scholarly journals Activities of levofloxacin, ofloxacin, and ciprofloxacin, alone and in combination with amikacin, against acinetobacters as determined by checkerboard and time-kill studies.

1997 ◽  
Vol 41 (5) ◽  
pp. 1073-1076 ◽  
Author(s):  
S Bajaksouzian ◽  
M A Visalli ◽  
M R Jacobs ◽  
P C Appelbaum
Keyword(s):  
Acinetobacter Baumannii ◽  
Active Compound ◽  
Inhibitory Concentration ◽  
Clinical Use ◽  
Fractional Inhibitory Concentration ◽  
Time Kill ◽  
Checkerboard Titration

A total of 101 Acinetobacter genospecies (77 Acinetobacter baumannii strains and 24 non-A. baumannii strains) were tested for their susceptibilities to levofloxacin, ofloxacin, and ciprofloxacin and for synergy between the quinolones and amikacin by checkerboard titration and time-kill analyses. The MICs at which 50% of the isolates are inhibited (MIC50)/MIC90s for the 101 strains were as follows (in micrograms per milliliter): levofloxacin, 0.25/16.0; ofloxacin, 0.5/32.0; ciprofloxacin, 0.25/> 64.0; and amikacin, 1.0/> 32.0. At empiric breakpoints of < or = 2.0 microg/ml, 61% of the strains were susceptible to all three quinolones. At a breakpoint of < or = 16.0 microg/ml, 84% of the strains were susceptible to amikacin. Checkerboard titrations yielded synergistic fractional inhibitory concentration (FIC) indices (< or = 0.5) for one strain with levofloxacin and amikacin and for two strains with ofloxacin and amikacin. Indices of > 0.5 to 1.0 were seen for 57, 54, and 55 strains with levofloxacin plus amikacin, ofloxacin plus amikacin, and ciprofloxacin plus amikacin, respectively, and indices of > 1.0 in 43, 45, and 46 strains, respectively, were found with the above three combinations. No strains yielded antagonistic FIC indices (> 4.0). Most FIC results of > 1.0 occurred in strains for which the quinolone MICs were > 2.0 microg/ml and for which the amikacin MICs were > or = 32.0 microg/ml. By contrast, synergy (defined as > or = 2 log10 decrease compared to the more active compound alone by time-kill analysis) was found in all seven strains tested for which the quinolone MICs were < or = 2.0 microg/ml. For eight other strains for which the quinolone MICs were > 2.0 microg/ml as determined by time-kill analysis, quinolone and amikacin concentrations in combination were usually too high to permit clinical use. Time-kill analysis was found to be more sensitive in detecting synergy than was the checkerboard method.

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.

scholarly journals Antipneumococcal activities of cefpirome and cefotaxime, alone and in combination with vancomycin and teicoplanin, determined by checkerboard and time-kill methods.

1996 ◽  
Vol 40 (9) ◽  
pp. 1973-1976 ◽  
Author(s):  
S Bajaksouzian ◽  
M A Visalli ◽  
M R Jacobs ◽  
P C Appelbaum
Keyword(s):  
Inhibitory Concentration ◽  
Fractional Inhibitory Concentration ◽  
Beta Lactams ◽  
Pneumococcal Infections ◽  
Titration Method ◽  
Resistant Strains ◽  
Time Kill ◽  
Checkerboard Titration

The checkerboard titration method was used to test the synergy of cefpirome and cefotaxime with teicoplanin or vancomycin against 35 penicillin-susceptible, 34 penicillin-intermediate, and 31 penicillin-resistant pneumococci. The MICs at which 50 and 90% of isolates are inhibited (MIC50s and MIC90s, respectively) of both cefpirome and cefotaxime were 0.016 and 0.06 microgram/ml, respectively, for penicillin-susceptible strains and 0.125 and 0.5 microgram/ml, respectively, for penicillin-intermediate strains. The MIC50s and MIC90s of cefotaxime for penicillin-resistant strains were 1.0 and 2.0 micrograms/ml, respectively, and those of cefpirome were 0.5 and 1.0 microgram/ml, respectively. All pneumococci were inhibited by cefpirome at MICs of < or = 1.0 microgram/ml. The MIC50s and MIC90s of vancomycin and teicoplanin (0.25 and 0.25 microgram/ml and 0.03 and 0.03 microgram/ml, respectively) did not differ for the three groups. Checkerboard synergy studies showed that cefpirome and vancomycin showed synergy for 31 strains (fractional inhibitory concentration [FIC] indices, < or = 0.5) cefpirome and teicoplanin showed synergy for 18 strains, cefotaxime and vancomycin showed synergy for 51 strains, and cefotaxime and teicoplanin showed synergy for 27 strains. Cefpirome and vancomycin had FIC indices indicating indifference (2.0) for two strains, and cefotaxime and vancomycin had FIC indices indicating indifference for one strain. All other FIC indices indicating indifference or additivity were > 0.5 to 1.0. No FIC indices indicating antagonism (> 4.0) were found. Synergy between beta-lactams and glycopeptides for three susceptible, three intermediate, and three resistant strains were tested by the time-kill assay, and all combinations were synergistic by this method. Synergy between cephalosporins and glycopeptides can be demonstrated and may be useful for the treatment of pneumococcal infections, especially meningitis.

