Inhibition of peptidoglycan cross-linking in growing cells of Escherichia coli by penicillins and cephalosporins, and its prevention by R factor-mediated beta-lactamase
| Autor: | Julia M. Hughes, Nigel Curtis, Gordon W. Ross |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
medicine.drug_class
Penicillin Resistance R Factors Antibiotics Penicillins Peptidoglycan Biology medicine.disease_cause Microbiology Amidohydrolases chemistry.chemical_compound medicine Cephaloridine Escherichia coli Pharmacology (medical) Cephalosporinase Pharmacology Penicillinase Chemistry Mechanisms of Action and Resistance Cephalosporins Penicillin Infectious Diseases chemistry Biochemistry Depression Chemical Diaminopimelic acid Lysozyme Cell envelope Rifampin medicine.drug Plasmids |
| Zdroj: | Antimicrobial agents and chemotherapy. 9(2) |
| ISSN: | 0066-4804 |
| Popis: | The degree of peptidoglycan cross-linking has been studied in growing cells of a Dap − Lys − auxotroph of Escherichia coli K-12 by following the incorporation of [ 3 H]diaminopimelic acid into the lysozyme digestion products of crude, isolated peptidoglycan. The percentage of inhibition of cross-linking increases with increasing concentrations of penicillin G, cephaloridine, and cefuroxime. When the R factor R1 drd 19 was introduced into the strain by conjugation, it was found that the type IIIa, β-lactamase specified by the plasmid was able to protect the cross-linking target against inhibition by penicillin G but not against cephaloridine, even though the β-lactamase hydrolyzes this substrate 50% faster than penicillin G. Cefuroxime, which is completely resistant to hydrolysis by the type IIIa β-lactamase, inhibited the peptidoglycan cross-linking target in both the R + and R − variants of the assay strain. A mutant plasmid, R1 drd 19 amp 2, which specified no type IIIa β-lactamase synthesis, could not provide protection of the cross-linking target against penicillin G. The significance of these results, in relation to the ability of the antibiotics to pass the permeability barrier of the bacterial envelope, is discussed. |
| Databáze: | OpenAIRE |
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