title: [In vitro effect of ceftriaxone on hospital bacteria. Line of regression and critical values].
abstract: Antimicrobial activity of ceftriaxone, a new third generation cephalosporin, against hospital isolates was investigated. 312 strains belonging to the most commonly recovered species were studied using the following methods: agar diffusion (disk antibiotic testing), agar dilution (determination of MIC) and dilution in a liquid medium with subculture to agar plates (determination of MBC). Except for a few Citrobacter strains and rare Serratia strains, all Enterobacteriaceae tested proved highly susceptible, with MICs less than or equal to 1 mg/l and mode MICs ranging from 0.003 mg/l (Proteus) to 0.25 mg/l (Enterobacter). MICs ranged from 16 to 32 mg/l for Acinetobacter (mode MICs: 16 mg/l) and 16 to greater than or equal to 128 for Pseudomonas (mode MIC greater than or equal to 128 mg/l). Methicillin-susceptible staphylococci were moderately susceptible to ceftriaxone (MIC: 2 to 8 mg/l) whereas methicillin-resistant staphylococci and enterococci were resistant (MIC greater than or equal to 64 mg/l). Bactericidal activity was excellent: MBC/MIC less than or equal to 2 (except for a few Serratia strains). A correlation curve was established. Given the high serum concentrations of ceftriaxone (achieved with the usual maximal dosage) and its unusually extended half-life (7 to 8 h), the following cutoff concentrations can be proposed: C less than or equal to 4 mg/l, corresponding to greater than or equal to 20 mm: susceptible bacteria C greater than 32 mg/l, corresponding to less than 15 mm: resistant bacteria.
mesh_terms: D000150:Acinetobacter / Q000187:drug effects; D002443:Ceftriaxone / Q000494:pharmacology*; D002954:Citrobacter / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004754:Enterobacter / Q000187:drug effects; D004755:Enterobacteriaceae / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects; D006761:Hospitals; D007709:Klebsiella / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D011513:Proteus mirabilis / Q000187:drug effects; D011532:Providencia / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012705:Serratia / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D002443:Ceftriaxone
vernacular_title: Activité de la ceftriaxone in vitro sur des bactéries hospitalières. Droite de régression et valeurs critiques.