scholarly journals Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method

10.3791/58636 ◽  
2019 ◽  
Author(s):  
Thea Brennan-Krohn ◽  
James E Kirby
Keyword(s):  
Inkjet Printer ◽  
Antimicrobial Synergy ◽  
Time Kill ◽  
Synergy Testing

scholarly journals Correlation of Checkerboard Synergy Testing with Time-Kill Analysis and Clinical Outcomes of Extensively Drug-Resistant Acinetobacter baumannii Respiratory Infections

2016 ◽  
Vol 60 (11) ◽  
pp. 6892-6895 ◽  
Author(s):  
Derek N. Bremmer ◽  
Karri A. Bauer ◽  
Stephanie M. Pouch ◽  
Keelie Thomas ◽  
Debra Smith ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Clinical Outcomes ◽  
Clinical Utility ◽  
Respiratory Infections ◽  
Drug Resistant ◽  
Content Type ◽  
Extensively Drug Resistant ◽  
Time Kill ◽  
Synergy Testing

ABSTRACTWe tested 76 extensively drug-resistant (XDR)Acinetobacter baumanniiisolates by the checkerboard method using only wells containing serum-achievable concentrations (SACs) of drugs. Checkerboard results were correlated by time-kill assay and clinical outcomes. Minocycline-colistin was the best combinationin vitro, as it inhibited growth in one or more SAC wells in all isolates. Patients who received a combination that inhibited growth in one or more SAC wells demonstrated better microbiological clearance than those who did not (88% versus 30%;P= 0.025). The checkerboard platform may have clinical utility for XDRA. baumanniiinfections.

scholarly journals Activities of Three Quinolones, Alone and in Combination with Extended-Spectrum Cephalosporins or Gentamicin, against Stenotrophomonas maltophilia

1998 ◽  
Vol 42 (8) ◽  
pp. 2002-2005 ◽  
Author(s):  
Melissa A. Visalli ◽  
Michael R. Jacobs ◽  
Peter C. Appelbaum
Keyword(s):  
Active Compound ◽  
Stenotrophomonas Maltophilia ◽  
Inhibitory Concentration ◽  
Fractional Inhibitory Concentration ◽  
Determination Method ◽  
Extended Spectrum ◽  
Time Kill ◽  
Synergy Testing ◽  
Checkerboard Titration ◽  
Concentration Indices

The present study examined the activities of trovafloxacin, levofloxacin, and ciprofloxacin, alone and in combination with cefoperazone, ceftazidime, cefpirome, and gentamicin, against 100 strains of Stenotrophomonas maltophilia by the MIC determination method and by synergy testing of the combinations by the time-kill and checkerboard titration methods for 20 strains. The respective MICs at which 50% and 90% of isolates were inhibited for the drugs used alone were as follows: trovafloxacin, 0.5 and 2.0 μg/ml; levofloxacin, 2.0 and 4.0 μg/ml; ciprofloxacin, 4.0 and 16.0 μg/ml; cefoperazone, >128.0 and >128.0 μg/ml; ceftazidime, 32.0 and >128.0 μg/ml; cefpirome, >128.0 and >128.0 μg/ml; and gentamicin, 128.0 and >128.0 μg/ml. Synergistic fractional inhibitory concentration indices (≤0.5) were found for ≥50% of strains for trovafloxacin-cefoperazone, trovafloxacin-ceftazidime, levofloxacin-cefoperazone, levofloxacin-ceftazidime, ciprofloxacin-cefoperazone, and ciprofloxacin-ceftazidime, with other combinations affecting fewer strains. For 20 strains tested by the checkerboard titration and time-kill methods, synergy (≥100-fold drop in count compared to the count achieved with the more active compound) was more pronounced after 12 h due to regrowth after 24 h. At 12 h, trovafloxacin at 0.004 to 0.5 μg/ml showed synergy with cefoperazone for 90% of strains, with ceftazidime for 95% of strains with cefpirome for 95% of strains, and with gentamicin for 65% of strains. Levofloxacin at 0.03 to 0.5 μg/ml and ciprofloxacin at 0.5 to 2.0 μg/ml showed synergy with cefoperazone for 80% of strains, with ceftazidime for 90 and 85% of strains, respectively, with cefpirome for 85 and 75% of strains, respectively, and with gentamicin for 65 and 75% of strains, respectively. Time-kill assays were more discriminatory than checkerboard titration assays in demonstrating synergy for all combinations.

