scholarly journals In vitro activity of tea-tree oil against clinical skin isolates of meticillin-resistant and -sensitive Staphylococcus aureus and coagulase-negative staphylococci growing planktonically and as biofilms

2006 ◽  
Vol 55 (10) ◽  
pp. 1375-1380 ◽  
Author(s):  
Aaron Brady ◽  
Ryan Loughlin ◽  
Deirdre Gilpin ◽  
Paddy Kearney ◽  
Michael Tunney
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Viable Count ◽  
Tea Tree Oil ◽  
Coagulase Negative Staphylococci ◽  
Tea Tree ◽  
Skin Flora ◽  
Significant Difference ◽  
Time Kill

The susceptibility of Staphylococcus aureus [meticillin-resistant (MRSA) and meticillin-sensitive (MSSA)] and coagulase-negative staphylococci (CoNS), which respectively form part of the transient and commensal skin flora, to tea-tree oil (TTO) was compared using broth microdilution and quantitative in vitro time–kill test methods. MRSA and MSSA isolates were significantly less susceptible than CoNS isolates, as measured by both MIC and minimum bactericidal concentration. A significant decrease in the mean viable count of all isolates in comparison with the control was seen at each time interval in time–kill assays. However, the only significant difference in the overall mean log10 reduction in viable count between the groups of isolates was between CoNS and MSSA at 3 h, with CoNS isolates demonstrating a significantly lower mean reduction. To provide a better simulation of in vivo conditions on the skin, where bacteria are reported to grow as microcolonies encased in glycocalyx, the bactericidal activity of TTO against isolates grown as biofilms was also compared. Biofilms formed by MSSA and MRSA isolates were completely eradicated following exposure to 5 % TTO for 1 h. In contrast, of the biofilms formed by the nine CoNS isolates tested, only five were completely killed, although a reduction in viable count was apparent for the other four isolates. These results suggest that TTO exerts a greater bactericidal activity against biofilm-grown MRSA and MSSA isolates than against some biofilm-grown CoNS isolates.

scholarly journals Dalbavancin, Vancomycin and Daptomycin Alone and in Combination with Cefazolin against Resistant Phenotypes of Staphylococcus aureus in a Pharmacokinetic/Pharmacodynamic Model

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 696 ◽  
Author(s):  
Jacinda C. Abdul-Mutakabbir ◽  
Razieh Kebriaei ◽  
Kyle C. Stamper ◽  
Zain Sheikh ◽  
Philip T. Maassen ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Inhibitory Concentration ◽  
Pharmacodynamic Model ◽  
In Vitro Tests ◽  
Beta Lactam ◽  
Fold Reduction ◽  
The One ◽  
Time Kill

The most efficacious antimicrobial therapy to aid in the successful elimination of resistant S. aureus infections is unknown. In this study, we evaluated varying phenotypes of S. aureus against dalbavancin (DAL), vancomycin (VAN), and daptomycin (DAP) alone and in combination with cefazolin (CFZ). The objective of this study was to observe whether there was a therapeutic improvement in adding a beta-lactam to a glycopeptide, lipopeptide, or a lipoglycopeptide. We completed a series of in vitro tests including minimum inhibitory concentration testing (MIC) of the antimicrobials in combination, time-kill analysis (TKA), and a 168 h (7-day) one-compartment pharmacokinetic/pharmacodynamic (PK/PD) model on two daptomycin non-susceptible (DNS), vancomycin intermediate S. aureus strains (VISA), D712 and 6913. Results from our MIC testing demonstrated a minimum 2-fold and a maximum 32-fold reduction in MIC values for DAL, VAN, and DAP in combination with CFZ, in contrast to either agent used alone. The TKAs completed on four strains paralleled the enhanced activity demonstrated via the combination MICs. In the one-compartment PK/PD models, the combination of DAP plus CFZ or VAN plus CFZ resulted in a significant (p < 0.001) improvement in bactericidal activity and overall reduction in CFU/ml over the 7-day period. While the addition of CFZ to DAL improved time to bactericidal activity, DAL alone demonstrated equal and more sustained overall activity compared to all other treatments. The use of DAL alone, with or without CFZ and the combinations of VAN or DAP with CFZ appear to result in increased bactericidal activity against various recalcitrant S. aureus phenotypes.

