Hodnotila sa antibakteriálna účinnosť 12 dezinfekčných látok na báze kvartérnych amóniovýchzlúčenín (KAZ) na izoláty Salmonella enterica sérovar Typhimurium definitívneho fágového typu104 (DT104). Jeden izolát – 5551/99 – predstavoval multirezistentný fenotyp, rezistentný naampicilín (A), chloramfenikol (C), streptomycín (S) a tetracyklín (T). Druhý izolát – 577/99 – bolcitlivý na všetky testované antibiotiká. Prezentovaná štúdia ďalej zisťovala schopnosť sub-MICkoncentrácií dezinfektantov zasahovať do povrchovej hydrofobicity a motility testovaných kmeňov.Naše výsledky ukázali, že všetky študované dezinfektanty prejavili vysokú antibakteriálnu aktivitu.Je zaujímavé, že izolát rezistentný na antibiotiká bol citlivejší na dezinfekčné látky v porovnanís izolátom citlivým na antibiotiká. Na kmeň 5551/99 (R-typ) boli najúčinnejšie látky: Sokrena,Triquart, Hexaquart plus, ID213 a Microbac forte a na kmeň 577/99 (S-typ) boli najúčinnejšie:Benzalkonium chlorid a Hexaquart plus (MIC 0,09–0,19 µl/ml). Povrchová hydrofobicita obidvoch testovaných kmeňov po pôsobení sub-MIC (1/16, 1/8, 1/4 MIC) dezinfektantov nebola výraznejšie ovplyvnená. V prípade kmeňa 5551/99 najvyššie percento inhibície adherencie na xylén na 69,5 %oproti kontrole vyvolala 1/4 MIC látky Triquart a v celom koncentračnom rozsahu látka Microbacforte. Po účinku väčšiny látok na kmeň 577/99 dochádzalo ku stimulácii adherencie. Jedine látkaID213 spôsobila inhibíciu adherencie v celom koncentračnom rozsahu. Soľnoagregačné schopnosti oboch kmeňov neboli výraznejšie ovplyvnené. Výnimku predstavuje len pôsobenie 1/4 MIC látokCetrimid, Sokrena, ID212, Forten a 1/8 MIC Hexaquartu S na kmeň 577/99, kde došlo k poklesuhydrofobicity. Mierna inhibícia motility sa zistila po účinku 1/4 MIC Benzalkonium chloridu (na87,5 %) a A.D.L. 007 (na 85,2 %) na kmeň 5551/99. V prípade citlivého izolátu 577/99 sa inhibičnenaj výraznejšie prejavil účinok Sokreny v celom koncentračnom rozsahu a 1/4 MIC ID213. Výsledkyje možné využiť pri zvažovaní výberu vhodnej dezinfekčnej látky na dekontamináciu pevných povrchov. Vplyv študovaných látok na povrchovú hydrofobicitu a motilitu významného, potravou prenášaného patogéna v zmysle inhibície či stimulácie poukazuje na zásah do jeho patogénneho potenciálu.
