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Biomedical subjects

B Pangon

Publications and source records attributed to B Pangon.

At least 37 records · Page 2Linked to original sources

TEM-4, a new plasmid-mediated beta-lactamase that hydrolyzes broad-spectrum cephalosporins in a clinical isolate of Escherichia coli.

A clinical isolate of Escherichia coli, strain CB-134, recovered in 1986 from an abdominal abscess, exhibited resistance to penams, oxyimino-beta-lactams including broad-spectrum cephalosporins (cefotaxime, ceftriaxone, ceftazidime), and aztreonam but remained susceptible to cephamycins (cefoxitin, cefotetan) and to moxalactam and imipenem. Clavulanate (2 micrograms/ml) restored the susceptibility of the strain to broad-spectrum cephalosporins and aztreonam. A beta-lactamase with an isoelectric point (pI) of 5.9 was detected in strain CB-134, and the corresponding gene was transferred by conjugation to E. coli together with the associated aminoglycoside resistance determinant [AAC(3)-II] and tetracycline, trimethoprim, and sulfonamide resistance. The beta-lactamase efficiently hydrolyzed cefotaxime and ceftriaxone but only moderately hydrolyzed ceftazidime and was inhibited by clavulanate and sulbactam (1 microM) and by anti-TEM-1 and anti-TEM-2 sera. This extended-spectrum beta-lactamase, conferring resistance to cefotaxime, ceftriaxone, ceftazidime, and aztreonam, was comparable to CTX-1 (TEM-3) but differed from it by pI. Agarose gel electrophoresis of the plasmid DNA indicated that this new enzyme was coded by pUD16, a plasmid of 220 kilobases which belongs to the Inc6 incompatibility group. Hybridization with an intragenic probe for TEM-1 revealed that this beta-lactamase derives from TEM-type beta-lactamases and hence it was named TEM-4.

Cephalosporins↗

Ceftriaxone-netilmicin combination in single-daily-dose treatment of experimental Escherichia coli endocarditis.

We evaluated the activities of ceftriaxone (15 mg/kg), netilmicin (6 mg/kg), and their combination given intramuscularly once daily for 4 days for the treatment of experimental Escherichia coli endocarditis in rabbits. In vitro, a greater rate of killing and an increased trough serum bactericidal titer (P less than 0.01) were achieved with the combination. In vivo, the combination had a greater bactericidal effect (P less than 0.01) and resulted in a greater number of sterile vegetations (P less than 0.05) than single-drug therapy. Thus, in vivo, an increased effect can be obtained despite a single daily dose of a long-acting cephalosporin and an aminoglycoside.

Animals↗

Pharmacokinetics of cefsulodin in rat cerebrospinal fluid during experimental Pseudomonas aeruginosa meningitis.

Experimental meningitis was induced in rats with Pseudomonas aeruginosa. Bacteria were inoculated in the second ventricle. Twenty hours later cefsulodin penetration was studied in CSF by on-line cannula system which permitted sampling of CSF in the third ventricle. Comparison with healthy animals indicated breakdown of the blood-CSF barrier and high concentrations of cefsulodin were found in CSF.

Animals↗

[A fosfomycin-gentamicin combination in the treatment of experimental endocarditis caused by Klebsiella pneumoniae producing type TEM-3 beta-lactamase].

The authors studied the activity of fosfomycin (FOS) and/or gentamicin (GEN) against a Klebsiella pneumoniae strain resistant to all beta-lactams--except cephamycins and imipenem--by production of a plasmid mediated extended broad-spectrum beta-lactamase-TEM-3, to all aminoglycosides--except gentamicin--by production of a plasmid mediated 6' aminoglycoside acetyltransferase IV, to sulfonamides and to tetracyclines. In vitro, the combination FOS (MIC = MBC = 32 mg/l) + GEN (MIC = MBC = 2) appeared indifferent (FIC = 0.75; FBC = 1). In vivo, on experimental endocarditis in rabbits, FOS alone was ineffective, GEN alone was active but only at high dose regimen, FOS - GEN combination was active as compared with controls. Fosfomycin - gentamicin combination may be an alternative in the therapy of severe infections due to multiresistant Enterobacteriacae.

Animals↗

[Retrospective bacteriological study of mycobacterial infections in patients with acquired immunodeficiency syndrome].

