Staphylococcus simulans Recombinant Lysostaphin: Production, Purification, and Determination of Antistaphylococcal Activity.

Staphylococcus simulans lysostaphin is an endopeptidase lysing staphylococcus cell walls by cleaving pentaglycine cross-bridges in their peptidoglycan. A synthetic gene encoding S. simulans lysostaphin was cloned in Escherichia coli cells, and producer strains were designed. The level of produced biologically active lysostaphin comprised 6-30% of total E. coli cell protein (depending on E. coli M15 or BL21 producer) under batch cultivation conditions. New methods were developed for purification of lysostaphin without affinity domains and for testing its enzymatic activity. As judged by PAGE, the purified recombinant lysostaphin is of >97% purity. The produced lysostaphin lysed cells of Staphylococcus aureus and Staphylococcus haemolyticus clinical isolates. In vitro activity and general biochemical properties of purified recombinant lysostaphin produced by M15 or BL21 E. coli strains were identical to those of recombinant lysostaphin supplied by Sigma-Aldrich (USA) and used as reference in other known studies. The prepared recombinant lysostaphin represents a potential product for development of enzymatic preparation for medicine and veterinary due to the simple purification scheme enabling production of the enzyme of high purity and antistaphylococcal activity.

[Burkholderia cepacia persistence in patients with mucoviscidosis].

AIM: Study features of persistence of Burkholderia cepacia in mucoviscidosis patients. MATERIALS AND METHODS: In the period from 2008 to 2009, 56 B. cepacia strains isolated from children with mucoviscidosis were obtained. 114 medical histories of children with mucoviscidosis from various age groups were analyzed. The developed algorithm for identification and typing including phenotype and molecular biology methods was used to identify B. cepacia bacteria. Strain genotyping was carried out by RAPD-PCR with random oligonucleotide primer as well as pulse-electrophoresis. RESULTS: Persistence of associations ofmicroogranisms in 59.4% of cases was established to be the feature of persistent infection in mucoviscidosis. The feature of persistence of B. cepacia strains in patients with diagnosis ofmuco-viscidosis mixed form, severe course is persistence in association with Pseudomonas aeruginosa. B. cepacia bacteria that can persist in mucoviscidosis patients are characterized by resistance to many antibiotics. A prolonged (up to 1 year and 5 months) persistence of B. cepacia strains isolated from 1 patient was proven by using microflora monitoring of lower respiratory tract. CONCLUSION: B. cepacia bacteria may colonize lower respiratory tract of mucoviscidosis patients, persist for a long time and be transmitted between patients.

[Persistence of Pseudomonas aeruginosa strains in patients of Federal Scientific Center of Transplantology and Artificial Organs].

AIM: Study genetic diversity of P. aeruginosa strains persisting in patients of Federal Scientific Center of Transplantology and Artificial Organs, and main factors facilitating persistence of strains in the hospital. MATERIALS AND METHODS: 136 P. aeruginosa strains isolated from patients of the center for 3 years 6 months were genotyped by RAPD-PCR and MLST methods and studied for antibiotics resistance and presence of integrons. RESULTS: Genetic diversity of strains persisting in hospital was established. Strains of main genotypes ST235, ST446, ST598 were isolated from patients of various surgical departments. Patients were shown to be colonized by these strains during stay in reanimation and intensive therapy department (RITD) of the hospital. Strains of dominant genotype 235 were isolated from 47% of examined patients during more than 3 years. Only genotype 235 strains contained integron with cassettes of antibiotics resistance genes blaGES5 and aadA6 in the genome. CONCLUSION: The data obtained show that over the period of observation in the center 1 clone of P. aeruginosa that belonged to genotype 235 dominated. This clone was endemic for this hospital and in the process of prolonged persistence became more resistant to antibiotics. Colonization of patients with these strains occurs in RITD. This confirms the necessity of constant monitoring of hospital microflora for advance detection of potentially dangerous epidemic hospital strains able to cause hospital infections.

[Prospects for the use of low-temperature gas plasma as an antimicrobial agent].

Results of application of LTP at atmospheric pressure as an antibacterial agent during the last decade are considered with reference to physicochemical mechanisms of its bactericidal action. The principles of designing modern LTP sources are described in conjunction with the results of LTP application against pathogenic bacteria in vitro and in biofilms. The possibility to destroy biofilm matrix by LTP is estimated along with the results of its testing for the treatment of acute and chronic wound surfaces. Prospects for the development of "plasma medicine" in this country and abroad are discussed with special emphasis on its advantages, such as the absence of long-acting toxic compounds, small probability of spontaneous mutations accounting for resistance to LTP, relatively low cost of LTP sources, independence of LTP effect of the surface relief, painless application.

