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Biomedical subjects

M O Husson

Publications and source records attributed to M O Husson.

At least 19 recordsLinked to original sources

Tolerance, pharmacokinetics and efficacy of once daily amikacin for treatment of Pseudomonas aeruginosa pulmonary exacerbations in cystic fibrosis patients.

UNLABELLED: Twenty cystic fibrosis patients aged 1.8-22 years (mean +/- SD: 9.6 +/- 4.8 years) with Pseudomonas aeruginosa pulmonary exacerbations were treated with amikacin (AM) (35 mg/kg/day in one daily 30 min infusion) associated with either ceftazidime (200 mg/kg/day in 3 i.v. injections) (n = 19) or imipenem (n = 1) at the same dose. Glomerular and tubular functions (creatinine clearance, 24-h proteinuria, beta 2 microglobulinuria, lysozymuria) and audiometry remained within normal ranges from day 0 to day 14. A peak concentration of AM of 83 +/- 19 mg/l and a trough concentration of 0.8 +/- 0.5 mg/l were observed in blood while AM levels in sputum were above the minimal inhibitory concentration 50 from 30 min to 16 h. No serum accumulation of AM was observed during the treatment. From day 0 to day 14, the following changes were observed: weight/height ratio: 96%-100% (P < 0.001); daily energy intake: 111%-128% of RDA (P < 0.001); prealbumin: 195-290 mg/l (P < 0.001); forced vital capacity (FVC): 66%-81% (P < 0.01); forced expiratory volume in 1 s: 60%-75% (P < 0.01); forced expiratory flow between 25% and 75% of FVC: 42%-56% (P < 0.01); nocturnal SaO2 also improved significantly; cardiac rate decreased from 89 +/- 18/min to 76 +/- 16/min (P < 0.001); respiratory rate decreased from 31 +/- 15/min to 26 +/- 10/min (P < 0.05); inflammatory parameters (white blood cells, polymorphonuclear cells, erythrocyte sedimentation rate) also improved. CONCLUSION: Once daily amikacin administration associated with ceftazidime is well tolerated for the treatment of Pseudomonas aeruginosa pulmonary exacerbations in cystic fibrosis patients. Serum peak levels and diffusion in sputum are higher than with a conventional schedule.

Adolescent

[In vitro study of antibacterial activity of cefepime (Axepim) against gram negative bacteria: comparison with cephalosporins and other beta-lactams].

The susceptibility to cefepime and to other beta-lactams of 1017 inducible cephalosporinase-producing enterobacteria, 897 Pseudomonas aeruginosa strains, and 295 Acinetobacter baumanii strains was studied over a two-year period (July 1, 1993 to June 30, 1995). The isolates were from patients in visceral surgery, intensive care, and clinical hematology wards. Cefepime was compared to other third-generation cephalosporins and to imipenem, aztreonam, and the piperacillin-tazobactam combination. Cefepime was more active than the other cephalosporins against Enterobacter cloacae, Serratia marcescens and Citrobacter freundii. Activity of cefepime on the study isolates was also greater than that of aztreonam and of the piperacillin-tazobactam combination. Cefepime exhibited outstanding activity against Pseudomonas aeruginosa strains except those with the O12 serotype.

Acinetobacter

Importance in diagnosis of gastritis of detection by PCR of the cagA gene in Helicobacter pylori strains isolated from children.

The cagA gene has been detected by PCR and DNA hybridization in 45 Helicobacter pylori strains isolated from children. For each child, clinical symptoms, endoscopic aspect of the gastric mucosa, and histological gastritis were evaluated. Gene-positive strains were associated with hemorrhagic gastritis in 66.6% of the children, while gene-negative strains were associated with hemorrhagic gastritis in 11.2% of the children (P = 0.0001). In addition, 88.8% of gene-positive strains were associated with severe histological gastritis (scores of 3 and 4), and gene-negative strains were collected from the gastric mucosa with the same type of infiltration of neutrophils and lymphocytes in the lamina propia in 55.5% of the children. These differences were statistically significant (P = 0.017). Gene-positive strains were also isolated more frequently from children with vomiting (P = 0.04), while the absence of clinical signs was not significantly different in cagA gene-positive or -negative patients. All of these observations confirmed the role of this cagA gene as a marker of gastric inflammation in children. The detection of this gene might be helpful to determine the degree of inflammation of the gastric mucosa in the absence of abdominal symptoms. We might better understand the natural history of H. pylori infection if we studied the evolution of gastritis in children with regard to the cagA status of isolated strains.

