In-vitro bactericidal activity of quinupristin/dalfopristin alone and in combination against resistant strains of Enterococcus species and Staphylococcus aureus. 1997

S L Kang, and M J Rybak
School of Pharmacy, University of the Pacific, Santa Barbara, CA, USA. uoplena@aol.com

In-vitro activities of quinupristin/dalfopristin, a semisynthetic injectable streptogramin, and vancomycin were compared against multidrug-resistant Enterococcus faecium and Enterococcus faecalis, methicillin-susceptible Staphylococcus aureus ATCC 25923 and a methicillin-resistant S. aureus (MRSA). Combinations of quinupristin/dalfopristin and/or vancomycin with ofloxacin or gentamicin were evaluated using the chequerboard technique. The only synergy observed was that between quinupristin/dalfopristin plus vancomycin and quinupristin/dalfopristin plus gentamicin against E. faecium (FIC index < 0.5). Time-kill curves were performed over 24 h with an inoculum of 1 x 10(7) cfu/mL and clinically achievable concentrations of quinupristin/dalfopristin, vancomycin, ofloxacin and gentamicin (6, 30, 5 and 5 mg/L, respectively). In time-kill studies, combinations of quinupristin/dalfopristin plus vancomycin and quinupristin/dalfopristin plus gentamicin were additive, not synergic, against E. faecium and achieved 99.9% killing in 21.2 h and 19.6 h, respectively. None of the combination regimens suppressed the regrowth of E. faecalis. Quinupristin/dalfopristin combined with vancomycin demonstrated consistent synergy against ATCC 25923 and the MRSA, achieving 99.9% killing in 12.1 h and 11.9 h, respectively. Overall, quinupristin/dalfopristin alone demonstrated inhibitory activity against E. faecium, but not against E. faecalis, and bactericidal activity was achieved only with quinupristin/dalfopristin in combination with vancomycin or gentamicin against E. faecium. Quinupristin/dalfopristin plus vancomycin was the most potent and reliable combination against both strains of S. aureus in time-kill studies.

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
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
D000900 Anti-Bacterial Agents Substances that inhibit the growth or reproduction of BACTERIA. Anti-Bacterial Agent,Anti-Bacterial Compound,Anti-Mycobacterial Agent,Antibacterial Agent,Antibiotics,Antimycobacterial Agent,Bacteriocidal Agent,Bacteriocide,Anti-Bacterial Compounds,Anti-Mycobacterial Agents,Antibacterial Agents,Antibiotic,Antimycobacterial Agents,Bacteriocidal Agents,Bacteriocides,Agent, Anti-Bacterial,Agent, Anti-Mycobacterial,Agent, Antibacterial,Agent, Antimycobacterial,Agent, Bacteriocidal,Agents, Anti-Bacterial,Agents, Anti-Mycobacterial,Agents, Antibacterial,Agents, Antimycobacterial,Agents, Bacteriocidal,Anti Bacterial Agent,Anti Bacterial Agents,Anti Bacterial Compound,Anti Bacterial Compounds,Anti Mycobacterial Agent,Anti Mycobacterial Agents,Compound, Anti-Bacterial,Compounds, Anti-Bacterial
D013211 Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications.
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor
D014640 Vancomycin Antibacterial obtained from Streptomyces orientalis. It is a glycopeptide related to RISTOCETIN that inhibits bacterial cell wall assembly and is toxic to kidneys and the inner ear. AB-Vancomycin,Diatracin,VANCO-cell,Vanco Azupharma,Vanco-saar,Vancocin,Vancocin HCl,Vancocine,Vancomicina Abbott,Vancomicina Chiesi,Vancomicina Combino Phar,Vancomicina Norman,Vancomycin Hexal,Vancomycin Hydrochloride,Vancomycin Lilly,Vancomycin Phosphate (1:2),Vancomycin Phosphate (1:2), Decahydrate,Vancomycin Sulfate,Vancomycin-ratiopharm,Vancomycine Dakota,Hydrochloride, Vancomycin,Sulfate, Vancomycin
D014769 Virginiamycin A cyclic polypeptide antibiotic complex from Streptomyces virginiae, S. loidensis, S. mitakaensis, S. pristina-spiralis, S. ostreogriseus, and others. It consists of 2 major components, VIRGINIAMYCIN FACTOR M1 and virginiamycin Factor S1. It is used to treat infections with gram-positive organisms and as a growth promoter in cattle, swine, and poultry. Staphylomycin,Antibiotic 899,Eskalin,Founderguard,Stajac,Virgimycine
D015169 Colony Count, Microbial Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing. Agar Dilution Count,Colony-Forming Units Assay, Microbial,Fungal Count,Pour Plate Count,Spore Count,Spread Plate Count,Streak Plate Count,Colony Forming Units Assay, Microbial,Colony Forming Units Assays, Microbial,Agar Dilution Counts,Colony Counts, Microbial,Count, Agar Dilution,Count, Fungal,Count, Microbial Colony,Count, Pour Plate,Count, Spore,Count, Spread Plate,Count, Streak Plate,Counts, Agar Dilution,Counts, Fungal,Counts, Microbial Colony,Counts, Pour Plate,Counts, Spore,Counts, Spread Plate,Counts, Streak Plate,Dilution Count, Agar,Dilution Counts, Agar,Fungal Counts,Microbial Colony Count,Microbial Colony Counts,Pour Plate Counts,Spore Counts,Spread Plate Counts,Streak Plate Counts
D016106 Methicillin Resistance Non-susceptibility of a microbe to the action of METHICILLIN, a semi-synthetic penicillin derivative. Methicillin-Resistant,Methicillin Resistant,Resistance, Methicillin
D016983 Enterococcus A genus of gram-positive, coccoid bacteria consisting of organisms causing variable hemolysis that are normal flora of the intestinal tract. Previously thought to be a member of the genus STREPTOCOCCUS, it is now recognized as a separate genus.

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