Pseudomonas aeruginosa efflux pump superfamily (review of literature).

The significant increase in the number of antibiotic-resistant microorganisms observed in recent years is a public health problem worldwide. One of the molecular mechanisms for the formation of antimicrobial resistance in bacteria is the presence of efflux pumps. The review presents an analysis of experimental studies related to the study of efflux pumps in clinical strains of Pseudomonas aeruginosa, one of the representatives of hospital pathogens of the ESKAPE group. This review is intended for specialists developing new types of drugs against antibiotic-resistant strains, as well as researchers studying the mechanisms of bacterial resistance to antibiotics, heavy metals, biocides and other antimicrobial factors.

The sensitivity of planktonic cultures and biofilms of gram-negative bacteria to commercial disinfectant and antiseptic preparations.

The in vitro antibacterial activity of 11 commercial disinfectant preparations and 8 antiseptics against 10 strains of the bacteria Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloaceae and Providencia stuartii obtained from international collections and isolated from neuroresuscitation patients in Moscow in 2018 was studied. The sensitivity of planktonic cultures to the preparations was determined by the method of serial dilutions in broth and the spot method on solid nutrient media, the sensitivity of biofilms by the applicator method. A general pattern was revealed: the level of sensitivity to tested disinfectants in clinical strains was lower than in reference strains. It was found that the disinfectants «Mikrobak-Forte¼, «SAT-22¼, «Neobak-Oksi¼ at the concentrations recommended by the manufacturers were effective against bacteria of all test strains, both in the plankton state and in the form of biofilms. On the contrary, the disinfectant preparations «Biodez-Optima¼, «Biodez-Extra DVU¼, «Novodez-Aktiv¼, «Triosept-Oksi¼, «Tristel Fusion for Surfaces¼, «Effect-Forte Plus¼, «Lactic-Oxy¼ did not have sufficient effectiveness in the concentrations recommended by the manufacturers, therefore it is proposed to use these drugs in higher concentrations. It was found that the disinfectant «Biodez-Extra DVU¼ is able to inhibit the growth of biofilms of bacteria of the species K. pneumoniae. The ability to suppress the growth of bacterial biofilms of K. pneumoniae, A. baumannii, P. aeruginosa was revealed for the «Triestel Fusion for surfaces disinfectant¼. The bacteria of all used test strains in the planktonic state were sensitive to all tested antiseptic preparations. However, the biofilms of the clinical strains of P. aeruginosa and P. stuartii. possessed resistance to the antiseptics «Octenidol¼, «Octenisept¼, «Miramistin¼, «Hexoral¼. Our studies indicate the need for sensitivity analysis of antibacterial drugs in representatives of hospital pathogens, including the modeling of bacterial biofilms, which is a very relevant and important scientific direction, necessary to improve the control of nosocomial infections in the Russian Federation.

A study of antibiotic and disinfectant susceptibility of Elizabethkingia meningoseptica.

For the local health service, Elizabethkingia meningoseptica remains a relatively new and little-known pathogen, whereas in many countries of Europe, Asia and other continents it is considered as a potential causative agent of nosocomial infections, especially in premature infants and immunocompromised patients. An analysis of the literature data, as well as our results indicate that E. meningoseptica should be considered as a potential pathogen, which is characterized by a unique profile of susceptibility to antimicrobial agents (AMP) and disinfectants. This article presents the results of a study of susceptibility to AMP and disinfectants of three isolates of E. meningoseptica, isolated during an investigation of an outbreak in one of the perinatal centers of the Russian Federation, where three cases of sepsis with a fatal outcome in premature infants caused by co-infection with Acinetobacter baumannii and E. meningoseptica were recorded between January and February 2016.

Next-Generation Antibiotics, Bacteriophage Endolysins, and Nanomaterials for Combating Pathogens.