Adolescent

[Bacteriological monitoring of the treatment of Pseudomonas aeruginosa infections with amikacin administrated at once-daily dosis in patients with cystic fibrosis].

The interest of the treatment with a single daily dose of amikacin (AMK) in cystic fibrosis (CF) patients with P. aeruginosa infections has been much debated. The aim of work was to study the efficiency of this treatment on (CF) patients with chronic bronchopulmonary P. aeruginosa infections previously treated for two weeks with the combination ceftazidime (CAZ 200 mg/day in 3 inj. IVD) and AMK (35 mg/day in one IV perf. of 30 minutes). The bacteriological supervision of this treatment was performed 1: by the determination of MICs before and after treatment, 2: by the decrease of P. aeruginosa colonization immediately after this treatment and during 11 months, 3: by the identification of P. aeruginosa strains with phenotypic methods (serotyping and antibiotyping) and with genotypic method (pulsed field gel electrophoresis). The use of AMK in a single daily dose in order to treat chronic lung infections colonized with P. aeruginosa susceptible to this antibiotic shows encouraging results as far as bacteriology is concerned: this treatment has given means to reduce colonization for a month in 15 of 18 patients. For 9 of the 18 patients, no P. aeruginosa strains were isolated for nine months. The serotyping and antibiotyping systems do not enable us to study the P. aeruginosa epidemiology. Genome macrorestriction fingerprinting of P. aeruginosa in pulsed field gel electrophoresis confirms that patient with CF were colonized with one or several clones. In our study no variation of these clones was noticed for the first eleven months. Genome macrorestriction fingerprinting appears to be one of the most effective methods for delineate strains of P. aeruginosa colonizing CF patients.

Adolescent

High prevalence of Helicobacter pylori infection in cohabiting children. Epidemiology of a cluster, with special emphasis on molecular typing.

Intrafamilial cases of infection with the same strain of Helicobacter pylori (H pylori) have been reported but these clusters were too small to distinguish between person to person spread or coinfection from a common environmental source. To gain more information on the mode of transmission of H pylori, an epidemiological survey with bacterial strain differentiation by restriction endonuclease analysis of chromosomal DNA was carried out in an institution of 117 children with encephalopathy (aged 3.5 to 19 years). All children with antibodies against H pylori had gastroscopy to obtain gastric biopsy specimens. The prevalence of infection (confirmed histologically or microbiologically, or both) was 38% (45/117), and rose to 67% in one of the five sections of the institution. H pylori was isolated in 34/45 cases, and 22 different strains were found of which five strains were present in more than one child. Up to seven children were infected by the same strain, five of them were living in the same section. Analysis of the characteristics of infected children showed the predominant role of living conditions and the period of time cohabiting in this unexpectedly high prevalence of H pylori infection in children living in good sanitary conditions.

Adolescent

Detection of H. pylori in saliva using a monoclonal antibody.

The presence of Helicobacter pylori in saliva specimens collected from infected children examined before and after specific therapy and from a non-infected pediatric population was detected by indirect immunofluorescence assay (IIF) using a specific monoclonal antibody. Among the 25 children with H. pylori-negative antral biopsies, 4 had in their salivas bacterial cells similar to H. pylori, but a retrospectively performed serologic test showed a positive response. No false-positive reaction was observed among non-infected and seronegative children. The observation of bacterial cells with H. pylori morphology in saliva by IIF was consistent with the presence of this bacterium in antral biopsies. A person-to-person transmission of H. pylori by saliva thus appeared to be possible.

Adolescent

Iron acquisition by Helicobacter pylori: importance of human lactoferrin.

Helicobacter pylori is known to be an etiologic agent of gastritis and peptic ulcer disease in humans. However, the mechanism by which this organism acquires iron has not been studied. For this investigation, H. pylori was grown in iron-restricted medium. Siderophore production was not detected by chemical assays, and the strains were unable to use enterochelin and pyochelin for growth in low-iron media. Human lactoferrin supported full growth of the bacteria in media lacking other iron sources, but neither human transferrin, bovine lactoferrin, nor hen ovotransferrin served as a source for iron. Since lactoferrin was found in significant amounts in human stomach resections with superficial or atrophic gastritis, the iron acquisition system of H. pylori by the human lactoferrin receptor system may play a major role in the virulence of H. pylori infection.