[Genetic diversity of Staphylococcus aureus strains that colonize nose mucous membrane of children living in a large industrial city].

AIM: Study of genetic diversity of Staphylococcus aureus strains that colonize nose mucous membrane of children living in an ecologically unfavorable district of Krasnoyarsk. MATERIALS AND METHODS: 20 S.aureus strains isolated from mucous membrane of anterior part of nose of children were genotyped by RAPD-PCR (random ampliphied polymorphic DNA) with an oligonucleotide primer (10 Sh1 nucleotide). RESULTS: Presence of 6 genotypes, with 3 of those including 3 and more strains, was detected among the studied strains. The extent of genetic similarity between genotype 1 and 2 was established at 85%. CONCLUSION: 20 of 63 (31.7%) of examined students were resident carriers of S. aureus. 3 main genotypes of S. aureus that circulate in students were detected by RAPD-PCR. This confirms the necessity to use RAPD-PCR method for timely evaluation of epidemic situation in organized groups of children.

[Microbial population of lower respiratory tract in children from different age groups with cystic fibrosis].

AIM: To study microflora of lower respiratory tract of children from different age groups with cystic fibrosis during follow-up for determination of its variability and possible sources of infectious complications. MATERIALS AND METHODS: One hundred forty-one medical histories of patients from different age groups with cystic fibrosis living in various regions of Russian Federation were analyzed. Eighty-four children with cystic fibrosis living in Moscow and Moscow region treated as outpatients and inpatients were prospectively followed. For identification and characterization of microorganisms, microbiological, molecular biological, and statistical methods were used. RESULTS: It was demonstrated that chronic pseudomonas, staphylococcal or mixed infection was already diagnosed in 25% of children aged 1-4 years, and identified in 80% of patients to the age of 18 years. In two-thirds of cases association of microorganisms was identified, and in hospitalized patients these associations were comprised by 3-5 microorganisms in 60% of cases. Aside from main agents in associations (Pseudomonas aeruginosa and Staphylococcus aureus), representatives of Gram-negative nonfermentative microorganisms (Burkholderia cepacia, Stenotrophomonas maltophilia, Acinetobacter baumanii) were often identified that possibly determined by tropism of these species to lung tissue. CONCLUSION: Chronic mixed infection is characteristic for patients with cystic fibrosis. Identification of possible mechanisms of lung infection in patients with cystic fibrosis will allow to develop evidence-based system of prevention of infectious complications in these patients.

[Role of "quorum sensing" regulatory system in formation of biofilms by Burkholderia cepacia and Pseudomonas aeruginosa].

AIM: To study influence of chemically synthesized lactones with different length of carbonic chain on formation of biofilms by Burkholderia cepacia and Pseudomonas aeruginosa. MATERIALS AND METHODS: Fifty-four strains of B. cepacia including reference strains and clinical isolates as well as etalon strain PA103 of P. aeruginosa were used. Lactones C4 [N-(3-hydroxybutanoyl-L-gomoserine lactone], C6 [N-(3-oxoohexanoyl)-L-gomoserine lactone], C8 [N-(3-oxooctanoyl)-L-gomoserine lactone], C0 [L-gomoserine lactone-HBr] were synthesized and purified by column chromatography. Formation of biofilms was studied by determination the ability of B. capacia strains to adhesion on the surface of 96-well polystyrene plate. RESULTS: Ability to biofilms formation was identified in 83.3% studied strains. It was shown that lactones C4+C8 and C6+C8 when added to cultivation medium improve growth of B. cepacia biofilm. Analysis of optical density (OD) values for P. aeruginosa biofilm revealed that lactones C4, C8, C4+C6, C4+C8, C6+C8 inhibit the formation of biofilm. The most prominent decrease of P. aeruginosa biofilm OD was observed during growth of culture in presence of C0. CONCLUSION: Obtained data point to different effects of lactones and their combinations on formation of biofilms by B. cepacia and P. aeruginosa. Suppression of biofilm formation by P. aeruginosa induced by lactone C0 confirms the need for development of new bacteriostatic drugs, which will be able to inhibit function of the "quorum sensing" regulatory system.

[Genotypic features of Pseudomonas aeruginosa strains circulating in surgical hospital].

