Methods for detecting drug-resistant staphylococci in the human body under natural conditions]

Two methods were compared for determination of drug resistant staphylococci on the nasal mucosa of patients, i. e. the routine method for determination of staphylococcal sensitivity to antibiotics and the method of direct plating out of the starting material onto agarized media containing antibiotics. Staphylococci resistant to streptomycin, tetracycline, chloramphenicol, erythromycin, monomycin, axacillin and less frequent to penicillin were found more often with the 2nd method. A method of proportions was developed for testing sensitivity of staphylococci in purulent inflammatory foci of the patients. It provided characterization of the staphylococcal population from the foci by the number of the antibiotic resistant microbial cells.     

Alternative localization of the determinant of pathogenicity coded by the Yersinia pseudotuberculosis pVM82 plasmid]

The chromosomal DNA regions in Yersinia pseudotuberculosis strains occur that are homologous to 25 Md DNA segment of the plasmid pVM82 encoding the bacterial capability of immunosuppression. The character of the chromosomal DNA regions dispersion reacting with the 25 Md segment probes is different in epidemiologically hazardous and nonvirulent strains of Yersinia pseudotuberculosis. The specific DNA regions occur as well as identical ones. The suppression of antibody formation to a number of main Yersinia pseudotuberculosis antigens by epidemiologically hazardous strain is demonstrated. The suppression is analogous to the one previously described for Yersinia pseudotuberculosis strains harbouring the plasmid pVM82.     

Hospital acquired infections among newborns and parturients from radionuclide contaminated and control territories

The comparative epidemiological study of hospital acquired infections (HAI) prevalence among newborns and parturient women in radionuclide contaminated territories (RT) and control territories (CT) was carried out. Observation covered altogether 2,837,471 newborns, of these 1,617,047 in CT, and 2,378,877 parturient women, of these 1,352,831 in CT. A high level morbidity of thyroid gland diseases, diabetes mellitus, as well as puerperal sepsis and urogenital tract diseases, was detected among parturient women at RT. The specific feature of HAI among newborns in RT was high prevalence of hematological disturbances and hemolytic disease. Profound studies followed by specifically targeted programs and development of prophylactic measures should be carried out.     

Bacteria of the Burkholderia cepacia complex: specific features of diagnostics,genome organization and metabolism

Modern data, related with the identification and typing of the complex B. cepacia bacteria, are analyzed in the article by using the poly-phase taxonomic approach. An optimal scheme for identifying and typing the complex B. cepacia bacteria, involving the microbiological and molecular-biological methods of laboratory diagnostics, is presented. The key and assumed factors of pathogenicity of the discussed bacteria are described. The possible phylogenetic relations of the complex B. cepacia bacteria with phytopathgens as well as with pathogenic bacteria of species Burkholderia, Pseudomonas, Escherichia, B. mallei, B. pdeudomallei, P. seruginosa and E. coli are described. A possible role of genome alterations and mutations in the genome of the complex B. cepacia bacteria (with the latter genome having unusual properties, i.e. a big size, and a considerable quantity of insertion sequences) in creating the conditions for the "pulsing" evolution "jerks", i.e. for a rapid change-over from saprophytism in the soil to a pathogenic causative agent of a viral-and-bacteriological infection. Such mechanism can be regarded as a rapid and radical adaptation of a microorganism under the conditions of changing ecological niches.     

Genetic heterogeneity of Borrelia afzelii in the natural focus of the Middle Urals

As shown by sequencing the spacer rrf (5S)--rrl (23S) in 72 isolates of B. afzelii (one of the causative agents of Ixodes tick borne Borrelia infections) and the chromosomal gene coding protein P66 in 22 isolates, that in the natural focus located in the Middle Urals two different genetic subgroups (VS461 and NT28) of this genospecies simultaneously circulate. These subgroups are represented by 5 gene variants (rrf) 5S--(rrl) 23S and 5 allelic variants in gene p66. The latter, similarly to spacer gene variants, are not linked with a definite host and occur in different rrf--rrl variants of the infective agent. At the same time the definite species of vectors and carriers may be the host of several different B. afzelii variants, both in the spacer and in the gene coding protein P66, which maintains the genetic heterogeneity of B. afzelii population in the natural focus.     

Modification of a method of passive immune hemolysis on a solid medium for detecting the production of thermolabile enterotoxins by Vibrio cholerae and Escherichia coli strains

A modification of the passive immune hemolysis method for the determination of the production of thermolabile enterotoxins by V. cholerae and E. coli is proposed. This modification permits the use of solid culture media. Experiments with cholera enterotoxin have demonstrated that the sensitivity of the modified method is 8-10 times higher than that of the Elek method. Similar results have been obtained with the use of the proposed method in the study of the capacity of different V. cholerae and E. coli strains for producing enterotoxins. The results obtained with the use of this method have been found to correlate with those obtained by means of the skin test and passive immune hemolysis in a liquid medium. We have used the modified method in the study of the production of thermolabile enterotoxin in transconjugants obtained by the hybridization of E. coli strain GA 107 carrying plasmid pCG86 which determines the synthesis of thermolabile and thermostable enterotoxins and E. coli strain K12 C600 R. The results obtained in the study of toxin formation in 99 transconjugants, carried out with the use of the proposed method, the skin test and passive immune hemolysis, have been shown to coincide.