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PubMed1999

[In vitro effect of quinolones on the hydrophobicity of Acinetobacter baumannii].

Effects of subinhibitory concentrations (sub-MICs) (1/4, 1/8, 1/16 or 1/32 of the MICs) of four quinolone 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 aggregation in ammonium sulphate solutions. Norfloxacin in concentrations of 1/4 or 1/8 of the MIC decreased hydrophobicity of R1 strain and of R2 strain in concentration of 1/16 of the MIC. Ciprofloxacin was efficient for both strains mainly in concentration of 1/4 of their MICs. Enoxacin (1/8 MIC) more effectively reduced hydrophobic properties only in R2 strain. The other concentrations of the above-mentioned antibiotics as well as all tested concentrations of pefloxacin practically did not affect bacterial surface hydrophobicity.

Acinetobacter↗
PubMed2000

[Emphysematous pyelonephritis in lithiasic kidney caused by acinetobacter].

Emphysematous pyelonephritis is rare. It is exceptionally associated with urolithiasis with obstruction of the collecting system. It is generally observed in female diabetic patients. It is caused by gas-producing bacteria. We report a case in which emphysematous pyelonephritis was caused by an acinetobacter, associated with pelvic ureteral junction lithiasis. Drainage and nephrectomy were necessary to overcome this life threatening situation.

Acinetobacter Infections↗
PubMed2000

Effect of meropenem on the vascular permeability factor produced by Acinetobacter baumannii.

Eleven Acinetobacter baumannii strains produced a toxic substance--the vascular permeability factor--in the culture medium. Intradermal injection of this substance enhanced vascular permeability in the rabbit skin. The extent of permeability reactions varied from 0.28 cm2 to 1.61 cm2. Changes in the permeability factor activity of four A. baumannii strains after treatment with meropenem (CAS 96036-03-2) at suprainhibitory concentrations (2x, 4x or 8x) minimum inhibitory concentration (MIC) or supra-subinhibitory ones (2-8x MIC + 0.2x MIC) were tested in vitro. Meropenem at all suprainhibitory concentrations (with the exception of 8x MIC for one strain) was almost ineffective. Alterations in this activity were in the range of 93% to 106% of the control values. Supra-subinhibitory concentrations of meropenem significantly increased the permeability factor activity (to 150%-176% of the control values). These findings indicate that meropenem mainly at supra-subinhibitory concentrations can in vitro interfere with the vascular permeability factor produced by A. baumannii.

Acinetobacter↗
PubMed1975

Effect of Acinetobacter glutaminase-asparaginase treatment on free amino acids in mouse tissues.

Acinetobacter glutaminase-asparaginase (AGA) and Escherichia coli asparaginase were compared for their effects on plasma and tissue levels of amino acids, ammonia, and glutamyl transferase activity in the mouse. Free asparagine was depleted similarly in plasma and tissues by both enzymes. AGA treatment produced partial depletion of glutamine concentrations in muscle, spleen, small intestine, and liver. Brain and kidney glutamine concentrations actually rose with treatment. Despite over 100-fold increase in plasma glutamate, only the kidney showed a substantial increase in free glutamate levels during AGA treatment. Glutamine biosynthesis measured by glutamyl transferase activity showed an appreciable increase only in the kidney. Ammonia levels in tissues and plasma rose 1.3- to 4.3-fold. In general, E. coli asparaginase treatment had much less effect on these measurements than did AGA. The changes in these levels are discussed in relation to sites of possible toxicity and antitumor effects.

Acetyltransferases↗
PubMed2000

[Pharmacodynamic parameters of gentamicin and its effect on the surface hydrophobicity of Acinetobacter baumannii].

The postantibiotic effect (PAE) and postantibiotic effect of subinhibitory concentration (PA SME) of gentamicin as well as influence of these pharmacodynamic parameters on surface hydrophobicity of 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 concentration 2x MIC was in the range of 0.6 h to 3.4 h. Longer PAE was observed after treatment of bacteria with gentamicin at 4x MIC (1.5 h-5.1 h). Supra-subinhibitory concentrations of gentamicin (2x or 4x MIC + 0.2x MIC) caused still more effective delay of bacterial regrowth (PA SME) in comparison with suprainhibitory concentrations for one strain (9.1 h and 9.6 h) and in the case of further two strains they were so efficient that regrowth of bacteria was not observed for 24 h. Surface hydrophobicity of the gentamicin treated strains evaluated by adherence of bacteria to xylene ranged from 90.0% to 99.7% of the control values (without antibiotic).