This review presents various strategies to fight causative agents of infectious diseases. Species-specific programmable RNA-containing antibiotics open up new possibilities for creating next-generation of personalized drugs based on microbiome editing and can serve as a new tool for selective elimination of pathogenic bacterial species while keeping intact the rest of microbiota. Another promising approach in combating bacterial infections is genome editing using the CRISPR-Cas systems. Expanding knowledge on the molecular mechanisms of innate immunity has been actively used for developing new antimicrobials. However, obvious risks of using antibiotic adjuvants aimed at activation of the host immune system include development of the autoimmune response with subsequent organ damage. To avoid these risks, it is essential to elucidate action mechanisms of the specific ligands and signal molecules used as components of the hybrid antibiotics. Bacteriophage endolysins are also considered as effective antimicrobials against antibiotic-resistant bacteria, metabolically inactive persisters, and microbial biofilms. Despite significant advances in the design of implants with antibacterial properties, the problem of postoperative infections still remains. Different nanomodifications of the implant surface have been designed to reduce bacterial contamination. Here, we review bactericidal, fungicidal, and immunomodulating properties of compounds used for the implant surface nanomodifications, such as silver, boron nitride nanomaterials, nanofibers, and nanogalvanic materials.

[Phenotypic and molecular genetic properties of Escherichia coli clinical strains isolated from patients with urological diseases].

OBJECTIVE: Microbiological and molecular genetic characterization resistance profiles of Escherichia coli strains isolated in a pilot single-center clinical study from patients of the urological department in Yaroslavl in 2016-2017. MATERIALS AND METHODS: Clinical strains of E. coli (n=18) were isolated from the urine of women aged 23-84 years. The mobility of bacteria, colicinogenicity, and sensitivity to lactobacilli antagonism, biofilm formation, and susceptibility to antimicrobials were evaluated. The antibiotic resistance genes were identified. RESULTS: The E. coli strains had a wide heterogeneity in mobility, colicinogenicity, and biofilm formation. They were sensitive to Lactobacillus acidophilus antagonism, as well as to nitrofurantoin, meropenem, fosfomycin and the main functional classes of disinfectants and antiseptics, but are resistant to beta-lactams, fluoroquinolones and aminoglycosides. The mcr-1 gene providing resistance to colistin was identified in two strains. CONCLUSIONS: Analysis of genetic antibiotic resistance determinants revealed the genetic diversity of clinical E. coli strains. The obtained data on the strain sensitivity to antibacterials and disinfectants can be used by clinicians in choosing the optimal antibiotic therapy and treatment of abiotic surfaces in urological departments.

[Antimicrobial activity of dioxidine and a dioxidin-containing preparation «Nosolin-Ultra, nasal drops¼.]

The study is devoted to the study of the antimicrobial activity of the antioxidant dioxidin and the complex dioxin-containing preparation Nosolin-ultra, nasal drops against planktonic and biofilm cultures of pathogens of ENT infections, the dynamics of the formation of microbial resistance to dioxidine. 11 reference strains and 9 clinical strains of microorganisms were used in the study: Streptococcus spp., Staphylococcus spp., Micrococcus luteus, Haemophilus influenzae, Acinetobacter pittii, Klebsiella pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa. The antimicrobial activity of preparations against planktonic cultures was determined by serial dilution in broth and spot method on solid nutrient media, against biofilms by the applicator method. The dynamics of dioxidine resistance formation was studied by passaging cultures in a liquid nutrient medium with increasing concentrations of antiseptic. Based on the study, it was found that Dioxidin showed antimicrobial activity against plankton cells of all strains (MBC=0.08-5 mg/ml), except S. pyogenes SN345 (MBC>5 mg/ml), inhibited the growth of formed biofilms (MBC=0.08-2.5 mg/ml) of all strains except S. pyogenes SN345 (MBC>5 mg/ml). The drug «Nosolin-ultra, nasal drops¼ was highly active against plankton cells (MBC=0.04-0.63 mg/ml) and biofilms (MBC=0.02-0.31 mg/ml) of gram-negative bacteria, except A. pittii (MBC>2.5 mg/ml), less active against plankton cells (MBC=1.25-2.5 mg/ml) and biofilms (MBC=0.02-0.31 mg/ml) of gram-positive bacteria and C. albicans. One strain (S. aureus) formed a variant resistant to dioxidine at a concentration of 20 mg/ml, which exceeded the concentration of dioxidine in the complex preparation; other strains (P. aeruginosa, K. pneumoniae, C. albicans) did not form such variants. The data obtained indicate that the drug «Nosolin-ultra, nasal drops¼ can be effectively used against most pathogens of ENT infections. It is worth noting that with prolonged use of the drug for some types of ENT pathogens in the future, a slight decrease in effectiveness may be noted.

