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N Lambert-Zechovsky

Publications and source records attributed to N Lambert-Zechovsky.

At least 55 records · Page 3Linked to original sources
PubMed1992

Killing kinetics of five orally administered antibiotics at clinically achievable concentrations against Moraxella catarrhalis.

Time-kill kinetic studies were used to measure the bactericidal activity of amoxicillin/clavulanic acid (in a new form for pediatric use), cefaclor, cefuroxime, cefixime and erythromycin against 30 beta-lactamase producing Moraxella catarrhalis strains. Antibiotics were tested at the mean maximum serum concentration observed after administration of a standard dose and at 0.5 x Cmax, 0.33 x Cmax and 0.25 x Cmax. A 2 log10 reduction in colony counts was obtained with the Cmax of amoxicillin/clavulanic acid and cefixime after 5 h of incubation. After 24 h of incubation a decrease of 3 and 4 log was observed with cefixime and amoxicillin/clavulanic acid respectively. At 0.5 x Cmax and 0.33 x Cmax, bactericidal activity was obtained only with amoxicillin/clavulanic acid.

Amoxicillin↗
PubMed1992

Rapid genotyping shows the absence of cross-contamination in Enterobacter cloacae nosocomial infections.

Restriction fragment length polymorphism analysis (RFLP) of total DNA and rDNA regions was used for the epidemiological evaluation of 10 Enterobacter cloacae nosocomial isolates obtained from nine patients in our hospital. Five of these patients were hospitalized during overlapping periods, thus raising the question of cross-contamination. A single biochemical pattern and antibiotic susceptibility profile was observed for all isolates but one. In contrast, based on the results of total DNA and rDNA RFLP patterns, the genetic unrelatedness of the isolates was clearly shown, thus excluding a common source of contamination or patient-to-patient transfer.

Adult↗
PubMed1992

In-vitro bactericidal activity of four oral antibiotics against pathogens responsible for acute otitis media in children.

This study was designed to test the in-vitro activity of four oral antibiotics against the four microorganisms most frequently isolated in acute otitis media: beta-lactamase-positive Haemophilus influenzae (N = 10), beta-lactamase-positive Moraxella catarrhalis (N = 10), penicillin-sensitive Streptococcus pneumoniae (N = 11) and methicillin-sensitive Staphylococcus aureus (N = 10), by the bactericidal curve method. Bactericidal kinetics were determined for concentrations of antibiotic equivalent to those found in the middle ear after treatment: amoxycillin-clavulanic acid (2.5 mg l-1/0.6 mg l-1 and 2.5 mg l-1/1.2 mg l-1), cefaclor (1 mg l-1), erythromycin (0.5 mg l-1) and erythromycin/sulfisoxazole (0.2/3 mg l-1). The inoculum was of 10(6) colony-forming units (cfu) ml-1. The bacterial counts were performed after 5 h and 24 h using a spiral inoculator system. The results showed that amoxycillin-clavulanic acid had rapid bactericidal activity (< 24 h) on the tested organisms at each of the doses used (reduction < or = 3 log10 cfu ml-1) which was not observed with the other antibiotics at either 5 or 24 h. Erythromycin alone or combined with sulfisoxazole had a bacteriostatic effect on Moraxella catarrhalis and Streptococcus pneumoniae but not on Haemophilus influenzae or Staphylococcus aureus. Cefaclor had no bactericidal action under these conditions.

Acute Disease↗
PubMed1992

Molecular analysis provides evidence for the endogenous origin of bacteremia and meningitis due to Enterobacter cloacae in an infant.

We analyzed the restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA regions (ribotyping) to document the occurrence of endogenous, systemic bacteremia and meningitis due to Enterobacter cloacae in a newborn. Five strains of E. cloacae were isolated from this newborn. Three of these strains were recovered from stool at counts of 10(8), 10(9), and 10(9) organisms/g of feces, respectively; one strain was isolated from blood; and one strain was isolated from cerebrospinal fluid. In addition, five epidemiologically unrelated strains of E. cloacae were studied for comparison. Our study clearly shows the genetic relatedness of the strains isolated sequentially from cultures of stool, blood, and cerebrospinal fluid. RFLP analysis of total DNA and ribotyping seem particularly well suited to the study of the epidemiology of nosocomial E. cloacae strains.

Bacteremia↗
PubMed1992

Mother-to-infant vertical transmission and cross-colonization of Streptococcus pyogenes confirmed by DNA restriction fragment length polymorphism analysis.

