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Biomedical subjects

A Hostacká

Publications and source records attributed to A Hostacká.

At least 73 records · Page 4Linked to original sources
PubMed1995

[The effect of subinhibitory concentrations of norfloxacin, erythromycin and roxithromycin on Pseudomonas aeruginosa virulence factors].

The effect of sub-MICs (1/4 MIC, 1/8 MIC, 1/16 MIC) of norfloxacin, erythromycin, roxithromycin on Pseudomonas aeruginosa virulence factors was studied. It was found that 1/4 of the MIC of norfloxacin inhibited most effectively elastase as well as proteinase activity (to 30.1% or 29.2% of the control values). Macrolide antibiotics did not reduce the tested enzymic activities but caused their increase.

Anti-Bacterial Agents↗
PubMed1995

Suppression of virulence factors of pseudomonas aeruginosa by subinhibitory concentrations of quaternary ammonium salts.

The effect of subinhibitory concentrations (sub-MICs) of two homologous series of "soft" quaternary ammonium salts (QATs) upon the expression of phospholipase C (Pseudomonas aeruginosa strain 72/92), elastase, proteinase and permeability activity (P. aeruginosa 9/92) was studied. Both strains were isolated from the patients suffering from nosocomial infections. Phospholipase C was the most markedly inhibited enzyme. The inhibitory effect was directly proportional to the concentration of substances but the degree of inhibition in the two homologous series was different. In the second strain of P. aeruginosa its production of elastase, permeability factor and mainly its proteinase activity were less affected by the series of tested QATs. A significant inhibition of production of these factors was manifested only in higher concentrations particularly by the substances with longer alkyls. The effect of QATs on the production of virulence factors could be attributed to their influence on the metabolic activity of organisms.

Animals↗
PubMed1995

Effect of quaternary ammonium salts and amine oxides on Pseudomonas aeruginosa.

Two quaternary ammonium salts, viz (1-methyldodecyl) trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as two amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trimethylamine oxide (TMANO), were tested for their inhibitory activity on a Pseudomonas aeruginosa strain isolated from nosocomial infections. Only those compounds with long alkyl chains in their molecules (ATDBr and ATDNO) showed antimicrobial efficacy. In subinhibitory concentrations both compounds inhibited incorporation of [14C]-adenine and [14C]-leucine as precursors of macromolecular biosynthesis. Endogenous respiration of the cells was more sensitive to both agents than the respiration of various substrates. Among the virulence factors only the production of phospholipase C was inhibited by sub-MICs, while the activities of elastase and proteinase were stimulated until the inhibitory concentrations were reached. The short-chain analogues TMABr and TMANO did not show these effects. It is suggested that the production of virulence factors is affected by amphiphilic compounds due to their antimicrobial activity.

Cross Infection↗
PubMed1994

Production of enterotoxin, verotoxin, hemolysin and cytotoxic necrotizing factor by Escherichia coli of intestinal and extraintestinal origin.

Seventy-six Escherichia coli strains were examined for heat-labile enterotoxin (LT), verotoxin (VT), hemolysin (HLy) and cytotoxic necrotizing factor (CNF). Thirty-six strains were isolated from patients suffering from diarrhea and forty from different extraintestinal infections. The number of LT-producing strains was low (2.6%) (one of intestinal and one of extraintestinal origin). Verotoxin was produced only by one extraintestinal strain. Four intestinal strains were hemolytic (11.2%) and also positive for CNF. From 24 hemolytic strains of extraintestinal origin (60%), 17 produced also CNF. Most of the hemolytic (30%) as well as CNF-producing strains (22.5%) were isolated from urine. Our results are similar to those of other studies confirming the close association between hemolysin and CNF production as well as a possible role of these toxic factors in pathogenesis of extraintestinal infections caused by E. coli.

Adolescent↗
PubMed1994

Enzymic and permeability activity of Pseudomonas aeruginosa after treatment with sub-MICs of organic ammonium salts.

The effects of subinhibitory concentrations (1/4, 1/8, 1/16 of the MIC) of 12 organic ammonium salts of A (hard-alkyltrimethylammonium bromides) and B (soft--2-(dodecanoylamino)ethylalkyldimethylammonium bromides) homologous series on phospholipase C, proteinase, elastase and permeability activity were studied. The substances with longer substituents were more effective in reducing phospholipase C activity (hard and soft series) as well as proteinase (hard series). Phospholipase C was the most frequently and the most markedly inhibited enzyme. The organic ammonium salts were less effective in inhibiting elastase and permeability activity. Only one of the substances under study reduced all the tested activities.

Anti-Bacterial Agents↗
PubMed1994

Effects of subinhibitory concentrations of antibiotics on biological properties of Salmonella typhimurium.