AIM: To study genetic diversity of Pseudomonas aeruginosa strains circulating in intensive care unit (ICU), to determine the source of these strains and duration of circulation of epidemically-significant clone in the hospital. MATERIALS AND METHODS: Genotyping of 106 P. aeruginosa strains isolated from patients, clinical specimens and fomites was performed by random amplified polymorphic DNA analysis with oligonucleotide primer Sh1 of 10 bp long. RESULTS: Out of 106 P. aeruginosa isolates, 72.6% belonged to the same genotype, which was dominated in ICU during whole study period. It was established that 58.3% of examined patients were colonized by identical strains belonged to prevalent genotype that indicates the intrahospital transmission of epidemic strain. CONCLUSION: Obtained data show that during the period of observation (15 months) one clone of P. aeruginosa dominated in ICU, which was characterized by multiple resistance to antibiotics and caused nosocomial infection in 58.3% of patients. This confirms the need of continuous molecular-microbiological monitoring of hospital microflora in order to early detect potentially dangerous epidemic hospital strains, which are able to cause nosocomial infections.

[Identification of clinical isolates of Burkholderia cepacia and assessment of their pathogenicity in animal experiments].

In experiments on animals study of pathogenicity of 9 clinical strains of Burkholderia cepacia isolated from patients with chronic lung diseases was performed. Preliminary identification of studied strains by means of biochemical and genetic methods allowed to establish their belonging to B. cepacia species. It was determined that 6 of 9 strains are epidemiologically significant. Experiments showed that bacteria of studied strains are not able to cause infectious process in white mice and hamadryas baboons. Conclusion about appropriateness of development and use of other biological models was made.

[Biofilm formation by strains of Burkholderia cepacia complex in dependence of their phenotypic and genotypic characteristics].

Biofilm formation was studied in 54 strains of Burkholderia cepacia complex isolated in 7 Moscow hospitals. 80% of strains (biofilm groups I and II) had the capacity to biofilm formation and only 16.7% of strains (group III) were not capable to biofilm formation. Molecular genetic methods allowed to identify one of the epidemic markers (CBL, IS hybrid sequence, Burkholderia Cepacia Epidemic Strain Marker - BCESM) in 46.7, 23.3, and 33.3% of strains from group I, II, and III respectively. Gene cepR from the Quorum Sensing system was identified in three biofilm groups in nearly equal frequency (92.3, 96.2 and 100% for group I, II, and III respectively), whereas cepl gene was found more often in group I (76.9%) and II (65.4%). Strains from all three groups had protease and lipase activity and 13.3% of group I strains had chitinolytic activity. B. cepacia strains from group I produced hemolysin in 33.3% of cases, from group II--in 26.6%, and from group III--in 11.1% of cases. The majority of Moscow hospital strains of B. cepacia complex were identified as B. cenocepacia (genomovar III, group A). RAPD-PCR method enabled to differentiate isolated strains into several genotypic variants. 13.3% of strains from group I were susceptible to imipenem/ciprofloxacin, as well as 33.3% of isolates from group II and 44.4% of isolates from group III.

[The role of "quorum sensing" regulation system in symbiotic interaction of bacteria Burkholderia cepacia and Pseudomonas aeruginosa during mixed infection].

Data concerning mechanisms of strengthening virulence of bacteria B.cepacia and P.aeruginosa during experimental mixed-infection are submitted. Results of in vitro studies of acylhomoserine lactones (AHL) with various length of a carbon lateral circuit have shown that butanoyl-homoser-ine lactone (C4), hexanoyl-homoserine lactone (C6) and octanoyl-homoserine lactone (C8) separately and in various combinations display different effects on growth of bacteria, formation of colonies and production of pathogenicity factors. Experiments on animals have shown strengthening virulence of bacteria B.cepacia by C4, C6 and C8 lactones when introduced simultaneously. Strengthening of virulence of the P.aeruginosa strain under the action of lactone C6 and simultaneous action of C4, C6 and C8 lactones was observed. The data obtained give grounds for assumption, that bacteria may use exogenous lactones, including those produced by closely related bacteria, during their life cycle.

[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.

[Antibiotic resistance and putative origin of Staphylococcus aureus and Klebsiella strains isolated from the children with intestinal dysbacteriosis].