Comparative activity of trovafloxacin, alone and in combination with other agents, against gram-negative nonfermentative rods.

1997 ◽  
Vol 41 (7) ◽  
pp. 1475-1481 ◽  
Author(s):  
M A Visalli ◽  
S Bajaksouzian ◽  
M R Jacobs ◽  
P C Appelbaum
Keyword(s):  
Burkholderia Cepacia ◽  
Inhibitory Concentration ◽  
Pseudomonas Stutzeri ◽  
Alcaligenes Faecalis ◽  
Gram Negative ◽  
Agar Dilution ◽  
Flavobacterium Odoratum ◽  
Time Kill ◽  
Synergy Testing ◽  
Comparative Activity

In the first part of this study, agar dilution MICs were used to test the activities of trovafloxacin, ciprofloxacin, ofloxacin, levofloxacin, sparfloxacin, clinafloxacin, ceftazidime, and imipenem against 458 gram-negative nonfermenters. The overall respective MICs at which 50% of isolates are inhibited (MIC50s) and MIC90s were as follows: trovafloxacin, 1.0 and 16.0 microg/ml; ciprofloxacin, 2.0 and 16.0 microg/ml; ofloxacin, 2.0 and 32.0 microg/ml; levofloxacin, 1.0 and 16.0 microg/ml; sparfloxacin, 1.0 and 16.0 microg/ml; clinafloxacin, 0.5 and 4.0 microg/ml; ceftazidime, 8.0 and 128.0 microg/ml; imipenem, 2.0 and 256.0 microg/ml. Clinafloxacin was the most active of all the quinolones tested. The MIC90s of trovafloxacin were < or = 4.0 microg/ml for Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Flavobacterium odoratum, and Chryseobacterium meningosepticum; trovafloxacin MIC90s were < or = 2.0 microg/ml for Moraxella spp., Pseudomonas stutzeri, and Chryseobacterium indologenes-C. gleum. Of the other quinolones tested, the MICs of sparfloxacin and levofloxacin were lower than those of ciprofloxacin and ofloxacin. High ceftazidime MICs (> or = 32.0 microg/ml) were observed for all nonfermentative species tested. Although for the majority of strains tested imipenem MICs were < or = 8.0 microg/ml, high imipenem MICs were observed for many species, especially S. maltophilia, Burkholderia cepacia, F. odoratum, and Chryseobacterium meningosepticum. For Alcaligenes xylosoxidans strains, the MICs of all compounds were generally a few dilutions lower than those for Alcaligenes faecalis-A. odorans. Time-kill studies with five strains revealed that trovafloxacin and all quinolones yielded more rapid time-kill kinetics than ceftazidime and imipenem. Synergy testing by checkerboard titrations of 286 strains with trovafloxacin combined with ceftazidime, amikacin, and imipenem revealed fractional inhibitory concentration (FIC) indices in the range indicating synergism (< or = 0.5) for 81, 41, and 40 strains, respectively, and FIC indices indicating additivity or indifference (> 0.5 to 4.0) for 205, 245, and 246 strains, respectively. No FIC indices indicating antagonism (> 4.0) were observed. Synergy between trovafloxacin and ceftazidime was found for 32 of 36 S. maltophilia strains. Time-kill studies with 20 strains showed that for most strains for which FIC indices were in the range indicating additivity or indifference, FIC indices indicated synergy by the time-kill method. Synergy was particularly noticeable for S. maltophilia strains with combinations of ceftazidime and trovafloxacin.

In vitro synergy of ceftolozane/tazobactam in combination with fosfomycin or aztreonam against MDR Pseudomonas aeruginosa

2020 ◽  
Vol 75 (7) ◽  
pp. 1874-1878 ◽  
Author(s):  
Gabriel T Cuba ◽  
Gerlan Rocha-Santos ◽  
Rodrigo Cayô ◽  
Ana Paula Streling ◽  
Carolina S Nodari ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistance Mechanisms ◽  
Density Reduction ◽  
Carbapenem Resistant ◽  
Gradient Diffusion ◽  
Fold Reduction ◽  
The Face ◽  
Antimicrobial Synergy ◽  
Time Kill

