Comparative in vitro synergistic activity of new beta-lactam antimicrobial agents and amikacin against Pseudomonas aeruginosa and Serratia marcescens.

ABSTRACTWe evaluated thein vitroactivity of polymyxin B plus imipenem, meropenem, or tigecycline against six KPC-2-producingEnterobacteriaceaestrains with high MICs for these antimicrobial agents. Polymyxin B with carbapenems, especially meropenem, were the most active combinations forKlebsiella pneumoniaeandEnterobacter cloacaeregardless of the polymyxin B concentration used in the time-kill assay. This combination was also synergistic against twoSerratia marcescensstrains that are intrinsically resistant to polymyxins. Polymyxin B and tigecycline also presented synergistic activity in most experiments.

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In vitro synergistic activities of tobramycin and selected beta-lactams against 75 gram-negative clinical isolates.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.11.2586 ◽

1997 ◽

Vol 41 (11) ◽

pp. 2586-2588 ◽

Cited By ~ 22

Author(s):

R C Owens ◽

M A Banevicius ◽

D P Nicolau ◽

C H Nightingale ◽

R Quintiliani

Keyword(s):

Pseudomonas Aeruginosa ◽

Enterobacter Cloacae ◽

Clinical Isolates ◽

Synergistic Activity ◽

Beta Lactam ◽

Beta Lactams ◽

Acinetobacter Baumanii ◽

Gram Negative ◽

Combination Regimens

The microdilution checkerboard technique was utilized to distinguish synergistic activity between tobramycin and four beta-lactams: piperacillin-tazobactam, ticarcillin-clavulanate, ceftazidime, and ceftriaxone. Beta-lactam-aminoglycoside combinations were tested against 75 clinical isolates of Pseudomonas aeruginosa, Acinetobacter baumanii, Citrobacterfreundii, Serratia marcescens, and Enterobacter cloacae. Despite in vitro susceptibilities, all isolates demonstrated either synergism or indifference; no antagonism was observed. Against pathogenic gram-negative nosocomial isolates, a greater percentage of synergy was consistently observed with combination regimens containing tobramycin and piperacillin-tazobactam or ticarcillin-clavulanate than with the cephalosporin-containing regimens.

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Evaluation of the Bactericidal Activity of Fosfomycin in Combination with Selected Antimicrobial Comparison Agents Tested against Gram-Negative Bacterial Strains by Using Time-Kill Curves

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02549-18 ◽

2019 ◽

Vol 63 (5) ◽

Cited By ~ 6

Author(s):

Robert K. Flamm ◽

Paul R. Rhomberg ◽

Jill M. Lindley ◽

Kim Sweeney ◽

E. J. Ellis-Grosse ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Species Complex ◽

Antimicrobial Agents ◽

Acinetobacter Calcoaceticus ◽

Synergistic Activity ◽

Bacterial Strains ◽

Gram Negative ◽

Content Type ◽

Time Kill

ABSTRACT The effects of combining fosfomycin with various antimicrobial agents were evaluated in vitro by broth microdilution checkerboard and time-kill kinetic studies. Checkerboard analyses were used to evaluate the following 30 Gram-negative isolates: 5 Pseudomonas aeruginosa, 5 Acinetobacter baumannii-Acinetobacter calcoaceticus species complex, and 20 Enterobacteriaceae isolates. No isolate exhibited antagonism when fosfomycin was tested in combination, and synergy was observed in more than 25% of the drug combinations tested. The most frequent instances of synergy occurred when testing fosfomycin with β-lactams. Two isolates of Pseudomonas aeruginosa, 2 of Klebsiella pneumoniae, and 1 of the A. baumannii-A. calcoaceticus species complex that exhibited synergy when fosfomycin was tested in combination were subjected to time-kill kinetic analyses for confirmation. Time-kill assays confirmed synergistic activity. These data indicated that combination therapy with fosfomycin may be beneficial.

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In Vitro Activity of β-Lactam Antimicrobial Agents in Combination with Aztreonam Tested Against Metallob-β-Lactamase-Producing Pseudomonas aeruginosa and Acinetobacter baumannii

Journal of Chemotherapy ◽

10.1179/joc.2005.17.6.622 ◽

2005 ◽

Vol 17 (6) ◽

pp. 622-627 ◽

Cited By ~ 11

Author(s):

H.S. Sader ◽

P.R. Rhomberg ◽

R.N. Jones

Keyword(s):

Pseudomonas Aeruginosa ◽

Acinetobacter Baumannii ◽

Antimicrobial Agents ◽

Vitro Activity ◽

In Vitro Activity

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Activities of Tobramycin and Six Other Antibiotics against Pseudomonas aeruginosa Isolates from Patients with Cystic Fibrosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.43.12.2877 ◽

1999 ◽

Vol 43 (12) ◽

pp. 2877-2880 ◽

Cited By ~ 73

Author(s):

Ribhi M. Shawar ◽

David L. MacLeod ◽

Richard L. Garber ◽

Jane L. Burns ◽

Jenny R. Stapp ◽

...