Animals

Resistance to cefotaxime and seven other beta-lactams in members of the family Enterobacteriaceae: a 3-year survey in France.

During the second quarter each of 1988, 1989, and 1990, a French collaborative study group, including 12 university hospital laboratories, surveyed the resistance to beta-lactams of clinical isolates from hospitalized patients: consecutively, 10,641, 10,692, and 9,382 isolates were tested. The distribution of bacterial species over time was similar in each laboratory. The susceptibilities of microorganisms to amoxicillin, ticarcillin, cephalothin, cefoxitin, cefotaxime (CTX), ceftazidime (CAZ), aztreonam (ATM), and imipenem (IPM) were measured by the disk diffusion method in accordance with the recommendations of the Antibiogram Committee of the French Society for Microbiology. Five reference strains were included for quality control. Extended-spectrum beta-lactamases were detected by the synergistic effect of the combination of clavulanic acid-amoxicillin with CTX, CAZ, and ATM in the double-diffusion test. A synergistic effect with CTX, CAZ, and ATM was detected for 1.5% of all strains, mainly those of Klebsiella pneumoniae (13.3%). For this species, the synergy test enabled the detection of roughly 50% of the resistant strains misclassified as susceptible on the basis of interpretative standards. Extended-spectrum beta-lactamases disseminated in 1990 in most enterobacterial species but at a low frequency. Important variations in the percentages of resistant strains were observed in terms of bacterial species, hospitals, and wards. However, when the total number of strains was considered, the percentages of resistance to newer beta-lactams remained low.

Anti-Bacterial Agents

Rapid detection of members of the family Enterobacteriaceae by a monoclonal antibody.

Six monoclonal antibodies directed against enterobacteria were produced and characterized. The specificity of one of these antibodies (CX9/15; immunoglobulin G2a) was studied by indirect immunofluorescence against 259 enterobacterial strains and 125 other gram-negative bacteria. All of the enterobacteria were specifically recognized, the only exception being Erwinia chrysanthemi (one strain tested). Bacteria not belonging to members of the family Enterobacteriaceae were not detected, except for Plesiomonas shigelloides (two strains tested), Aeromonas hydrophila (five strains tested), and Aeromonas sobria (one strain tested). This recognition spectrum strongly suggested that CX9/15 recognized the enterobacterial common antigen. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) experiments, the six antienterobacteria antibodies presented similar specificities; they all revealed only one band with an apparent molecular weight of about 20,000 from the crude extract of an enterobacterium. The six monoclonal antibodies, and especially CX9/15, can be used to develop new tests for rapid and specific detection of enterobacteria.

Antibodies, Monoclonal

Detection of Helicobacter pylori in stomach tissue by use of a monoclonal antibody.

Monoclonal antibodies were produced against an acid glycine extract of Helicobacter pylori ATCC 43504T. One of these appeared to be specific for H. pylori; it recognized all H. pylori isolates by an indirect immunofluorescence assay (IIF) but it did not cross-react with the other strains tested, including different species of the genera Helicobacter, Campylobacter, and Wolinella. Different strains of members of the families Enterobacteriaceae and Pseudomonadaceae or other gram-negative bacteria tested also gave negative reactions. Indirect immunofluorescence assay of antral biopsy specimens identified 54 of 56 infected patients (96.4%), and it may be able to detect nonviable organisms after antibiotic therapy.

Acridines

Anti-Helicobacter pylori IgG levels in abattoir workers.

The aim of our study was to detect antibodies against Helicobacter pylori (H. pylori) in abattoir workers whose activity was variable (pig, poultry-carcasses, poultry-intestinal organs treatment). An adsorption of all sera with H. pylori and Campylobacter species known to be ubiquitous and responsible for zoonosis was included in the ELISA reaction to eliminate possible cross-reactions between these species. Statistically higher specific titres of IgG antibodies against H. pylori were observed in men and women who had only worked for 1 or 2 years versus matched controls, indicating a possible transmission of H. pylori from animal to man. The role of poultry or pigs as contaminants alone or in association remains to be determined.

Abattoirs

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

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

[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

[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

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