title: Prevalence of blaZ gene types and the inoculum effect with cefazolin among bloodstream isolates of methicillin-susceptible Staphylococcus aureus.
abstract: We sought to define the prevalence of blaZ gene types and the inoculum effect to cefazolin among methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections. The blaZ gene was present in 142/185 (77%) isolates. A total of 50 (27%) isolates had a ≥4-fold increase in the cefazolin MIC from a standard to a high inoculum, and 8 (4%) demonstrated a nonsusceptible cefazolin MIC, all type A blaZ strains. The efficacy of cefazolin in the presence of the inoculum effect requires further study.
authors.affiliation: Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA. dlivorsi@iupui.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Livorsi
authors.forename: E
authors.initials: E
authors.lastname: Crispell
authors.forename: S W
authors.initials: SW
authors.lastname: Satola
authors.forename: E M
authors.initials: EM
authors.lastname: Burd
authors.forename: R
authors.initials: R
authors.lastname: Jerris
authors.forename: Y F
authors.initials: YF
authors.lastname: Wang
authors.forename: M M
authors.initials: MM
authors.lastname: Farley
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology*; D002437:Cefazolin / Q000494:pharmacology*; D002648:Child; D006801:Humans; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases; D002437:Cefazolin