Restriction fragment length polymorphism (RFLP) analysis of total DNA and of ribosomal DNA (rDNA) regions (ribotyping) were used to document Streptococcus pyogenes vertical mother-to-infant transmission and to investigate the spread of S. pyogenes in an obstetric unit. Two isolates from a newborn, two isolates from his mother (patient 1), and two isolates from two other mothers (patients 2 and 3) were studied. RFLP of total DNA, both after HindIII and PvuII digestions and ethidium bromide staining, gave indistinguishable patterns for the strains isolated from the neonate, his mother, and patient 2. Strains from patient 3 and six unrelated strains studied for comparison showed different patterns. In our system, ribotyping was less discriminative than total DNA RFLP analysis. DNA RFLP analysis therefore provides a valuable molecular tool for studying S. pyogenes epidemiology.

Adult↗
PubMed1992

Analysis of DNA restriction fragment length polymorphism extends the evidence for breast milk transmission in Streptococcus agalactiae late-onset neonatal infection.

Analysis of restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA (ribotyping) was used to document four cases of Streptococcus agalactiae mother-to-infant transmission potentially associated with ingestion of infected mother's milk. Twenty strains were analyzed. Ten strains were mother-baby pairs, five from the milk of five mothers, four from their neonates with late-onset infection, and one from a colonized neonate. All mothers had early postpartum mastitis. Ten unrelated strains were studied for comparison. In each case, the two strains of each mother-baby pair produced identical RFLP patterns of total DNA. The 10 unrelated strains generated 10 different patterns, one of which, though, was observed in one of the mother-baby pairs. Ribotyping was less discriminative than total DNA RFLP analysis (6 different patterns vs. 13). These data extend the evidence for breast milk transmission in S. agalactiae late-onset neonatal infection.

Breast Feeding↗
PubMed1992

Bactericidal activity of beta-lactams and amikacin against Haemophilus influenzae: effect on endotoxin release.

Ampicillin or cefotaxime, alone or in combination with amikacin, were tested at levels achievable in CSF for bactericidal activity against eight clinical isolates of Haemophilus influenzae serotype b. Endotoxin release was determined by the limulus amoebocyte lysate test and by macrophage tumour necrosis factor production for each beta-lactam antibiotic, alone and in combination with amikacin. Accelerated killing was observed when amikacin was added to ampicillin or cefotaxime; however, the additional antibiotic-induced bacterial lysis observed after the addition of amikacin to beta-lactam antibiotics was not associated with an increase in endotoxin release.

Amikacin↗
PubMed1992

DNA restriction fragment length polymorphism differentiates recurrence from relapse in treatment failures of Streptococcus pyogenes pharyngitis.

In the evaluation of treatment failure in Streptococcus pyogenes pharyngitis it is necessary to distinguish between persistence of the original streptococcus and acquisition of a new strain. We used the analysis of restriction fragment length polymorphism (RFLP) of total DNA and of ribosomal DNA (rDNA) regions (ribotypes) as epidemiological tools to compare 43 pre- and post-treatment S. pyogenes strains obtained from 20 patients. In 16 cases pre- and post-treatment strains gave indistinguishable RFLP patterns of total DNA, strongly suggesting relapse with the same strain. However, in four cases different patterns were obtained for the pre- and post-treatment isolates, indicating recurrence due to the acquisition of a new strain. Ribotyping did not improve discrimination among strains. Thus, analysis of DNA RFLP is a promising method for distinguishing recurrence from relapse in failures of pharyngitis treatment.

DNA, Bacterial↗
PubMed1992

[Comparative in vitro activity of glycopeptides against coagulase negative staphylococci isolated in pediatric hospital units].

The minimum inhibitory concentrations (MICs) of vancomycin and teicoplanin were determined for 32 coagulase-negative staphylococci strains recovered from blood specimens from pediatric intensive care patients. All the strains were susceptible to vancomycin (MIC less than 4 mg/l). Sixteen strains were susceptible to teicoplanin (MIC less than 4 mg/l) and the sixteen remaining strains exhibited intermediate susceptibility, with MICs of 8 mg/l (10 strains) or 16 mg/l (6 strains). Inhibition zone diameters seen with vancomycin during agar diffusion susceptibility testing were consistently greater than 17 mm. Inhibition zones obtained with teicoplanin were 17 mm or more in diameter for 30 strains and under 17 mm in diameter for 2 strains. For 14 strains (44%), agar diffusion testing failed to detect the decreased susceptibility to teicoplanin revealed by MIC determinations. The agar diffusion method does not seem reliable for the determination of in vitro susceptibility to teicoplanin.

Anti-Bacterial Agents↗
PubMed1991

Bactericidal activity of daptomycin against vancomycin-resistant Enterococcus faecium in an in vitro pharmacokinetic model.

