title: Antibiotic susceptibilities and plasmid profiles of nosocomial methicillin-resistant Staphylococcus aureus: a retrospective study.
abstract: Methicillin-resistant Staphylococcus aureus strains isolated at a single Melbourne Hospital between 1969 and 1981 were examined for susceptibility to a range of antimicrobial agents and for the presence of plasmid DNA. Isolates obtained during 1969 possessed a plasmid of mol. wt 20 X 10(6), encoding heavy metal resistance and penicillinase production, and a plasmid of mol. wt 2.8 X 10(6), mediating tetracycline resistance. In the majority of isolates obtained after 1973, these functions were chromosomally encoded. Before 1980, both high- and low-level chromosomally-encoded gentamicin resistances were encountered, whereas isolates from 1980 and 1981 displayed low-level gentamicin resistance only; the latter phenotype was most commonly mediated by a plasmid of mol. wt 18 X 10(6) that also encoded resistance to tobramycin and kanamycin. Chloramphenicol resistance in strains isolated throughout the period was mediated by one of three plasmids, each of mol. wt c. 3 X 10(6).
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001315:Australia; D001434:Bacteriophage Typing; D002104:Cadmium / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D003428:Cross Infection / Q000382:microbiology*; D004917:Erythromycin / Q000494:pharmacology; D006801:Humans; D008712:Methicillin / Q000494:pharmacology*; D010403:Penicillin Resistance; D010641:Phenotype; D010957:Plasmids; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D002104:Cadmium; D004917:Erythromycin; D002701:Chloramphenicol; D013752:Tetracycline; D008712:Methicillin