Effect of detergents on pathogenicity plasmids of escherichias

The study dealth with effects of cationic detergents miramistin (alkylamidopropyldimethylbenzylammonium chloride), catamine AB (alkyldimethylbenzylammonium chloride) and the anionic compound sodium dodecyl sulphate (SDS) on the elimination from E. coli cells of plasmids determining the Hly, Ent and, indirectly, Col, F, and R markers of pathogenicity as well as their transfer upon conjugation. At subbacteriostatic concentrations, miramistin and catamine AB were found to suppress the transfer of Hly, Ent, F, and R plasmids during conjugation when applied to the donor, recipient or added to the conjugation medium without, however, eliminating plasmids. This is due to the disruption by detergents of F, J pili and other surface cell structures resulting in diminished ability to conjugate. Anionic SDS eliminated F and R plasmids without affecting Hly, Ent and Col.     

Effect of surface-active antiseptics on plasmid transduction of drug resistance and the transducing bacteriophages of staphylococci]

Anionic surface active substances (SAS), such as sodium alkylsulfates, iodonate, sulfanol NP-3 used in subbacteriostatic concentrations lowered at least 100 times the intensity of the erythromycin resistance plasmid in vitro on mixed cultivation of the staphylococcal cells of the donor (strain 8325/11 de) and the recipient (strain 825-1). The cationic SAS, i. e. roc cal, chlorhexidine had no such capacity. The above anionic and cationic SAS had an antiphage effect with respect to the transducing staphylococcal bacteriophages of the serological group B (80, 85, 52A, 53). Such an effect (on the example of sodium alkylsulfates) increased with prolongation of the alkyl radical from C8 to C14. A decrease in the transduction intensity of the erythromycin resistant plasmid in staphylococci was observed in the presence of the anionic SAS either possessing (alkylsulfates, iodonate) or not (sulfonol NP-3) the antiphage activity.     

Action of various surface-active substances on the genetic transmission of R-plasmids in E. coli]

The effect of 4 groups of surface active-substances (SAS) on conjugation and transduction transfer of plasmid RIdrd from the donor of E. coli J 5-3 to the recipient of E. coli C600 was studied. It was shown that the anionic SAS (8 compounds) had the highest inhibitory effect. They completely inhibited both the conjugation and the transduction transfer of R-plasmids. The amphoteric SAS, i. e. tego-51 and ampholan had the same effect only on the transduction R-transfer. The conjugation R-transfer was inhibited by the above compounds to a significant extent but not completely, i. e. by 70.8 and 361.9 times respectively. The effect of the non-ionogenic preparations, i. e. sintanol DT-7 was even less (the inhibition coefficients of 54.8 and 22.8 on conjuction and transduction respectively). The cationic SAS, i. e. catamine AB and HIPC-200 had no effect on the genetic R-transfer. It was shown that the anionic SAS had a phagocytic effect on phage Plks. It is of interest to note that the anionic SAS, i. e. sintanol NP-3 effectively suppressed the conjugation transfer even in a concentration of 100 gamma/ml which was 1000 times lower than the subbacteriostatic one. The effectiveness of the anionic SAS did not depend on the length of the dydrocarbon chain and was the same in separate homologues and their mixtures. The high inhibitory activity of most of the SAS and especially the anionic ones with respect to both the conjugation and the transduction R-transfer was of interest.     

Effect of anionic surfactants on some dehydrogenases and phosphofructokinase activities in loach embryos

Glucose-6-phosphatedehydrogenase (EC 1.1.1.49), lactatedehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.38) and phosphofructokinase (EC 2.7.1.11) activities in loach (Misgurnus fossilis L.) embryos were determined after incubation of the latter in the media containing surfactants--alkyl benzol sulphonates NP-1, NP-3, RAS and secondary alkyl sulphate "Progress". The determined activities changed under the influence of the used surfactants. Minimal changes of the activities were observed in the media with sulphonol np-1, and maximal ones--with the "Progress" preparation. The dependence is revealed of the enzyme activities changes upon the surfactant concentration and the stage of the embryo development.     

