[Wild small mammals are the reservoir hosts of the Bartonella genus bacteria in the south of Moscow region].

A total of 103 blood samples collected from wild small mammals captured in the Prioksko-Terrasny Reserve on the south of Moscow region were studied to determine the bartonellae prevalence. The examined species were the yellow-necked mice Apodemus flavicollis (35 samples), the European wood mouse Apodemus uralensis (10 samples), the bank vole Clethrionomys glareolus (51 samples), the house mouse Mus musculus (3 samples), the common vole Microtus arvalis (2 samples), and the shrew Sorex araneus (2 samples). Initially, we obtained 76 bacterial Bartonella-like isolates after plating onto the surface of the solid nutrient media. 66 of them were PCR-positive at least for three of four targets, gltA, ftsZ, ribC and 16S RNA. Thus, the percentage of the infection in the studied community was 64%. Subsequent RFLP assay showed that obtained isolates belonged to the Bartonella grahamii and/or B. taylorii species. In 7 cases we found both bartonellae species in one animal. These data were confirmed by direct sequencing of four ftsZ, four ribC and two gltA amplicons. According to our data, there is no any marked host specificity for these bartonellae species. Now we have laid the bartonellae strain collection consisting of 31 isolates. To our knowledge, this is the first investigation of the bartonellae prevalence in wild small mammals performed in Russia. The comparison of our data with those obtained by European researchers and issues of coinfection by different bartonellae species and host specificity are discussed.

[Bacteria of Bartonella genus: characteristics, pathogenicity factors and methods of molecular-genetic investigation]. / Bakterii roda Bartonella--kharakteristika, faktory patogennosti i metody molekuliarno-geneticheskogo issledovaniia.

Bartonella bacteria are an agent of a variety of human and animal diseases whose etiology used to be unknown. The survey contains a description of the above bacteria with the established pathogenicity factors and with the molecular and genetic approaches to studies of genes' functions and of their regulation being in the focus of attention. Modern methods related with the genus-specific and species-specific determination and identification of Bartonella bacteria are discussed.

[Sensitivity of Escherichia coli cell membranes to various classes of detergents]. / Chuvstvitel'nost' membran kletok Escherichia coli k detergentam raznykh klassov.

The mechanisms of interaction between non-ionic or cationic surfactants with Escherichia coli K-12 cell membranes were studied using an approach based on the registration of changes in the membrane permeability to ethidium bromide, a fluorescent dye for nucleic acids. Triton X-100, a non-ionic detergent, was shown to exert no effect on the permeability of intact cell membranes. Triton X-100 interacted with the bacteria only after treatment with EDTA, a complexing agent for bivalent cations. Cetyltrimethyl ammonium bromide increased the permeability to ethidium bromide and the action of this cationic detergent did not require the pretreatment with the complexing agent. SDS, an anionic detergent, damaged E. coli K-12 and this could be registered by the lowering of intensity of light scattering by the bacterial suspension. The surface charge of E. coli K-12 cells was shown to influence the interaction of ionic detergents with bacterial cell membranes. Its variation by changing the pH of the incubation medium did not make E. coli K-12 sensitive to Triton X-100.

[Kinetic analysis of the action of cetyltrimethylammonium bromide on the membranes of the capsular variant of Escherichia coli CA189 recorded by ethidium bromide fluorescence]. / Analiz kinetiki deistviia tsetiltrimetilammoniibromida na membrany kapsul'nogo varianta Escherichia coli CA189, registriruemoi po fliuorestsentsii bromistogo étidiia.

A mathematical model, describing the kinetics of ethidium bromide probe fluorescence in the suspension of E. coli CA 189 capsular antigen after introduction of cetyltrimethylammonium bromide (a detergent), has been developed. Experimental testing of this mathematical model has confirmed that it describes the kinetics of the probe fluorescence augmentation sufficiently accurately. The new model permits the quantitative characterization of the rate of surfactant diffusion through the bacterial capsule.

[Comparative study of the morphology and sensitivity to damaging factors of capsular and acapsular variants of Escherichia coli CA 189]. / Sravnitel'noe isuchenie morfologii i chuvstvitel'nosti k povrezhdaiushchim faktoram kapsul'nogo i beskapsul'nogo variantov Escherichia coli CA 189.

E. coli strain SA 189 has been isolated from a calf with E. coli infection. The cultivation of this strain on a solid culture medium has resulted in its dissociation into two variants due to the loss of the capsule by the cells of the initial culture. Both variants of E. coli strain SA 189 (capsular and acapsular) are equally sensitive to antibiotics. The capsular variant has a narrower range of sensitivity of colicins and shows greater resistance to the bactericidal action of normal blood serum than the acapsular one. Bacteria belonging to these two variants differ perceptibly in the kinetics of disturbances in the barrier properties of their membrane apparatus under the action of cetyltrimethylammonium bromide, a cation detergent. The conditions permitting the differentiation of the capsular and acapsular forms of E. coli strain SA 189 by the kinetics of the damaging action of this detergent have been experimentally selected.