Determination of Activities of Levofloxacin, Alone and Combined with Gentamicin, Ceftazidime, Cefpirome, and Meropenem, against 124 Strains of Pseudomonas aeruginosa by Checkerboard and Time-Kill Methodology

1998 ◽  
Vol 42 (4) ◽  
pp. 953-955 ◽  
Author(s):  
Melissa A. Visalli ◽  
Michael R. Jacobs ◽  
Peter C. Appelbaum
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Inhibitory Concentration ◽  
Fractional Inhibitory Concentration ◽  
Time Kill

ABSTRACT A total of 124 Pseudomonas aeruginosa strains were tested for synergy between levofloxacin and cefpirome, ceftazidime, gentamicin, and meropenem. Checkerboards yielded synergistic fractional inhibitory concentration (FIC) indices (≤0.5) with 25 of 496 possible combinations. All other FIC indices were >0.5 to 2 (additive or indifferent), with no antagonism. Time-kill studies with 12 strains showed that levofloxacin (0.06 to 0.5 μg/ml) was synergistic with cefpirome, ceftazidime, gentamicin, and meropenem in 10, 9, 4, and 11 strains, respectively.

scholarly journals In VivoandIn VitroEfficacy of Minocycline-Based Combination Therapy for Minocycline-Resistant Acinetobacter baumannii

2016 ◽  
Vol 60 (7) ◽  
pp. 4047-4054 ◽  
Author(s):  
Ya-Sung Yang ◽  
Yi Lee ◽  
Kuo-Chuan Tseng ◽  
Wei-Cheng Huang ◽  
Ming-Fen Chuang ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Acinetobacter Baumannii ◽  
Concentration Index ◽  
Care Setting ◽  
Inhibitory Concentration ◽  
Associated Bacteria ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Time Kill ◽  
Number Of Bacteria

ABSTRACTMinocycline-based combination therapy has been suggested to be a possible choice for the treatment of infections caused by minocycline-susceptibleAcinetobacter baumannii, but its use for the treatment of infections caused by minocycline-resistantA. baumanniiis not well established. In this study, we compared the efficacy of minocycline-based combination therapy (with colistin, cefoperazone-sulbactam, or meropenem) to that of colistin in combination with meropenem for the treatment of minocycline-resistantA. baumanniiinfection. From 2006 to 2010, 191 (17.6%) of 1,083A. baumanniicomplex isolates not susceptible to minocycline from the Taiwan Surveillance of Antimicrobial Resistance program were collected. Four representativeA. baumanniiisolates resistant to minocycline, amikacin, ampicillin-sulbactam, ceftazidime, ciprofloxacin, cefepime, gentamicin, imipenem, levofloxacin, meropenem, and piperacillin-tazobactam were selected on the basis of the diversity of their pulsotypes, collection years, health care setting origins, and geographic areas of origination. All four isolates hadtetBand overexpressedadeABC, as revealed by quantitative reverse transcription-PCR. Among all minocycline-based regimens, only the combination with colistin produced a fractional inhibitory concentration index comparable to that achieved with meropenem combined with colistin. Minocycline (4 or 16 μg/ml) in combination with colistin (0.5 μg/ml) also synergistically killed minocycline-resistant isolates in time-kill studies. Minocycline (50 mg/kg of body weight) in combination with colistin (10 mg/kg) significantly improved the survival of mice and reduced the number of bacteria present in the lungs of mice compared to the results of monotherapy. However, minocycline (16 μg/ml)-based therapy was not effective at reducing biofilm-associated bacteria at 24 or 48 h when its effectiveness was compared to that of colistin (0.5 μg/ml) and meropenem (8 μg/ml). The clinical use of minocycline in combination with colistin for the treatment of minocycline-resistantA. baumanniimay warrant further investigation.