Acinetobacter↗
PubMed2000

Influence of some antibiotics on lipase and hydrophobicity of Acinetobacter baumannii.

Effect of four antibiotics (cefotaxime, ceftazidime, cefepime and ofloxacin) at subinhibitory concentrations (sub-MICs) (1/4, 1/8 or 1/16 of the MICs) on lipase and cell surface hydrophobicity of a clinical isolate of Acinetobacter baumannii 16265 was studied. Lipase activity in the majority of the cases was not significantly changed. Small alterations were drug and concentration dependent. The most efficient ceftazidime at 1/4 of the MIC reduced lipolytic activity to 78.7% of the control value. On the other hand, all beta-lactam antibiotics mainly at the highest concentration (1/4 of the MICs) most effectively decreased surface hydrophobicity of the studied strain. Hydrophobicity of treated bacteria evaluated by their adherence to xylene was in the range of 11.2 to 29.9% of the control values. The most efficient was cefepime. Whether the modifications in potential virulence factors of the bacteria tested observed in in-vitro experiments would have the clinical importance, remains to be evaluated.

Acinetobacter↗
PubMedDate not supplied

[Respiratory activity of bacteria Acinetobacter calcoaceticus TM-31 during assimilation of alkane hydrocarbons].

The respiratory activity of Acinetobacter calcoaceticus TM-31 with resect to alkane hydrocarbons was studied. The dynamics of oxygen consumption by the cells while assimilating n-hexadecane was assayed by a modified technique using an oxygen electrode. The dependence of cell respiratory activity on the amount of n-hexadecane within the concentration range of 0.03-0.66% was determined. It was demonstrated that the cells also displayed respiratory activity towards other medium-chain n-alkanes: hexane, octane, decane, tridecane, and heptadecane. Thus, we demonstrated the possibility of determining alkanes by measuring the respiratory activities of microorganisms.

Acinetobacter calcoaceticus↗
PubMed2000

[Presence of integrons and their relationships with the resistance to third generation cephalosporins among nosocomial isolates of Acinetobacter baumannii].

BACKGROUND: Acinetobacter baumannii is an important etiological agent causing nosocomial infections. High level of resistance for different kind of antimicrobials has been observed, including beta-lactam antibiotics. This feature, chromosomal or plasmid encoded, has been associated to integrons harbouring antibiotic resistance gene cassettes. AIMS: To investigate the presence of integrons among clinical isolates resistant to third generation cephalosporins (3GC). MATERIAL AND METHODS: One hundred A. baumannii strains isolated from several Chilean hospitals were included in this study. Minimal inhibitory concentrations (MIC) of 3GC by an agar dilution method were carried out. Integrons class 1, 2 and 3 were investigated by colony blot hybridisation and confirmed by PCR. RESULTS: High level of resistance to all assayed 3GC was observed. On the other hand, integrón class 2 was the most prevalent (77% of isolates) followed by integron class 1 (52%). Forty six percent of isolates hybridised with probes for both of them. However, no positive hybridisation was detected for integron class 3. CONCLUSIONS: Nevertheless, most isolates harboured one or both class of integron; there was no direct relationship between the presence of these genetic structures and the resistance to this kind of beta-lactam antibiotics.

Acinetobacter↗
PubMedDate not supplied

[Ecological aspects and prophylaxis of Acinetobacter baumannii nosocomial infection].

Acinetobacter Baumannii is an aerobic strit gram negative bacteria cause of epidemic infection in intensive care units this bacteria is isolated from the patient and its environment. The detection of AB infection require the isolation of patients and decontamination of the material despite the virulence of the germ, these measures are necessary due to the rapid extension of epidemic in the absence of adequate means.

Acinetobacter Infections↗
PubMed1975

Biologic and physical properties of succinylated and glycosylated Acinetobacter glutaminase-asparaginase.

