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A Hostacká

Publications and source records attributed to A Hostacká.

At least 19 recordsLinked to original sources
PubMed2006

Immunological properties of complex conjugates based on Vibrio cholerae O1 Ogawa lipopolysaccharide antigen.

Host protection by humoral immunity against Vibrio cholerae O1 confers lipopolysaccharide (LPS)-specific vibriocidal antibodies. Levels of relevant specific antibodies are closely related to complement-mediated inactivation of the vibrios inoculum, especially on the mucosal surface of intestine. We have tested complex V. cholerae O1 Ogawa-detoxified lipopolysaccharide (dLPS) conjugates. The first conjugate contained glucan both as the immunomodulator and the matrix; the second conjugate contained immunologically inert amylose as matrix. Both d-LPS conjugates contain multiply attached dLPS antigen. These conjugates elicited a statistically significant increase of antigen-specific IgG levels in mice (P<0.001 and P<0.05, respectively). The specific anti-conjugate IgG and IgA response after the second (booster) dose were significantly higher compared to pre-immune and whole-cell response. The most effective vibriocidal activity was observed in the case of conjugate, with glucan as the matrix. The highest correlation was found between vibriocidal activity and specific IgG2b (r=0.765) and IgA (r=0.887) sera levels. The determination of specific IgG subclasses and IgG2a + 2b/IgG1 ratio revealed a dominant T(H)1 cell response crucial for effective vaccine candidate.

Adjuvants, Immunologic↗
PubMed2005

[Biological characteristics of Plesiomonas shigelloides strains of human and animal origin].

We focused on serotyping and biological characteristics of Plesiomonas shigelloides strains potentially associated with virulence. Thirteen strains isolated from humans (H) and 14 strains of animal origin (A) were tested. The most frequent serotype among H strains was 040:H6 while 066:H3 predominated among A strains. All of the H strains and 92.8% of A strains were hydrophobic. H isolates showed lower motility (30.1 mm) compared to A isolates (46.8 mm). As many as 76.9% and 71.4% of H and A strains, respectively, produced beta-hemolysis. Both H and A strains exhibited low biofilm production on a glass surface. No significant differences were found between H and A strains in lipase production and histidine decarboxylase production. The zones of bacterial growth inhibition in response to oxidative stress were on average 26.6 mm and 28.1 mm for H and A strains, respectively. None of the strains tested produced unsubstituted short-chain acyl homoserine lactones. Our results showed that tested Plesiomonas shigelloides strains produced multiple potential virulence factors that may play a role in the pathogenesis of infections caused by this agent.

Animals↗
PubMed2004

[Type III bacterial secretion systems and their relation to virulence].

Newer data on type III secretion systems (SST systems) associated with virulence in gramnegative bacteria are summarized. The focus is on substrates of SST systems (effector proteins), recognition of type III secretion signals, structural components of SST systems and their genetic determination.

Bacterial Proteins↗
PubMed2004

[The role of iron in bacterial virulence].

Data on the role of iron in host-bacterium interaction in relation to virulence are summarized. Attention is focused on host iron acquisition pathways in bacteria. Host iron can be acquired by several mechanisms, e.g. from hemoglobin degradation products such as heme and hemin, directly from ferrated transferrin and lactoferrin, indirectly from iron binding proteins by the production of siderophores and from intracellular iron stores (ferritin). Regulation of iron uptake is discussed.

Bacteria↗
PubMed2003

Some properties of Plesiomonas shigelloides treated with aminoglycosides.

