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Polyfunctional penicillinase plasmid in Staphylococcus epidermidis: bacteriophage restriction and modification
Abstract:
Growth of multiply resistant Staphylococcus epidermidis BV strains at 45 C resulted in the independent elimination of tetracycline resistance, of kanamycin resistance coupled with oxacillin resistance, or of penicillinase activity. The pH optimum for the elimination of kanamycin and oxacillin resistance was 5.6, whereas that for elimination of penicillinase activity was 8.0. The genetic determinant for penicillinase activity was linked with the genetic determinants for the active uptake of mannitol and beta-glucosides, ribose fermentation, and phospho beta-glucosidase activity. The penicillinase linkage group also contained determinants for phage adsorption, restriction, and modification, and for growth factor requirements of still unknown nature. The same linkage group, which is apparently of extrachromosomal nature, was eliminated from several S. epidermidis BV strains. By selection for novobiocin resistance, deletion mutants affecting several loci of the penicillinase plasmid were isolated. The isolation of restriction-negative and modification-negative mutants which retained phage susceptibility allowed the investigation of restriction and modification phenomena. A preliminary deletion map of the polyfunctional penicillinase plasmid is proposed.
Insights
Multiply resistant Staphylococcus epidermidis strains lost resistance genes at high temperatures. Researchers mapped these linked resistance genes on a plasmid, aiding in understanding bacterial resistance mechanisms.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Staphylococcus epidermidis (S. epidermidis) is a significant opportunistic pathogen.
- Multiply resistant strains pose a therapeutic challenge.
- Understanding the genetic basis of resistance is crucial for developing new treatment strategies.
Purpose of the Study:
- To investigate the genetic basis of multiple drug resistance in Staphylococcus epidermidis.
- To characterize the genetic linkage of various resistance determinants.
- To construct a preliminary deletion map of the penicillinase plasmid.
Main Methods:
- Culturing multiply resistant S. epidermidis BV strains at 45°C to induce gene elimination.
- Investigating pH optima for the elimination of specific resistance traits.
- Isolating deletion mutants by selecting for novobiocin resistance.
- Analyzing phage adsorption, restriction, and modification phenomena in isolated mutants.
Main Results:
- Independent elimination of tetracycline resistance, kanamycin/oxacillin resistance, and penicillinase activity observed.
- Distinct pH optima (5.6 and 8.0) for elimination of different resistance traits.
- Penicillinase activity linked with mannitol/beta-glucosides uptake, ribose fermentation, phospho-beta-glucosidase, phage interactions, and growth factor requirements on an extrachromosomal element.
- Preliminary deletion map of the polyfunctional penicillinase plasmid constructed.
Conclusions:
- The study elucidates the genetic organization and extrachromosomal nature of a polyfunctional penicillinase plasmid in S. epidermidis.
- The findings provide insights into the mechanisms of resistance gene linkage and elimination.
- Characterization of restriction and modification mutants aids in understanding these phage-related phenomena.