The paper evaluated antibacterial efficacy of 12 disinfectants on the basis of quaternary ammoniumcompounds (KAZ) on the isolates of Salmonella enterica serovar Typhimurium of the definitive phagetype 104 (DT104). One isolate – 5551/99 – represented the multiresistant phenotype, resistant toampicillin (A), chloramphenicol (C), streptomycin (S), and tetracycline (T). The second isolate –577/99 – was sensitive to all antibiotics tested. The present study further examined the capabilityof sub-MIC concentrations of disinfectants to intervene into surface hydrophobicity and motility ofthe strains tested.The results showed that all disinfectants under study exhibited high antibacterialactivity. It is of interest that the isolate resistant to antibiotics was more sensitive to disinfectantsin comparison with the isolate resistant to antibiotics. The most effective substances against strain5551/99 (R-type) were Sokrena, Triquart,Hexaquart plus, ID213,and Microbac forte,and those mosteffective against strain 577/99 (S-type) were Benzalkonium chloride and Hexaquart plus (MIC0.09–0,19 µl/ml). Surface hydrophobicity of both tested strains after the action of sub-MIC (1/16, 1/8,1/4 of MIC) of disinfectants was not influenced in a more marked way. In the case of strain 5551/99,the highest percentage of inhibition of adherence to xylene, to 69.5 % versus the control, wasproduced by 1/4 of MIC of the substance Triquart and, in the whole concentration range, by the substance Microbac forte. After the action of most substances to strain 577/99, stimulation ofadherence took place. Only substance ID213 induced inhibition of adherence in the whole concentrationrange.The salt-aggregative capabilities of both strainswere not influenced in amoremarkedway. The only exceptions were the action of 1/4 of MIC of the substances Cetrimid, Sokrena, ID212,Forten, and 1/8 of MIC of Hexaquart S on strain 577/99, where a decrease in hydrophobicity wasobserved.Amoderate inhibition ofmotilitywas found after the action of 1/4 of MIC of Benzalkoniumchloride (to 87.5 %) and A.D.L. 007 (to 85.2 %) on strain 5551/99. In the case of sensitive isolate577/99, the most markedly manifested inhibition effect was that of Sokrena within the wholeconcentration range and that of 1/4 of MIC ID213. The results can be used in the selection ofa suitable disinfectant for decontamination of solid surfaces. The effect of substances under studyon surface hydrophobicity and motility of the important, food-transferred pathogen in the sense ofinhibition or stimulation points out to intervention into its pathogenic potential.
Testoval sa vplyv subinhibičných koncentrácií (sub-MICs) (1/4, 1/8, 1/16 a 1/32 MICs) štyrochchinolónových antibiotík na povrchovú hydrofobicitu dvoch kmeňov Acinetobacter baumannii (R1a R2). Hydrofobicita sa hodnotila testom adherencie baktérií na xylén a ich agregáciou v roztokochsíranu amónneho. Norfloxacín v koncentráciách 1/4 a 1/8 MIC znížil hydrofobicitu kmeňa R1a kmeňa R2 v koncentrácii 1/16 MIC. Ciprofloxacín bol účinný pre obidva kmene najmä v koncen-trácii 1/4 MICs. Enoxacín (1/8 MIC) významnejšie redukoval hydrofóbne vlastnosti len kmeňa R2.Ostatné koncentrácie vyššie uvedených antibiotík ako aj všetky testované koncentrácie pefloxacínuprakticky neovplyvnili povrchovú bakteriálnu hydrofobicitu.
Effects of subinhibitory concentrations (sub-MICs) (1/4, 1/8, 1/16 or 1/32 of the MICs) of fourquinolone antibiotics on surface hydrophobicity of two Acinetobacter baumannii strains (R1 and R2)were tested. Hydrophobicity was evaluated by adherence of bacteria to xylene and their aggregationin ammonium sulphate solutions. Norfloxacin in concentrations of 1/4 or 1/8 of the MIC decreasedhydrophobicity of R1 strain and of R2 strain in concentration of 1/16 of the MIC. Ciprofloxacin wasefficient for both strains mainly in concentration of 1/4 of their MICs. Enoxacin (1/8 MIC) moreeffectively reduced hydrophobic properties only in R2 strain. The other concentrations of theabove-mentioned antibiotics as well as all tested concentrations of pefloxacin pract ically did notaffect bacterial surface hydrophobicity.
Študovali sme ovplyvnenie povrchovej hydrofobicity kmeňa Klebsiella pneumoniae po účinkuofloxacínu, pefloxacínu a tobramycínu v subinhibičných koncentráciách (1/4, 1/8 a 1/16 MIC). Tes-tované antibiotiká v koncentračnej závislosti znížili bunkovú povrchovú hydrofobicitu. Najúčinnej-šia redukcia bola zistená po pôsobení 1/4 MIC testovaných antibiotík. Bunková hydrofobicitaúčinkom týchto koncentrácií bola znížená na 44 % (ofloxacín), 50,7 % (pefloxacín) a 56,1 % (tobramy-cín) kontrolných hodnôt.
