Activity of trovafloxacin (with or without ampicillin-sulbactam) against enterococci in an in vitro dynamic model of infection. 1998

S H Zinner, and D Gilbert, and M N Dudley
Department of Medicine, Brown University, Roger Williams Medical Center, Providence, Rhode Island 02908, USA. Stephen.Zinner@brown.edu

Antibiotic-resistant enterococci are being increasingly identified as causal agents of infection. Trovafloxacin is a new fluoronaphthyridone with enhanced activity against gram-positive cocci and variable activity reported against Enterococcus spp. Twenty-one strains of vancomycin-resistant Enterococcus faecium and two strains of Enterococcus faecalis (one vancomycin resistant) were studied at an initial inoculum of 10(6) CFU/ml in time-kill assays with trovafloxacin (3 mg/liter), ampicillin-sulbactam (100/50 mg/liter), and the combination. Six strains of E. faecium (five vancomycin resistant) also were studied in an in vitro two-compartment dynamic model that mimics human pharmacokinetics with trovafloxacin simulated at 300 mg every 12 h (q12h), ampicillin-sulbactam at 2/1 g q6h, and the combination. Peripheral compartments were sampled q2h for 30 h for bacterial counts. Trovafloxacin MICs ranged from 0.5 to 32 mg/liter, and the nine strains of vancomycin-resistant E. faecium for which MICs were < or =2 mg/liter were more likely to show a reduction of 2 log units or more in viable counts in time-kill assays than were strains for which MICs were higher. Synergism with ampicillin-sulbactam was found for only one strain (trovafloxacin MIC, 16 mg/liter). Similar results were obtained in the pharmacokinetic model, with 2- to 4-log-unit reductions in viable bacteria for trovafloxacin-susceptible strains. Although no convincing evidence of synergism was found, ampicillin-sulbactam in combination minimized late bacterial regrowth of two trovafloxacin-susceptible strains. These data suggest that this high dose of trovafloxacin (with or without ampicillin-sulbactam) might be useful against strains of vancomycin-resistant E. faecium for which MICs were < or =2 mg/liter.

UI MeSH Term Description Entries
D008826 Microbial Sensitivity Tests Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses). Bacterial Sensitivity Tests,Drug Sensitivity Assay, Microbial,Minimum Inhibitory Concentration,Antibacterial Susceptibility Breakpoint Determination,Antibiogram,Antimicrobial Susceptibility Breakpoint Determination,Bacterial Sensitivity Test,Breakpoint Determination, Antibacterial Susceptibility,Breakpoint Determination, Antimicrobial Susceptibility,Fungal Drug Sensitivity Tests,Fungus Drug Sensitivity Tests,Sensitivity Test, Bacterial,Sensitivity Tests, Bacterial,Test, Bacterial Sensitivity,Tests, Bacterial Sensitivity,Viral Drug Sensitivity Tests,Virus Drug Sensitivity Tests,Antibiograms,Concentration, Minimum Inhibitory,Concentrations, Minimum Inhibitory,Inhibitory Concentration, Minimum,Inhibitory Concentrations, Minimum,Microbial Sensitivity Test,Minimum Inhibitory Concentrations,Sensitivity Test, Microbial,Sensitivity Tests, Microbial,Test, Microbial Sensitivity,Tests, Microbial Sensitivity
D009287 Naphthyridines A group of two-ring heterocyclic compounds consisting of a NAPHTHALENES double ring in which two carbon atoms, one per each ring, are replaced with nitrogens.
D004352 Drug Resistance, Microbial The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS). Antibiotic Resistance,Antibiotic Resistance, Microbial,Antimicrobial Resistance, Drug,Antimicrobial Drug Resistance,Antimicrobial Drug Resistances,Antimicrobial Resistances, Drug,Drug Antimicrobial Resistance,Drug Antimicrobial Resistances,Drug Resistances, Microbial,Resistance, Antibiotic,Resistance, Drug Antimicrobial,Resistances, Drug Antimicrobial
D004357 Drug Synergism The action of a drug in promoting or enhancing the effectiveness of another drug. Drug Potentiation,Drug Augmentation,Augmentation, Drug,Augmentations, Drug,Drug Augmentations,Drug Potentiations,Drug Synergisms,Potentiation, Drug,Potentiations, Drug,Synergism, Drug,Synergisms, Drug
D004359 Drug Therapy, Combination Therapy with two or more separate preparations given for a combined effect. Combination Chemotherapy,Polychemotherapy,Chemotherapy, Combination,Combination Drug Therapy,Drug Polytherapy,Therapy, Combination Drug,Chemotherapies, Combination,Combination Chemotherapies,Combination Drug Therapies,Drug Polytherapies,Drug Therapies, Combination,Polychemotherapies,Polytherapies, Drug,Polytherapy, Drug,Therapies, Combination Drug
D000667 Ampicillin Semi-synthetic derivative of penicillin that functions as an orally active broad-spectrum antibiotic. Penicillin, Aminobenzyl,Amcill,Aminobenzylpenicillin,Ampicillin Sodium,Ampicillin Trihydrate,Antibiotic KS-R1,Omnipen,Pentrexyl,Polycillin,Ukapen,Aminobenzyl Penicillin,Antibiotic KS R1,KS-R1, Antibiotic,Sodium, Ampicillin,Trihydrate, Ampicillin
D000890 Anti-Infective Agents Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection. Anti-Infective Agent,Anti-Microbial Agent,Antimicrobial Agent,Microbicide,Microbicides,Anti-Microbial Agents,Antiinfective Agents,Antimicrobial Agents,Agent, Anti-Infective,Agent, Anti-Microbial,Agent, Antimicrobial,Agents, Anti-Infective,Agents, Anti-Microbial,Agents, Antiinfective,Agents, Antimicrobial,Anti Infective Agent,Anti Infective Agents,Anti Microbial Agent,Anti Microbial Agents
D013293 Enterococcus faecalis A species of gram-positive, coccoid bacteria commonly isolated from clinical specimens and the human intestinal tract. Most strains are nonhemolytic. Streptococcus Group D,Streptococcus faecalis
D013407 Sulbactam A beta-lactamase inhibitor with very weak antibacterial action. The compound prevents antibiotic destruction of beta-lactam antibiotics by inhibiting beta-lactamases, thus extending their spectrum activity. Combinations of sulbactam with beta-lactam antibiotics have been used successfully for the therapy of infections caused by organisms resistant to the antibiotic alone. Bétamaze,CP-45899,Combactam,Penicillanic Acid Sulfone,Sulbactam Sodium,CP 45899,CP45899,Sodium, Sulbactam,Sulfone, Penicillanic Acid
D016908 Gram-Positive Bacterial Infections Infections caused by bacteria that retain the crystal violet stain (positive) when treated by the gram-staining method. Bacterial Infections, Gram-Positive,Infections, Gram-Positive Bacterial,Bacterial Infection, Gram-Positive,Bacterial Infections, Gram Positive,Gram Positive Bacterial Infections,Gram-Positive Bacterial Infection,Infection, Gram-Positive Bacterial,Infections, Gram Positive Bacterial

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