Bacteriostatic and bactericidal activities of beta-lactams against Streptococcus (Enterococcus) faecium are associated with saturation of different penicillin-binding proteins. 1987

M M Lleó, and P Canepari, and G Cornaglia, and R Fontana, and G Satta
Istituto di Microbiologia dell'Università di Verona, Italy.

The MICs and MBCs of benzylpenicillin, ampicillin, cefotaxime, and methicillin were evaluated against a Streptococcus (Enterococcus) faecium wild-type strain and against three mutants hyperproducing PBP 5 in cells incubated at both optimal and suboptimal temperatures. In the wild-type strain grown at optimal temperature, the MBCs of all beta-lactams were significantly greater than the MICs (bacteriostatic effect). As opposed to this, in the same cells grown at suboptimal temperature and in the mutants hyperproducing PBP 5 at all temperatures, the MICs of all antibiotics coincided with the MBCs (bactericidal effect). Under all conditions in which the MIC and MBC were the same, with all antibiotics, growth inhibition occurred only at the minimal concentration saturating all penicillin-binding proteins (PBPs) (or at higher concentrations). On the contrary, under conditions in which the MIC was lower than the MBC, only some of the PBPs were saturated (or bound) at both the MIC and the MBC, PBP 5 in no case being either saturated or bound. Under all conditions in which saturation of all PBPs was needed for growth inhibition, cells died at all antibiotic MBCs with kinetics which were much faster than those with which they died at the MBCs under conditions in which not all PBPs were saturated (or bound). In addition, under the former conditions, antibiotic concentrations above the MBCs did not significantly accelerate cell death kinetics, while under the latter conditions there was an acceleration in kinetics with increasing antibiotic concentrations up to full saturation of PBPs. It is suggested that the killing that occurs when all PBPs are saturated is a direct consequence of inactivation of PBP functions, while killing occurring when only some of them are saturated or bound is also (or mainly) an indirect consequence of inability of cells to grow and that, in S. faecium, the targets for growth inhibition and cell killing reside in different PBPs: for the latter effect, inactivation of one (or more) of the high-molecular-weight PBPs is sufficient, whereas in the former case inactivation of PBP 5 is necessary (after saturation of all other PBPs).

UI MeSH Term Description Entries
D008826 Microbial Sensitivity Tests Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses). Bacterial Sensitivity Tests,Drug Sensitivity Assay, Microbial,Minimum Inhibitory Concentration,Antibacterial Susceptibility Breakpoint Determination,Antibiogram,Antimicrobial Susceptibility Breakpoint Determination,Bacterial Sensitivity Test,Breakpoint Determination, Antibacterial Susceptibility,Breakpoint Determination, Antimicrobial Susceptibility,Fungal Drug Sensitivity Tests,Fungus Drug Sensitivity Tests,Sensitivity Test, Bacterial,Sensitivity Tests, Bacterial,Test, Bacterial Sensitivity,Tests, Bacterial Sensitivity,Viral Drug Sensitivity Tests,Virus Drug Sensitivity Tests,Antibiograms,Concentration, Minimum Inhibitory,Concentrations, Minimum Inhibitory,Inhibitory Concentration, Minimum,Inhibitory Concentrations, Minimum,Microbial Sensitivity Test,Minimum Inhibitory Concentrations,Sensitivity Test, Microbial,Sensitivity Tests, Microbial,Test, Microbial Sensitivity,Tests, Microbial Sensitivity
D010458 Peptidyl Transferases Acyltransferases that use AMINO ACYL TRNA as the amino acid donor in formation of a peptide bond. There are ribosomal and non-ribosomal peptidyltransferases. Peptidyl Transferase,Peptidyl Translocase,Peptidyl Translocases,Peptidyltransferase,Transpeptidase,Transpeptidases,Peptidyltransferases,Transferase, Peptidyl,Transferases, Peptidyl,Translocase, Peptidyl,Translocases, Peptidyl
D002267 Muramoylpentapeptide Carboxypeptidase Enzyme which catalyzes the peptide cross-linking of nascent CELL WALL; PEPTIDOGLYCAN. Carboxypeptidase Transpeptidase,Carboxypeptidase, Muramoylpentapeptide,Transpeptidase, Carboxypeptidase
D002352 Carrier Proteins Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes. Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D006602 Hexosyltransferases Enzymes that catalyze the transfer of hexose groups. EC 2.4.1.-.
D000900 Anti-Bacterial Agents Substances that inhibit the growth or reproduction of BACTERIA. Anti-Bacterial Agent,Anti-Bacterial Compound,Anti-Mycobacterial Agent,Antibacterial Agent,Antibiotics,Antimycobacterial Agent,Bacteriocidal Agent,Bacteriocide,Anti-Bacterial Compounds,Anti-Mycobacterial Agents,Antibacterial Agents,Antibiotic,Antimycobacterial Agents,Bacteriocidal Agents,Bacteriocides,Agent, Anti-Bacterial,Agent, Anti-Mycobacterial,Agent, Antibacterial,Agent, Antimycobacterial,Agent, Bacteriocidal,Agents, Anti-Bacterial,Agents, Anti-Mycobacterial,Agents, Antibacterial,Agents, Antimycobacterial,Agents, Bacteriocidal,Anti Bacterial Agent,Anti Bacterial Agents,Anti Bacterial Compound,Anti Bacterial Compounds,Anti Mycobacterial Agent,Anti Mycobacterial Agents,Compound, Anti-Bacterial,Compounds, Anti-Bacterial
D001426 Bacterial Proteins Proteins found in any species of bacterium. Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D013291 Streptococcus A genus of gram-positive, coccoid bacteria whose organisms occur in pairs or chains. No endospores are produced. Many species exist as commensals or parasites on man or animals with some being highly pathogenic. A few species are saprophytes and occur in the natural environment.
D013696 Temperature The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms. Temperatures
D046915 Penicillin-Binding Proteins Bacterial proteins that share the property of binding irreversibly to PENICILLINS and other ANTIBACTERIAL AGENTS derived from LACTAMS. The penicillin-binding proteins are primarily enzymes involved in CELL WALL biosynthesis including MURAMOYLPENTAPEPTIDE CARBOXYPEPTIDASE; PEPTIDE SYNTHASES; TRANSPEPTIDASES; and HEXOSYLTRANSFERASES. Penicillin-Binding Protein,Penicillin-Binding Protein 1,Penicillin-Binding Protein 1A,Penicillin-Binding Protein 1b,Penicillin-Binding Protein 2,Penicillin-Binding Protein 2a,Penicillin-Binding Protein 2b,Penicillin-Binding Protein 3,Penicillin-Binding Protein 4,Penicillin-Binding Protein 5,Penicillin-Binding Protein 6,Penicillin-Binding Protein 7,Penicillin-Binding Protein-2a,Peptidoglycan Synthetase,Penicillin Binding Protein,Penicillin Binding Protein 1,Penicillin Binding Protein 1A,Penicillin Binding Protein 1b,Penicillin Binding Protein 2,Penicillin Binding Protein 2a,Penicillin Binding Protein 2b,Penicillin Binding Protein 3,Penicillin Binding Protein 4,Penicillin Binding Protein 5,Penicillin Binding Protein 6,Penicillin Binding Protein 7,Penicillin Binding Proteins,Protein 1A, Penicillin-Binding,Protein 1b, Penicillin-Binding,Proteins, Penicillin-Binding,Synthetase, Peptidoglycan

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