scholarly journals In Vitro Antibacterial Activity of Cefiderocol against Multidrug-Resistant Acinetobacter baumannii

2021 ◽  
Author(s):  
Jacinda C. Abdul-Mutakabbir ◽  
Logan Nguyen ◽  
Philip T. Maassen ◽  
Kyle C. Stamper ◽  
Razieh Kebriaei ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Susceptibility Testing ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Synergistic Activity ◽  
Strong Activity ◽  
Gram Negative ◽  
In Vitro Antibacterial Activity ◽  
Time Kill

Cefiderocol (CFDC), a novel siderophore cephalosporin, demonstrates strong activity against multidrug-resistant (MDR) Acinetobacter baumannii. Limited studies have evaluated CFDC alone and in combination with other Gram-negative antibiotics against MDR A. baumannii isolates. Susceptibility testing revealed lower CFDC minimum inhibitory concentration (MIC) values than the comparator Gram-negative agents (87% of MICs ≤ 4mg/L). Six isolates, with elevated CFDC MICs (16-32 mg/L), were selected for further experiments. Time-kill analyses presented with synergistic activity and beta-lactamase inhibitors increased CFDC susceptibility in each of the isolates.

scholarly journals In Vitro Synergy of Colistin in Combination with Meropenem or Tigecycline against Carbapenem-Resistant Acinetobacter baumannii

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 880
Author(s):  
Jacinda C. Abdul-Mutakabbir ◽  
Juwon Yim ◽  
Logan Nguyen ◽  
Philip T. Maassen ◽  
Kyle Stamper ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Inhibitory Concentration ◽  
Treatment Strategies ◽  
Dual Therapy ◽  
Therapy Regimen ◽  
Carbapenem Resistant ◽  
Fold Reduction ◽  
Triple Therapy Regimen ◽  
Time Kill

Acinetobacter baumannii is currently classified as one of six pathogens that contribute to increased patient mortality. Thus, exploratory studies navigating alternative treatment strategies are of supreme interest. Herein, we completed minimum inhibitory concentration (MIC) testing, and time-kill analyses (TKA) on 50 carbapenem-resistant Acinetobacterbaumannii isolates including 28 colistin-resistant isolates. Upon testing of MEM or TGC in the presence of sub-inhibitory COL against the 50 isolates, there was a median 2-fold reduction in MEM and TGC MICs. In the TKAs, the COL+MEM combination was synergistic in 45 (90%) isolates and bactericidal in 43 (86%) isolates at 24 hours, whereas the COL+TGC combination TKAs demonstrated synergy in 32 (64%) isolates and bactericidal activity was shown in 28 (56%) isolates. Additionally, sulbactam (SUL) and TGC were added to the COL+MEM dual therapy regimen to assess the possible utility of a triple therapy regimen against five non-responsive isolates. The COL+MEM+SUL and COL+MEM+TGC regimens effectively restored synergy in (5/5) 100% of the isolates. The results of this study demonstrate the potential utility of COL combinations in the treatment of carbapenem-resistant isolates.

scholarly journals Synergistic Effect of Colistin and Rifampin Against Multidrug Resistant Acinetobacter baumannii: A Systematic Review and Meta-Analysis

2017 ◽  
Vol 11 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Maryam Mohammadi ◽  
Hatef Khayat ◽  
Koroush Sayehmiri ◽  
Setareh Soroush ◽  
Fatemeh Sayehmiri ◽  
...  
Keyword(s):  
Systematic Review ◽  
Acinetobacter Baumannii ◽  
Literature Search ◽  
Inhibitory Concentration ◽  
Meta Analysis ◽  
Multidrug Resistant ◽  
Antagonistic Effect ◽  
Resistance Rate ◽  
Test Method ◽  
Time Kill