The main species of mycobacteria isolated in 62 of the 316 acquired immunodeficiency syndrome patients admitted to the Claude Bernard Hospital, Paris, between January, 1983 and October, 1986 were studied retrospectively according to their site of isolation and their pathogenic role. Mycobacterium tuberculosis was isolated in 19 cases (from pulmonary specimens in 17 cases); this species was present in 59 percent of our African patients as against 20 percent of our European patients. M. avium intracellulare was isolated in 33 cases (17 from blood, 12 from the lung and 11 from the gastrointestinal tract) and was found in 55 p. 100 of our European patients. Other species that were isolated less frequently were M. xenopi (5 cases), M. kansasii (3 cases), M. aurum, M. chelonae, M. fortuitum, M. gordonae, M. simiae and M. terrae (1 case each). Post mortem specimens obtained from 110 acquired immunodeficiency syndrome patients were cultivated during the same period. In 20 patients, at least one specimen was positive for a mycobacterium: M. tuberculosis in 2 cases, M. avium intracellulare in 18 cases. Twenty-nine of the 33 patients in whom M. avium intracellulare was isolated were considered a posteriori as being infected by this organism. The therapeutic approach varies according to the species involved. No treatment seems to be truly effective against M. avium intracellulare. Pending the results of cultures, no direct bacteriological examination can provide information on the mycobacterial species concerned; however, a conventional antituberculosis treatment may be instituted, particularly in patients from Africa or Haiti.

Acquired Immunodeficiency Syndrome↗

The pharmacokinetics and extravascular diffusion of teicoplanin in rabbits and comparative efficacy with vancomycin in an experimental endocarditis model.

The serum protein binding, extravascular diffusion and urinary excretion of teicoplanin were studied in rabbits. Extravascular diffusion was studied after a 20 min iv infusion, and after one or five im injections (7.5 mg/kg), and was compared with the results obtained after im administration of vancomycin (7.5 and 15 mg/kg). In an experimental model of Staphylococcus aureus endocarditis, the efficacy of both antibiotics was also investigated. We observed teicoplanin serum protein binding of 87 +/- 4%. The serum concentrations of teicoplanin showed a three-phase exponential decline: T1/2 alpha, 0.11 +/- 0.01 h; T1/2 beta, 1.4 +/- 0.4 h; T1/2 gamma, 8.3 +/- 2.2 h. Teicoplanin appeared to be slightly secreted by renal tubules. The extravascular diffusion and the therapeutic efficacy of both drugs were studied with intervals between two injections based on the same multiple of beta half-life. Teicoplanin, like vancomycin, appeared slowly in extravascular fluid and the diffusibility of both drugs was similar. Peak extravascular concentrations of teicoplanin after 5 im injections were greater when the compound was administered every 16 h, rather than every 24 h and, for this drug, iv administration induced higher peak extravascular concentrations (P less than 0.01) than im injection. In the experimental model of S. aureus endocarditis, vancomycin 9 mg/kg/12 h and teicoplanin 4.5 mg/kg/16 h were similarly active and more effective than teicoplanin 4.5 mg/kg/24 h.

Animals↗

Enhancement of the therapeutic effect of cephalosporins in experimental endocarditis by altering their pharmacokinetics with diclofenac.

We studied the effect of a nonsteroidal anti-inflammatory drug, diclofenac, in rabbits on the kinetics of three cephalosporins: cefotiam, cefmenoxime and ceftriaxone, and compared the antibacterial effect of these antibiotics, given alone or with diclofenac, in experimental endocarditis. Diclofenac significantly increased (P less than .05) the area under the curve in tissue-cage fluid of ceftriaxone and cefotiam-treated animals, and the terminal half-life of ceftriaxone in their sera (3.45 +/- 0.4 vs. 2.8 +/- 0.5 hr). Diclofenac reduced urinary excretion of cefotiam only. Cefmenoxime pharmacokinetics remained unchanged by diclofenac. The alteration of ceftriaxone kinetics appeared to be due to nonrenal mechanisms and could suggest reduction of biliary excretion. In Escherichia coli endocarditis, diclofenac enhanced the concentration (P less than .05) of cefotiam (23 +/- 16 vs. 8.9 +/- 5 micrograms/g) and ceftriaxone (13.2 +/- 3 vs. 8.5 +/- 4 micrograms/g) in infected vegetations, but not that of cefmenoxime. The antibacterial effect of ceftriaxone increased with diclofenac (5.5 +/- 1 vs. 7.2 +/- 1 log10 colony forming unit/g of vegetation). In vitro, neither protein binding to rabbit serum proteins nor intrinsic activity on the E. coli strain of each antibiotic was modified by diclofenac. These results suggest that anti-inflammatory drugs could increase antibiotic efficacy by altering their pharmacokinetics. The renal and nonrenal site of interaction may be involved for drugs belonging to the same class. Results obtained in tissue-cage fluid were predictive of the interference at the infected site.

Animals↗

[Treatment with a cefotaxime-fosfomycin combination of staphylococcal or enterobacterial meningitis in adults].