A dynamic in vitro model was used to determine the killing kinetics of daptomycin against 15 vancomycin-resistant clinical isolates of Enterococcus faecium. Concentration profiles simulating those observed in serum following administration of both low-dose (2 mg/kg) and high-dose (6 mg/kg) daptomycin were bactericidal within 5.5 and 2.8 h, respectively. In contrast, when albumin was added to the growth medium, the corresponding bacterial killing times were slowed to greater than 24 h and 7 h; these results suggest that in the clinical setting, daptomycin dosages of approximately 6 mg/kg are required to achieve bactericidal activity against vancomycin-resistant Enterococcus faecium.

Albumins↗
PubMed1991

Killing kinetics of cefuroxime axetil against Haemophilus influenzae in an in-vitro model simulating serum concentration profiles after oral administration.

We have used a dynamic in-vitro model to determine the killing kinetics of two formulations of cefuroxime axetil against 18 clinical strains of Haemophilus influenzae. The concentration of cefuroxime axetil was adjusted dynamically to simulate the mean serum profile in healthy volunteers following the administration of a single 250 mg dose in oral suspension or tablet form. Bacterial numbers were reduced by 3 log10 cfu/mL during the eight-hour experimental period with both dosage form simulations. Our results suggest that cefuroxime axetil, 250 mg in oral suspension or tablet form, may protect against the dissemination of H. influenzae during episodes of bacteraemia.

Administration, Oral↗
PubMed1991

[Vancomycin in 1991: current status and perspectives].

Vancomycin is a narrow-spectrum glycopeptide antibiotic which is primarily active against Gram-positive organisms. Bacterial resistance develops rarely due to its numerous modes of action. The mode of action of vancomycin involves the inhibition of peptidoglycan synthesis. Vancomycin forms a stoichiometric complex with the peptidoglycan precursor UDP-N-acetylmuramyl pentapeptide by forming hydrogen bonds. In patients with renal insufficiency vancomycin clearance is reduced and elimination half-life prolonged. Vancomycin is the drug of choice in the treatment of methicillin-resistant staphylococcal infections and in the treatment of Gram-positive endocarditis and has been used as alternative therapy in the treatment or prophylaxis of Gram-positive infections in penicillin-allergic patients.

Cell Division↗
PubMed1990

[Antibiotic therapy of nosocomial infections in children].

The choice of antibiotics for the treatment of hospital-acquired infections in children is a rational choice based on the child's general condition, on the site of infection, on the most probable pathogens and on their current sensitivity to antibiotics. The antibiotic chosen must reach bactericidal concentrations at the site of infection for rapid reduction or the inoculum and to limit the systemic spread of infection, thereby decreasing the risk of a rapidly expanding infectious process in the younger children. The optimal antibiotic is selected on the basis of what is known about bacterial resistance. General therapeutic rules must be adjusted to the epidemiological situation prevailing in each hospital department.

Anti-Bacterial Agents↗
PubMed1990

Bacterial counts in cerebrospinal fluid of children with meningitis.

Eighty-five cerebrospinal fluid (CSF) specimens from the same number of pediatric patients with meningitis were examined to determine the bacterial count and the relationship of this count to the microscopy results, the ages of the patients and the bacterial species isolated. Bacterial counts ranged from 2 x 10 to 4 x 10(9) CFU/ml CSF. Twenty-five percent of the 85 CSF specimens positive for Haemophilus influenzae type b, Neisseria meningitidis, Streptococcus pneumoniae, Escherichia coli K1 and group B streptococci had counts of 10(7) CFU/ml or higher. Children between 1 and 6 months of age had significantly higher counts (p less than 0.05) than the other age groups. The three patients who had positive CSF cultures 24 h after the start of therapy all had initial bacterial counts of 10(7) CFU/ml or higher. The detection limit for Gram stain/microscopy was 10(5) CFU/ml. No correlation was found between bacterial count and the number of polymorphonuclear leukocytes.

Age Factors↗
PubMed1990

Bactericidal activity of vancomycin, daptomycin, ampicillin and aminoglycosides against vancomycin-resistant Enterococcus faecium.

Daptomycin, vancomycin, ampicillin and aminoglycosides, alone or in combination, were tested for their bactericidal activity against 15 isolates of vancomycin-resistant Enterococcus faecium from immunocompromised children. The kill-kinetic studies at clinically achievable concentrations demonstrated that daptomycin alone or in combination with ampicillin had the greatest bactericidal activity.

Aminoglycosides↗
PubMed1989

[Structure-activity relationship of oral cephalosporins].

The advances achieved in the field of oral cephalosporins consist of improved bioavailability and enhanced intrinsic activity of the compounds. Oral absorption is facilitated either by creating prodrugs or by modifying the compound itself with addition of the alpha-amino group at position 7 on the cephem ring or of a vinyl group at position 3. Antibacterial activity and resistance to beta-lactamases are facilitated by the presence of an amino-2-thiazole heterocycle at position 7, associated with a methoxy-imino group or an oxy-imino-acetoxy group.

Absorption↗