title: [Should resistance to methicillin of RH mutant staphylococci be necessarily attributed to cephalosporins?].
abstract: The resistance to cephalosporins of 48 heterogeneous methicillin-resistant strains ("RH" mutants) of Staphylococcus pyogenes var. aureus is studied in vitro with various methods: sensitivity discs test on Mueller-Hinton medium with 5 per cent NaCl at 37 degrees C; M.I.C. in solid medium by spots medium with two inocula: a light inoculum (10(7) bacterial/ml) and a heavy inoculum (10(9) bacteria/ml). With light inoculum all strains have M.I.C. to cephaloridin less than 2 meg/ml and seem sensitive. With heavy inoculum 45 sc. equal or superior to 64 meg/ml and then are resistant. These resistances occur after 3 degrees C. The varied methods of detection of mutants to cephalosporins are discussed in this paper.
mesh_terms: D002511:Cephalosporins / Q000494:pharmacology*; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D008712:Methicillin / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods; D009154:Mutation; D010068:Oxacillin / Q000494:pharmacology*; D010403:Penicillin Resistance; D010405:Penicillinase / Q000032:analysis; D010641:Phenotype; D013210:Staphylococcus / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D002511:Cephalosporins; D003470:Culture Media; D010405:Penicillinase; D008712:Methicillin; D010068:Oxacillin
vernacular_title: La résistance a la méthicilline des staphylocoques mutants RH doit-elle étre obligatoirement extrapolée aux céphalosporines?