The existence of infections caused by multidrug resistant (MDR)Acinetobacter baumanniiis a growing problem because of the difficulty to treat them. We examined the published literature and focused our analysis on the investigation of the synergism of colistin and rifampin against MDRA. baumanniiisolatesviasystematic review and meta-analysis. A systematic literature search was performed using the following 4 databases (PubMed, Scopus, EMBASE and ISI Web of Sciences). The related articles were evaluated during the period from December 2014 to January 2015. Information based on resistance and sensitivity to antibiotics, the minimum inhibitory concentration and the effects of two antibiotics on each other including synergism, antagonism, relative synergism and additive antagonism were extracted. A meta-analysis of 17 studies including 448 samples was brought into process and 2% (95% CI 0-4%) and 72% (95% CI 56-89%) resistance to colistin and rifampin were observed, respectively. 42% of all isolates showed MIC = 4 µg/ml (95% CI 14-69%) to rifampin and 30% MIC= 2 µg/ml to colistin (95% CI 3.8-78%). MIC50and MIC90for both rifampin and colistin were 2 µg/ml and 4 µg/ml, respectively. 63% of the strains demonstrated synergy (95% CI 37-90%), 7% were highlighted as relative synergism (95% CI 0.0- 13%), 3% showed an additive effect (95% CI -0.0-7%) and 14% were indifferent (95% CI 6-23%). The antagonistic effect was not observed in this combination. Synergy rates of time-kill assay in rifampin and colistin combinations were generally higher than those of check bored microdilution and E-test method. The results demonstrated that the combination therapy could be more useful when compared to monotherapy and that this strategy might reduce the resistance rate to rifampin in MDRA. baumanniiisolates.

In Vitro Synergism of Sulbactam- Cefoperazone and Fosfomycin Against Escherichia Coli and Klebsiella Aeromobilis from Indonesia

2021 ◽  
Vol 71 (5) ◽  
pp. 209-214
Author(s):  
Agus Syahrurachman ◽  
Atna Permana
Keyword(s):  
Inhibitory Concentration ◽  
Clinical Laboratory ◽  
Independent Effect ◽  
E Coli ◽  
Susceptibility Data ◽  
Antibiotic Effect ◽  
Time Kill ◽  
Checkerboard Titration ◽  
Post Antibiotic Effect

Introduction: There is no susceptibility data of E. coli and K. aeromobilis in Indonesia, even data regarding minimal inhibitory concentration (MIC)-based susceptibility of E. coli and K. aeromobilis towards single antibiotic or combination of fosfomycin (FOS) and sulbactam-cepoferazone (SUL-CPZ) is very scarce, even though the data is required by clinicians. Methods: A descriptive observational study was carried out at the Microbiology Clinical Laboratory of the Faculty of Medicine, Universitas Indonesia. Thirty strains each of clinical isolates of E. coli and K. aeromobilis were subjected to MIC determination against FOS and SUL-CPZ. For susceptibility criteria, we adopted the Eucast guideline. The synergism of the combined antibiotics was determined by checkerboard titration. One strain of E. coli and K. aeromobilis showing a synergistic and independent effect against the combined antibiotics was subjected to a time-kill assay. The post-antibiotic effect (PAE) was determined on a strain of E. coli showing synergism against the combined antibiotics. Results: The MIC level of all strains decreased when the bacteria were exposed to the combined antibiotics. Synergism was observed in 53.3% of E. coli and 56.8% of K. aeromobilis. No antagonism was observed. Higher bacterial death during the first four hours occurred with the isolate, showing synergism compared to the isolate showing an independent effect. The PAE of E. coli was longer when exposed to combined antibiotics. Conclusion: In vitro synergism of FOS and SUL-CPZ was observed in the majority of isolates and could be used as the basis for further research on empirical treatment

scholarly journals Potent Synergy and Sustained Bactericidal Activity of a Vancomycin-Colistin Combination versus Multidrug-Resistant Strains of Acinetobacter baumannii

2010 ◽  
Vol 54 (12) ◽  
pp. 5316-5322 ◽  
Author(s):  
N. C. Gordon ◽  
K. Png ◽  
D. W. Wareham
Keyword(s):  
Health Care ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Clinical Use ◽  
Gram Negative ◽  
Resistant Strains ◽  
Bacterial Outer Membrane ◽  
Gram Negative Organisms ◽  
Time Kill ◽  
Emergence Of Resistance

ABSTRACT Multidrug-resistant Acinetobacter baumannii (MDRAB) presents an increasing challenge to health care. Although colistin has been used as a treatment of last resort, there is concern regarding its potential for toxicity and the emergence of resistance. The mechanism of action of colistin, however, raises the possibility of synergy with compounds that are normally inactive against Gram-negative organisms by virtue of the impermeability of the bacterial outer membrane. This study evaluated the effect of colistin combined with vancomycin on 5 previously characterized epidemic strains and 34 MDRAB clinical isolates by using time-kill assay, microdilution, and Etest methods. For all the isolates, significant synergy was demonstrated by at least one method, with reductions in the MIC of vancomycin from >256 μg/ml to ≤48 μg/ml for all strains after exposure to 0.5 μg/ml colistin. This raises the possibility of the clinical use of this combination for infections due to MDRAB, with the potential for doses lower than those currently used.

Sign in / Sign up

Export Citation Format

Share Document