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Biomedical subjects

E Yourassowsky

Publications and source records attributed to E Yourassowsky.

At least 19 recordsLinked to original sources
PubMed1992

[Is there in Belgium an increase in resistance to the combination amoxicillin/clavulanic acid of Escherichia coli as reference bacteria?].

The difficulties encountered in measuring the susceptibility of the association amoxicillin/clavulanate can be a cause for disagreements between laboratories. With an inoculum standardized at 10(4) CFU/spot, the resistance level of E. coli approaches 10%. If the variety of current methods is taken into account, the evaluation of a resistance increase can only be an internal one, specific for each laboratory, provided that methods do not change in the course of time.

Amoxicillin↗
PubMed1992

Comparative kill and growth rates determined with cefdinir and cefaclor and with Streptococcus pneumoniae and beta-lactamase-producing Haemophilus influenzae.

The relationship between the growth rate and the kill rate was used to evaluate and to compare the in vitro bactericidal activities of cefdinir, a new oral cephalosporin, and cefaclor against Streptococcus pneumoniae and beta-lactamase-producing strains of Haemophilus influenzae. These frequently encountered pathogens of community-acquired respiratory tract infections are usually susceptible to both drugs. The MIC ranges for cefdinir and cefaclor were, respectively, 0.03 to 0.06 and 0.25 to 0.5 micrograms/ml for S. pneumoniae and 0.25 and 4 to 8 micrograms/ml for H. influenzae. The colony counts (CFU per milliliter) measured after 6 h of exposure to a range of antibiotic concentrations in broth were plotted against the colony count of the control culture over the same period of time. Higher kill rates versus bacterial growth rates were noted for S. pneumoniae for both drugs (positive balance). Conversely, lower kill rates versus growth rates were noted for H. influenzae for both drugs (negative balance). In conclusion, the bactericidal activities of both drugs against S. pneumoniae and H. influenzae were similar when expressed by the relationship between the growth rate and the kill rate at 6 h, but cefdinir was more active at lower concentrations.

Cefaclor↗
PubMed1992

Killing rate and growth rate comparison for newer beta-lactamase-stable oral beta-lactams against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.

A new method of data presentation that takes into account the relationship between growth and killing rate was used to evaluate the comparative in vitro bactericidal activity of cefpodoxime, cefuroxime, cefixime and an amoxicillin/clavulanic acid combination against Streptococcus pneumoniae and beta-lactamase-producing strains of Haemophilus influenzae and Moraxella catarrhalis. For each strain, the viable count decrease (log CFU/ml) after 6 h of exposure to different antibiotic concentrations was plotted against the viable count increase in the control culture, over the same time. Higher killing rates than those predicted by growth rates were defined as a positive balance; lower rates than those predicted by growth rates were defined as a negative balance. The activity of the 4 drugs against S. pneumoniae and M. catarrhalis was characterized by a positive balance. Conversely, the 3 cephalosporins showed a negative balance for H. influenzae.

Anti-Bacterial Agents↗
PubMed1992

Susceptibility of anaerobic microorganisms to hypothiocyanite produced by lactoperoxidase.

The susceptibility of Capnocytophaga ochracea, Eikenella corrodens, Eubacterium yurii, Fusobacterium nucleatum, Peptostreptococcus micros, Prevotella intermedia, Selenomonas sputigena, Wolinella recta to hypothiocyanite (OSCN-) produced by the lactoperoxidase system was tested. Results showed a decrease of bacterial survival rate after OSCN- exposure, with an intra- and inter-species variability from 0 to 95% for C. ochracea, 34-100% for E. corrodens, 0-83% for E. yurii, 1-15% for F. nucleatum, 8-61% for P. micros, 0-100% for P. intermedia, 0-44% for S. sputigena and 0-8% for W. recta. The survival rate did not correlate with the NADH/OSCN- oxidoreductase activity present in the lysed bacteria (r = -0.3248; N = 15; NS).

Anti-Bacterial Agents↗
PubMed1979

[Listeriosis in the kidney transplant recipients. Ten cases (author's transl)].

Three clinical pictures were found in ten cases of listeriosis after renal transplantation: septicemia (six cases), meningo-encephalitis (three cases) and asymtomatic but recurrent bacteriuria (one case). Several features demonstrate profound immunologic disturbances in the recipient: close relationship in 9 cases out of 10 between infection and high doses of immunosuppressive drugs, unfavorable outcome of graft (accelerated rejection in 4 cases out of 10) and association in one case with lethal pulmonary infection due to opportunistic agents (cytomegalovirus and Pneumocystis carinii).

Adrenal Cortex Hormones↗
PubMed1979

[Pseudomonas cepacia hospital infections; uncertainties and experiences with an epidemiological investigation (author's transl)].

During a hospital outbreak of Pseudomonas cepacia a traditional epidemiological investigation was proved to be misleading. Suppression of the suspected antiseptic did not stop the epidemics. A further investigation proved that it was due to the intravenous injection of contamineted anesthetic vials. Fever, chills, lack of hemodynamic disorders and of metastatic absceses characterize the clinical state of the infected patients. The removal of the catheters for perfusion was sometimes necessary to stop the bacteraemia. A lack of medical information is responsible of the outbreak.

Anesthetics↗
PubMed1979

In vitro comparison of synergism between cefamandole and gentamicin or tobramycin by the triple layer agar method with enzymatic inactivation.

A synergistic effect was shown with gentamicin and tobramycin by means of a triple layer agar technique and enzymatic inactivation of cefamandole after only four hours' incubation. When the strain is sensitive to cefamandole and aminoglycosides, synergy is observed against all the strains studied (Staphylococcus aureus, Proteus, Klebsiella, Escherichia coli, Enterobacter, and Haemophilus influenzae). No significant difference was noted between the cefamandole-tobramycin and the cefamandole-gentamicin combinations when the microbial strains were sensitive to the three antibiotics.

