Borderline susceptibility to antistaphylococcal penicillins is not conferred exclusively by the hyperproduction of beta-lactamase
Autor: | Henry F. Chambers, Douglas S. Kernodle, N L Barg |
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Rok vydání: | 1991 |
Předmět: |
Staphylococcus aureus
Penicillin binding proteins Penicillin Resistance medicine.medical_treatment Microbial Sensitivity Tests Penicillins Muramoylpentapeptide Carboxypeptidase Biology medicine.disease_cause beta-Lactamases Microbiology Muramoylpentapeptide carboxypeptidase Plasmid Bacterial Proteins Phage group medicine Penicillin-Binding Proteins Pharmacology (medical) Bacteriophage Typing Phage typing Pharmacology Nucleic Acid Hybridization Blotting Northern Penicillin Phenotype Infectious Diseases Hexosyltransferases Peptidyl Transferases Beta-lactamase Carrier Proteins DNA Probes Plasmids Research Article medicine.drug |
Zdroj: | Antimicrobial Agents and Chemotherapy. 35:1975-1979 |
ISSN: | 1098-6596 0066-4804 |
DOI: | 10.1128/aac.35.10.1975 |
Popis: | Staphylococcus aureus strains bearing the 17.2-kb beta-lactamase plasmid pBW15 and belonging to phage group 94/96 exhibit borderline susceptibility to the antistaphylococcal penicillins. Borderline susceptibility within phage group 94/96 is thought to be mediated by the hyperproduction of type A staphylococcal beta-lactamase. Evaluation of 84 non-94/96 phage type S. aureus strains that also produced the type A enzyme identified 7 additional hyperproducing strains. However, none of these isolates contained pBW15, and only one met the criteria for borderline susceptibility. To determine the role of pBW15 and the 94/96 phage type in the expression of borderline susceptibility, pBW15 was transformed in two plasmid-free, penicillin-susceptible strains, one of which belonged to phage group 94/96. Penicillin MICs for both transformants and quantitative beta-lactamase activity were comparable to those for the parent pBW15-containing strain. A fourfold difference in the oxacillin MICs for the 94/96 and non-94/96 phage type transformants (1.0 and 0.25 microgram/ml, respectively) was identified, and only the 94/96 phage type transformant met the criteria for borderline susceptibility. Chromosomal DNA from borderline-susceptible phage group 94/96 strains did not hybridize with a probe for mecA, and the beta-lactam binding affinity of PBPs 1, 2, 3, and 4 from a penicillin-susceptible 94/96 phage type strain and a non-94/96 phage type strain were comparable. Although hyperproduction of the type A beta-lactamase appears to be necessary for the expression of borderline susceptibility within certain phage group 94/96 strains, beta-lactamase production of a comparable magnitude by a group of S. aureus strains belonging to other phage types does not confer borderline susceptibility. These data suggest that borderline susceptibility is not solely due to the hyperproduction of beta-lactamase. |
Databáze: | OpenAIRE |
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