scholarly journals ComparativeIn VitroActivities of Oritavancin, Dalbavancin, and Vancomycin against Methicillin-Resistant Staphylococcus aureus Isolates in a Nondividing State

2016 ◽  
Vol 60 (7) ◽  
pp. 4342-4345 ◽  
Author(s):  
Adam Belley ◽  
David Lalonde Seguin ◽  
Francis Arhin ◽  
Greg Moeck
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Antibacterial Agents ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Content Type ◽  
Skin Structure ◽  
Persistent Infections ◽  
Time Kill

ABSTRACTAntibacterial agents that kill nondividing bacteria may be of utility in treating persistent infections. Oritavancin and dalbavancin are bactericidal lipoglycopeptides that are approved for acute bacterial skin and skin structure infections in adults caused by susceptible Gram-positive pathogens. Using time-kill methodology, we demonstrate that oritavancin exerts bactericidal activity against methicillin-resistantStaphylococcus aureus(MRSA) isolates that are maintained in a nondividing statein vitro, whereas dalbavancin and the glycopeptide vancomycin do not.

scholarly journals Comparative In Vitro Activities and Postantibiotic Effects of the Oxazolidinone Compounds Eperezolid (PNU-100592) and Linezolid (PNU-100766) versus Vancomycin against Staphylococcus aureus, Coagulase-Negative Staphylococci, Enterococcus faecalis, and Enterococcus faecium

1998 ◽  
Vol 42 (3) ◽  
pp. 721-724 ◽  
Author(s):  
Michael J. Rybak ◽  
Diane M. Cappelletty ◽  
Tabitha Moldovan ◽  
Jeffrey R. Aeschlimann ◽  
Glenn W. Kaatz
Keyword(s):  
Staphylococcus Aureus ◽  
Enterococcus Faecalis ◽  
Inhibitory Activity ◽  
Enterococcus Faecium ◽  
Antibacterial Agents ◽  
Clinical Isolates ◽  
Postantibiotic Effect ◽  
Coagulase Negative Staphylococci ◽  
Time Kill

ABSTRACT The activities of the oxazolidinone antibacterial agents eperezolid (PNU-100592) and linezolid (PNU-100766) were compared with that of vancomycin against clinical isolates of methicillin-susceptible and -resistant Staphylococcus aureus (n = 200), coagulase-negative staphylococci (n = 100), and vancomycin-susceptible and -resistant Enterococcus faecalisand Enterococcus faecium (n = 50). Eperezolid and linezolid demonstrated good in vitro inhibitory activity, regardless of methicillin susceptibility for staphylococci (MIC at which 90% of the isolates are inhibited [MIC90] range, 1 to 4 μg/ml) or vancomycin susceptibility for enterococci (MIC90 range, 1 to 4 μg/ml). In time-kill studies, eperezolid and linezolid were bacteriostatic in action. A postantibiotic effect of 0.8 ± 0.5 h was demonstrated for both eperezolid and linezolid against S. aureus, S. epidermidis, E. faecalis, and E. faecium.

scholarly journals The Combination of Daptomycin and Fosfomycin Has Synergistic, Potent, and Rapid Bactericidal Activity against Methicillin-ResistantStaphylococcus aureusin a Rabbit Model of Experimental Endocarditis

2018 ◽  
Vol 62 (6) ◽  
Author(s):  
Cristina García-de-la-Mària ◽  
Oriol Gasch ◽  
Javier García-Gonzalez ◽  
Dolors Soy ◽  
Evelyn Shaw ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Combined Therapy ◽  
Rabbit Model ◽  
Bactericidal Effect ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains ◽  
Time Kill

