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Biomedical subjects

H Leclerc

Publications and source records attributed to H Leclerc.

At least 55 records · Page 3Linked to original sources
PubMed1989

Isolation and characterization of monoclonal antibodies against alkaline phosphatase of Pseudomonas aeruginosa.

Monoclonal antibodies against the alkaline phosphatase of Pseudomonas aeruginosa were produced from spleen cells of BALB/c mice primed with purified alkaline phosphatase of P. aeruginosa ATCC 10145 and SP20/Ag-14 myeloma cells. The eight stable clones established produced antibodies that reacted by enzyme-linked immunosorbent and indirect immunofluorescence assays with all bacterial strains of P. aeruginosa, including the 17 serotypes and two nontypable strains. Three of the clones cross-reacted only with some Pseudomonas species of the rRNA homology group I defined by N. J. Palleroni (in N. R. Krieg and J. G. Holt, ed., Bergey's Manual of Systematic Bacteriology, 8th ed., p. 140-218, 1984). The other clones also interacted with other species, including Pseudomonas acidovorans and Xanthomonas maltophilia. Because other species of the genera Aeromonas and Acinetobacter and species of the family Enterobacteriaceae were not detected by these monoclonal antibodies, the antibodies could be used as reagents for routine detection of P. aeruginosa in clinical specimens. Interactions of the antibodies with other Pseudomonas species such as P. fluorescens and P. stutzeri are not important, since these species are susceptible to the same antipseudomonal agents.

Alkaline Phosphatase↗
PubMed1989

Alkaline phosphatase capture test for the rapid identification of Escherichia coli and Shigella species based on a specific monoclonal antibody.

A specific monoclonal antibody for Escherichia coli and Shigella sp. alkaline phosphatase was used in an immunocapture assay and allowed identification of E. coli either in culture isolates or directly in clinical specimens. The assay was easy and required only four steps: (i) alkaline phosphatase was released within 10 min by using a gentle lysis procedure, (ii) cell lysates were transferred to antibody-coated tubes for 45 min, (iii) p-nitrophenyl phosphate substrate was added, and (iv) alkaline phosphatase activity was detected in a microsample spectrophotometer at 410 nm. This immunocapture assay was highly specific: only one false-positive reaction was observed with a Klebsiella pneumoniae lysate among the 205 non-E. coli strains tested. The assay was sensitive, detecting 10(7) CFU/ml from culture isolates or 10(5) CFU/ml from urine specimens which had first been grown in phosphate-limiting medium for 2 h. At these bacterial concentrations, the percentages of detected E. coli were high: 91% for blood cultures, 95.4% for culture isolates, and 96.8% for urine specimens.

Alkaline Phosphatase↗
PubMed1989

[Molecular markers and identification of Campylobacter pylori strains].

Campylobacter pylori was studied to define the classification of species and the typing of strains. The mol p. 100 G + C of 17 strains ranged from 34.1 to 37.5 (average value: 35.2; SD: 1.0). The strains are closely related (80 to 100 p. 100 DNA/DNA relatedness) and to the type strain NCTC 11367. The endonuclease restriction profiles were specific of strains. DNA analysis (REA) is a sensitive method in pathogenic and epidemiological studies.

Biomarkers↗
PubMed1988

[Pharmacokinetics of cefotaxime in cirrhotic patients with or without ascites].

Pharmacokinetic values of cefotaxime were measured in 12 cirrhotic male patients (6 without ascites and 6 with ascites) after intravenous injection of a single 2 gram dose of the antibiotic. In patients without ascites elimination of the drug was about the same as in normal subjects or control patients, although clearance was increased. In patients with ascites, the drug elimination half-life was significantly more prolonged (7.5 +/- 3.9 h versus 1.3 +/- 0.4 h, P less than 0.01) and the drug clearance was significantly lower (193.6 +/- 92.4 ml/min versus 475.8 +/- 152.2 ml/min, P less than 0.01) than in the other group. The accumulation of cefotaxime in these patients produced concentration in the ascites fluid that were above the critical therapeutic values for about 20 hours.