[Trials of the domestically produced nutrient medium «Agar Muller-Hinton II - Obolensk¼.]

The results of the comparative tests of the «Agar Muller-Hinton II - Obolensk¼ nutrient medium developed in SRCAMB, Obolensk, and the control nutrient medium imported «Mueller Hinton II Agar¼ are presented in the study. The susceptibility of bacterial clinical strains to antimicrobial agents (AMP) was determined by the disc diffusion method and the method of gradient diffusion (E-test). The carbapenemase activity of the strains carrying the carbapenemase genes was determined by CIM-test. Total 173 characterized bacterial strains of species Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Proteus mirabilis, Serratia marcescens, Enterobacter aerogenes, Escherichia coli; Photorhabdus spp., Staphylococcus aureus, Enterococcus spp. were used in the study, including producers of OXA- and NDM-types carbapenemases for gram negative bacteria. A high degree of coincidence of the results obtained on both nutrient media was shown. The consistency index of the strain sensitivity categories to AMPs (S, I, and R) was 98.2% for the disc diffusion method, and 94.4-100% - for E-test and CIM-test methods. Thus, within the framework of the Import Substitution Program, the domestic nutrient medium «MHA II-Obolensk¼ has been successfully developed. The nutrient medium meets the requirements of GOST R ISO 20776-2-2010 «Clinical laboratory testing and in vitro diagnostic test systems - Susceptibility testing of infectious agents and evaluation of performance of antimicrobial susceptibility test devices¼.

[The study of patterns of development of resistance of Staphylococcus aureus to triclosan].

The article presents the results of studying molecular genetic mechanisms of development of resistance to antiseptic Triclosan in strain Staphylococcus aureus АТСС25923. The modifcations of strain S. aureus АТСС25923 (Tr1, Tr2, Tr1С и Tr2С) are obtained resistant to 64 mg/l of Triclosan and stably preserving the given characteristic under cultivation in absence of selective pressure. The strain S. aureus Tr1was characterized by slightly delayed growth and the strain S. aureus Tr2 was characterized by growth velocity comparable with initial strain. In the Triclosan-resistant strains a mutation C284T in gene fabI was detected resulting in amino-acid replacement A95V in enzyme enoyl-acyl protein reductase FabI, triclosan target. Besides, in these strains a stably inheriting mutation was detected in genes associated with transport of substances in cell: hypothetical transport protein HlyC/CorC family transporter, protein-transporter of ions of Na+, K+, Li+ and alkali of Na+/H+ antiporter subunit F, membrane hypothetical protein and ATP-binding protein. It is demonstrated that resistance to triclosan in staphylococci is associated with acquirement of point mutations in genes of enoyl-acyl protein reductase and also in other genes related to transport of substances in bacterial cell.

[The characteristic of diarrheagenic Escherichia separated from children aged under 5 years old in Yaroslavl.]

The diarrheagenic bacteria coli take a significant place among agents of acute intestinal infections in children aged under 5 years. The main danger among these pathogens is represented by both enterotoxigenic E. coli causing enteritis and enterocolitis accompanied by acute dehydration diarrhea and Escherichia producing shiga-toxin being agents of hemorrhagic colitis and hemolytic uremic syndrome. The fast and proper identification of agents of these two groups of pathogens is an important task of bacteriologists to be resolved for successful treatment of patient because tactics of therapy of enterotoxigenic diarrhea and hemorrhagic colitis and hemolytic uremic syndrome significantly differ. The high capacity of Escherichia coli to form populations resistant to anti-microbial medications, including pan-resistant ones, also is a serious problem for science and public health. The object of study was a collection of isolates of E. coli (n = 112), separated from 112 children aged under 5 years with clinical manifestations of acute intestinal infection, food toxic infection hemocolitis and diarrhea of obscure etiology in Yaroslavl in 2015-2017. Initially, the strains of E. coli were tested using diagnostic agglutinating coli-serums and then using reagents' kit «AmpliSens®Escherichiosis-FL¼ for detection and differentiation DNAof diarrheagenic bacteria coli and also with specific oligonucleotide primers to genes of virulence and O-serum group belonging. The obtained data permitted to determine belonging of analyzed strains of E. coli to four sub-groups: ЕНЕС (n = 9), EPEC (n = 17), ETEC (n = 1) и EAgEС (n = 1). All of them were agents of genes of pathogenicity specific for every pathogroup. The most numerous group EPEC was represented by strains of five serogroups with dominating among them serogroup O26 (9 strains). Therefore, studying collection of strains of diarrheagenic Escherichia isolated during 2015-1017 in Yaroslavl from children aged under 5 years with acute intestinal infections permitted to demonstrate efficiency of application of molecular genetic methods of analysis for characterizing E. coli i.e. establishment their serogroups, detection of genes of virulence and attributing to pathogroups.