We followed the effects of subinhibitory concentrations (sub-MICs) of 7 antibiotics (ticarcilin, cefotaxim, streptomycin, gentamicin, ciprofloxacin, pefloxacin, mitomycin C) on the sensitivity of a Salmonella typhimurium strain to standard bacteriophages, on the phage DNA as well as on the factors of virulence (permeability and cytotoxic activity). The phage type was not changed by the sub-MICs of the tested antibiotics. However, differences were found in culture filtrates prepared from the bacterial suspensions of the strain cultivated with the sub-MICs. Marked inducing effects on phage DNA were exhibited by mitomycin C (1/2, 1/4, 1/8 of the MIC), pefloxacin (1/2, 1/4, 1/8 of the MIC) and ciprofloxacin (1/2, 1/4, weakly also 1/8 of the MIC). Ticarcilin (1/2 of the MIC), like the aminoglycosides streptomycin and gentamicin (1/2, 1/4, 1/8 of the MIC), had a weak effect. Sub-MICs of the studied antibiotics (with the exception of 1/8 of the MIC of ciprofloxacin and 1/4 of the MIC of ticarcilin) decreased the permeability reaction in rabbit skin. Most effective was streptomycin (1/2 of the MIC). Sub-MICs of the tested antibiotics (with the exception of 1/4 and 1/8 of the MIC of ciprofloxacin and 1/4 of the MIC of pefloxacin) caused also an inhibition of the factor responsible for morphological changes on Vero cells. Gentamicin and streptomycin were effective at all the sub-MICs tested.

Animals↗
PubMed1993

Alterations in Pseudomonas aeruginosa exoproducts by sub-MICs of some antibiotics.

Aminoglycoside antibiotics, most effective at the level of 1/4 of the MIC, suppressed all the tested activities of P. aeruginosa, except cytotoxicity. Proteinase activity was decreased to 60% (gentamicin) and 63% (streptomycin), permeability was reduced to 61% (gentamicin) and 73% (streptomycin), phospholipase C to 13% (gentamicin) and 51% (streptomycin) of the control values. Subinhibitory concentrations of beta-lactams inhibited only phospholipase C activity to 89% (ticarcillin) and 64% (cefotaxim) of the control values. These antibiotics did not suppress the cytotoxic activity and increased protease activity up to 155% (ticarcillin) and 192% (cefotaxim) as well as permeability up to 121% (ticarcillin) and 154% (cefotaxim) of the control values.

Anti-Bacterial Agents↗
PubMed1993

Enterohaemolysin production in Escherichia coli strains.

Enterohaemolysin production was found in 11 (20.3%) out of 54 Escherichia coli strains isolated from stools of infants with dyspepsia and in 3 (2.3%) out of 130 E. coli strains isolated from urinary tract infections. Enterohaemolysin producing E. coli strains isolated from stools belonged to O groups 25 and 111 and the strains from urine to O groups 1 and 15. None of the enterohaemolysin-producing strains isolated from dyspepsia was shown to cause any damage on Vero cells.

Bacterial Toxins↗
PubMed1993

[The effect of subinhibitory levels of antimicrobial agents on bacteria].

The authors reviewed data in the literature about influencing the virulence factors and other properties of important gram-negative and gram-positive bacteria by sub-MICs of antimicrobial substances. Special attention is devoted to influencing the exo-products as well as adherent properties of Pseudomonas aeruginosa.

Anti-Bacterial Agents↗
PubMed1992

Permeability factor, cytotoxicity and serotyping of Pseudomonas aeruginosa strains.

We analyzed in detail the permeability and cytotoxic activity as well as the serotypes of 127 Pseudomonas aeruginosa strains. Sixty-seven strains were isolated from immunocompromised patients (51 from patients with tumors and 16 from patients after transplantation) and 60 strains were isolated from patient's ears. Culture filtrates of strains isolated from patients after transplantation were responsible for the highest part of permeability reactions corresponding to an intermediate toxin production (68.8%) (categories 2 and 3) and culture filtrates of strains isolated from patients with tumors caused the highest percentage of permeability reactions corresponding to a strong toxin production. Culture filtrates of strains isolated from ears of patients were responsible for the highest percentage of negative permeability reactions (15%). With positive permeability reaction size (categories 2-6) increased also the percentage of cytotoxicity as well as the intensity of morphological changes on Vero cells after 1 and 2 d. We did not observe any relationship between a particular permeability reaction category and the most frequent serotypes (O4, O6) or nontypable strains of the tested groups.

Animals↗
PubMed1992

[Plasmid profile and toxicity of Klebsiella pneumoniae strains isolated at a neonatal department].

