Presence of insertion sequences (IS elements) in group B streptococci of bovine origin.

BACKGROUND & OBJECTIVES: Streptococcus agalactiae (group B streptococci, GBS) is one of the leading causative agents of human and animal infections. Recently it was demonstrated that integration of different IS elements could inactivate some of the GBS virulence properties. The presence of IS elements in human isolates has been studied while the bovine isolates were not investigated till now. The objective of the study was to perform IS analysis of a large number of bovine GBS and to use the IS elements for classification and molecular epidemiology of GBS strains. METHODS: A total of 101 GBS isolates obtained from the dairy cows were tested. These were analyzed by PCR and multiplex PCR. Southern hybridization was accomplished with the Enzo(TM) DNA Labeling and Detection Kit. The computer techniques were used for selection of the specific primers and for analysis of the sizes of PCR products. RESULTS: GBS isolates collected at three different dairy farms were studied for the presence of IS elements. Multiplex PCR was used for the fast screening. It was found that IS861 presented in 29 GBS isolates (28.7%), IS1548 in 9 (8.9%), ISSa4 in 48 (47.5%) and IS1381 in 26 isolates (25.7%). A total of 28 bovine GBS isolates (27.7%) did not possess any of the IS elements, 36 (35.6%) possessed, 35 (34.7%) possessed two and 2 (1.9%) possessed three different IS elements. The GBS with four different IS elements were not found. Taken together, 10 different variants of GBS strains were discovered. Two out of 10 variants being specific for 51 isolates (50.5%) were predominant in bovine GBS. The results of the study demonstrated that the presence of IS elements significantly varied in bovine GBS. INTERPRETATION & CONCLUSION: The present data demonstrated that variants of IS elements present in GBS genome could be used as effective criteria for molecular epidemiology. In future this approach could probably be used as an additional tool for the epidemiological control and prevention of other bacterial infections.

[Methods of molecular epidemiology of infections caused by group B streptococci]. / Metody molekuliarnoi épidemiologii infektsii, vyzyvaemykh streptokokkami gruppy B.

In this review the comparative analysis of advantages and disadvantages of the known methods for the immunological diagnostics of streptococcal infections (serotyping, phage typing), as well as the methods of molecular epidemiology (PCR typing with the use of "disseminated" priming, ribotyping, electrophoresis in the pulsing electric field, etc.), is presented. Essentially new approaches, capable of being used in future for the control of epidemically topical clones of group B streptococci, are discussed.

The presence of insertion elements IS861 and IS1548 in group B streptococci.

The presence of insertion elements (IS) IS861 and IS1548 in the collection of 211 Streptococcus agalactiae strains isolated from pregnant women and dairy cows was assayed. IS861 was found in 67 human strains (59%) and 36 bovine strains (37%), IS1548 in 13 human strains (12%) and 16 bovine strains (16%). Two combinations, IS861+ IS1548- and IS861- IS1548-, were widely distributed in both human and bovine strains. The copy number and the restriction fragment length polymorphism (RFLP) of the two IS were determined in human group B streptococcus (GBS) strains. A minimum of 8 copies of IS1548 were detected in GBS strains while the copy number of IS861 varied from 1 to 9. The number of different hybridizing patterns with IS861 and IS1548 probes was 9 and 6, respectively. These hybridization patterns were divided into several clusters. All strains with IS were also clustered according to pulsed field-gel electrophoresis (PFGE) patterns. A correlation was found between the results of PFGE- and IS-based clustering.

Genetic heterogeneity of the pathogenic potentials of human and bovine group B streptococci.

One-hundred seventy-two B-streptococcal strains of human and bovine origin were analyzed for the presence of 9 genes potentially involved in virulence. Some of genes (glnA, cyl, hylB, scaA and cfb) were revealed in all the strains. However, the presence of others (bca, bac, scpB, lmb) varied from strain to strain. Taken together, 3 and 5 different types of pathogenic potential were found among human and bovine group B streptococci (GBS) strains, respectively, and only one type (bca+ bac scpB+ glnA+ cyl+ hylB+ lmb+ scaA+ cfb+) was common for both kinds of strains. We propose that different virulence genes can be involved in the development of infectious processes in humans and animals. A reliable PCR protocol with 3 pairs of primers (for the genes bca, bac and scpB) in the same reaction mixture was developed for the fast identification of the pathogenic potential of GBS. In comparison with the classical immunological methods this procedure displayed higher specificity and sensitivity as well as a shorter time of analysis. It can be recommended for use in the clinical and veterinary practice for studying the epidemiological relationship between the isolates and the ready identification of the clone causing the infection.

Criteria for the health evaluation of polymeric materials building.

Various polymer-based synthetic materials have become increasingly ubiquitous in manufactured materials in the U.S.S.R. These release various chemical compounds to the ambient air. The maximum permissible concentrations that have been established for various hazardous chemicals in ambient air must be adjusted to account for the conditions of apartment life. Studies have been conducted to determine exactly what compounds are released and at what rate. Toxicological studies and studies of various physical and chemical properties are required to determine the health effects of these chemicals at concentrations at which they are expected to occur in apartments. More research has to be carried out in this field to further expand our knowledge, and we must beware of any introduction of new polymeric materials without first studying their contribution to possible detrimental health effects.