[Molecular-genetic characterization of shiga-toxin producing Escherichia coli isolated during a food-borne outbreak in St. Petersburg in 2013].

UNLABELLED: Shiga toxin-producing Escherichia coli (STEC) food-borne infections are reported worldwide and represent a serious problem for public healthcare. In the Russian Federation there is little information on epidemiology and etiology of STEC-infections as well as on molecular-genetic peculiarities of STEC pathogens. OBJECTIVE: Our aim was to describe a food-borne outbreak as hemorrhagic colitis (HC) along with hemolytic uremic syndrome (HUS), enterocolitis, and acute gastroenteritis in children in St. Petersburg in 2013. METHODS: Epidemiological, microbiological, molecular-genetic and bioinformatic methods were applied. RESULTS: Objects to study were clinical specimens, milk and food samples, as well as STEC strains isolated during the outbreak. The outbreak of food-borne infection was found to be caused by STEC-contaminated raw milk as confirmed by epidemiological analysis, detection of STEC DNA and isolation of relevant pathogens in milk and sick children fecal specimens. The whole-genome sequencing revealed two groups ofpathogens, E. coli O157:H7 and E. coli O101:H33 among collected strains. Group I strains were attributed to the previously known sequence type ST24, while group II strains belonged to the previously non-described sequence type ST145. In strain genomes of both groups there were identified nucleotide sequences of VT2-like prophage carrying stx2c gene, plasmid enterohemolysin gene, and gene of the STEC main adhesion factor intimin. Gene of intimin gamma was identified in E. coli O157:H7 strains and intimin iota 2 in E. coli O101:H33 strains. The latter previously was identified only in enteropathogenic E. coli (EPEC) strains. CONCLUSION: The additional knowledge of epidemiology and biology of STEC pathogens would assist clinicians and epidemiologists in diagnosing, treating and preventing hemorrhagic colitis.

[An algorithm for identification of CTX-M-type beta-lactamase genes using restriction fragment length polymorphism analysis of PCR-product].

The algorithm of the identification of the bla(CTX-M) genes coding CTX-M-type beta-lactamases providing resistance to cephalosporins III-IV was developed. This algorithm provides identification of 49 genes of 96 genes presented in the GenBank database so far. Remaining 47 genes can be identified as consisting of small sub-groups composed of 2-6 genes with the exception of sub-group of the bla(CTX-M-14)-like genes composed of 13 genes. The identification of the bla(CTX-M) genes is based on two-step restriction fragment length polymorphism analysis of 544 bp PCR-product (PCR-RFLP). In the first step, determination of subtype (cluster) of the bla(CTX-M) gene occurred using the restriction nuclease Alu I: cluster 1, -2, -8, -9 or -25. Moreover, four genes can be identified just at this step: bla(CTX-M)-59, (cluster 2); bla(CTX-M-63) (cluster 8), bla(CTX-M-45) (cluster 9), and bla(CTX-M-78) (hybrid gene between cluster 2 and cluster 25). At the second step gene identification goes on inside of each cluster separately using a set of 26 restriction nucleases. As a result of the PCR-RFLP-analysis, 23 bla(CTX-M) genes can be identified at the cluster 1, 11 genes--at the cluster 2, 4 genes--at the cluster 8, 9 genes--at the cluster 9, 1 gene--at the cluster 25, and 2 hybrid genes: bla(CTX-M-78) (between clusters 2 and 25), and bla(CTX-M-64) (between clusters 1 and 9). The described algorithm was used for identification of the blac(CTX-M) genes (n = 585) detected in Enterobacteriaceae nosocomial isolates (n = 877), collected from Russial hospitals in 2003-2007. It was shown that major genes belonged to cluster 1 (n = 543), namely--bla(CTX-M-15) gene (n = 515), bla(CTX-M-3) (n = 25), bla(CTX-M-22) (n = 1), bla(CTX-M-23) (n = 1), and bla(CTM-34) (n = 1). Moreover, the genes atributed to cluster 2 were identified: bla(CTX-M-2) (n = 1), and bla(CTX-M-5) (n = 4); and genes belonged to cluster 9: bla(CTX-M-9) (n = 2), and bla(CTX-M-14) (n = 35).