The effect of ofloxacin, pefloxacin and tobramycin at subinhibitory concentrations (1/4, 1/8 and 1/16of the MICs) on surface hydrophobicity of the Klebsiella pneumoniae strain was studied. Theantibiotics tested decreased cell surface hydrophobicity in a dose-dependent manner. The mostsignificant reduction of surface hydrophobicity was found after treatment with antibiotics at 1/4 oftheir MICs. Surface hydrophobicity of K. pneumoniae after exposure to these concentrations wasdecreased to 44% (ofloxacin), 50.7% (pefloxacin) and 56.1% (tobramycin) compared with controls.
Študoval sa účinok subinhibičných koncentrácií chinolónov (ciprofloxacín, enoxacín, norfloxacín,ofloxacín, pefloxacín) a aminoglykozidov (amikacín, gentamicín, netilmicín, tobramycín) na povr-chovú hydrofobicitu a motilitu klinického izolátu Serratia marcescens. Hydrofobicita bola hodno-tená metódami adherencie na hydrokarbón xylén (BATH) a v soľno-agregačnom teste síranu amón-neho (SAT). Testované chinolóny v subinhibičných koncentráciách inhibovali adherenciu S.marcescens na xylén s výnimkou 1/16 MIC ofloxacínu, kde došlo k miernej stimulácii. Najvýraznejšiainhibícia adherencie sa pozorovala po pôsobení 1/4 MIC ciprofloxacínu (na 13,2 %) a pefloxacínu (na31,0 %) oproti kontrole. Z aminoglykozidov netilmicín výrazne inhiboval adherenciu v celom kon-centračnom rozsahu, pričom 1/8 MIC ju potlačila na 0,7 %. S týmito údajmi korelovali aj výsledkysoľno-agregačného testu. Študované antibiotiká výraznejšie neovplyvnili motilitu S. marcescens.
The authors investigated the effect of subinhibitory quinolone concentrations (ciprofloxacin, eno-xacin, norfloxacin, ofloxacin, pefloxacin) and aminoglycosides (amicacin, gentamicin, netilmicin,tobramycin) on the surface hydrophobicity and motility of the clinical isolate of Serratia marces-cens. The hydrophobicity was evaluated by methods of adherence to the hydrocarbon xylene (BATH)in a salt-aggregation ammonium sulphate (SAT) test. The tested quinolones in subinhibitory con-centrations inhibited the adherence of S. marcescens to xylene with the exception of 1/16 MICofloxacin where slight stimulation took place. The most marked inhibition of adherence wasobserved after the action of 1/4 MIC ciprofloxacin (to 13.2%) and pefloxacin (to 31.0%) as comparedwith the control. Among aminoglycosides netilmicin markedly inhibited the adherence over thewhole range of concentrations, whereby 1/8 MIC suppressed it to 0.7%. With these data correlatedalso the results of the salt-aggregation test. The investigated antibiotics did not have a major effecton the motility of S. marcescens.
Testovali sme citlivosť na baktericídny účinok séra a povrchovú hydrofobicitu kmeňov Acinetobac-ter baumannii izolovaných z močovej a z respiračnej sústavy pacientov po účinku imipenemuv subinhibičných koncentráciách (sub-MIC) (1/4, 1/8 a 1/16 MIC). Antibiotikum v uvedených koncen-tráciách významne znížilo citlivosť kmeňa z močovej sústavy na baktericídnu aktivitu ľudskéhoséra. Citlivosť na baktericídny účinok séra kmeňa z respiračnej sústavy bola ovplyvnená len veľminevýrazne. Imipenem v koncentrácii 1/4 MIC znížil povrchovú hydrofobicitu na 76,1 % (kmeňz močovej sústavy) a na 81,9 % (kmeň z respiračnej sústavy) kontrolných hodnôt (bez imipenemu).Nižšie koncentrácie antibiotika ovplyvnili bunkovú povrchovú hydrofobicitu len v menšom rozsa-hu. Možné zníženie citlivosti baktérií na baktericídny účinok séra po účinku sub-MIC imipenemuaj v pokusoch in vivo by mohlo znamenať zvýšenie virulencie týchto kmeňov.
