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Biomedical subjects

A Pascual

Publications and source records attributed to A Pascual.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Effect of five fluoroquinolones on the bactericidal activity of human polymorphonuclear leukocytes against Staphylococcus aureus].

It has been evaluated the effect of norfloxacin, ofloxacin, levofloxacin, fleroxacin and lomefloxacin of the respiratory burst of human polymorphonuclear leukocytes and their intracellular activity against Staphylococcus aureus. None of these agents significantly affected the superoxide and hydrogen peroxide radicals production by the polymorphonuclear leukocytes. All the quinolones except norfloxacin showed significant intracellular activity against S. aureus.

Anti-Infective Agents↗
PubMed1995

Factors affecting the intracellular accumulation and activity of azithromycin.

Azithromycin is a new macrolide which accumulates in high concentrations in human phagocytes. The cellular to extracellular ratio (C/E) of azithromycin concentrations (fixed extracellular concentration 1 mg/L) in human polymorphonuclear leucocytes (PMN) were significantly affected by small increases in the environmental temperature (C/E 20.3 +/- 2 and 59.4 +/- 6 at 37 degrees C and 40 degrees C, respectively). PMN-associated azithromycin was not affected by the presence of different concentrations of human serum. The intracellular accumulation of azithromycin decreased slightly (C/E approximately 5) when cells were activated with PMA or opsonized with zymosan. The phagocytosis of opsonized Staphylococcus aureus or Haemophilus influenzae, however, slightly increased the intracellular concentrations of azithromycin. At different extracellular concentrations, azithromycin did not affect the production of hydrogen peroxide and superoxide radicals by PMN. The intracellular survival of H. influenzae in human PMN was abolished in the presence of concentrations higher than 0.125 mg/L of azithromycin. Under the same experimental conditions, however, azithromycin did not show any intracellular activity against S. aureus.

Azithromycin↗
PubMed1995

Activity of sparfloxacin on Staphylococcus epidermidis attached to plastic catheters.

The activity of sparfloxacin on Staphylococcus epidermidis biofilms on different plastic catheters was evaluated. Sparfloxacin showed high bactericidal activity against S. epidermidis biofilms on Vialon and polyvinylchloride catheters. The combination of sparfloxacin with amikacin or rifampicin significantly increased its activity against bacterial biofilms on polyurethane and Teflon catheters.

Amikacin↗
PubMed1995

[False sensitivity of Enterococcus faecium to amoxicillin-clavulanic acid with the MicroScan system].

BACKGROUND: We have observed by using MicroScan automatic system discrepancies in susceptibility results of Enterococcus faecium strains to ampicillin and amoxicillin/clavulanic acid. METHODS AND RESULTS: Seventy-six strains of E. faecium were studied with MicroScan; 98.7% of them were inhibited by 16 mg/l of amoxycillin-clavulanic acid versus 60.5% inhibited by the same concentration of ampicillin. We have evaluated the susceptibility to ampicillin, amoxicillin and amoxicillin-clavulanic acid of 7 strains of E. faecium by both MicroScan and standard microdilution assay. MIC values of ampicillin were similar by both methods but MIC values of amoxicillin/clavulanic acid obtained by MicroScan (< or = 4/2 mg/l in 6 strains) were considerably lower than those obtained by standard microdilution (> or = 16/8 in 6 strains). This phenomenon was not dependent of betalactamase production or bacterial inocula. CONCLUSIONS: When using MicroScan, E. faecium strains resistant to ampicillin (betalactamase non producers) must be also considered resistant to amoxicillin/clavulanic acid without considering the values obtained by this system.

Amoxicillin↗
PubMed1995

[Antimicrobial activity in Staphylococcus epidermidis biofilms on polyvinyl chloride catheters].

OBJECTIVES: We have evaluated the effect of polyvinylchloride (PVC) catheters on the activity of eight antimicrobials. Secondly the activity of these antimicrobials against Staphylococcus epidermidis biofilms on PVC catheters was also studied. METHOD: The MIC and MBC values of amikacine, clindamycine, cloxacilline, ciprofloxacine, vancomycine, teicoplanine, daptomycine and rifampicine was evaluated by a microdilution assay in the presence of 0.5 cm length segments of PVC catheters. Catheter segments with bacteria attached for different periods of time were used as inocula for the studies of antimicrobial activity against bacterial biofilms. Both slime producing and non-producing strains were evaluated. RESULTS: The presence of PVC did not affect the activity of the antimicrobials evaluated against S. epidermidis. For the non-slime producing strains MBC values against sessile bacteria were significantly higher than those against planktonic bacteria. For the slime-producing strain MBCs of ciprofloxacine, amikacine and teicoplanine against both bacterial populations were similar. At high concentrations (16 x MBC), clindamycine was the only antimicrobial that sterilized non-slime producing S. epidermidis biofilms on PVC. Against the slime producing strains ciprofloxacine yielded the highest reduction on bacterial viability (99.9%). CONCLUSIONS: S. epidermidis biofilms on PVC were more resistant to antimicrobials than planktonic bacteria. Slime production is not the only factor involved in this phenomenon.

Anti-Bacterial Agents↗
PubMed1994

Sequence and structure of the RNA subunit of RNase P from the cyanobacterium Pseudoanabaena sp. PCC6903.

The catalytic RNA subunit of ribonuclease P (RNase P) from the cyanobacterium Pseudoanabaena sp. PCC6903 has been cloned and sequenced. The RNA has a primary and secondary structure with overall similarity to other cyanobacterial RNase P RNAs characterized so far but contains some peculiarities of its own. A consensus promoter sequence can be identified at the 5' end of the gene.