[Antimicrobial activity of bacteriocin S760 produced by Enterococcus faecium strain LWP760].

Antimicrobial activity of bacteriocin S760 (enterocin) produced by Enterococcusfaecium strain LWP760 was studied. Bacteriocin S760 is a cationic, hydrophobic, and heat stable peptide with the molecular weight of 5.5 kDa and pl of 9.8. Enterocin S760 is shown to inhibit in vitro the growth both of sensitive and resistant to antibacterials gramnegative and grampositive bacteria of 25 species. MICs of the bacteriocin S760 vary between 0.05-1.6 mg/l for Escherichia coli 0157:H117, Salmonella typhimurium, Salmonella enteritidis, Campylobacter jejuni, Yersinia enterocolitica, Yersinia pseudotuberculosis, Listeria monocytogenes and Clostridium perfringens, that are main food-borne pathogens, and from 0.4-1.6 mg/l for Streptococcus pyogenes, Streptococcus pneumoniae and Corynebacterium diphteriae. It is also active against antibioticresistant strains of Staphylococcus aureus, Enterobacter cloacae, Acinetobacter baumannii (with MICs of 0.05-3 mg/l), Klebsiella pneumoniae (with MICs of 6 mg/l), Pseudomonas aeruginosa (with MICs of 0.4-25 mg/1), as well against fungi belonging to species of Candida albicans, Candida krusei and Aspergillus niger (with MICs of 0.1-0.2 mg/l). Enterocin S760 is a novel antimicrobial agents useful in medicine, veterinary and food industry.

[Genetic environments of bla(CTX-M) genes located on conjugative plasmids of Enterobacteriaceae nosocomial isolates collected in Russia within 2003-2007].

The study showed that bla(CTX-M) genes were present in the genomes of 71% of cephalosporin resistant Enterobacteriaceae nosocomial isolates (n=833) collected in Russian hospitals within 2003-2007, including 91% of E.coli, 90% of Klebsiella spp., 38% of Enterobacter spp., 31% of Citrobacter spp. (n=9), and 36% of the other Enterobacteriaceae species. The genes belonging to the following subtypes (clusters) were identified: bla(CTX-M-1) (529 bla(CTX-M-15) genes; 25 bla(CTX-M-3) genes; 1 bla(CTX-M-22) gene, 1 bla(CTX-M-23) gene, and 1 bla(CTX-M-34) gene); bla(CTX-M-2) (1 bla(CTX-M-2) gene, and 4 bla(CTX-M-5) genes), and bla(CTX-M-9) (2 bla(CTX-M-9) genes, and 28 bla(CTX-M-14) genes). It was shown that bla(CTX-M) genes were located on high-molecular weight (60-160 bp) conjugative plasmids belonging mainly to the incompatibility groups IncF, IncL/M and IncA/C (bla(CTX-M-15) gene); IncL/M(bla(CTX-M-3) gene); and IncF, IncL/Mand IncI1-ly (CTX-M-14 gene). The gene environments of bla(CTX-M) genes were shown specific for the subtype of the genes. A mobile genetic element ISEcp1 (in some cases deleted or inserted by IS26, IS1, IS10, resTn2, or resTn3 sequences, in direct or reverse position) were detected upstream of bla(CTX-M-3), bla(CTX-M-14), and bla(CTX-M-15) genes. A special characteristic was the sequence between ISEcp1 and bla(CTX-M) gene: 48 bp for bla(CTX-M-15) (except 1 E.coli isolate having such a sequence deleted by 3 bp); 127 bp for bla(CTX-M-3); 42 bp for bla(CTX-M-14). Downstream of bla(CTX-M) and bla(CTX-M-15) genes in the major bacterial isolates orf477 mucA and Delta orf477-Delta mucA sequences were detected respectively. Two isolates had additional Delta orf3 insertion inside of Delta orf477-Delta mucA sequence. Insertion sequence IS903 (intact or deleted) was detected downstream of bla(CTX-M-14) gene. Unlike the others, bla(CTX-M-2) and bla(CTX-M-9) genes were located inside of ISCR1 mobile element, downstream of class 1 integron and orf513 sequence.

