Biomedical subjects

A Hostacká

Publications and source records attributed to A Hostacká.

At least 55 records · Page 3Linked to original sources

PubMed1997

Hydrophobicity and outer membrane proteins of Shigella dysenteriae type 1 after treatment with subinhibitory concentrations of aminoglycosides.

Hydrophobicity and profiles of outer membrane proteins of Shigella dysenteriae type 1 after treatment with subinhibitory concentrations (1/2 or 1/4 of the MIC) of aminoglycosides were studied. The antimicrobial activity of the antibiotics tested was 3.12 mg/L (amikacin, tobramycin) and 6.25 mg/L (gentamicin). The hydrophobicity of the cell surface of S. dysenteriae type 1 was decreased after exposure to all aminoglycosides at a concentration of 1/2 of the MICs; 1/4 of the MICs of the antibiotics did not affect bacterial aggregation in the presence of ammonium sulfate. SDS-polyacrylamide gel electrophoresis showed that the profiles of outer membrane proteins of the strain treated with aminoglycosides at both subinhibitory concentrations were not changed as compared to the control.

Amikacin↗

PubMed1997

Postantibiotic effect of norfloxacin and its influence on profiles of outer membrane proteins of Pseudomonas aeruginosa.

Norfloxacin at suprainhibitory concentrations induced postantibiotic effects (PAEs) in the range of 6 h to 11.4 h (2.MIC) and of 10.1 to more than 13.4 h (4, MIC) against three P. aeruginosa strains. After PAEs, the outer membrane profile proteins of the strains studied was changed. Overproduction of 41 kDa protein as well as strong reduction of 23 kDa and 45 kDa proteins were found in all three strains. A reduction of the protein band in the range of 35 kDa was also observed in all strains, but to a smaller extent.

Anti-Infective Agents↗

PubMed1997

Influencing virulence factors of Pseudomonas aeruginosa by commercially manufactured disinfectants.

Some commercially manufactured disinfectants tested (Desur, Dezox, Diesen forte, Lysoformin 3,000, Sokrena, Topax 91) depressed Pseudomonas aeruginosa virulence factors (elastase and proteinase), Nobacel did not. The degree of inhibition was directly proportional to the disinfectant concentration. The most effective concentrations were 1/4 of the MICs. Topax 91 most significantly suppressed proteinase activity (20.3%), Dezox was the most efficient in case of elastase (47.8%).

Depression, Chemical↗

PubMed1997

In vitro postantibiotic effect of imipenem and enoxacin alone and in combination against Pseudomonas aeruginosa.

The postantibiotic effects (PAEs), i.e. suppression of growth of three Pseudomonas aeruginosa strains (386, 648, 659) after a short treatment (30 min) with imipenem and enoxacin alone and in combination were evaluated. Imipenem (2 x MIC) induced PAEs for two strains for 0.5 h (386, 648) at concentrations of 4 x MIC, PAEs lasted 0.8 h (386), 2 h (648) and 1.5 h (659). The PAE values of enoxacin (2 x MIC) were 4.6 h (386), 1.7 h (648), 1.6 h (659) and those of enoxacin (4 x MIC) were 6.1 h (386), 3.2 h (648) and 2.1 h (659). PAEs manifested by an imipenem/enoxacin combination were longer than the mathematical sum of PAEs induced by individual antibiotics. Prolongation of PAEs induced by the imipenem (2 x MIC)/enoxacin (2 x MIC) combination was 25.5% and 27.3% (strains 386 and 648) as well as 27.8%, 32.4% and 16.1% (strains 386, 648 and 659) after treatment with imipenem (4 x MIC)/enoxacin (2 x MIC).

Anti-Infective Agents↗

PubMed1997

Comparison of postantibiotic effects of imipenem and netilmicin alone and in combination against Pseudomonas aeruginosa.

Imipenem (CAS 64221-86-9) as well as netilmicin (CAS 56391-57-2) at suprainhibitory concentrations induced the postantibiotic effects against three P. aeruginosa strains. Imipenem (2 x or 4 x minimal inhibitory concentration (MIC)) showed postantibiotic effects in the range of 0.3-1.6 h and 0.9-4.0 h. Netilmicin at the same concentrations produced postantibiotic effects of 3.0-3.8 h and 3.5-4.5 h. Postantibiotic effects manifested by imipenem (2 x or 4 x MIC) + netilmicin (2 x MIC) combination were somewhat longer (in the range of 4.6-4.9 h and 5.8-7.4 h) than the mathematical sum of postantibiotic effects induced by drugs alone (in the range of 4.1-4.7 h and 4.7-7.0 h).

