Vol 31, No 1 (2016)

The classification system of transposable elements is shortly reviewed. Special attention is paid to the retrotransposon Bov-B LINE, a retroelement of the LINE group. The history of its origin and distribution in nature is discussed. Data indicating the phenomenon of horizontal transfer of the retrotransposon Bov-B LINE between evolutionarily distant classes are given.

Research on staphylococci research is important because of their ability to cause such severe infections as soft tissue infections, endocarditis, sepsis, toxic shock syndrome, and food poisoning. Coagulase-positive Staphylococcus aureus is the main infection agent of intrahospital infections. This agent has many factors of pathogenicity, which are well known. Among the coagulase-negative staphylococcus (CNS) strains, S. haemolyticus and S. epidermidis are clinically important, because they cause infections in patients with weakened immune system. The mechanisms of the CNS pathogenicity are understood insufficiently. The goal of this work was to evaluate the potential pathogenicity of clinical CNS strains based on their capacity to form biofilms and their character of interaction with the human cells through an example of HT-29 cell culture. The research was carried out on the laboratory strain S. aureus ATCC 29213 and clinical strains S. haemolyticus SH39 and S. epidermidis SE 36-1, which were isolated from neonatal autopsy materials. The visual tests of biofilm formation by each strain and testing the impact of the strains on HT-29 cell culture were carried out in this work. Two CNS species form biofilms with a higher rate than S. aureus. Upon incubation for 2 h of HT-29 cells with the staphylococcus strains tested in this work, adhesion of bacteria on the cells’ surfaces was observed. The adhesion was most pronounced in the case of S. aureus ATCC 29213 and S. haemolyticus SH39. Upon 3 h of incubation with S. aureus ATCC 29213 and S. haemolyticus SH39, the destruction of a monolayer of HT-29 cells was observed. The incubation for 24 h with three strains tested in this work caused the complete destruction of the monolayer of HT-29 cells. The maximal toxic effect on HT-29 cells was inherent in S. haemolyticus SH39 strain. The cumulative results obtained in this work indicate the presence of the pathogenicity factors in S. haemolyticus SH39 strain, and their molecular nature needs to be researched further.

The goal of this work was to obtain genotypic characteristics of multidrug-resistant (MDR) strains of Mycobacterium tuberculosis (i.e., strains that are resistant at least to rifampicin and isoniazid) isolated from consumptives in Northwestern Russia in 2011–2012. Spoligotyping of 195 strains of Mycobacterium tuberculosis revealed 14 spolingotypes belonging to genetic families Beijing (n = 162), LAM (n = 15), H3/URAL (n = 14), T, Harleem, and X. Spolingotypes SIT1 (Beijing), SIT42 (LAM), and SIT62 (H3/URAL) were predominant. Regardless of genotype, all studied strains were resistant to streptomycin. Multidrug-resistant strains were resistant to ethionamide (56%), amikacin (31%), kanamycin (40%), and capreomycin (33%). The fractions of the strains resistant to ethambutol were 71 (n = 115) and 42% (n = 14) among the Beijing and nonBeijing strains, respectively (p < 0.05). Representatives of the Beijing genetic family remain predominant in Northwestern Russia in the population of multidrug-resistant strains of Mycobacterium tuberculosis (83%).

Comparative analysis of MLVA25-typing and MLVA7-typing for their ability to identify focal affiliation of the Yersinia pestis strains have been performed on the basis of the bv. Medievalis isolates obtained from the Central Caucasus highland natural plague focus. For purposes of analysis, MLVA25 genotypes were identified for 82 isolates and further introduced into a database containing data on the 949 strains of the plague-causing agent obtained in other natural foci in Russia and countries within the former Soviet Union and beyond. The dendrograms were reconstructed by the UPGMA method with a categorical coefficient using data on all 25 VNTR loci or on only 7 of them, which were recommended by the experts from the Microbe Russian Research Anti-Plague Institute to be used for Y. pestis strains differentiation by their focal affiliation. The results of the analysis indicate the higher possibility of diagnostic errors when using the MLVA7-typing for distinguishing between the Y. pestis strains and suggest that it should be useful to subdivide the Central Caucasus highland plague focus into two subfoci.