Base Sequence↗
PubMed1994

Radical surgery of thalamic tumors in children.

The authors review eight cases of thalamic tumors in children. Radical surgery was performed in seven cases. All cases were diagnosed by computed tomographic scanning, and histological diagnosis showed seven benign astrocytomas and one malignant astrocytoma. All patients are still alive. The treatment of these tumors is discussed.

Astrocytoma↗
PubMed1994

Activity of glycopeptides in combination with amikacin or rifampin against Staphylococcus epidermidis biofilms on plastic catheters.

The in vitro activity of vancomycin and teicoplanin (fourfold the MBC), alone and in combination with amikacin (16 mg/l) or rifampin (1 mg/l), against Staphylococcus epidermidis (slime-producing and non slime-producing strains) biofilms on different plastic catheters was evaluated. The addition of amikacin or rifampin significantly increased the activity of glycopeptides against sessile bacteria. With the slime-producing strain, these combinations were able to sterilize the surface of Vialon and polyvinylchloride catheters. It is concluded that the in vitro activity of glycopeptides against Staphylococcus epidermidis biofilms on plastic catheters can be increased by the addition of amikacin or rifampin.

Amikacin↗
PubMed1994

Activity of eight antibacterial agents on Staphylococcus epidermidis attached to Teflon catheters.

The presence of a Teflon catheter had no effect on the in-vitro activity of a range of antibacterial agents against slime producing and non-producing Staphylococcus epidermidis strains as determined by a microdilution assay. The susceptibility of S. epidermidis attached to Teflon catheters for 6, 24 and 48 h was also evaluated. MICs for planktonic and attached bacteria were similar. When bacteria attached to Teflon for 6 h were used as inocula, MBC values increased 32-8192-fold for the antibacterial agents tested. Similar results were observed when bacteria attached for 24 and 48 h were used as inocula. The activity of a high concentration (16 x MBC) of these antimicrobial agents against S. epidermidis biofilms in Teflon catheters was evaluated; for five slime non-producing strains, the highest reduction (around 99%) in bacterial viability was produced by cloxacillin and teicoplanin; for the slime producers, the highest effect (99.5% reduction) was shown by amikacin, clindamycin cloxacillin and ciprofloxacin but all cases still showed bacterial counts higher than 10(3) cfu/catheter segment. It is concluded that adherence of S. epidermidis to Teflon catheters decreases the bactericidal activity of the antibacterial agents tested in vitro.

Anti-Bacterial Agents↗
PubMed1994

Intracellular penetration and activity of BAY Y 3118 in human polymorphonuclear leukocytes.

The penetration of a new quinolone (BAY Y 3118) into human polymorphonuclear leukocytes (PMNs) was evaluated by a fluorometric assay. The cellular concentration-to-extracellular concentration (C/E) ratio was higher than 6.3 at extracellular concentrations ranging from 2 to 100 mg/liter. The uptake of BAY Y 3118 was rapid, reversible and nonsaturable. The intracellular penetration of BAY Y 3118 was significantly affected by environmental temperature (C/E ratio at 4 degrees C, 5.4 +/- 0.5; control, 7.5 +/- 0.9; P < 0.05) and cell viability (C/E ratio in dead PMNs, 5.5 +/- 0.8; control 7.5 +/- 0.9; P < 0.05), but it was not affected by metabolic inhibitors. The ingestion of opsonized zymosan or opsonized Staphylococcus aureus significantly decreased the levels of PMN-associated BAY Y 3118. Cell stimulation by a membrane activator, however, significantly increased the intracellular concentration of this quinolone. At therapeutic extracellular concentrations (0.5, 2, and 5 mg/liter), BAY Y 3118 showed intracellular activity greater than that of ciprofloxacin against S. aureus in human PMNs. It was concluded that BAY Y 3118 reaches high intracellular concentrations within human PMNs and remains active intracellularly.

Anti-Infective Agents↗
PubMed1993

Effect of antimicrobial and antineoplastic drugs on the uptake of fluconazole by human neutrophils and tissue culture cells.

The effect of eight antimicrobial and three antineoplastic drugs on the uptake of fluconazole by human neutrophils and culture epithelial cells was evaluated. Fluconazole reached higher concentrations intracellularly than extracellularly (cellular to extracellular concentration ratio C/E > or = 1.3) in the presence of therapeutical concentrations of the antimicrobial and antineoplastic agents evaluated.

Anti-Infective Agents↗
PubMed1993

Susceptibility to antimicrobial agents of Pseudomonas aeruginosa attached to siliconized latex urinary catheters.

The effect of siliconized latex urinary catheters on the in vitro activity of amikacin, ceftazidime, ciprofloxacin, norfloxacin and meropenem against Pseudomonas aeruginosa was determined by a microdilution assay. MICs of amikacin and meropenem increased at least 4-fold and 16-fold respectively in the presence of catheter material. The effect of catheter material on meropenem activity was not strain dependent and was similar for different brands of catheters. The susceptibility to antimicrobial agents of Pseudomonas aeruginosa attached to catheters for 6 and 24 hours was also evaluated. When bacteria attached for 6 hours were used as inoculum, MBCs increased at least 8-fold for amikacin, 64-fold for ceftazidime, 64-fold for ciprofloxacin, 32-fold for norfloxacin and 2048-fold for meropenem. Similar results were observed when bacteria attached to catheters for 24 hours were used as inoculum. It is concluded that catheter material itself affected the in vitro activity of meropenem, and that the bactericidal activity of all antimicrobial agents against Pseudomonas aeruginosa present in biofilms on the surface of siliconized latex urinary catheters decreased dramatically, this effect being more pronounced with meropenem.

Anti-Bacterial Agents↗