Ascites↗
PubMed1988

[A method of bacterial count by epifluorescence with acridine orange. Application to skin biopsies performed in burnt patients].

Acridine orange was used for staining and counting micro-organisms obtained from 136 skin biopsies performed in burned patients. The number of organisms per gram of tissue was compared to the number of colony-forming-units (CFU) calculated from cultures of the same biopsies. The staining method was positive in 97 per cent of septic samples, and in 25 per cent of these it proved more sensitive than bacterial cultures, with a 100 to 1000-fold greater number of pathogens detected. Acridine orange also demonstrated bacteria in 69 biopsies which remained sterile after culture. In some cases, the same bacterial species was found in other samples taken a few days later.

Acridine Orange↗
PubMed1988

Susceptibilities to antibiotics and antiseptics of new species of the family Enterobacteriaceae.

One hundred and sixty-nine strains of new species of the family Enterobacteriaceae, isolated mainly from the environment, were tested to determine their susceptibilities to 13 antibiotics and 4 antiseptics or disinfectants. All the species were susceptible to aminoglycosides, doxycycline, and trimethoprim but were resistant to chloramphenicol. Susceptibility to beta-lactams varied more among the strains. However, all the strains were cefotaxime susceptible, apart from some Buttiauxella agrestis strains for which MICs were greater than 256 micrograms/ml. The antiseptic MBCs were similar to those published elsewhere for species of the Enterobacteriaceae of clinical origin. No resistance to chlorhexidine was observed. On the other hand, the environmental strains presented a greater resistance to active chlorine than did the reference strains.

Anti-Bacterial Agents↗
PubMed1987

A rapid chemical procedure for isolation and purification of chromosomal DNA from gram-negative bacilli.

A rapid and simple method for preparing chromosomal DNA from gram-negative bacilli is presented. It is based on the alkaline (NaOH 0.03 M) lysis of cell walls. The resulting emulsion is purified by proteinase K (0.625 mg/g of wet wt), SDS, and the deproteinizing agent (chloroform isoamyl alcohol). The purity, molecular nature, and yield of DNA obtained by the present method are compared with those of DNA extracted by Marmur's procedure and a Marmur's modified procedure. We have developed and standardized this original method to isolate double-stranded DNA, free of proteins and RNA contamination and with a significantly higher yield of DNA than the two other methods. This procedure is particularly useful for strains with low growth and can be applied in every field concerned with DNA analysis.

Cell Wall↗
PubMed1987

N-nitrosamine formation by microorganisms isolated from human gastric juice and urine: biochemical studies on bacteria-catalysed nitrosation.

Twelve out of 14 bacterial strains isolated from patients with urinary infections and nine out of 30 microorganisms isolated from gastric juice from patients with gastric achlorhydria were shown to catalyse the formation of N-nitrosomorpholine (NMOR) from nitrite and morpholine at neutral pH. The effects of various metal ions and cofactors on the bacterial nitrosation reaction was investigated. The presence of nitrate in the culture medium was required to induce nitrosating activity in bacteria, but low nitrate concentrations inhibited the nitrosation reaction.

Escherichia coli↗
PubMed1987

Intragastric nitrosation and precancerous lesions of the gastrointestinal tract: testing of an etiological hypothesis.

The N-nitrosoproline (NPRO) test was used to study whether subjects with precancerous conditions of the stomach have an elevated potential for endogenous nitrosation. The highest yield of NPRO after ingestion of beetroot juice (as a source of nitrate) and proline was seen in subjects whose pH of fasting gastric juice was about 1.5-2. No increased level of NPRO was detected in subjects with more advanced lesions, compared to those with a normal stomach. Counts of total and nitrate-reducing bacteria were positively correlated with the pH of gastric juice but did not correlate with the urinary level of NPRO in the same individuals. Bacteria and intragastric nitrosation are discussed as possible etiological factors in human stomach cancer.

Adult↗
PubMed1986

Urinary N-nitrosamino acids as indices of endogenous formation of N-nitroso compounds.