Sensitivity to the serum bactericidal activity and surface hydrophobicity of Acinetobacter bauman-nii strains isolated from the urinary (UT) or respiratory tract (RT) of patients after exposure toimipenem at subinhibitory concentrations (sub-MICs) (1/4, 1/8 or 1/16 of their MICs) were tested. Theantibiotic at the mentioned concentrations decreased significantly the sensitivity of strain UT tothe bactericidal activity of human serum. Sensitivity to the bactericidal activity of serum of strainRT was affected only very ineffectively. Imipenem at 1/4 of their MICs reduced the cell surfacehydrophobicity to 76.1% (strain UT) and to 81.9% (strain RT) compared with control values (withoutimipenem). Lower concentrations of antibiotic influenced cell surface hydrophobicity only toa smaller extent. Possible decrease in sensitivity of bacteria to the bactericidal activity of serumafter treatment with imipenem in „in vivo“ experiments would manifest an increase in virulence ofthese strains.
Adsorption properties of protein Papain at the solid|liquid (0.1 M KCl) interfaces of different hydrophobicity [highly oriented pyrolytic graphite (HOPG), bare gold, CH3, OH, and COOH-terminated self-assembled monolayers on gold] were studied by a combined quartz crystal microbalance and atomic force microscopy techniques. It was found that Papain forms an incomplete monolayer at hydrophobic interfaces (HOPG and CH3-terminated substrate), whereas on more hydrophilic ones, a complete monolayer formation was always observed with either the onset of the formation of a second layer (bare gold substrate) or adsorption in a multilayer fashion, possibly a bilayer formation (OH-terminated substrate). The surface concentration and compact monolayer film thickness was much lower on the COOH-terminated substrate compared to other surfaces studied. This result was explained by partial dissociation of the interfacial COOH groups leading to additional electrostatic interactions between the positively charged protein domains and negatively charged carboxylate anions, as well as to local pH changes promoting protein denaturation.
V podmienkach in vitro sa sledovali postantibiotický účinok (PAE) a postantibiotický účinok sub-inhibičnej koncentrácie (PA SME) gentamicínu ako aj vplyv týchto farmakodynamických paramet-rov na povrchovú hydrofobicitu troch kmeňov Acinetobacter baumannii. Supresia bakteriálnehorastu (PAE) po krátkodobom účinku gentamicínu (30 min.) v suprainhibičnej koncentrácii 2x MICbola v rozsahu od 0,6 do 3,4 h. Dlhšie PAE sme pozorovali po pôsobení gentamicínu v koncentrácii4x MIC (1,5–5,1 h). Supra-subinhibičné koncentrácie gentamicínu (2x a 4x MIC + 0,2x MIC)spôsobili ešte výraznejšie oneskorenie obnovenia bakteriálneho rastu (PA SME) ako suprainhibičnékoncentrácie u jedného kmeňa (9,1 h a 9,6 h) a v prípade dvoch ďalších kmeňov boli tak účinné, žebakteriálny rast sa neobnovil do 24 h. Povrchová hydrofobicita kmeňov po účinku gentamicínuhodnotená adherenciou baktérií na xylén sa pohybovala v rozsahu od 90,0 % do 99,7 % kontrolnýchhodnôt (bez antibiotika).
The postantibiotic effect (PAE) and postantibiotic effect of subinhibitory concentration (PA SME) ofgentamicin as well as influence of these pharmacodynamic parameters on surface hydrophobicityof three Acinetobacter baumannii strains were studied in vitro. Suppression of bacterial growth(PAE) after a short time exposure of bacteria to gentamicin (30 min) at suprainhibitory concentra -tion 2x MIC was in the range of 0.6 h to 3.4 h. Longer PAE was observed after treatment of bacteriawith gentamicin at 4x MIC (1.5 h – 5.1 h). Supra-subinhibitory concentrations of gentamicin (2x or4x MIC + 0.2x MIC) caused still more effective delay of bacterial regrowth (PA SME) in comparisonwith suprainhibitory concentrations for one strain (9.1 h and 9.6 h) and in the case of further twostrains they were so efficient that regrowth of bacteria was not observed for 24 h. Surfacehydrophobicity of the gentamicin treated strains evaluated by adherence of bacteria to xylene rangedfrom 90.0% to 99.7% of the control values (without antibiotic).