The effect of aminoglycoside antibiotics (amikacin, gentamicin, netilmicin and tobramycin) at sublethal concentrations (sub-MICs) on some properties of Plesiomonas shigelloides strains was evaluated. All agents decreased the bacterial surface hydrophobicity. Amikacin (1/4 of the MIC) and netilmicin (1/4 and 1/8 of the MIC) changed the hydrophobic character of P. shigelloides surface to a hydrophilic one. Treatment of the strains with aminoglycosides decreased also motility, netilmicin being the most effective. No significant changes were found in lipolytic activity of antibiotic-treated strains. In the majority of cases aminoglycosides increased sensitivity of bacteria to hydrogen peroxide. The tested antibiotics did not induce production of short-chained N-acylhomoserine lactones signal molecules. Aminoglycosides at sub-MICs affected important activities of P. shigelloides potentially associated with their virulence in dependence on strain, antibiotic and concentration.

Amikacin↗
PubMed2003

[Characteristics of strains of Acinetobacter spp. after culture in various media].

Growth, surface properties, production of lipase, histamine and some signal molecules (N-acyl-homoserine lactones, AHLs) in four Acinetobacter baumannii strains, in one Acinetobacter lwoffii and in one Acinetobacter haemolyticus strain cultivated in three complex media were studied. More intensive growth of bacterial suspensions was observed in Mueller-Hinton broth and in brain heart infusion in comparison with growth in proteose peptone. Greater growth of bacterial strains (with the exception of A. haemolyticus) in these two media was associated with more significant surface hydrophobicity of bacteria manifested by their adherence to xylene. A higher level of lipase was found in all strains (with the exception of A. haemolyticus) after cultivation in Mueller-Hinton broth. Composition of culture medium did not affect production of histamine. None of the studied strains in any medium tested produced short-chained unsubstituted AHLs that can be ones of the signal molecules shared with cell-to-cell communication.

Acinetobacter↗
PubMed2003

[Effect of tobramycin on characteristics of strains of Acinetobacter species].

Suppression of bacterial growth in seven strains of the Acinetobacter species after 30 min treatment with tobramycin at suprainhibitory concentrations (postantibiotic effect--PAE) and at supra-sub-inhibitory concentrations (postantibiotic effect of subinhibitory concentrations--PA SME) as well as changes in surface hydrophobicity and in the production of lipase and histamine in the exposed strains were studied. Pharmacodynamic parameters (PAE and PA SME) as well as changes in bacterial characteristics tested were dependent on antibiotic concentration and on the strain used. Suppression of bacterial growth after treatment with tobramycin at 2 x MIC was in a range of 0.6-4.5 h, a higher concentration (4 x MIC) induced a longer PAE (1.9-5.4 h). Tobramycin at supra-subinhibitory concentrations (2 x MIC + 0.2 x MIC and 4 x MIC + 0.2 x MIC) caused total suppression of bacterial growth. In the majority of the tobramycin-treated strains, an increase in hydrophobicity manifested by adherence of bacteria to xylene as well as an increase in lipolytic activity was observed. Tobramycin at the concentrations tested did not affect the production of histamine.

Acinetobacter↗
PubMed2003

Influence of growth media on potential virulence factors of Pseudomonas aeruginosa.

Potential virulence factors of three Pseudomonas aeruginosa strains after growth in three complex media (CM) and in one mineral medium (MM) were evaluated. Cell surface hydrophobicity demonstrated by adherence of bacteria to xylene as well as enzymatic activity (elastase, protease, lipase) of the strains grown in CM varied with composition of CM and with strain. All strains cultivated in CM showed higher hydrophobicity and higher elastase, protease and lipase (with the exception of one strain) activity in comparison with bacteria incubated in MM. Even no production of elastase was detected in the strains after growth in MM. Motility of bacteria was affected by culture media the least. In vitro composition of growth media influenced some potential virulence factors of P. aeruginosa.

Bacteriological Techniques↗
PubMed2002

Toxinogenicity and markers of pathogenicity of Pseudomonas aeruginosa strains isolated from patients with tumor diseases.