Exposure to their precursors (e.g., amines, nitrate/nitrite, NOx) can lead to formation in the human body of N-nitroso compounds (NOC), a class of potent animal carcinogens, which are also suspected of being carcinogenic in man. A non-invasive method, the 'N-nitrosoproline (NPRO) test', for estimating endogenous nitrosation in man was developed in our laboratory. This test, which monitors 24-hr-excretion of urinary N-nitrosamino acids, is now applied in clinical and field studies, with the aim of measuring nitrosamine exposure and of identifying dietary, life-style, and host factors, or disease states, that affect nitrosation in man. Results from such studies are used to identify populations/individuals at high risk for cancers of the stomach, oesophagus, and oral cavity possibly caused by endogenous nitrosamines, and to indicate preventive measures by which the body burden of endogenous nitroso carcinogens can be lowered efficiently.

Amino Acids↗
PubMed1986

Nosocomial infection and colonization by Klebsiella trevisanii.

During an 18-month period we identified two cases of septicemia and 24 examples of colonization of humans by Klebsiella trevisanii. Organisms were identified using the API 20EC and API 147 assimilation galleries. Of 147 clinical isolates initially identified as K. oxytoca, 18% were found to be K. trevisanii. Tracheal aspirate was the most common source of the organism. An extensive environmental sampling survey in the rooms of 12 colonized patients revealed a possible reservoir of the organism only once (a face cloth).

Aged↗
PubMed1986

Antimicrobial activity of cefotiam combinations against Enterobacteriaceae moderately susceptible or resistant to this new cephalosporin.

The interaction of cefotiam with each of the four aminoglycosides gentamicin, tobramycin, netilmicin and amikacin were studied by the broth microdilution method ("checkerboard" technique) against 36 strains of Enterobacteriaceae chosen for their moderate susceptibility (MIC: 4-32 mg/l) or resistance (MIC: 64-512 mg/l) to cefotiam. A high rate of synergistic combinations was found with all the aminoglycosides: 81% with gentamicin, 76% with amikacin, 67% with tobramycin and netilmicin. The therapeutic value of these interactions appeared excellent.

Amikacin↗
PubMed1986

In vitro activity of pefloxacin.

A broth dilution method was used to measure the minimal inhibitory concentrations of pefloxacin, a new quinolone derivative. Because this new agent could be used in systemic infections, mezlocillin, cefotaxime, ceftazidime and amikacin were used as comparative agents. Pefloxacin was found to be more active than mezlocillin and as active as or more active than cefotaxime, ceftazidime and amikacin. With the exception of Serratia marcescens, only 7% of Enterobacteriaceae strains were resistant to pefloxacin with a MIC greater than 8 micrograms/ml. Pefloxacin was also found to be the best agent against the non-fermenters Staphylococcus aureus and St. epidermidis. Resistance to ampicillin, carbenicillin and gentamicin did not affect the effectiveness of pefloxacin. However, pefloxacin appeared more susceptible to nalidixic acid resistance, with MICs four to sixfold higher.

Amikacin↗
PubMed1985

[Clinical value of rapid bacteriological results in nosocomial infections. Comparison with traditional methods].

With automated analysers, bacterial identification and susceptibility testing can be performed in 4-5 hours instead of 12-18 hours with conventional methods. A controlled trial was carried out in the surgical ward of a university hospital to evaluate the clinical repercussions of these rapid methods. The automated analyser reduced delays in the laboratory by about 25%, and optimizing information transfer from laboratory to ward brought the reduction up to 50%. It was found that earlier results of susceptibility testing modified prescriptions and this may be expected to result in a more rational use of antibiotics.

Autoanalysis↗
PubMed1985

The medical and economic consequences of automation in bacteriology: a case study in a French university hospital.

In a bacteriology laboratory where automated and non-automated procedures co-existed during the study period (1 year), patients were randomly assigned to each type of procedure and we observed the physicians behaviour as well as patients well-being in a surgical service using the results from the laboratory. Contrary to our expectations, the reduction in the time delay necessary to obtain information did not alter either the prescribing behaviour of physicians nor the welfare of patients. Besides, the gain in time was significantly lower than expected. We also discuss in detail the meaning and relevance of the results.

Automation↗