Cell surface hydrophobicity (CSH) plays a crucial role in the attachment to, or detachment from the surfaces. The influence of CSH on adhesion of microorganisms to biotic and abiotic surfaces in medicine as well as in bioremediation and fermentation industry has both negative and positive aspects. Hydrophobic microorganisms cause the damage of surfaces by biofilm formation; on the other hand, they can readily accumulate on organic pollutants and decompose them. Hydrophilic microorganisms also play a considerable role in removing organic wastes from the environment because of their high resistance to hydrophobic chemicals. Despite the many studies on the environmental and metabolic factors affecting CSH, the knowledge of this subject is still scanty and is in most cases limited to observing the impact of hydrophobicity on adhesion, aggregation or flocculation. The future of research seems to lie in finding a way to managing the microbial adhesion process, perhaps by steering cell hydrophobicity.
- MeSH
- Adhesiveness MeSH
- Bacteria pathogenicity MeSH
- Bacterial Adhesion * MeSH
- Bacterial Physiological Phenomena * MeSH
- Fungi pathogenicity physiology MeSH
- Hydrophobic and Hydrophilic Interactions * MeSH
- Humans MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Cell-penetrating and some antimicrobial peptides can translocate across lipid bilayers without disrupting the membrane structure. However, the molecular properties required for efficient translocation are not fully understood. We employed the Metropolis Monte Carlo method together with coarse-grained models to systematically investigate free-energy landscapes associated with the translocation of secondary amphiphilic peptides. We studied α-helical peptides with different length, amphiphilicity, and distribution of hydrophobic content and found a common translocation path consisting of adsorption, tilting, and insertion. In the adsorbed state, the peptides are parallel to the membrane plane, whereas, in the inserted state, the peptides are perpendicular to the membrane. Our simulations demonstrate that, for all tested peptides, there is an optimal ratio of hydrophilic/hydrophobic content at which the peptides cross the membrane the easiest. Moreover, we show that the hydrophobicity of peptide termini has an important effect on the translocation barrier. These results provide general guidance to optimize peptides for use as carriers of molecular cargos or as therapeutics themselves.
- MeSH
- Cell Membrane metabolism MeSH
- Hydrophobic and Hydrophilic Interactions * MeSH
- Protein Conformation MeSH
- Monte Carlo Method MeSH
- Peptides chemistry metabolism MeSH
- Molecular Dynamics Simulation MeSH
- Thermodynamics MeSH
- Protein Transport MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Pyrazine derivatives show a wide range of biological activities. 1-Pyrazin-2-ylethan-1-ones have served as food flavourants, and together with pyrazine-2-carbonitriles have been widely used as intermediates in the synthesis of various heterocyclic compounds. In our laboratory, substituted pyrazine-2-carbonitriles and 1-pyrazin-2-ylethan-1-ones have been used as intermediates for the preparation of potential antifungal and antimycobacterial drugs. Using established methods, a library of pyrazine derivatives was synthesized. Homolytic alkylation of commercially available pyrazine-2-carbonitrile yielded a series of 5-alkylpyrazine-2-carbonitriles which were converted into the corresponding 1-(5-alkylpyrazin-2-yl)ethan-1-ones (5-alkyl-2-acetylpyrazines) via the Grignard reaction. Homolytic acetylation of pyrazine-2-carbonitrile yielded 5-acetylpyrazine-2-carbonitrile. Using the same procedure, 3-acetyl-5-tert-butylpyrazine-2-carbonitrile was obtained with 5-tert-butylpyrazine-2-carbonitrile as a starting material. The hydrophobicity of the compounds was determined both experimentally (RP-HPLC) and by computation (CS ChemOffice Ultra version 9.0, ACD/LogP version 1.0 and ACD/LogP version 9.04), and both the approaches were compared. New hydrophobicity constants ? based on experimental results were derived. These constants are markedly different from tabulated constants ? valid for benzene rings, and can be widely used in estimating physicochemical properties of new biologically active pyrazines.