Carbapenems↗

PubMed1997

Outer membrane proteins profiles of Pseudomonas aeruginosa after the post-antibiotic effect of imipenem.

A suppression of bacterial growth of three Pseudomonas aeruginosa strains after 30 min treatment with imipenem at supra-inhibitory concentrations (post-antibiotic effect; PAE) was observed. Imipenem (4x MIC) showed PAEs in the range of 0.5-0.9 h for stains studied. The PAEs manifested by imipenem at 8x MIC concentration varied between 2.4 and 4.0 h. Supra-inhibitory concentrations of imipenem did not affect the profiles of the outer membrane proteins of the stains. The treated strains revealed the same protein bands (45, 38, 35 and 23 kD) compared with controls.

Bacterial Outer Membrane Proteins↗

PubMed1997

Serotyping and virulence factors of Pseudomonas aeruginosa clinical isolates.

Pseudomonas aeruginosa is one of the major opportunistic human pathogens very often responsible for severe infections mainly in immunocompromised hosts. These bacteria may cause the broad spectrum of infections which are associated with urinary, respiratory and gastrointestinal tract, burn wounds, eyes as well as other sites. P. aeruginosa also significantly contributes to high morbidity and mortality rates of nosocomial infections. This microorganism produces a number of exoproducts which have been implicated in the pathogenesis of pseudomonas infections. Among them, the activity of elastase, proteinase and alginate were well established. The aim of the present study was to determine the distribution of P. aeruginosa strains (isolated from urinary and respiratory tract infections) in O-serotypes and to evaluate some of their characteristics (elastase, proteinase and alginate).

Alginates↗

PubMed1997

[Effect of superinhibitory levels of imipenem and amikacin singly or in combination on Pseudomonas aeruginosa].

Suppression of bacterial growth of a clinical Pseudomonas aeruginosa strain after 30 min treatment with imipenem and amikacin alone as well as after treatment with a combination of these antibiotics (postantibiotic effect-PAE) was studied. Imipenem (2xMIC) induced PAE lasting 0.7 h, at a concentration of 4xMIC caused suppression of bacterial growth for 1.5 h. The effect of suprainhibitory concentrations of amikacin was more substantial. Amikacin (2x or 4xMIC) manifested PAE of 1.9 h or 4.0 h. The postantibiotic effect induced by antibiotic combination-imipenem (2xMIC) + amikacin (2xMIC) (3.0 h) as well as imipenem (4xMIC) + amikacin (2xMIC) (4.0 h) was longer than the mathematical sum of the postantibiotic effects produced by individual antibiotics at the mentioned concentrations (2.6 h or 3.4 h). Prolongation of the suppression of bacterial growth induced by a combination of imipenem (2xMIC) + amikacin (2xMIC) was 15.4%, and 17.6% after treatment with a combination of imipenem (4xMIC) + amikacin (2xMIC).

Amikacin↗

PubMed1997

Hydrophobicity and serum sensitivity of Klebsiella pneumoniae treated with sub-MICs of quinolones.

Cell surface hydrophobicity and serum sensitivity of Klebsiella pneumoniae, after treatment with sub-minimum inhibitory concentrations (sub-MICs) of ciprofloxacin, norfloxacin and enoxacin, were studied. The quinolones tested at 1/4, 1/8 and 1/16 of the MICs decreased surface hydrophobicity. The most significant reduction of the bacterial cell surface hydrophobicity was found after treatment with antibiotics at 1/16 of the MICs (to 20.3% for both ciprofloxacin and norfloxacin, and to 23.6% for enoxacin, compared with control values). The most significant increase in the susceptibility of the bacteria to serum bactericidal activity was seen after 180 min incubation with ciprofloxacin and enoxacin at 1/16 of their MICs. Survival of treated bacteria was 55 +/- 8% 56 +/- 10% as compared with controls without antibiotics.

Anti-Infective Agents↗

PubMed1996

Influence of the postantibiotic effect and postantibiotic sub-MICs effect of netilmicin, tobramycin, ciprofloxacin and pefloxacin on alginate production by Pseudomonas aeruginosa.

