Transfer of plasmid-borne aminoglycoside-resistance determinants in staphylococci.
Aminoglycoside-resistance determinants in staphylococci are borne on conjugative and non-conjugative plasmids. The conjugative plasmids were found in methicillin-resistant strains of Staphylococcus aureus isolated recently in Darwin and Sydney, Australia and in Houston, Texas, USA. These plasmids and the class-2 conjugative plasmid reported by Archer and Johnston (1983) had similar patterns of EcoR1 restriction-endonuclease fragments, encoded resistance to gentamicin, kanamycin and neomycin, transferred to a non-lysogenic recipient in conditions that promoted close cell-to-cell contact and mobilised a small, non-conjugative plasmid. A further plasmid, pWG14, encoding resistance to kanamycin, neomycin, streptomycin, erythromycin and lincomycin, also displayed conjugative properties but did not mobilise the small, non-conjugative plasmid. The transfer frequency of all conjugative plasmids was stimulated by the addition of polyethylene glycol, particularly at concentrations above 20%, to mixtures of donor and recipient broth cultures. Polyethylene glycol appeared to promote close cell-to-cell contact between donor and recipient cells. A representative of the most common aminoglycoside-resistance plasmids in Australian isolates of methicillin-resistant S. aureus was non-conjugative and transferred by a bacteriophage-mediated system to a lysogenic recipient. With the exception of plasmid pWG14, the conjugative plasmids were also transferred by a bacteriophage-mediated system. Furthermore, cultural conditions that favoured conjugative transfer of plasmids inhibited bacteriophage-mediated transfer and vice versa. The efficacy of the two transfer systems for analysing the plasmids of gentamicin-resistant, methicillin-resistant isolates of S. aureus has been compared.
Townsend
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DE
Bolton
S
S
Ashdown
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N
Grubb
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WB
D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003227:Conjugation, Genetic / Q000187:drug effects; D003470:Culture Media; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D008242:Lysogeny; D008712:Methicillin / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology; D011815:R Factors; D013203:Staphylococcal Infections / Q000382:microbiology; D013204:Staphylococcus Phages; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*; D014161:Transduction, Genetic / Q000187:drug effects
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D003470:Culture Media; D005839:Gentamicins; D011092:Polyethylene Glycols; D008712:Methicillin