Directed isolation of gram-negative asporogenous bacteria from natural substrates

A method for selective isolation of gramnegative nonsporulating bacteria from soil substrates was developed. The method consists of plating out the substrates on a glucose-yeast medium with addition of benzylpenicillin and nalidixic acid. The isolation frequency of gramnegative nonsporulating bacteria increased under such conditions from 9-16 (control) to 80-100 per cent. At the same time the isolation frequency of gram-positive bacteria decreased from 88.5 to 9.6 per cent.     

The effect of a cationic surface-active substance (catamine AB) on the physiological-morphological properties of B. cereus and E. coli

Catamine AB (0.05-0.5%) promotes transfer of B. cereus st 96, and E. coli st. 906 cell cultures into metabolic rest. Detergent-treated cells have no energetic metabolism and autolytic processes, have high light-scattering coefficient, and peculiar ultrastructural organization. Viable cells can be observed in the detergent-treated cell suspension after 1 year of incubation. Difference in action of different catamine AB concentrations on stationary and exponential B. cereus cells has been revealed.     

Aminoglycoside 3'-phosphotransferase gene: its cloning, characteristics and use as a molecular probe

Aminoglycoside resistance genes were cloned from transconjugates of aminoglycoside resistant clinical strains of gramnegative bacteria. The resistance determinant cloned from the strains of E. coli transferred kanamycin, monomycin and neomycin resistance to laboratory strains. It was shown that the cloned resistance gene encoded the type I 3'-aminoglycoside phosphotransferase. The results of spot and blot hybridization of the gramnegative bacteria clinical strains with the Bam HI-Pst I fragment of the cloned resistance determinant were indicative of wide-spread distribution of the APH 3' (I) and closely related genes in clinical microbial populations.     

Effect of surface-active substances on bioluminescence intensity of bacteria

The study of sensitivity of luminous bacteria isolated from the Black and Azov seas to surfactants from various classes was carried out. It was shown that cationic surfactants had a strong inhibition effect on bacterial luminescence in contrast to anionic and in particular nonionic surfactants. To increase the luminous bacteria sensitivity to the action of OP-10 (nonionic surfactant) and ABS (anionic surfactant), which are widely used in industry, several approaches have been developed. They include modulation of bacterial sensitivity by the additives of cationic substances, use of luminous bacteria at a logarithmic stage of growth, realization of biotesting at low pH = 5.5. The use of these approaches allows to lower effective concentrations of OP-10 and ABS, which caused a decrease of bioluminescence by 50%, 3-200 times and opens perspectives for the use of the bioluminescent method to study these surfactants toxicity on the principle of biosensorics.     

Combined action of antibiotics and deoxyribonuclease on bacteria]

The impact of DNase on formation of biofilms by grampositive and gramnegative bacteria was studied. The enzyme was shown to inhibit the biofilm formation and have no toxicity to bacteria. When applied to the formed associations, DNase potentiated the effect of antibiotics on the bacteria located in them. An increase in the antimicrobial effect of various nonrelated antibiotics was not connected with a change in the bacteria susceptibility but likely resulted from a break of the genetic cooperation of the cells' community, connected with functions of extracellular DNA of the biofilm's matrix.     

Antibiotic susceptibility of isolates from blood of patients in intensive care units of emergency medical service

The microbiological tests of 769 blood samples from 220 patients, treated in 4 intensive care units of the N.V. Sklifosovsky Research Institute for Emergency Medical Service within a period from January 2009 to June 2010, were analysed. Etiologically significant microorganisms were detected in 323 samples (42%). 253 isolates were used in the analysis. Grampositive and gramnegative pathogens were detected in 47 and 42% of the cases respectively. Candida and anaerobic organisms were isolated in 8 and 3% of the cases respectively. Staphylococcus aureus and enterococci were isolated in 24 and 15% of the cases respectively. Nonfermenting gramnegative bacteria and enterobacteria were revealed in 25 and 17% of the cases respectively. Differences in the spectrum of the sepsis pathogens depending on the patients contingent were shown. The maximum summary susceptibility of the grampositive cocci was observed with respect to vancomycin and linezolid and that of the gramnegative bacteria was stated with respect to imipenem and meropenem.     