ABSTRACTWe investigated whether the addition of fosfomycin or cloxacillin to daptomycin provides better outcomes in the treatment of methicillin-resistantStaphylococcus aureus(MRSA) experimental aortic endocarditis in rabbits. Five MRSA strains were used to performin vitrotime-kill studies using standard (106) and high (108) inocula. Combined therapy was compared to daptomycin monotherapy treatment in the MRSA experimental endocarditis model. A human-like pharmacokinetics model was applied, and the equivalents of cloxacillin at 2 g/4 h, fosfomycin at 2 g/6 h, and daptomycin at 6 to 10 mg/kg/day were administered intravenously. A combination of daptomycin and either fosfomycin or cloxacillin was synergistic in the five strains tested at both inocula. A bactericidal effect was detected in four of five strains tested with both combinations. The MRSA-277 strain (vancomycin MIC, 2 μg/ml) was used for the experimental endocarditis model. Daptomycin plus fosfomycin significantly improved the efficacy of daptomycin monotherapy at 6 mg/kg/day in terms of both the proportion of sterile vegetations (100% versus 72%,P= 0.046) and the decrease in the density of bacteria within the vegetations (P= 0.025). Daptomycin plus fosfomycin was as effective as daptomycin monotherapy at 10 mg/kg/day (100% versus 93%,P= 1.00) and had activity similar to that of daptomycin plus cloxacillin when daptomycin was administered at 6 mg/kg/day (100% versus 88%,P= 0.48). Daptomycin nonsusceptibility was not detected in any of the isolates recovered from vegetations. In conclusion, for the treatment of MRSA experimental endocarditis, the combination of daptomycin plus fosfomycin showed synergistic and bactericidal activity.

scholarly journals Activities of the Combination of Quinupristin-Dalfopristin with Rifampin In Vitro and in Experimental Endocarditis Due to Staphylococcus aureus Strains with Various Phenotypes of Resistance to Macrolide-Lincosamide-Streptogramin Antibiotics

2001 ◽  
Vol 45 (4) ◽  
pp. 1244-1248 ◽  
Author(s):  
Virginie Zarrouk ◽  
Bülent Bozdogan ◽  
Roland Leclercq ◽  
Louis Garry ◽  
Celine Feger ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Conjugative Transfer ◽  
Constitutive Resistance ◽  
Combination Studies ◽  
Kill Curve ◽  
Time Kill ◽  
High Mics

ABSTRACT We evaluated the activities of quinupristin-dalfopristin (Q-D), alone or in combination with rifampin, against three strains ofStaphylococcus aureus susceptible to rifampin (MIC, 0.06 μg/ml) and to Q-D (MICs, 0.5 to 1 μg/ml) but displaying various phenotypes of resistance to macrolide-lincosamide-streptogramin antibiotics: S. aureus HM1054 was susceptible to quinupristin and dalfopristin (MICs of 8 and 4 μg/ml, respectively); for S. aureus RP13, the MIC of dalfopristin was high (MICs of quinupristin and dalfopristin for strain RP13, 8 and 32 μg/ml, respectively); and S. aureus HM1054R was obtained after conjugative transfer of macrolide-lincosamide-streptogramin B constitutive resistance to HM1054, and the MIC of quinupristin for this strain was high (MICs of quinupristin and dalfopristin, 64 and 4 μg/ml, respectively). In vitro time-kill curve studies showed no difference between Q-D and rifampin, at a concentration of four times the MIC, against the three strains. Rabbits with aortic endocarditis were treated 4 days with Q-D, rifampin, or their combination. In vivo, the combination was highly bactericidal and synergistic against strains susceptible to quinupristin (HM1054 and RP13) and sterilized 94% of the animals. In contrast, the combination was neither synergistic nor bactericidal against the quinupristin-resistant strain (HM1054R) and did not prevent the emergence of mutants resistant to rifampin. We conclude that the in vivo synergistic and bactericidal activity of the combination of Q-D and rifampin against S. aureus is predicted by the absence of resistance to quinupristin but not by in vitro combination studies.

scholarly journals Evaluation of Bactericidal Activities of LY333328, Vancomycin, Teicoplanin, Ampicillin-Sulbactam, Trovafloxacin, and RP59500 Alone or in Combination with Rifampin or Gentamicin against Different Strains of Vancomycin-Intermediate Staphylococcus aureus by Time-Kill Curve Methods

1999 ◽  
Vol 43 (3) ◽  
pp. 717-721 ◽  
Author(s):  
Ellie Hershberger ◽  
Jeffrey R. Aeschlimann ◽  
Tabitha Moldovan ◽  
Michael J. Rybak
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
In Vitro Study ◽  
Synergistic Activity ◽  
Added Benefit ◽  
Bactericidal Activities ◽  
Kill Curve ◽  
Different Strains ◽  
Time Kill