Thirty-two patients were included in this trial: 22 with staphylococcal meningitis (including 5 methicillin-resistant) and 10 with enterobacterial meningitis. Mean duration of treatment was 14.5 and 15.9 days respectively. The combination was synergistic in vitro against 10 of the 12 strains of Staphylococcus and 5 of the 6 strains of Enterobacteriaceae studied. Bacteriological sterilization occurred in all cases which could be evaluated, and clinical recovery was obtained in 95.2% of patients with staphylococcal meningitis (4 unrelated deaths) and 100% of patients with enterobacterial meningitis (2 deaths). Bactericidal power of the cerebro-spinal fluid, often less than 1/8, was not correlated with effectiveness against Staphylococci. Mean CSF concentrations of cefotaxime, desacetylcefotaxime and fosfomycin on the 2nd and 15th days of treatment were 4, 3.5 and 39.8 mg/l and 2.2, 2.1 and 28.0 mg/l, respectively. Clinical and biological acceptability was satisfactory. There were three cases of superinfection or colonization, by Pseudomonas and Enterobacter.

Adolescent↗

Value of antibiotic levels in serum and cardiac vegetations for predicting antibacterial effect of ceftriaxone in experimental Escherichia coli endocarditis.

In a rabbit model of Escherichia coli endocarditis, we studied the penetration into infected vegetations and the antibacterial effect of ceftriaxone. Ceftriaxone was given at different dosages, alone or with an interfering agent, diclofenac, a nonsteroidal anti-inflammatory drug, to determine the predictive value of the antibiotic levels in serum or infected vegetations on the antibacterial efficacy. Diclofenac increased the serum terminal half-life of ceftriaxone and increased its extravascular diffusion in tissue cage fluid, as well as in infected vegetations, allowing us to obtain various antibiotic concentrations in the infected site. Two hours after the fourth injection, around the time of peak level in serum, we observed a linear relationship between (i) serum and local antibiotic levels in vegetations, (ii) local antibiotic levels in a range of 142 to 600 X MBC and bacterial titer (log10 CFU/g) in vegetations, and (iii) serum antibiotic levels in a range of 800 to 1,400X MBC and bacterial titer in vegetations. In vivo, antibacterial effect was obtained only with high antibiotic levels in vegetations (greater than or equal to 220X MBC). This was confirmed by incubating vegetations sampled from infected animals in rabbit serum containing ceftriaxone (ex vivo experiment). Given once daily at a therapeutic dosage (30 mg/kg) for 4 days, ceftriaxone exhibited good efficacy (log10 CFU/g of vegetation = 2.41 +/- 2.7 versus 7.41 +/- 0.92 in control animals) and prevented regrowth of bacteria until 24 h after the last injection. We concluded that (i) provided the dose is sufficient, a long-acting cephalosporin can prove effective in severe gram-negative infections even when given infrequently, and (ii) serum antibiotic levels around the peak value, reflecting high effective local levels, could predict the therapeutic efficacy and represent a simple test to monitor the clinical course of a severe infectious process.

Animals↗

Bactericidal activity against Haemophilus influenzae of cerebrospinal fluid of patients given amoxicillin-clavulanic acid.

Patients with purulent meningitis received amoxicillin-clavulanic acid (200/20 mg/kg [body weight] per day). Clavulanic acid levels in cerebrospinal fluid were less than or equal to 0.05 micrograms/ml in 5 of 18 samples and ranged from 0.1 to 0.8 micrograms/ml in the others. Of 12 cerebrospinal fluid samples tested, 10 lacked bactericidal activity in vitro against a beta-lactamase-producing strain of Haemophilus influenzae.

Adolescent↗

Comparative efficacy of cefotiam, cefmenoxime, and ceftriaxone in experimental endocarditis and correlation with pharmacokinetics and in vitro efficacy.