Tefluthrin modulates a novel anionic background conductance (I(AB)) in guinea-pig ventricular myocytes

This report describes for the first time a novel anionic background current (I(AB)) identified in guinea-pig isolated ventricular myocytes. It also shows that I(AB) has both novel and differential pharmacology from other (cardiac) chloride currents. Using the whole-cell patch-clamp technique and external anion substitution, I(AB) was found to be outwardly rectifying and highly permeable to NO(-)(3), with a relative permeability sequence of NO(-)(3) > I(-) > Cl(-). I(AB) was not blocked by 50 microM DIDS, by hypertonic external solution, or by the nonselective protein kinase inhibitor H7-DHC. Exposure to the pyrethroid agent tefluthrin (10 microM) increased the current density of I(AB) significantly at positive voltages (P < 0.05), but had no significant effect on other cardiac chloride currents. We conclude that I(AB) possesses a distinct pharmacology and does not fall into the three major classes of cardiac chloride conductance commonly reported.     

恶性疟合成多肽抗原基因在大肠杆菌中表达产物的分离纯化

我们用化学方法合成的两个恶性疟原虫杂合抗原基因,即A基因和B基因〔1.2〕,分别与表达载体pwR450·1重组并转化到大肠杆菌使其表达〔3.4〕。经筛选获得了pwR／A·7和pwR／B·164两个表达较高的克隆菌(经扫描测定表达融合蛋白量分别为菌体总蛋白的8．8％和11．O％)。叉将A基因和B基因串连后与pwR450·l重组并转化到大肠杆菌JMl03株,经筛选鉴定获得了上述两个基因串连的pwR／AB·20克隆菌(表达融合蛋白量为35．8％)。为了进一步研究这3个克隆菌表达蛋白的免疫功能等活性,用8．0mol／L脲处理包涵体,离心沉淀上清液进行DEAE-ephacel柱层析,用Tris梯度缓冲液洗脱,但分离效果不好,而应用PAGE方法进行分离纯化,则可得到电泳纯、稳定又具有免疫原性的产物。     

Impact of exogenic proteolytic enzymes on bacteria]

The impact of papain, trypsin and the enzyme complex vobenzyme on formation of biofilms by grampositive and gramnegative bacteria was studied. The enzymes were shown to inhibit the biofilm formation. When applilied to the formed associations, the enzymes potentiated the effect of antibiotics on the bacteria located in them. An increase in the antimicrobial effect of various nonrelated antibiotics was not connected with a change in the bacteria susceptibility but likely resulted from higher bioavailability of the drugs in the presence of the enzymes.     

Effect of surfactants on PAH biodegradation by a bacterial consortium and on the dynamics of the bacterial community during the process

The aim of this work was to evaluate the effect of a non-biodegradable (Tergitol NP-10) and a biodegradable (Tween-80) surfactant on growth, degradation rate and microbial dynamics of a polycyclic aromatic hydrocarbon (PAHs) degrading consortium (C2PL05) from a petroleum polluted soil, applying cultivable and non cultivable techniques. Growth and degradation rate were significantly lower with Tergitol NP-10 than that with Tween-80. Toxicity did not show any significant reduction with Tergitol NP-10 whereas with Tween-80 toxicity was almost depleted (30%) after 40 days. Regarding to the cultured bacteria, Pseudomonas and Stenotrophomonas groups were dominant during PAH degradation with Tergitol NP-10, whereas Enterobacter and Stenotrophomonas were dominant with Tween-80. DGGE analyses (PRIMER and MDS) showed that bacteria composition was more similar between treatments when PAHs were consumed than when PAHs concentration was still high. Community changes between treatments were a consequence of Pseudomonas sp., Sphingomonas sp., Sphingobium sp. and Agromonas sp.     

Inactivating action of bacteria on the lipolytic activity of solizyme and its prevention by antibacterial drugs]

Bacteria capable of producing exoproteases were isolated from intermediate products of microbial lipase. The proteolytic enzymes produced by the bacteria were able to inactivate 20 to 80 per cent of the lipase depending on the time of incubation, protease production by the contaminating microbe and the experimental conditions. Antibiotics and antiseptics inhibiting growth of bacteria prevented or limited their inactivating action on lipase. Except catamine, the tested antimicrobial drugs as such had no effect on lipase activity.     

