title: [Mathematical study of the sensitivity curves of Escherichia coli exposed to polymyxins].
abstract: The time killing curves of five strains of Escherichia coli (ATCC 25922, ATCC 29194, CIP 54125, CIP 54127, CIP 54117 (K 12)) exposed to five concentrations of polymyxin B are similar: latency phasis, two decreasing phasis and for the low polymyxin B concentrations growth phasis. In our experimental conditions, the Mg(+)+ and Ca(+)+ concentrations of the medium (Mueller-Hinton; medium A: Ca(+)+ = 9 mg/l, Mg(+)+ = 0.5 mg/l; medium B: Ca(+)+ = 35 mg/l, Mg(+)+ = 15.5 mg/l; medium C: Ca(+)+ = 60 mg/l, Mg(+)+ = 20 mg/l) have no time effect upon the killing curves. A decreasing biexponential model can be fitted to the data. Such a model is compatible with interaction between antibiotic and bacterium and can be formalized accorrding to the equation: T + ATB K1 in equilibrium of K2 T* - ATB K3----ATB + dead with ATB: Polymyxine B in excess, T: target bacterium and T*: modification target bacterium.
authors.affiliation: Laboratoire de Bactériologie, Faculté de Médecine Lyon Sud, Université Claude Bernard Lyon, Pierre-Benite.
authors.forename: M
authors.initials: M
authors.lastname: Peyret
authors.forename: G
authors.initials: G
authors.lastname: Carret
authors.forename: C
authors.initials: C
authors.lastname: Carre
authors.forename: G
authors.initials: G
authors.lastname: Fardel
authors.forename: J P
authors.initials: JP
authors.lastname: Flandrois
mesh_terms: D004926:Escherichia coli / Q000187:drug effects*; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D011112:Polymyxin B / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011930:Reaction Time; D012044:Regression Analysis
chemical_list: D011113:Polymyxins; D011112:Polymyxin B
vernacular_title: Etude mathématique de la courbe de mortalité d'Escherichia coli exposé aux polymyxines.