[Genetic determinants of antibacterial resistance among nosocomial Escherichia coli, Klebsiella spp., and Enterobacter spp. isolates collected in Russia within 2003-2007].

Nosocomial bacterial isolates collected within 2003-2004 (n=411) and 2005-2007 (n=422) were highly resistant to cephalosporins III-IV and antibacterials of other groups (aminoglycosides, fluoroquinolons, chloramphenicol, and co-trimoxazole). Genes encoding TEM, SHV, CTX-M, OXA-2, and AmpC types of beta-lactamases (BLs) in the E. coli, Klebsiella spp., and Enterobacter spp. isolates were detected using polymerase chain reaction (PCR). Prevalent CTX-M-type BLs were detected in 85% of the E. coli, 87% of the Klebsiella spp., and 38% of the Enterobacter spp. isolates of the first strain collection and in 94% of the E. coli, 91% of the Klebsiella spp., and 38% of the Enterobacter spp. isolates of the second one. Genes belonging to three subtypes of blacTx-M genes were identified: bla(CTX-M-1) (228 bla(CTX-M-15) and six bla(CTX-M-3) of the first strain collection; 275 bla(CTX-M-15), three bla(CTX-M-3), and one bla(CTX-M-22) of the second one), bla(CTX-M-2) (one bla(CTX-M-5) of the first strain collection and one bla(CTX-M-2) of the second one), bla(CTX-M-9) (17 bla(CTX-M-14) and one bla(CTX-M-9) of the first strain collection; seven bla(CTX-M-14) and one bla(CTX-M-9) of the second one). Three isolates of the first strain collection and one isolate of the second one carried two genes belonging to two different subtypes, i.e., bla(CTX-M-15) and bla(CTX-M-14) simultaneously. The bacterial isolates had high levels of associative resistance to ciprofloxacin, co-trimoxazole, gentamicin, amikacin, and chloramphenicol associated with the resistance gene cassettes aadA1, aadA2, aadA5, aadB, aacA4, aac(6')Ib; dfrA1, dfrA5, dfrA12, dfrA17, cmlA1, ereA2, and catB8 in the class 1 integrons and the resistance gene cassettes dfrA1, sat1, and aadA1 in the class 2 integrons.

[Electrokinetic potential of Yersinia pestis and Escherichia coli cells with an intact or defective ycaA gene (caf1M) of the fra-operon of plague pathogen]. / Elektrokineticheskii potentsial kletok Yersinia pestis i Escherichia coli s intaktnym ili defektnym genom ucaA (caf1M) fra-operona vozbuditelia chumy.

The dependence of the amount of electrokinetic potential in cells of Escherichia coli and Yersinia pestis, which differ in the rate of reduction of lipopolysaccharide (LPS), on the presence or absence of typical and atypical capsules of Y. pestis, encoded by intact and mutant fra operons, respectively, was studied. The ycaA+ycaF+(caf1 M+caf1+) genotype was shown to be expressed in serological stability of a classical capsular antigen, irrespective of the producer strain, and a decrease in the negative charge of microbial cells compared to their noncapsular variants. Blocking of the synthesis of the product of the ycaA gene of the fra operon resulted in formation of encapsulated bacteria, whose surface electricity and serological characters varied in dependence on the LPS structure. Data obtained support the assumption that a product of the ycA gene stabilizes the conformation of the typical capsule of the plague-causing agent, which was formed from YcaF (Caf1) monomers.

[Vaccination against typhoid fever: results and perspectives]. / Vaktsinoprofilaktika briushnogo tifa: itogi i perspektivy.