The authors tested the plasmid profile of 11 and the toxicity of 16 strains of K. pneumoniae isolated in a neonatal department. Based on examination of the plasmid profile it may be assumed that very probably a nosocomial spread of the strains was involved. This is suggested by the identical plasmid profile of all strains isolated in the environment and five strains isolated from neonates. On investigation of the enterotoxicity of culture filtrates of the investigated strains the authors did not reveal the presence of a thermolabile or thermostable enterotoxin. In the skin test on rabbits 93.8% of the tested samples were positive. Morphological changes on Vero cells after 48 hours action were produced by four culture filtrates. Only two strains caused haemolysis of agar with 6% sheep and rabbit blood after incubation at 37 degrees C. Another 14 strains caused lightening of the agar with rabbit blood after subsequent incubation at 4 degrees C.

Animals↗
PubMed1992

Toxic properties of Bacillus cereus strains isolated from different foodstuffs.

Toxic activity of 89 culture filtrates of Bacillus cereus strains were examined. From the total number of the filtrates tested, 3 were found to cause fluid accumulation in the ligated rabbit ileal loop. 71 samples caused a vascular permeability increase in the rabbit skin corresponding to an intermediate or strong toxin production. 59 of the 89 culture filtrates were cytotoxic on Vero cells, 31 had a lethal effect, 81 induced hemolysis of 0.5% rabbit erythrocytes and 55 tested samples showed lecithinase activity. The results showed that relationships exist between the extent of the permeability reaction and cytotoxicity, lecithinase and lethality. No relationship was found between permeability reaction size and reaction in the ligated rabbit ileal loop, nor a strict correlation between permeability reaction and hemolysin. Similarly, the part of culture filtrates showing a weak, or no reaction in the rabbit skin showed hemolytic activity.

Animals↗
PubMed1991

[New findings on virulence factors in Salmonella species].

The authors present a review of the literature on most recent findings pertaining to the properties of the most important factors of virulence of Salmonellae, in particular from the aspects of their biological and physico-chemical properties. These findings can contribute towards the elucidation of factors of pathogenicity and virulence of these microbes and mechanisms of the pathogenesis of diseases they produce.

Salmonella↗
PubMed1991

On the toxinogenicity of Pseudomonas aeruginosa strains.

Investigation of 367 P. aeruginosa strains primarily isolated from clinical and other biological material as well as from the environment yielded results suggesting a substantial toxinogenic potential. 92.6% of the assayed culture filtrates derived from the strains under investigation proved positive in the early skin tests on rabbits. 49.7% of the assayed material induced cytotoxic alterations on Vero cells, the rates for Y1 and CHO cells being 50.3% and 43.5% respectively. 54.3% culture filtrates caused haemolysis of rabbit RBC and 52.7% lysed horse RBC. Gelatinase activity was found in 96.3% of tested material, protease in 89.8%, lecithinase in 62.4% and elastase in 29.6%. 12.6% of tested material induced fluid accumulation in a ligated intestinal loop. None of the culture filtrates elicited a positive reaction in the suckling mice test suggesting the absence of the thermostable enterotoxin.

Child, Preschool↗
PubMed1990

[Products of Bacillus cereus contributing to its pathogenicity].

In a review the author describes the most important exoproducts of strains of Bacillus cereus which contribute to its pathogenicity. The toxic product are evaluated with regard to their physical, chemical and biological properties as well with regard to mechanism of their pathogenic action.

Bacillus cereus↗
PubMed1989

[Use of the coagglutination test in the detection of thermolabile enterotoxin of Escherichia coli].

The authors examined 39 strains of E. coli isolated from patients with the clinical diagnosis of diarrhoea for the presence of thermolabile enterotoxin (LT-I). For assessment of LT-I adaptation of the staphylococcal coagglutination technique was used. Suspension of a strain of staphylococcus aureus Cowan I, MAU, 55/64 was sensitized with a specific antibody against LT-I (not diluted and diluted). 50 ng purified enterotoxin created with the thus sensitized staphylococcal suspension a still reproducible coagglutination. The above test revealed that none of the tested strains of E. coli produced the thermolabile LT-I enterotoxin.

Agglutination Tests↗
PubMed1989

Our experiences with isolation of heat-labile enterotoxin from Escherichia coli.

From the Escherichia coli strain isolated from a patient suffering from diarrhoea a homogenate and concentrated culture filtrate were prepared. From these materials the heat-labile enterotoxin was isolated after its elution with 0.2 M D-galactose from Sepharose 6B column. The obtained enterotoxin was positive in the rabbit ileal loop test up to a concentration of 1 microgram protein/ml. In the immunodiffusion test it reacted in a concentration up to 5 micrograms protein/ml with anticholeragen and in a concentration up to 30 micrograms protein/ml with its specific antiserum. This antiserum was prepared by intramuscular immunization of rabbits by enterotoxin with complete Freund's adjuvant.

Bacterial Toxins↗