Anti-Bacterial Agents↗
PubMed1979

Growth curves, microscopic morphology, and subcultures of beta-lactamase-positive and -negative Haemophilus influenzae under the influence of ampicillin and cefamandole.

In contrast to the results obtained with ampicillin, the minimum inhibitory concentrations of cefamandole against Haemophilus influenzae were within the same range (0.5 to 1.5 mug/ml) whether or not the strains were beta-lactamase producers. The minimum bactericidal concentrations were somewhat higher for beta-lactamase-positive strains (6.4 mug/ml) than for negative strains (1.2 mug/ml). In a culture with high initial microbial density, monitored by recording optical densities, the addition of 10 mug of cefamandole per ml brought about rapid lysis of a beta-lactamase-negative strain. Observation of a beta-lactamase-positive strain revealed, in the early part of the growth curve, absence of lysis and an increase of biomass similar to that observed in a drug-free control curve. In contrast to the results obtained with ampicillin, the culture consisted uniformly of spherical forms, probably in the process of division, which were capable of generating colonies. When the microbial density exposed to cefamandole was increased still further, persistent bacillary forms were observed, and after 24 h hydrolysis had eliminated every trace of microbiologically active cefamandole.

Ampicillin↗
PubMed1979

Significance of the detection of beta-galactosidase and of beta-xylosidase in the taxonomic study of the genus Haemophilus.

A total of 314 strains of Haemophilus, isolated from clinical samples, were studied for the production of beta-galactosidase and beta-xylosidase. None of the H. influenzae strains studied (9 beta-lactamase positive strains and 129 beta-lactamase negative strains) possessed these enzymes. Both enzymes were almost constantly observed among strains of H. paraphrophilus (10 strains studied) and of H. paraphrohaemolyticus (9 strains studied). Among the other species (H. parainfluenzae, 55 strains; H. haemolyticus, 5 strains; H. parahaemolyticus, 97 strains), beta-galactosidase was present in about 30% of the strains studied whereas beta-xylosidase was detected occasionally (3% of the strains studied). Detection of these two enzymes could be a valuable test for the taxonomic study of the genus Haemophilus. However, the type of substrate used for the detection of beta-xylosidase is important: use of the para-nitro-phenyl-beta-xylopyranoside yielded more positive results than the use of its ortho-isomer.

Culture Media↗
PubMed1979

Use and interpretation of Schlichter's test on Haemophilus influenzae: relation of in vitro to in vivo results for cefamandole.

When Haemophilus influenzae infections are treated by an antibiotic acting on the bacterial wall, the adequacy of antimicrobial therapy can be assessed by Schlichter's test. This test may be carried out using Mueller Hinton broth (or Mueller Hinton broth with 50% pooled serum and a supplement of Ca++ and Mg++) supplemented with Fildes' enrichment and an inoculum adjusted to the 0.5 McFarland turbidity standard diluted 200x. However, correct reading of end points can be obtained only by phase contrast microscopic examination, which allows the establishment of good correlation between the in vitro and in vivo findings. In patients with lung infections successfully treated with cefamandole, the presence of spheroplasts in samples derived from Schlichter's tests correlates well with clinical improvement and eradication of the pathogenic organism checked by transtracheal aspiration.

Blood Bactericidal Activity↗
PubMed1979

Clinical and pharmacological evaluation of different preparations of oral erythromycin.

The activity of erythromycin stearate in respiratory tract infections was evaluated. This study involved 269 out-patients. Of these, 76 satisfied the strict criteria for detailed bacteriological study with positive cultures of a known pathogen before treatment and bacteriological follow-up after treatment. The results of erythromycin stearate were good against the haemolytic streptococcal infections. The activity of this antibiotic was shown to be insufficient against Haemophilus influenzae. A second clinical trial with 20 patients with acute exacerbations of chronic bronchitis demonstrated quite good activity from erythromycin ethylsuccinate and no intolerance when administered in a dose of 1 g q.i.d. The administration of 1 g of the ethylsuccinate immediately after a meal gave a peak serum concentration after 60 min of 3.36 micrograms/ml. Blood levels on the fourth day of this treatment showed some accumulation, concentrations of greater than 4 micrograms/ml being found at 30, 60 and 90 min after the dose. With its good absorption, its lack of toxicity and its reputation for good diffusion into bronchial secretions, we consider that erythromycin ethylsuccinate should have a major place in the treatment of respiratory tract infections.

Administration, Oral↗
PubMed1979

[Ampicillin-resistant "Haemophilus": their detection and occurrence in Brussels area (author's transl)].

Three hundred and five strains of Haemophilus (129 H. influenzae, 55 H. parainfluenzae, 97 H. parahaemolyticus, 5 H. haemolyticus, 10 H. paraphrophilus and 9 H. paraphrohaemolyticus) isolated from pathological material over the year 1976, were systematically tested for beta-lactamase production. Only 2 strains of H. parainfluenzae produced this enzyme. Both were able to transfer ampicillin resistance to Escherichia coli K12. All strains but the two beta-lactamase producers were susceptible to penicillin G, ampicillin and cephalotin. However, the correct interpretation of the susceptibility tests needed the microscopic observation of prints of the inhibition zones surrounding the disks: all sensitive strains presented a hazy growth around the disks which corresponded to the presence of spheroplasts; this phenomenon was not observed with the 2 beta-lactamase producing strains of H. parainfluenzae which grew up to the disks but presented a typical bacillary form.

Ampicillin↗