The postantibiotic effect (PAE) (postantibiotic phase induced by 2x or 4x MIC) as well as the postantibiotic effect of subinhibitory concentrations (0.1x, 0.2x and 0.3x MIC) (PA SME) of netilmicin, tobramycin, ciprofloxacin and pefloxacin affected the production of the virulence factor alginate by a P. aeruginosa strain. Aminoglycosides and ciprofloxacin at a concentration of 4x MIC inhibited the alginate production more significantly than 2x MIC. Suprainhibitory concentrations of aminoglycosides were more effective than pefloxacin (2x or 4x MIC) and ciprofloxacin (2x MIC). PA SME demonstrated by the above antibiotics (with the exception of ciprofloxacin 2x MIC + 0.1x MIC) suppressed alginate production more efficiently.

Alginates↗

PubMed1996

Pharmacodynamic parameters of aminoglycosides and their effect on exoenzymes of Pseudomonas aeruginosa.

Aminoglycosides at 2x or 4x minimum inhibitory concentration induced postantibiotic effects against Pseudomonas aeruginosa lasting 3.5-4.9 h (gentamicin) and 0.5-3.7 h (selemycin). Postantibiotic effects of subinhibitory concentrations of the aminoglycosides tested were substantially longer. Some combinations of supra- and subinhibitory concentrations of antibiotics did not even allow any regrowth of the bacterial strain. The postantibiotic effects and postantibiotic effects of subinhibitory concentrations of gentamicin and selemycin were associated with changes of P. aeruginosa elastase and proteinase. Combinations of supra- and subinhibitory concentrations more pronouncedly suppressed enzymic activities than did suprainhibitory concentrations alone.

Anti-Bacterial Agents↗

PubMed1996

Postantibiotic effects of subinhibitory concentrations of some antibiotics and their influence on Pseudomonas aeruginosa enzymic activity.

The postantibiotic effects of subinhibitory concentrations (PA SMEs) and virulence factor alterations induced by ciprofloxacin, tobramycin and netilmicin in Pseudomonas aeruginosa were studied. After induction of the postantibiotic phase (PA) (2x or 4x MIC) the cultures were exposed to subinhibitory concentrations (0.1, 0.2 and 0.3x MIC) of the same antibiotic (PA SME). The regrowth of treated as well as control cultures was followed for 24 or 45 h. In the sterile culture filtrates obtained from these bacterial cultures, elastase and proteinase were determined. Ciprofloxacin and aminoglycosides exhibited PA SMEs of 35-35 h for certain combinations of supra-subinhibitory antibiotic concentrations. Longer PA SMEs were observed after treatment with higher sub-MICs. Tobramycin at 0.2 and 0.3x MIC (postantibiotic phase induced by 2x MIC) and at alt sub-MICs added to the bacteria previously exposed to 4x MIC do not allow any regrowth of bacterial culture. PA SMEs of tested antibiotics affected virulence factors of P. aeruginosa. Elastase compared to proteinase was suppressed more effectively. Ciprofloxacin at 0.3x MIC reduced elastase and proteinase activity most significantly (to 14.2 and 60% of the control values).

Anti-Bacterial Agents↗

PubMed1996

[Postantibiotic effects and postantibiotic effects of subinhibitory levels of quinolines on Pseudomonas aeruginosa].

The postantibiotic effect (PAE) (PA phase induced by 2x or 4x MIC) and postantibiotic effect of subinhibitory concentrations (PA SME) of three quinolones-enoxacin, norfloxacin and pefloxacin against Pseudomonas aeruginosa were determined. It was observed that the tested antibiotics at suprainhibitory concentrations 2x MIC induced PAEs of 2.1-6.7 h. Longer PAEs were observed after treatment with antibiotics at concentration 4x MIC (4.1-9.0 h). Subinhibitory concentrations of quinolones added to bacterial suspensions in the postantibiotic phase (2x or 4x MIC) displayed longer delay of bacterial regrowth (PA SMEs) compared to PAEs. No regrowth of bacterial culture was observed even at 48 h in the case of pefloxacin (2x MIC + 0.3x MIC, 4x MIC +0.2x MIC, 4x MIC + 0.3x MIC) as well as norfloxacin (4x MIC + 0.2x MIC, 4x MIC + 0.3x MIC).

Anti-Infective Agents↗

PubMed1996

Effects of amphiphilic compounds on metabolic and biological activities of Salmonella typhimurium.