The results of the statistical treatment of data on the analyses of 766 children, the residents of Moscow, for dysbacteriosis are presented; of these children, 34 were aged up to 1 month and 732, from 1 month to 1 year. This study revealed that in the fist year of life in children with dysbacteriosis the dominating bacterial species were S. aureus, bacteria of the genus Klebsiella and fungi of the genus Candida. From the intestine of children aged up to 1 month S. aureus and Klebsiella were isolated more often than from children aged up to 1 year. The results of the study of antibioticograms demonstrated that 21.6% of S. aureus strains and 74.4% of Klebsiella strains were multiresistant to antibiotics. Taking into account the fact that multiresistance to antibiotics was characteristic of hospital strains, the suggestion was made that the isolated strains were of hospital origin and such strains could colonize the intestine of children in maternity hospitals.

[A study of the polymorphism of mec dna in methycillin-resistant strains of Staphylococcus aureus isolated at permanent stations in different regions of Russia].

Polymorphism of the chromosome staphylococcus cassette mec (SCCmec), a mobile and heterological genetic element providing resistance to beta-lactam antibiotics was studied in methycillin-resistant strains of Staphylococcus aureus (MRSA) isolated at permanent stations situated in different regions of Russia. Type SCCmec was identified using the PCR method by determining allotypes of 3 different structural genetic complexes incorporated in the cassettes mec. It was found that the isolates studied in this work contained 3 different types of SCCmec: I, III, and IVb. Both isolates containing 2 different copies of SCCmec and isolates containing defective copies of SCCmec were identified. It was demonstrated that determination of the SCC-mec type provided an opportunity to differentiate the isolates studied in this work from one another. The isolates attributed to the same genotype variant (identified by polymorphism of coagulase gene) but isolated at different hospitals located in different regions of Russia were found to contain the same type of the chromosome staphylococcus cassette mec, whereas the isolates of different coagulase groups (i.e., different genotype variants) contained different types of SCCmec. It was found that at least 2 epidemic strains circulated in the permanent hospitals of Russia. The strains differ from one another by the polymorphism of the coagulase gene and the mec DNA polymorphism. According to results of studies of several molecular markers (including mec DNA), these strains proved to be identical to the international strains EMRSA-1 and EMRSA-2. Possible mechanisms of MRSA formation and circulation in Russia and CIS countries are discussed.

[Epidemiological aspects of the present-day demographic situation in Russia].

Study of reference rate in healthcare institutions in 1991 - 2001 demonstrated a steady growth of general mortality and disease incidence among the population (by 22.7% and 8.1%, respectively). The number of patients with acute and chronic diseases registered in 2001 was by 16.4% higher than that in 1991. These trends were characteristic of all disease classes, but the most intensive growth was observed in such classes as diseases of blood and hemopoetic organs (2.5 times), endocrinal and urogenital diseases (1.8 times). Disease incidence and general mortality among children aged 0 to 14 had grown by 25% and 33.2%, among adolescents--by 60% and 71.1%, among adults--by 5.2% and 20.3%, respectively. These negative trends in population health were accompanied by a constant growth of incapacitation rate in 1990 - 2000 (2.4 times, and 4.3 times among children and adolescents younger than 18). There is a correlation between mortality and traditionally used demographic parameters, which suggests that mortality should be recognized the key demographic parameter. In order to achieve a satisfactory level of population health and adequate demographic transition, and to develop general sanatory strategy, the State should undertake powerful, goal-seeking, society-oriented measures, including deep clinical and epidemiological study of human pathology.

[Molecular genetic typing of methicillin-resistant Staphylococcus aureus strains, isolated in hospitals of different regions of the Russia and Belarus].

The study of the length of the amplification products of the coagulase gene with the subsequent restriction analysis (the method of PCR--restrictive fragment length polymorphism, or RFLP) was used for typing 90 S. aureus strains. Among the strains under study, 78 were methicillin-resistant S. aureus (MRSA) strains, including 74 obtained in 1986 - 2002 in hospitals of different cities of the Russia and Belarus, as well as epidemic strains EMRSA-1, -2, -3, -12, obtained from the National Laboratory of Health, London (UK). The use of this method made it possible to type all the strains under study, which were differentiated into 9 groups by means of endonuclease Sfo1 and 7 groups by means of Alu1. Majority of clinical MRSA strains, belonged, according to the type of restriction, to groups 4 and 5. The study of the coagulase gene by the method of PCR - RFLP made it possible: to analyze the epidemic situation in hospitals for a period of several years; to compare the properties of strains isolated in different hospitals; to establish the genetic relationship of strains, isolated in 1998 - 2002, with strains, isolated in 1986 - 1990. The results of the study suggest that at least two epidemic MRSA strains, genetically similar to international strains, circulate in hospitals of Russia.