Inhibition of Aflatoxin Production by Surfactants

The effect of 12 surfactants on aflatoxin production, growth, and conidial germination by the fungus Aspergillus flavus is reported. Five nonionic surfactants, Triton X-100, Tergitol NP-7, Tergitol NP-10, polyoxyethylene (POE) 10 lauryl ether, and Latron AG-98, reduced aflatoxin production by 96 to 99% at 1% (wt/vol). Colony growth was restricted by the five nonionic surfactants at this concentration. Aflatoxin production was inhibited 31 to 53% by lower concentrations of Triton X-100 (0.001 to 0.0001%) at which colony growth was not affected. Triton X-301, a POE-derived anionic surfactant, had an effect on colony growth and aflatoxin production similar to that of the five POE-derived nonionic surfactants. Sodium dodecyl sulfate (SDS), an anionic surfactant, and dodecyltrimethylammonium bromide, a cationic surfactant, suppressed conidial germination at 1% (wt/vol). SDS had no effect on aflatoxin production or colony growth at 0.001%. The degree of aflatoxin inhibition by a surfactant appears to be a function of the length of the hydrophobic and hydrophilic chains of POE-derived surfactants.     

Interaction of micro-dispersed forms of anionites and surface-active agents with serum albumin

The interaction of serum albumin with microdispersed forms of anion-exchange resins AV-16 GS and AV-17 I (USSR), obtained by mechanochemical destruction of polymers, and with low-molecular weight anionic (oleic acid, sulfonol) and cationic (cetazol, catamine) surfactants was being studied. Catamine and cetazol as well as microdispersions of anion-exchange resins are able to precipitate 90% of protein from the equilibrium solution, the content of protein in the initial solution being constant and equal to 6.5 mg/ml. Studies on the equilibrium in the system serum albumin--microdispersions of anion-exchange resins in the presence of ionogenic surfactants revealed that cationic surfactants are able to increase the amount of the precipitated protein, while in the presence of anionic surfactants the interactions between the protein macromolecules and microdispersions of polyelectrolytes become much weaker.     

Comparative in vitro activity of cefepime and other antibiotics against clinical strains of gram-negative bacteria]

In vitro activity of cefepime against etiologically significant strains of gramnegative microflora of patients treated in the Reanimation and Intensive Care Unit after cardiosurgical operations was evaluated. Sixty four strains of gramnegative aerobic bacteria isolated within the period from October 2001 to April 2002 were tested. The isolates susceptibility was determined by the disk diffusion method. Cefepime had an obvious advantage over the 3rd generation cephalosporins. Low incidence of cefepime resistant strains of the problem organisms in the Reanimation and Intensive Care Unit should be taken into account in empirical therapy of infections due to such pathogens.     

医院内感染的病原菌分布及其耐药谱的分析

本文统计了我院１９９２年８月—１９９４年７月两车间医院内感染病原菌的分离结果,分离出病原菌２５种７５８株,其中革兰氏阳性菌１６３株（占２１．５１％）,革兰氏阴性菌３７８株（占４９．８７％）,真菌２１７株（占２８．６２％）。院感病原菌依次为,白色念珠菌、绿脓假单胞菌表、葡菌、肺炎克雷伯氏菌、酵母菌及大肠艾希氏菌等,显示了真菌及表葡菌在院内感染中已经上升到不可忽略的地位。用１８种常用抗生素,对除真菌外的上述病原菌５４１株做耐药谱测定,并发现除了表葡菌及多数革兰氏阴性菌对喹谱酮类及少数头孢三代抗生素尚属敏感外,大部分均具有越来越广泛的耐药性。     

Some Surface-Active Agents and Their Virucidal Effect on Foot-and-Mouth Disease Virus

Selected cationic and anionic surface-active compounds were tested to determine their virucidal effect on the foot-and-mouth disease virus, type O, strain M11, propagated in primary calf kidney cells. The chemical inactivation of the virus was tested with 0.5, 1.0, 2.0, and 5.0% concentrations of the selected compounds. Virus controls with pH adjusted to cover the expected range of the mixtures of the chemicals and virus were also tested. The absence of virus from the mixtures of chemical and virus after reaction at 28 C for 2 hr was assayed by inoculating suckling mice with the mixtures. One cationic compound, alkyl methyl isoquinilinium chloride, showed considerable antiviral activity due largely to pH effect. The use of the surface-active agents investigated in this study, in the presence of organic material, would not be recommended as virucides.