The effect of two quaternary ammonium salts, (1-methyldodecyl)trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as that of two amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trimethylamine oxid (TMANO), on both metabolic and biological activities of a S. typhimurium strain isolated from nosocomial infection were studied. The compounds with long alkyl chain in the molecule (ATDBr, ATDNO) affected the growth, synthesis of biomacromolecules (DNA, RNA, proteins) and respiration. The compounds lacking the alkyl chain (TMABr, TMANO) were ineffective with exception of the endogenous respiration that they inhibited in a less degree in the highest concentrations tested. The highest inhibition of respiration was evoked by ATDBr and ATDNO in the presence of pyruvate as an exogenous carbon substrate. The sub-MICs of quaternary ammonium salts induced a prophage of the lysogenic S. typhimurium strain, amine oxides were ineffective. The tested compounds decreased at one-fourth of the MICs the permeability reaction. The results showed that both physiologic and metabolic processes were inhibited in dependence on the length of the alkyl chain, however, amine oxides were less effective in biological activities.

Amines↗

PubMed1996

[The effect of pharmacodynamic parameters of pefloxacin on elastase and protease activity in Pseudomonas aeruginosa].

The effect on Pseudomonas aeruginosa virulence factors (elastase and proteinase) after short-time treatment (30 min) with suprainhibitory (2x or 4x MIC) as well as with supra-subinhibitory concentrations (2x MIC + sub-MICs or 4x MIC + sub-MICs) of pefloxacin was studied. An effective decrease of elastase activity (to 42.6% of the control value) was observed only after higher suprainhibitory antibiotic concentration. More significant depression of the activities tested was found after the postantibiotic effect of subinhibitory concentrations. Elastase as well as proteinase activity were suppressed by supra-subinhibitory concentration of 4x MIC + 0.1x MIC to 13.1% or 37.9%, as compared to controls.

Anti-Infective Agents↗

PubMed1996

Influence on Pseudomonas aeruginosa elastase, proteinase and alginate by supra-inhibitory and supra-subinhibitory concentrations of quinolones.

Suppression of elastase, proteinase and alginate of Pseudomonas aeruginosa after the exposure of a bacterial suspension (30 min) to supra-inhibitory concentrations (2x or 4x MIC) of norfloxacin was found. The norfloxacin at 4x MIC was more effective, and this concentration depressed elastase to 13.0%, proteinase to 14.6% and alginate to 0% of the control values. Enoxacin at 2x MIC did not affect the virulence factors studied, and at a concentration of 4x MIC only elastase was effectively reduced to 61% of the control value. Supra-subinhibitory concentrations of the quinolones tested (2x or 4x MIC + sub-MICs) severely diminished all of the activities tested compared with supra-inhibitory concentrations alone. Combinations of 4x MIC + sub-MICs were more effective in the majority of cases.

Alginates↗

PubMed1995

Antimicrobial efficacy of quaternary bisammonium salts and the effect of their sub-MICs on Pseudomonas aeruginosa virulence factors.

Antipseudomonadal activity of homologous series of six quaternary bisammonium salts (QBAS) (4,7-dioxo-3,8-dioxadekan-1,1-[bis(alkyldimethyldiammonium dibromide)] as well as the effect of their subinhibitory concentrations (sub-MICs) on Pseudomonas aeruginosa virulence factors was studied. Antibacterial activity of QBAS increased up to a certain length of the chain and then decreased with further elongation. All the tested sub-MICs of QBAS caused a significant suppression of phospholipase C activity (to 0-41%). Elastase and proteinase activity were less efficiently reduced. A more effective decrease of these activities was only found after treatment with one-fourth of the MICs of the tested substances. QBAS caused only an erratic decrease of alginate production.

Alginates↗

PubMed1995

Subinhibitory concentrations of organic ammonium salts: the effect on biological properties of Salmonella typhimurium.

The effect of subinhibitory concentrations (subMICs) of new organic ammonium salts of four homologous series of alkylammonium bromides (32 compounds) was determined with respect to the induction of lysogenic strain prophage, influence of permeability reactions in a rabbit skin test and cytotoxic changes of monolayers of Vero cells. The culture filtrates were prepared by 1-d cultivation of Salmonella typhimurium in a synthetic culture medium under conditions of intensive aeration at 37 degrees C after addition of subinhibitory concentrations of organic ammonium salts. The results showed that substances of the homologous series of 2-(10-undecenoyloxy)ethyl-alkyldimethylammonium bromides were characterized by a prophage-inducing effect in lysogenic strain cells. The induction of prophage raised with rising concentrations of subMICs of the substances, and its titer in the culture filtrates was mostly 4.10(6) PFU/mL. Substances C3, C9 and C12 of the same homologous series had the strongest effect on the permeability reaction in rabbit skin in 1/2 MICs. One-half MICs of four substances (B14, C3, C12, C14) and 1/4 MICs of substance A16 influenced cytotoxic changes on Vero cells, the other substances were ineffective.

Animals↗