Acinetobacter glutaminase-asparaginase was chemically modified by succinylation and glycosylation with glycopeptides from human fibrin and gamma-globulin. These modifications markedly prolonged the half-lives of the enzyme in mice, rats, and rabbits. The plasma half-life in mice increased with decreasing isoelectric point. Glycosylation caused greater prolongation in rodents than succinylation. The kinetic properties of the modified enzymes were unchanged. Succinylation protected the enzyme from trypsin digestion. Glycosylated preparations had less heat inactivation than native and succinylated enzyme. Sedimentation equilibrium studies on a succinylated preparation showed reversible dissociation to a dimer (71, 400 g/mol) with an association constant of 1.3 times 10-6 liters/mol. This dissociation was identical with native enzyme, except for a 3% increase in molecular weight due to succinate groups. Sedimentation equilibrium studies on glycosylated preparations showed mixtures of molecular weight from 60, 000 to over 180, 000. Gel filtration and active enzyme sedimentation showed active polymers, but no active species smaller than tetramer.

Acinetobacter↗
PubMed2001

Effects of low temperature, cold shock, and various carbon sources on esterase and lipase activities and exopolysaccharide production by a psychrotrophic Acinetobacter sp.

The activities of isocitrate lyase, esterase, and lipase by the psychrotrophic Acinetobacter sp. strain HH1-1 were monitored during incubation at 25 degreesC, 5 degreesC, and after a 25 degreesC to 5 degreesC down shift in growth temperature. During growth at 25 degreesC, isocitrate lyase activity was detected in cell-free extracts, but at 5 degreesC and after cold shock, activity was measured primarily in the cell culture supernatant. Strain HH1-1 produced two cell-associated esterases and an extracellular esterase and lipase. Activities of the extracellular esterase and lipase were reduced when cells were grown at 5 degreesC and after cold shock. In contrast, an increased synthesis of a 53-kDa cell-associated esterase was observed 50 h after cold shock. An extracellular polysaccharide was also produced, indicated by a decrease in surface tension in cell culture supernatant when cells were incubated at 25 degreesC; but like extracellular enzyme activity, production of the exopolymer was reduced when cells were subjected to low temperatures. These results indicated that the intracellular enzyme, isocitrate lyase, leaked out of the cell after cold shock and during growth at 5 degreesC. The increased activity of a cell-associated esterase suggested this enzyme is required for growth at low temperatures. In contrast, activities of extracellular lipolytic enzymes and production of an extracellular polysaccharide were negatively affected at the lower temperatures.

Acinetobacter↗
PubMed2001

A new extraction method for Acinetobacter species ODB-L2 rough form lipopolysaccharide from culture broth.

The Gram-negative bacterium Acinetobacter species ODB-L2 produces lipopolysaccharide (LPS) in culture broth. The LPS could not be purified by conventional extraction methods using 90% phenol/water or 90% phenol/chloroform/petroleum ether mixed solvent. Extraction was achieved employing an admixture of chloroform, ethanol, and 4 M HCI solution. The LPS was purified from dissolving the crude extracts in 90% phenol and LPS sediment formed by addition of methanol. The LPS was characterized by chemical, biochemical, and physicochemical methods as rough form 3-hydroxydodecanoic acid rich LPS.

Acinetobacter↗
PubMedDate not supplied

[Degradation of mineral oil by Acinetobacter calcoaceticus strain].

The Acinetobacter calcoaceticus strain TM-31 has been isolated from a microbial assemblage of a pilot plant purifying waste water polluted with mineral oil. This strain is capable of efficient degradation of components of mineral oil (alkanes, isoalkanes, and alkyl residues of the naphthene and arene fraction. The strain bears stably inherited plasmids of sizes 120, 9, and 8 kb, which can be transferred into plasmid-free cells of the parental strain and into bacteria of the genus Pseudomonas and ensure the degradation of hexadecane and mineral oil.

Acinetobacter calcoaceticus↗
PubMed2001

[Community-acquired empyema caused by Acinetobacter baumannii].

We referred a fourty-four years old male, without interesting personal history and who was accepted in the hospital due to dyspnea and fever and who was diagnosed with empyema by Acinetobacter baumannii acquired in the community; we have found no references about this in the medical literature.

Acinetobacter Infections↗
PubMedDate not supplied

[Intracellular accumulation of monomer precursors of polyphosphates and polyhydroxyalkanoates from Acinetobacter calcoaceticus and Escherichia coli].