This in vitro study evaluated the activities of vancomycin, LY333328, and teicoplanin alone and in combination with gentamicin, rifampin, and RP59500 against Staphylococcus aureusisolates with intermediate susceptibilities to vancomycin. Ampicillin-sulbactam and trovafloxacin were also evaluated. LY333328 and ampicillin-sulbactam resulted in bactericidal activity against all isolates. The combination of gentamicin with glycopeptides showed synergistic activity, while rifampin had no added benefit.

scholarly journals In Vitro and In Vivo Synergistic Activities of Linezolid Combined with Subinhibitory Concentrations of Imipenem against Methicillin-Resistant Staphylococcus aureus

2005 ◽  
Vol 49 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Cédric Jacqueline ◽  
Dominique Navas ◽  
Eric Batard ◽  
Anne-Françoise Miegeville ◽  
Virginie Le Mabecque ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Methicillin Resistant ◽  
In Vivo Experiments ◽  
Low Concentrations ◽  
Mrsa Strains ◽  
Kill Curve ◽  
Time Kill

ABSTRACT Indifference or moderate antagonism of linezolid combined with other antibiotics in vitro and in vivo have mainly been reported in the literature. We have assessed the in vitro activities of linezolid, alone or in combination with imipenem, against methicillin-resistant Staphylococcus aureus (MRSA) strains using the dynamic checkerboard and time-kill curve methods. Linezolid and low concentrations of imipenem had a synergistic effect, leading us to evaluate the in vivo antibacterial activity of the combination using the rabbit endocarditis experimental model. Two MRSA strains were used for in vivo experiments: one was a heterogeneous glycopeptide-intermediate clinical S. aureus strain isolated from blood cultures, and the other was the S. aureus COL reference strain. Animals infected with one of two MRSA strains were randomly assigned to one of the following treatments: no treatment (controls), linezolid (simulating a dose in humans of 10 mg/kg of body weight every 12 h), a constant intravenous infusion of imipenem (which allowed the steady-state concentration of about 1/32 the MIC of imipenem for each strain to be reached in serum), or the combination of both treatments. Linezolid and imipenem as monotherapies exhibited no bactericidal activity against either strain. The combination of linezolid plus imipenem showed in vivo bactericidal activity that corresponded to a decrease of at least 4.5 log CFU/g of vegetation compared to the counts for the controls. In conclusion, the combination exhibited synergistic and bactericidal activities against two MRSA strains after 5 days of treatment. The combination of linezolid plus imipenem appears to be promising for the treatment of severe MRSA infections and merits further investigations to explore the mechanism underlying the synergy between the two drugs.

scholarly journals Pharmacodynamic Evaluation of a Single Dose versus a 24-Hour Course of Multiple Doses of Cefazolin for Surgical Prophylaxis

Antibiotics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 602
Author(s):  
Aaron Heffernan ◽  
Jowana Alawie ◽  
Steven C Wallis ◽  
Saiyuri Naicker ◽  
Santosh Adiraju ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Single Dose ◽  
Immunocompetent Patient ◽  
Hollow Fibre ◽  
Infection Model ◽  
Bacterial Killing ◽  
Initial Inoculum ◽  
Skin Flora ◽  
Time Kill

The optimal perioperative duration for the administration of cefazolin and other prophylactic antibiotics remains unclear. This study aimed to describe the pharmacodynamics of cefazolin for a single 2 g dose versus a 24 h course of a 2 g single dose plus a 1 g eight-hourly regimen against methicillin-susceptible Staphylococcus aureus. Static concentration time–kill assay and a dynamic in vitro hollow-fibre infection model simulating humanised plasma and interstitial fluid exposures of cefazolin were used to characterise the pharmacodynamics of prophylactic cefazolin regimens against methicillin-sensitive Staphylococcus aureus clinical isolates. The initial inoculum was 1 × 105 CFU/mL to mimic a high skin flora inoculum. The static time–kill study showed that increasing the cefazolin concentration above 1 mg/L (the MIC) did not increase the rate or the extent of bacterial killing. In the dynamic hollow-fibre model, both dosing regimens achieved similar bacterial killing (~3-log CFU/mL within 24 h). A single 2 g dose may be adequate when low bacterial burdens (~104 CFU/mL) are anticipated in an immunocompetent patient with normal pharmacokinetics.

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