title: Determination of an inoculum effect with various cephalosporins among clinical isolates of methicillin-susceptible Staphylococcus aureus.
abstract: Using 98 clinical methicillin-susceptible Staphylococcus aureus isolates of known beta-lactamase (Bla) type, we found a pronounced inoculum effect for cephalexin (mostly Bla type A and C strains), a mild inoculum effect for cephalothin (especially types B and C), and no inoculum effects for ceftriaxone and cefuroxime. Ceftobiprole showed the lowest MICs at a high inoculum but with a slight increase for Bla-positive versus Bla-negative strains. Since a potential therapeutic effect associated with a cephalosporin inoculum effect has been described, further studies are warranted.
authors.affiliation: Division of Infectious Diseases, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Provincia de Santa Fe, Argentina. enannini@cimero.org.ar
authors.forename: Esteban C
authors.initials: EC
authors.lastname: Nannini
authors.forename: Martin E
authors.initials: ME
authors.lastname: Stryjewski
authors.forename: Kavindra V
authors.initials: KV
authors.lastname: Singh
authors.forename: Tom H
authors.initials: TH
authors.lastname: Rude
authors.forename: G Ralph
authors.initials: GR
authors.lastname: Corey
authors.forename: Vance G
authors.initials: VG
authors.lastname: Fowler
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Murray
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology; D002444:Cefuroxime / Q000494:pharmacology; D002506:Cephalexin / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D002512:Cephalothin / Q000494:pharmacology; D006801:Humans; D008712:Methicillin; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development*
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D002443:Ceftriaxone; D002444:Cefuroxime; D002506:Cephalexin; D008712:Methicillin; D002512:Cephalothin