The review deals with the world history and the current status of typhoid fever vaccination. It analyzes parenteral and oral killed cellular, oral live attenuated, molecular vaccines are analyzed. The results of field trials of parenteral and oral vaccines in the areas showing different epidemiology and incidence are analyzed. The problems in the designing of molecular typhi vaccines are considered. The results of designing the new generation vaccines S. typhi strains attenuated by means of site-specific mutagenesis and Vi-polysaccharide-protein conjugates are presented.

[Recombinant plasmids carrying yersinia pestis fra-operon: specific features of genetic transmission, inheritance and expression in attenuated enterobacterial cells]. / Rekombinantnye plazmidy, soderzhashchie fra-operon chumnogo mikroba: osobennosti geneticheskoí peredachi, nasledovaniia i ékspressii v kletkakh attenuirovannykh énterobakterií.

The study was undertaken to study the specific features of transformation of E. coli strains having different R-chemotypes, Y. pestis, S. minnesota R595, and S. typhi Ty21a by plasmids carrying Yersinia pestis Fra-operon which controls the formation of a plague microbe capsular F1 antigen in this microorganism. Calcium transformation was shown to be rather effective for the plasmids constructed on the basis of a cosmid vector (pFS1), rather than those designed by using the Y. pestis plasmid pPst I (pFSK3, pP3). The level of plasmid stability varied and failed to correlate with taxonomy fitting and the chemotype of a recipient strain. The cells of all recombinant strains produced F1 antigen, secreted it into the environment; the synthesis was temperature-regulated. F1 was identified both in the diffuse precipitation and serological tests. The levels of F1 antigen synthesis decreased whereas nutritious requirements for the maintenance of protein synthesis increased for bacterial strains with higher levels of LPS reduction.

Antimicrobial Activities of Bacteriocins E 50-52 and B 602 Against Antibiotic-Resistant Strains Involved in Nosocomial Infections.

The antimicrobial spectra of previously published bacteriocin E 50-52 (39 a.a.; 3,932 Da; pI = 8.5) and bacteriocin B 602 (29 a.a.; 3,864 Da; pI = 7.2) were determined. Named peptides were related to class IIa (pediocin-like) bacteriocins. Minimal inhibitory concentrations (MICs) of bacteriocins have been determined for bacterial isolates that were causative agents of nosocomial infections collected from Russian hospitals in 2003-2007, namely methicillin-resistant Staphylococcus aureus (MRSA) (n = 10); Acinetobacter baumannii (n = 11); Citrobacter freundii (n = 8); Escherichia coli (n = 9); Klebsiella pneumoniae (n = 10); Proteus spp. (n = 6); and Pseudomonas aeruginosa (n = 10). The majority of these tested isolates have been shown to be multidrug resistant and carry genetic determinants of antimicrobial resistance that were detected using polymerase chain reaction (PCR). The MICs of bacteriocin B 602 ranged from ≤0.025-1.56 µg/ml, and for bacteriocin E 50-52 from 0.05 to 6.25 µg/ml for all of 64 bacterial clinical isolates tested. Interestingly, the bacteriocins studied demonstrate activity on both Gram-positive and Gram-negative bacteria. Bacteriocins E 50-52 and B 602 show good activity against nosocomial bacterial agents resistant to many classes of modern antibacterials used in clinical practice. These bacteriocins should be examined as an alternative in treating infections caused by such agents.

[Comparative characterization of the physico-chemical properties of lipopolysaccharides of Yersinia pestis and R-mutants of enterobacteria]. / Sravnitel'naia kharakteristika fiziko-khimicheskikh svoistv lipopolisakharidov Yersinia pestis i R-mutantov énterobakterii.

Electrokinetic potentials (EKP) of the cells of R mutants of Escherichia coli and Salmonella minnesota and cells of Yersinia pestis strains EV (line NIIEG), 358/12 P-, TWJ, Java, and 231 (708) were determined, as well as EKP of lipopolysaccharide (LPS) preparations isolated from these bacteria. The electric characteristics of the cell surfaces of the strains under investigation were demonstrated to correlate with the LPS charge and the reduction extent of their molecules. Acidic hydrolysis of LPS on the cell surface resulted in the leveling of the distinctions in EKP values (their reduction to the same level). EKP values and the size of LPS micelles of the studied Y. pestis strains corresponded to those of the deep R mutants of enterobacteria, while the aggregation extent of the molecules was higher for Y. pestis.