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M Guionie

Publications and source records attributed to M Guionie.

11 recordsLinked to original sources
PubMed1986

Beta-lactamase stability of imipenem.

The beta-lactamase stability and interactions of imipenem were analysed in comparison with those of cefazolin, cefuroxime, cefoxitin, cefotaxime, ceftazidime, mezlocillin, piperacillin and penicillin G for a set of representative beta-lactamases. These enzymes included penicillinases such as those obtained from Staphylococcus aureus, Escherichia coli and other Enterobacteriaceae (TEM-1 and similar enzymes) (group A); cephalosporinases produced by Esch. coli (Amp C type), Serratia liquefaciens, Enterobacter cloacae, Pseudomonas aeruginosa (group B); and beta-lactamases produced by Klebsiella spp., Proteus vulgaris and Bacteroides fragilis and with a high hydrolytic activity for the newer cephalosporins (group C). Enzymes of group A were demonstrated to be highly active against penicillins and also against the early cephalosporins; enzymes of group B showed hydrolytic activity for all other tested compounds, including the newer cephalosporins and cephamycins, but not imipenem, whereas enzymes of group C were highly active against the new cephalosporins but not against cephamycins and imipenem. In conclusion, imipenem shows a moderate affinity for all these enzymes but no detectable hydrolysis.

Enzyme Stability↗
PubMed1986

[Klebsiella oxytoca beta-lactamases: study of their action on 3d-generation cephalosporins].

Indole-positive Klebsiella pneumoniae or K. oxytoca are usually resistant to penicillins as a result of the production of a chromosomally-mediated beta-lactamase with a low level of synthesis (specific activity approximately 50 to 100 mU/mg). Although most strains are susceptible to the majority of cephalosporins, some strains exhibit resistance to cephalosporins including third-generation drugs. These resistant strains produce a chromosomally-mediated beta-lactamase with a high level of synthesis (specific activity approximately 5,000 mU/mg or higher). Four beta-lactamases have been identified on the basis of their isoelectric points: pI = 5.5, 5.7, 6.0 and 6.3; nevertheless they have similar kinetic constants, and are inhibited by clavulanic acid. These enzymes hydrolyze most third-generation cephalosporins, in the following order of decreasing velocities: cefoperazone, ceftriaxone, cefotaxime, cefodizime, cefpirome; ceftazidime, and cefoxitin, cefotetan, latamoxef, cephamycins which are totally resistant to these enzymes.

Cephalosporins↗
PubMed1978

Beta-lactamases: determination of their isoelectric points.

Important discrepancies in isoelectric points (pI) of beta-lactamases were observed depending on the experimental procedure used for their determination: isoelectric focusing (IEF) in sucrose density gradients or analytical IEF in thin-layer polyacrylamide gels (PA). The variations, negligable in the case of TEM-like beta-lactamases, appeared to be important in the case of cephalosporinases and are related to an artifact which appears in PA-IEF. This has been clearly shown with beta-lactamase preparations from the following bacterial strains: Pseudomonas aeruginosa NCTC 8203 (pI = 8.7), P. aeruginosa NCTC 10701 (pI = 9.4), and Proteus morganii NCTC 235 (pI = 8.3). The data previously obtained by PA-IEF were much lower.

Amidohydrolases↗
PubMed1977

Beta-lactamases produced by a Pseudomonas aeruginosa strain highly resistant to carbenicillin.

A Pseudomonas aeruginosa strain isolated at Besançon Hospital, France, proved to be highly resistant to carbenicillin and showed a high hydrolytic activity toward this antibiotic. We clearly demonstrated that two beta-lactamases were synthetized: one of them, constitutive, has its enzymatic activity directed mainly toward penicillins, and carbenicillin appears to be its best substrate (higher V(max)); thus, this beta-lactamase is a "carbenicillinase" that differs from the well-known "TEM-like" enzymes. The isoelectric point of this carbenicillinase is 5.30 +/- 0.03. The other one is an inducible cephalosporinase, very similar to the cephalosporinases usually found in these organisms. Its isoelectric point is 8.66 +/- 0.04. These two enzymes have been separated by affinity chromatography and isoelectric focusing. The kinetic constants were measured by computerized microacidimetry.

Amidohydrolases↗
PubMed1976

[Inducible cephalosporinases from Proteus morganii].

It has been shown that two Proteus morganii strains produce an inducible cephalosporinase. No significative difference was shown between them: they present the same isoelectric poit: 8,3 and very similar kinetic constants. The parameter tau, proportional to the half life of antibiotic at low concentration, in presence of beta lactamase, shows that cefamandole is the most stable cephalosporin studied.

Amidohydrolases↗
PubMed1976

[Kinetics of a new cephalosporinase from Pseudomonas aeruginosa].

Pseudomonas aeruginosa strain RL 39 produces an inducible cephalosporinase possessing an isoelectric point of 8,66. The kinetic constants have been measured by computerized microacidimetry. The results allow to differenciate this enzyme from the one produced by Ps. aeruginosa GN 918 (Yaginuma et al. (1973) Jap. J. Microbiol., 17, 141-149) showing a similar isoelectric point.

Amidohydrolases↗
PubMedDate not supplied

[Affinity of N-formimidoyl-thienamycin (MK-0787) for beta-lactamases, analysis by a statistical method: correspondence analysis].

N-formimidoyl-thienamycin (MK-0787) is not subject to beta-lactamase hydrolysis. Nevertheless, this compound does show some affinity for the TEM-type penicillinases, cephalosporinases and a few other beta-lactamases. Surprisingly no affinity was found for the penicillinases of the CARB-type. The results thus obtained for affinity constants Ki and Km were submitted to a statistical analysis treatment, i.e. correspondence analysis and hierarchic ascendent classification. This confirms the fact that MK-0787 presents an unusual behaviour towards beta-lactamases.

Cephalosporinase↗
PubMedDate not supplied

Semi-quantification of a microbiological method using beta-lactamases in detecting the hydrolysis of beta-lactam antibiotics.

The so-called "double disc" technique of Masuda et al. for detecting the hydrolysis of beta-lactams by beta-lactamases was semi-quantified. This semi-quantification consisted of using beta-lactamase preparations progressively diluted by a factor of ten. The last dilution producing a detectable hydrolysis of the antibiotic was thus noted. By using the species Escherichia coli (potentially cephalosporinase producer) as a model, we studied the possible applications of this method. Due to its great sensitivity it was possible to analyse and appreciate the degradation of some cephalosporins reputedly resistant to beta-lactamases, such as cefoxitin, cefuroxime, cefamandole and cefotaxime. The carboxy-penicillins (carbenicillin and ticarcillin) were the most stable beta-lactams towards the cephalosporinase of E. coli 0002.

Cephalosporins↗