Transduction of Methicillin Resistance in Staphylococcus aureus Dependent on an Unusual Specificity of the Recipient Strain

Abstract

Resistance to methicillin was transduced by phage 80 or 53 from two naturally occurring methicillin-resistant strains of Staphylococcus aureus to methicillinsusceptible recipient strains at frequencies of 10-v to 10-9. Ultraviolet irradiation of transducing phage and posttransductional incubation at 30 C were essential for useful frequencies of transduction. Effectiveness as a recipient for this transduction was highly specific. Strain NCTC 8325 (PS47) in its native state was an ineffective recipient but became effective after it had received by transduction one of several penicillinase plasmids. This acquired effectiveness was retained in most cases after elimination of the plasmid by ethidium bromide treatment. Like the donor strain, the progeny were heterogeneous in the degree of their resistance to methicillin, which was expressed by a higher proportion of cells as the temperature of incubation was lowered from 37 to 30 C. Separate transductants varied widely in the degree of resistance acquired by transduction. Methicillin resistance was stable in the donor and transductant strains. We favored the interpretation that methicillin resistance in our strains was determined by a single chromosomal gene, although the possibility that it was determined by two or more closely linked genes could not be excluded.

Bacteriophages of Staphylococcus aureus efficiently package various bacterial genes and mobile genetic elements including SCCmec with different frequencies

“…Transfer of the SCCmec element via bacteriophages has not yet been proven, it is hypothesized that in particular the elements of size smaller than the S. aureus siphophage genome (45 kb), such as the SCCmec type I or type IV elements, can be transferred via generalized transduction. Experimental evidence for phage-mediated transduction of methicillin resistance by bacteriophages j80 and j53 from different naturally occurring MRSA strains to strain 8325 variants with low frequencies, which depended on the selected transducing systems had been described by Cohen and Sweeney (1970). Later, it was shown that this transduction is efficient only in recipient strains with a penicillinase plasmid (Cohen and Sweeney, 1973;Stewart and Rosenblum, 1980).…”

Phenotypic Suppression of Methicillin Resistance in Staphylococcus aureus by Mutant Noninducible Penicillinase Plasmids

“…The genetic locus of methicillin resistance is still uncertain. Transduction experiments with our strains have shown no linkage of this determinant with penicillinase plasmids (8). However, other workers, using different strains, have reported some co-transduction of methicillin resistance and penicillinase plasmids and have suggested that methicillin resistance may be plasmid-mediated (9,10).…”

“…Organisms. The nomenclature and the designations of most of the organisms employed have been described (8,25). The methicillin-resistant S. aureus strain Dumas, originally described by Dornbusch et al (10), was obtained from S. J. Seligman.…”

Transduction and Plasmid Deoxyribonucleic Acid Analysis in a Multiply Antibiotic-Resistant Strain of Staphylococcus epidermidis

“…We were also unable to transduce the mth marker into strains 62, 108, or 247. Cohen and Sweeney (6) have observed that transduction of mth is more likely to occur in S. aureus if the recipient strains contain penicillinase plasmids. For this reason, we tried to transduce mth into an additional 12 S. epidermidis strains which were penicillinase producers, although it was not known if these resistances were due to chromosomal or plasmid genes.…”