Potential virulence factors (elastase, proteinase, lipase, phospholipase C, alginate) as well as surface properties (hydrophobicity, motility) were determined in 103 Pseudomonas aeruginosa strains isolated from patients with cancer. Nontypable strains were the dominant group (60%), followed by serotypes O11 (17%), O12 (7%) and O4 (5%). Seventy-one strains (69%) produced high level of elastase (10-60 mg/L), 87% of the strains possessed high activity of proteinase (bacterial) (10-250 mg/L) and 69% of the strains demonstrated higher level of lipase (20-150 U/mL); these elevated levels of enzymes were associated mainly with nontypable strains. On the other hand, 79% of the strains did not produce or produced only a low level of phospholipase C and 60% of isolates did not manifest any or very low production of alginate. Hydrophobicity demonstrated by adherence of the bacteria to xylene was shown by 69% of strains; 94% of strains aggregated with ammonium sulfate. Motility in the range of 31-80 mm was found in 76 strains (74%). The considerable virulence of tested P. aeruginosa strains was confirmed. The nontypable strains manifested the most frequent group with high level of elastase, proteinase, lipase, hydrophobicity and motility.

Alginates↗
PubMed2002

Characteristics of clinical Acinetobacter spp. strains.

Resistance to 13 antimicrobial agents, resistance to the bactericidal activity of human serum, hydrophobic properties, lipolytic activity and production of histamine were determined in a total of 50 clinical Acinetobacter spp. strains (A. baumannii, A. lwoffii, A. calcoaceticus, A. haemolyticus). None of the tested isolates showed resistance to meropenem and none of A. lwoffii, A. calcoaceticus and A. haemolyticus strains were resistant to amikacin. Forty-six strains (92%) manifested resistance to ampicillin, 90% to cefuroxime, 68% to ciprofloxacin, 58% to piperacillin, gentamicin and cotrimaxazole, 50% to cefotaxime, 44% to amikacin, 42% to ceftazidime, 38% to piperacillin/tazobactam, 24% to netilmicin and 16% to ampicillin/sulbactam. In particular, A. baumannii and A. calcoaceticus strains showed considerable antibiotic resistance. Thirty-one isolates (62%) showed serum resistance; intermediate sensitivity was found in 19 isolates (38%). The majority of the strains (72%) demonstrated a strongly hydrophobic character; 16% of isolates exhibited moderate hydrophobic properties. All strains showed lipolytic activity; production of histamine was detected in 14 of 43 strains examined.

Acinetobacter↗
PubMed2002

[Effect of culture media on surface and enzymatic activity in Klebsiella species].

The effect of three complex media (KM) [Mueller-Hinton broth (MHB), brain heart infusion (MSI) and proteose peptone (PP)] and one mineral medium (MM) on surface and enzyme activities of five strains Klebsiella species was studied. Klebsiella oxytoca and Klebsiella ornithinolytica had a marked hydrophobic character after growth in MHB, MSI and MM, Klebsiella terrigena only in PP. K. oxytoca and K. ornithinolytica had a higher motility after cultivation in KM compared with MM, the motility of K. terrigena was not affected. The lipolytic activity of all tested strains was highest after growth in MSI and PP. The composition of culture medium affected bacterial parameters tested to a different extent depending on the species.

Bacterial Adhesion↗
PubMed2001

Antibiotic susceptibility, serum response and surface properties of Klebsiella species.

Altogether 130 clinical isolates of five Klebsiella species (K. pneumoniae, K. planticola, K. oxytoca, K. ornithinolytica and K. terrigena) were characterized, for their susceptibility to five antibiotics, for susceptibility to serum bactericidal activity and for their hydrophobic properties. All strains exhibited ampicillin resistance. Ampicillin/sulbactam, gentamicin and ofloxacin showed effectiveness in 63.1, 67.7 and 71.5% of the Klebsiella isolates. K. planticola manifested the highest level of resistance to these antibiotics. The majority of Klebsiella strains (93.9%) were susceptible to cefuroxime. Sixty-four strains (49.2%) were serum resistant and intermediate serum sensitivity was shown by 57 strains (43.8%). A high percentage of serum resistant strains (65%) was found in K. planticola. Moderately hydrophobic properties determined by adherence of bacteria to xylene were demonstrated in 25 strains (19.2%).

