title: Cefotaxime and Amoxicillin-Clavulanate Synergism against Extended-Spectrum-β-Lactamase-Producing Escherichia coli in a Murine Model of Urinary Tract Infection.
abstract: We investigated the efficacies of cefotaxime (CTX) and amoxicillin (AMX)-clavulanate (CLA) (AMC) against extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli in vitro and in a murine model of urinary tract infection (UTI). MICs, the checkerboard dilution method, and time-kill curves were used to explore the in vitro synergism between cefotaxime and amoxicillin-clavulanate against two isogenic E. coli strains-CFT073-RR and its transconjugant, CFT073-RR Tc bla(CTX-M-15)-harboring a bla(CTX-M-15) plasmid and a bla(OXA-1) plasmid. For in vivo experiments, mice were separately infected with each strain and treated with cefotaxime, amoxicillin, and clavulanate, alone or in combination, or imipenem, using therapeutic regimens reproducing time of free-drug concentrations above the MIC (fT≥MIC) values close to that obtained in humans. MICs of amoxicillin, cefotaxime, and imipenem were 4/>1,024, 0.125/1,024, and 0.5/0.5 mg/liter, for CFT073-RR and CFT073-RR Tc bla(CTX-M-15), respectively. The addition of 2 mg/liter of clavulanate (CLA) restored the susceptibility of CFT073-RR Tc bla(CTX-M-15) to CTX (MICs of the CTX-CLA combination, 0.125 mg/liter). The checkerboard dilution method and time-kill curves confirmed an in vitro synergy between amoxicillin-clavulanate and cefotaxime against CFT073-RR Tc bla(CTX-M-15). In vivo, this antibiotic combination was similarly active against both strains and as effective as imipenem. In conclusion, the cefotaxime and amoxicillin-clavulanate combination appear to be an effective, easy, and already available alternative to carbapenems for the treatment of UTI due to CTX-M-producing E. coli strains.
authors.affiliation: INSERM UMR1137, IAME, Paris, France AP-HP, Hôpital Beaujon, Service de Médecine Interne, Clichy, France.
authors.forename: B
authors.initials: B
authors.lastname: Rossi
authors.affiliation: INSERM UMR1137, IAME, Paris, France.
authors.forename: J F
authors.initials: JF
authors.lastname: Soubirou
authors.affiliation: INSERM UMR1137, IAME, Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Chau
authors.affiliation: INSERM UMR1137, IAME, Paris, France AP-HP, Hôpital Bichat, Laboratoire de Toxicologie-Pharmacocinétique, Service de Pharmacie, Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Massias
authors.affiliation: INSERM UMR1137, IAME, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Dion
authors.affiliation: INSERM UMR1137, IAME, Paris, France.
authors.forename: R
authors.initials: R
authors.lastname: Lepeule
authors.affiliation: INSERM UMR1137, IAME, Paris, France AP-HP, Hôpital Beaujon, Service de Médecine Interne, Clichy, France.
authors.forename: B
authors.initials: B
authors.lastname: Fantin
authors.affiliation: INSERM UMR1137, IAME, Paris, France AP-HP, Hôpital Beaujon, Service de Médecine Interne, Clichy, France agnes.lefort@bjn.aphp.fr.
authors.forename: A
authors.initials: A
authors.lastname: Lefort
mesh_terms: D019980:Amoxicillin-Potassium Clavulanate Combination / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D002439:Cefotaxime / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D004195:Disease Models, Animal; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D015870:Gene Expression; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D051379:Mice; D008808:Mice, Inbred CBA; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011704:Pyelonephritis / Q000097:blood / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D014552:Urinary Tract Infections / Q000097:blood / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D056689:Uropathogenic Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D015378:Imipenem; D019980:Amoxicillin-Potassium Clavulanate Combination; D001618:beta-Lactamases; D002439:Cefotaxime