mitomycin C (MMC), that resulted in a higher level of induction of stx-carrying lambdoid Stx prophages. This is a first report on the induction of lambdoid Stx prophages in response to the enhancing effect of popular inductor (mitomycin C) under the influence of RMF.

Molecular typing of Staphylococcus aureus based on PCR-RFLP of coa gene and RAPD analysis.

The aim of this study was molecular identification of S. aureus strains isolated from mastitic milk samples and establishing the genetic relationship between strains isolated from cows belonging to the same herd. In all 43 isolated strains the gap gene (930 bp) was amplified, which enabled their affiliation to the Staphylococcus genus to be established. PCR-RFLP with AluI endonuclease of the gap gene as well as nuc (450 bp) and coa (1130 bp) gene amplification allowed precise S. aureus species identification. One hundred percent of the genetic relationship between strains was established via RAPD-PCR and coa-typing.

The presence of anti-Yersinia pseudotuberculosis immunoglobulins in equine serum.

The research was conducted on clinically healthy mares (n = 40) and foals (n = 78) during Y. pseudotuberculosis associated enzootics. The animals were divided into groups: I to IV--mares, IA to IVA--their offsprings, IB to IVB--foals which mothers were not treated with any medicaments. The animals in group I, IA and IB were injected with PBS; in group II, IIA and IIB--with Y. pseudotuberculosis strain-based vaccine, in group III, IIIA and IIIB--with P. acnes strain-based immunostimulator; in group IV, IVA and IVB--with P. acnes strain-based immunostimulator and (5 days after the immunostimulator injection) Y. pseudotuberculosis strain-based vaccine. The presence of antibodies was determined by means of ELISA. The study revealed anti-Yersinia pseudotuberculosis IgG only in 19 mares before, and in 25 mares and 26 foals 3 weeks after vaccination. The mean extinction 3 weeks after vaccination amounted to: II-0.489, IV-2.578, iiA-0.572, IVA-0.974, IIB-0.312, iVB-0.418. The cut-off extinction value was 0.154. The presence of anti-Yersinia pseudotuberculosis IgG before vaccination in the sera of clinically healthy mares may suggest that Y. pseudotuberculosis infection occurs definitely more often than is expected. Vaccination preceded by immunostimulation appeared to be the most efficient method of treatment against yersiniosis.

The detection and determination of potential virulence of Salmonella spp. using PCR method.

The aim of this study was to prove that PCR is a very useful method to identify Salmonella strains and to determine their virulence factors by amplification of characteristic genetic markers. Investigations included 5 strains of Salmonella which were obtained from pure cultures and 1 Salmonella strain from the mixed culture. Genotypic analysis of 6 examined strains revealed the 163-bp fragment of chromosomal DNA, which is the DNA rep. ori. gene, encoding the particular genus. In all of these strains 215-bp, 203-bp and 204-bp chromosomal DNA fragments were identified as representing the stn, stpA and spaO genes that confirmed their virulence. These amplification products were identified in both pure and mixed culture from pork. Sensitive and rapid PCR method may be used not only for identification of Salmonella strains and for determination of their virulence factors but also for routine microbiological diagnostic of food pathogens.