Abstract Objectives Carbapenem-resistant Pseudomonas aeruginosa (CR-PSA) imposes great limitations on empirical therapeutic choices, which are further complicated by metallo-β-lactamase production. This study evaluated in vitro antimicrobial synergy of ceftolozane/tazobactam in combination with aztreonam and fosfomycin against MDR PSA. Methods MICs were determined by broth microdilution and gradient strips. The effect of ceftolozane/tazobactam+aztreonam and ceftolozane/tazobactam+fosfomycin combinations were tested against 27 MDR PSA isolates carrying blaSPM-1 (n = 13), blaIMP (n = 4), blaVIM (n = 3), blaGES-1 (n = 2) and blaCTX-M-like (n = 2), and 3 isolates with no acquired β-lactamase production detected by gradient diffusion strip crossing (GDSC). Six genetically unrelated SPM-1-producing isolates were also evaluated by time–kill analysis (TKA). Results All CR-PSA isolates harbouring blaSPM-1, blaGES-1 and blaIMP-1 were categorized as resistant to ceftolozane/tazobactam, meropenem and fosfomycin, with 70% being susceptible to aztreonam. Synergism for ceftolozane/tazobactam+fosfomycin and ceftolozane/tazobactam+aztreonam combinations was observed for 88.9% (24/27) and 18.5% (5/27) of the isolates by GDSC, respectively. A 3- to 9-fold reduction in ceftolozane/tazobactam MICs was observed, depending on the combination. Ceftolozane/tazobactam+fosfomycin was synergistic by TKA against one of six SPM-1-producing isolates, with additional non-synergistic bacterial density reduction for another isolate. Aztreonam peak concentrations alone demonstrated a ≥3 log10 cfu/mL reduction against all six isolates, but all strains were within the susceptible range for the drug. No antagonism was observed. Conclusions In the context of increasing CR-PSA and the genetic diversity of resistance mechanisms, new combinations and stewardship strategies may need to be explored in the face of increasingly difficult to treat pathogens.

scholarly journals In Vitro Synergy of Levofloxacin Plus Piperacillin/Tazobactam againstPseudomonas aeruginosa

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Vladimir Chachanidze ◽  
Aixa Curbelo-Irizarry ◽  
Deborah Ashcraft ◽  
George Pankey
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Time Kill ◽  
Synergy Testing

In vitro synergy testing using levofloxacin (LVX) plus piperacillin/tazobactam (TZP) was performed by Etest and time-kill assay (TKA) for 31 unique fluoroquinolone-resistantPseudomonas aeruginosaisolates. The Etest method showed synergy for 9/31 (29%) of isolates, while TKA showed synergy with 14/31 (45%) of isolates. When comparing the Etest method and TKA, concordant results for synergy, antagonism, and indifference were obtained for 24/31 (77%) of the isolates tested.

scholarly journals In Vitro Synergy of Daptomycin plus Rifampin against Enterococcus faecium Resistant to both Linezolid and Vancomycin

2005 ◽  
Vol 49 (12) ◽  
pp. 5166-5168 ◽  
Author(s):  
George Pankey ◽  
Deborah Ashcraft ◽  
Nalini Patel
Keyword(s):  
Enterococcus Faecium ◽  
Time Kill ◽  
Synergy Testing

ABSTRACT In vitro synergy testing of daptomycin plus rifampin was performed against 24 unique isolates of Enterococcus faecium resistant to both linezolid and vancomycin. Synergy testing showed that 21/24 (88%) were synergistic and 3/24 (12%) were indifferent by the Etest method. Time-kill assays revealed synergy for 18/24 (75%) and indifference for 6/24 (25%).

scholarly journals Antistaphylococcal Activity of DX-619 Alone and in Combination with Vancomycin, Teicoplanin, and Linezolid Assessed by Time-Kill Synergy Testing

2007 ◽  
Vol 51 (4) ◽  
pp. 1508-1511
Author(s):  
Kim Credito ◽  
Genrong Lin ◽  
Peter C. Appelbaum
Keyword(s):  
Staphylococcus Aureus ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Antistaphylococcal Activity ◽  
Time Kill ◽  
Synergy Testing

ABSTRACT Time-kill synergy studies testing in vitro activity of DX-619 alone and with added vancomycin, teicoplanin, or linezolid against 101 Staphylococcus aureus strains showed synergy between DX-619 and teicoplanin at 12 to 24 h in 72 strains and between DX-619 and vancomycin in 28 strains. No synergy was found with linezolid, and no antagonism was observed with any combination.

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