Ampicillin↗
PubMed2001

In vitro effect of ampicillin/sulbactam on Acinetobacter species.

The effects of subinhibitory concentrations (sub-MIC) of ampicillin/sulbactam (AMP/sulbactam), on the surface hydrophobicity and the lipase activity of ten Acinetobacter strains, were examined. The alterations in the activities studied were strain and drug concentration dependent. Most of the strains treated showed a decrease in surface hydrophobicity to a different extent. The hydrophobic character of three strains exposed to 1/4 or 1/8 of the MIC of the antibiotic was changed to a hydrophilic state. The majority of Acinetobacter strains after treatment with antibiotic possessed increased lipolytic activity. AMP/sulbactam even at sub-MIC may interfere with possible virulence factors of Acinetobacter strains in vitro.

Acinetobacter↗
PubMed2000

The in vitro effect of imipenem and ofloxacin on enzymic activity of Klebsiella strains.

Fifty seven Klebsiella strains, viz. K. pneumoniae (28), K. planticola (19), K. oxytoca (6), K. ornithinolytica (3) and K. terrigena (1) possessed lipolytic and urealytic activity. The effect of imipenem and ofloxacin at subinhibitory concentrations (sub-MICs) on these enzymic activities of 4 strains was studied. At all the concentrations tested (mainly at 1/4 of the MICs) imipenem enhanced lipase activity manifested by cleavage of the substrate Tween 20. The effect of ofloxacin was strain- and concentration-dependent but in most cases lipolytic activity was also increased. The antibiotics practically did not affect the urease activity of the strains.

Anti-Infective Agents↗
PubMed2000

Lipase activity of Acinetobacter baumannii after treatment with meropenem.

The effects of meropenem (CAS 96036-03-2) at subinhibitory concentrations (sub-MICs; 1/4, 1/8 or 1/16 of the minimal inhibitory concentrations) on the lipase activity of 15 strains of Acinetobacter baumannii were evaluated in vitro. The lipolytic activity was demonstrated by hydrolysis of the substrate Tween 20. Meropenem at the concentrations tested affected the production of bacterial lipase. The degree of induced changes was strain and antibiotic concentration dependent. Eight strains showed an increased lipolytic activity after treatment with meropenem at all three sub-MICs tested; four strains after exposure to two concentrations, and two strains after the treatment with meropenem at one of the concentrations tested. Meropenem at all concentrations reduced the lipase activity only in one strain. In six strains the enzyme activity was decreased only after treatment with some antibiotic concentrations. The possible relevance of increased lipolytic activity in most A. baumannii strains after the effect with meropenem at subinhibitory concentrations has to be clarified by additional studies.

Acinetobacter↗
PubMed2000

Effect of aminoglycosides on surface hydrophobicity of Acinetobacter baumannii.

Effects of amikacin, gentamicin, netilmicin and tobramycin at subinhibitory concentrations (sub-MICs) (11/4, 1/8, 1/16 or 1/32 of their MICs) on the cell surface hydrophobicity of two Acinetobacter baumannii strains (7194 and 16265) were evaluated. Hydrophobicity was determined by two different methods - by adherence of bacteria to hydrocarbon (xylene) and by aggregation of bacteria in ammonium sulphate solutions at various concentrations. The adherence of A. baumannii strains to xylene decreased, mainly, after treatment with netilmicin at 1/4, 1/8 or 1/16 of the MIC (to 6.4%, 17.0% or 24.5% of the control value) (strain 7194) and after treatment with amikacin and gentamicin at 1/4 of their MICs (to 58.4% or 54.4%) (strain 16265). A decrease in surface hydrophobicity of exposed strains under these conditions was shown in salting-out test, too. Tobramycin reduced hydrophobic properties of A. baumannii strains at all tested sub-MICs to only a small extent.

Acinetobacter↗