Polyfunctional Penicillinase Plasmid in Staphylococcus epidermidis : Bacteriophage Restriction and Modification Mutants

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 determninants for the active uptake of mannitol and ,8-glucosides, ribose fermentation, and phospho ,B-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.

Antibiotic resistance plasmids of Staphylococcus aureus and their clinical importance.

“…(i) S. albus is often antibiotic resistant (52). (ii) Plasmids exist in S. albus (127,183). (iii) The plasmid coding for tetracycline resistance in a strain of S. albus has similar properties to those of S. aureus (127).…”

Rapid procedure for the detection of plasmids in Staphylococcus epidermidis

“…It was hard to correlate the presence of a typical plasmid size with Pc resistance in S. epidermidis because pcr and Pcs strains had similarly sized plasmid bands. This resistance has been shown to be carried on a 12to 21megadalton plasmid in S. aureus (4) and is suspected to be plasmid borne in S. epidermidis (1, 7,9,11). Unlike the situation in most strains of S. aureus, Pc and Cd resistance may not be linked in S. epidermidis (1, 15).…”

“…The evidence for a plasmid location for Pc resistance in S. epidermidis is based on curing procedures or on kinetics of transduction. However, because phage typing patterns have been found to change with loss or gain of Pc genes (9,11), as has novobiocin susceptibility (7, 11), we have found it convenient in our laboratory to check our cured derivatives and transductants with this mini-volume Brij lysis procedure. The prevalence of cryptic plasmids in S. epidermidis makes this an excellent method of identifying strains and ruling out contaminants that almost certainly would have a completely different plasmid set.…”

Coagulase-negative staphylococci and the epidemiological typing of Staphylococcus epidermidis.

“…It is also possible that the differences observed between genetically related strains may be due to the presence of extrachromosomal genes that encode some of the characters studied (76). Some evidence suggests that certain of the genes controlling carbohydrate fermentations are linked to the genes controlling penicillinase production, which has been shown to be located on a plasmid (130,160). However, except for the genetics of antimicrobial resistance, the genetics of other determinants in S. epidermidis has been largely unexplored.…”