To determine the influence of in vitro activity, pharmacokinetic properties, and therapeutic regimen on the antibacterial effect in vivo, we compared three cephalosporins, cefotiam, cefmenoxime, and ceftriaxone, in a rabbit model of experimental Escherichia coli endocarditis after 4 days of treatment. The MBCs of cefotiam, cefmenoxime, and ceftriaxone for the E. coli strain were 0.5, 0.125, and 0.06 microgram/ml, respectively. Killing curves at 10 times the MBC were similar for the three cephalosporins. In serum, the elimination half-life of ceftriaxone was twice as much as the elimination half-life of cefotiam or cefmenoxime (2.8 +/- 0.45 versus 1.4 +/- 0.25 or 1.3 +/- 0.4 h, respectively). Ceftriaxone was much more effective than cefotiam. The bacterial titer in the vegetations (log10 CFU per gram of vegetation) was 7.56 +/- 1 with cefotiam and 2.41 +/- 2.6 with ceftriaxone, as their concentrations were 18 and 466 times higher, respectively, than their MBCs. Although ceftriaxone and cefmenoxime exhibited a similar rate of killing and percentage of protein binding, ceftriaxone was more effective than cefmenoxime at the same regimen of 15 mg/kg twice a day (3.08 +/- 1.1 versus 4.82 +/- 3.2 log10 CFU/g of vegetation). When antibiotic was given as a single daily injection of 30 mg/kg, the antibacterial effect persisted for ceftriaxone, but not for cefmenoxime. The longer elimination half-life and the higher local concentration/MBC ratio of ceftriaxone explained these results. The bacterial titer measured 24 h after the fourth injection of 30 mg of ceftriaxone per kg confirmed that this regimen prevented regrowth of bacteria. These results suggest that the local antibiotic level/MBC ratio roughly correlated with the antibacterial effect and could represent an adequate basis to explain the differences observed between the drugs in vivo. They also demonstrate that, provided that the dose is sufficient, a long-acting broad-spectrum cephalosporin may be effective in severe gram-negative infections, even when given at relatively long dosing intervals, in contrast with a rapidly cleared drug with the same intrinsic activity.

Animals↗

Mycobacterium simiae and Mycobacterium avium-M. intracellulare mixed infection in acquired immune deficiency syndrome.

Acquired immune deficiency syndrome was diagnosed in a 43-year-old man, born and living in Congo. The patient presented a disseminated infection caused by mycobacteria which were recovered from blood, jejunal fluid, and duodenal and rectal biopsies. Identification, according to conventional tests and mycolate profile determination, showed that Mycobacterium avium-M. intracellulare and M. simiae were both involved.

Acquired Immunodeficiency Syndrome↗

Fifty cases of late prosthetic valve endocarditis: improvement in prognosis over a 15 year period.

The clinical course, prognostic factors, and management of 50 cases of late prosthetic valve endocarditis, occurring more than two months after valve replacement, were reviewed. Twenty nine cases that presented from 1971 to 1980 were compared with 21 cases that presented from 1981 to 1985. Apart from an appreciable decrease in the frequency of neurological complications between the first period (38%) and the second period (10%) no differences in clinical or bacteriological features were seen. Seventeen (59%) of the 29 cases in the earlier period and four (19%) of the 21 cases in the later period died. The rationale for antimicrobial treatment was similar during both periods. Cardiac surgery was performed in eight of 29 cases between 1971 and 1980 and in 11 of 21 between 1981 and 1985; the mean (SD) time between diagnosis of endocarditis and operation was 28 (19) days and 43 (44) days respectively. Six of the eight cases operated on in the first period died as did two of the 11 operated on in the second period. Twenty seven of the 29 cases presenting between 1971 and 1980 were treated with anticoagulants--either warfarin (15 of 27) or heparin sodium (12 of 27). Sixteen of the 21 cases presenting later were given anticoagulants and 15 of these cases were given heparin sodium. Control of anticoagulation was inadequate in nine of the 27 cases treated with anticoagulants during the first period and in only two of 16 treated during the second period. During the first treatment period neurological complications were more frequent when control of anticoagulation was inadequate.

Adult↗

[Diffusion of ceftriaxone in bronchial secretions for 24 hours after a single injection].

The authors have determined the bronchi concentration 1 h, 3 h, 6 h and 24 h after a single muscular injection of ceftriaxone in a series a 13 patient with tracheostomy that received ceftriaxone for prophylaxis. In spite of a large inter-individual variability the result is a good mean ceftriaxone concentration during the first 24 h. Theses results confirms the value or a single daily injection in the treatment of pulmonary injection whose germ is sensitive to the drug.

Bronchi↗

[Tonsillitis today. Epidemiologic review. Clinical correlates. Therapeutic impact].

A prospective study was conducted in 216 patients with ulceration of throat and 100 controls. Bacteriology showed, in the low percentage of case with positive results, the classical distribution of germs generally identified from throat swabs, with predominance of haemolytic streptococci AB and associated fusospirilla. Haemophilus influenzae was very rarely isolated (1%) and immunofluorescence tests for Chlamydia trachomatis in the pharyngeal exudate were always negative, in both patients and controls. These findings confirm utility of Penicillin V as single therapeutic agent in ulcerated throat. Correlations between clinical findings and between these and bacteriology results demonstrated that clinical examination failed to provide data contributive to the establishment of an aetiological diagnosis and therefore to treatment, which, in the absence of complementary examinations, must remain empirical.

Adolescent↗