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Antimicrobial Agents ◽

Active Drug ◽

Resistance Mechanisms ◽

Phase Iii ◽

In Vitro Activity ◽

Phase Iii Clinical Trials ◽

Multiple Antibiotics

ABSTRACT The in vitro activity of tobramycin was compared with those of six other antimicrobial agents against 1,240 Pseudomonas aeruginosa isolates collected from 508 patients with cystic fibrosis during pretreatment visits as part of the phase III clinical trials of tobramycin solution for inhalation. The tobramycin MIC at which 50% of isolates are inhibited (MIC50) and MIC90 were 1 and 8 μg/ml, respectively. Tobramycin was the most active drug tested and also showed good activity against isolates resistant to multiple antibiotics. The isolates were less frequently resistant to tobramycin (5.4%) than to ceftazidime (11.1%), aztreonam (11.9%), amikacin (13.1%), ticarcillin (16.7%), gentamicin (19.3%), or ciprofloxacin (20.7%). For all antibiotics tested, nonmucoid isolates were more resistant than mucoid isolates. Of 56 isolates for which the tobramycin MIC was ≥16 μg/ml and that were investigated for resistance mechanisms, only 7 (12.5%) were shown to possess known aminoglycoside-modifying enzymes; the remaining were presumably resistant by an incompletely understood mechanism often referred to as “impermeability.”

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Synergistic Antifungal Activity of Graphene Oxide and Fungicides against Fusarium Head Blight In Vitro and In Vivo

Nanomaterials ◽

10.3390/nano11092393 ◽

2021 ◽

Vol 11 (9) ◽

pp. 2393

Author(s):

Xiuping Wang ◽

Fei Peng ◽

Caihong Cheng ◽

Lina Chen ◽

Xuejuan Shi ◽

...

Keyword(s):

Graphene Oxide ◽

Plant Pathogens ◽

Antimicrobial Agents ◽

Plant Protection ◽

Disease Incidence ◽

Agricultural Science ◽

Plant Diseases ◽

Synergistic Activity

Plant pathogens constantly develop resistance to antimicrobial agents, and this poses great challenges to plant protection. Therefore, there is a pressing need to search for new antimicrobials. The combined use of antimicrobial agents with different antifungal mechanisms has been recognized as a promising approach to manage plant diseases. Graphene oxide (GO) is a newly emerging and highly promising antimicrobial agent against various plant pathogens in agricultural science. In this study, the inhibitory activity of GO combined with fungicides (Mancozeb, Cyproconazol and Difenoconazole) against Fusarium graminearum was investigated in vivo and in vitro. The results revealed that the combination of GO and fungicides has significant synergistic inhibitory effects on the mycelial growth, mycelial biomass and spore germination of F. graminearum relative to single fungicides. The magnitude of synergy was found to depend on the ratio of GO and fungicide in the composite. In field tests, GO–fungicides could significantly reduce the disease incidence and disease severity, exhibiting a significantly improved control efficacy on F. graminearum. The strong synergistic activity of GO with existing fungicides demonstrates the great application potential of GO in pest management.

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Short versus prolonged courses of antimicrobial therapy for patients with uncomplicated Pseudomonas aeruginosa bloodstream infection: a retrospective study

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkab358 ◽

2021 ◽

Author(s):

Moonsuk Bae ◽

Yunseo Jeong ◽

Seongman Bae ◽

Min Jae Kim ◽

Yong Pil Chong ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Bloodstream Infection ◽

Antimicrobial Therapy ◽

Antimicrobial Agents ◽

Propensity Score Analysis ◽

Tertiary Care ◽

Care Hospital ◽

Short Course ◽

Significant Difference

Abstract Background The optimal duration of antimicrobial therapy for uncomplicated Pseudomonas aeruginosa bloodstream infection (BSI) is unknown. We compared the outcomes of short and prolonged courses of antimicrobial therapy in adults with uncomplicated pseudomonal BSI. Methods All patients with uncomplicated P. aeruginosa BSI admitted at a tertiary-care hospital from April 2010 to April 2020 were included. We compared the primary outcome (a composite of the rate of recurrent P. aeruginosa infection and mortality within 30 days after discontinuing antimicrobial therapy) among patients who underwent short (7‒11 days) and prolonged (12‒21 days) courses of antimicrobial therapy using propensity score analysis with the inverse probability of treatment weighting (IPTW) method. Results We evaluated 1477 patients with P. aeruginosa BSI; of them, 290 met the eligibility criteria who received antimicrobial agents with in vitro activity, including 97 (33%) who underwent short-course therapy [median of 9 (IQR = 8‒11) days] and 193 (67%) who underwent prolonged-course therapy [median of 15 (IQR = 14‒18) days]. We found no significant difference in the risk of recurrence or 30 day mortality between the prolonged-course and short-course groups [n = 30 (16%) versus n = 11 (11%); IPTW-adjusted HR = 0.68, 95% CI = 0.34 − 1.36, P = 0.28]. The prolonged-course therapy did not significantly reduce the risk of the recurrence of P. aeruginosa infection within 180 days compared with short-course therapy [n = 37 (19%) versus n = 12 (12%); IPTW-adjusted HR = 0.57, 95% CI = 0.29 − 1.10, P = 0.09]. Conclusions Short-course antimicrobial therapy could be as effective as prolonged-course therapy for uncomplicated P. aeruginosa BSI.

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