[Microbiological aspects of enteric dysbacteriosis in patients of different age groups, visiting outpatient clinics of Moscow].

The analysis of the intestinal microflora in 2,378 patients of different age revealed changes in the state of enteric microflora in all examined patients. In the maximum percent of cases a decrease in the amount of bifidobacteria was observed in children of up to 1 month old and in the amount of lactobacilli, in children aged 6 - 14 years. In patients of all age groups the representatives of such facultative microflora as Staphylococcus aureus or fungi of the genus Candida dominated. The highest proportion of isolated staphylococci was characteristic of children in the first year of life. In the highest percent of cases a decrease in the amount of Escherichia coli with typical properties was observed in persons over 65 years old. Other enterobacteria were most often isolated from adults aged 56 - 65, but the percentage of their isolation was 1.5 times lower than that of Candida. The conclusion was made that the treatment of patients with quantitative and qualitative disturbances of normal enteric microflora needed individual approach in each concrete case with due regard to the patient's age.

[Study on the polymorphism of the coagulase gene by the method of sequencing in methicillin-resistant Staphylococcus aureus strains, isolated in hospitals in different regions of Russia and Belarus].

This method was used for typing of 31 Staphylococcus aureus methicillin-resistant (MRSA) strains; of these, 27 were clinical isolates obtained in hospitals of different cities of Russia and Belarus and 4 were international epidemic strains EMRSA-1, -2, -3, -12. The sequencing of the variable area, located in the middle part of the coagulase gene between nucleotides 979-1355 and detected with the use of information technologies, was carried out. The results of this sequencing were compared with those of the earlier study on the polymorphism of the area of the same gene between nucleotides 1513-2188, carried out by the method of PCR-restrictive fragment length polymorphism. The sequencing of the part of the coagulase gene made it possible to confirm the presence of essential differences in the nucleotide sequences of the coagulase gene in international strains EMRSA-1, -3, -12, grounds for classifying clinical isolates of MRSA strains with two groups (4 and 5), as well as the genetic relationship of different phage types, isolated in different clinics. The study revealed considerable similarity in the nucleotide composition of strains EMRSA-2 and EMRSA-12 despite the fact that, according to the results of Cfol restriction of the 3'-end, they were classified with different groups; the study also revealed the identity of the nucleotide sequences of the coagulase gene in the cultures of group 5, isolated in hospitals of Moscow, St. Petersburg, Orenburg, and strain EMRSA-2, as well as methicillin-sensitive S. aureus strain 8325-4; in addition, in clinical isolates of group 4 and strain EMRSA-1 a considerable degree of homology was revealed. The study of two different loci made it possible to find out the strain with the recombinant form of the coagulase gene. The approach used in this study permitted the differentiation of the international epidemic strains EMRSA-1, -2, -3 and -12 into individual groups, which coincided with the results of Enright et al. (2002) who used multilocus sequencing.

[The influence of bacteria of the Burkholderia cepacia and Pseudomonas aeruginosa complex on cell-mediated immune reactions in experimental animals].

The evidence has been obtained that various species, as well as individual strains having pathogenicity factors, produced different effect on the functional activity of immunocompetent B and T lymphocytes of mice infected intraperitoneally. The injection of live P. aerruginosa PA 103 and B. cepacia 8240 cells resulted in imunosuppression of antibody-forming cells, synthesizing antibodies to heterologous antigens. On the contrary, in the animals infected with B. cepacia 8236 the functional activity of B lymphocytes increased. An increase in the proliferative activity of spleen cells was noted in the presence of T and B mitogens after the infection of mice with P. aeruginosa PA 103 in comparison with B. cepacia 8236 and B. cepacia 8240 which produced a faintly pronounced modulating effect. The pathogenesis mechanisms of infections induced by these microorganisms as well as the development of chronic, persisting forms of the infectious process are discussed.

[A study of action of subinhibiting concentrations of antibiotics on the expression of genes regulating production of pathogenicity factors in Burkholderia cepacia and Pseudomonas aeruginosa].

Described in the paper are the results of a study of differential expression of pathogenicity of B. cepacia and P. aeruginosa in subinhibiting concentrations (SIC) of cyprofloxacyne. While identifying genes expressing differentially in the antibiotic SIC, genes cepR B. cepacia and P. aeruginosa expressing without cyprofloxacyne in the cultivation medium and not expressing in the antibiotic SIC were detected. Finally, involvement of cepR B. cepacia in regulating the pathogenicity expression factors according to "quorum sensing" is under discussion.