The formation of polyhydroxyalkanoates granules in anaerobically grown Escherichia coli cells was found to be preceded by the intracellular accumulation of carbonic acids (predominantly, acetic acid), amounting to 9% of the cytosol. The intracellular concentration of acidic metabolites increased after the lyophilization of the bacterial biomass and decreased after its long-term storage (3.5-13.5 years). The decrease in the concentration of acidic metabolites is likely due to the dehydration of dimeric carbonic acids in the viscoelastic cytosol of resting bacterial cells. The hydrophobic obligately aerobic cells of Acinetobacter calcoaceticus IEGM 549 are able to utilize a wide range of growth substrates (from acetate and citrate to hydrophobic hydrocarbons), which is considerably wider than the range of the growth substrates of E. coli (predominantly, carbohydrates). The minimal essential and optimal concentrations of orthophosphates in the growth medium of A. calcoaceticus were found to be tens of times lower than in the case of E. coli. The intracellular content of orthophosphates in A. calcoaceticus cells reached 35-77% of the total phosphorus content (Ptotal), providing for the intense synthesis of polyphosphates. The Ptotal of the A. calcoaceticus cells grown in media with different proportions between the concentrations of acetate and phosphorus varied from 0.7 to 3.3%, averaging 2%. This value of Ptotal is about two times higher than that observed for fermenting E. coli cells. Lowering the cultivation temperature of A. calcoaceticus from 37-32 to 4 degrees C augmented the accumulation of orthophosphates in the cytoplasm, presumably owing to a decreased requirement of growth processes for orthophosphate. In this case, if the concentration of phosphates in the cultivation medium was low, they were completely depleted.

Acinetobacter calcoaceticus↗
PubMed1975

[Inhibiton of isocitrate dehydrogenase and isocitrate lyase from Acinetobacter calcoaceticus by acids of the citrate and glyoxylate cycle].

Acinetobacter calcoaceticus contains two forms of NADP+-dependent isocitrate dehydrogenases differing, among others, by their molecular weights and regulatory properties. The regulation of the high-molecular form of isocitrate dehydrogenase and of isocitrate lyase by organic acids, either belonging or related to the citrate and glyoxalate cycle, is investigated. While alpha-ketoglutarate and oxalacetate competitively inhibit the isocitrate dehydrogenase against Ds-isocitrate, glyoxylate and pyruvate were found to increase Vmax and to lower the KM value for Ds-isocitrate and NADP+. Simultaneous addition of oxalacetate and glyoxylate (not, however, addition of the nonenzymatically formed condensation product of both compound) nullified the activation of isocitrate dehydrogenase by glyoxylate, and potentiates the inhibitory effect of oxalacetate. Alpha-ketoglutarate, succinate, and phosphoenolpyruvate inhibit the isocitrate lyase in a noncompetitive fashion against DS-isocitrate; L-malate, oxalacetate and glyoxylate inhibit competitively. The intermediates of the citrate and glyoxylate cycle afford additive inhibition of the isocitrate lyase. The importance of organic acids of the citrate and glyoxylate cycle and of phosphoenolpyruvate for the regulation of the citrate and glyoxylate cycle at the level of isocitrate dehydrogenase and isocitrate lyase is discussed.

Acinetobacter↗
PubMedDate not supplied

[Structure of an acylated exopolysaccharide synthesized by Acinetobacter sp].

The complex preparation ethapolan synthesized by Acinetobacter sp. consists of neutral (minor component) and two acidic exopolysaccharides (EPS) one of which is acylated. On the basis of chemical modification of EPS, solvolysis with anhydrous hydrogen fluoride resulting in a penta- and octasaccharide fragments, Smith degradation, 1H- and 13C NMR analysis the following structure of the acylated polysaccharide repeating unit has been established (scheme): It is suggested that in the acylated EPS at least one glucose residue and the galactose residue are O-acylated.

Acinetobacter↗
PubMedDate not supplied

[Effect on growing conditions on protein content and amino acid composition of acinetobacter calcoaticus].

The protein content and amino acid composition of Acinetobacter calcoaceticus were studied as dependent on the stages of development and different hydrocarbon sources. The protein content was always the greatest at the logarithmic stage and decreased approaching the stationary stage. When cultivating on different hyrocarbon sources only an insignificant differedce in the content of protein was observed. A relative amino acid composition of Ac. calcoaceticus remained practically constant during the growth up to the stationary stage. When using different sources of hydrocarbon no changes were found in the relative composition of amino acids as well as in the total content of protein.

Acinetobacter↗