scholarly journals Bactericidal Activity, Absence of Serum Effect, and Time-Kill Kinetics of Ceftazidime-Avibactam against β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

2014 ◽  
Vol 58 (9) ◽  
pp. 5297-5305 ◽  
Author(s):  
Tiffany R. Keepers ◽  
Marcela Gomez ◽  
Chris Celeri ◽  
Wright W. Nichols ◽  
Kevin M. Krause
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Human Serum ◽  
Bactericidal Activity ◽  
Minimum Bactericidal Concentration ◽  
Wild Type ◽  
Content Type ◽  
Positive Isolate ◽  
New Treatment ◽  
Time Kill ◽  
Kinetics Of

ABSTRACTAvibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18Pseudomonas aeruginosaisolates and 15Enterobacteriaceaeisolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2P. aeruginosaisolates (1blaVIM-positive isolate and 1blaOXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log10decrease in the number of CFU/ml was observed at 6 h for allEnterobacteriaceae, and a 2-log10reduction in the number of CFU/ml was observed at 6 h for 3 of the 6P. aeruginosaisolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused byEnterobacteriaceaeandP. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.

scholarly journals Evaluation of the Bactericidal Activity of Plazomicin and Comparators against Multidrug-Resistant Enterobacteriaceae

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
M. Thwaites ◽  
D. Hall ◽  
D. Shinabarger ◽  
A. W. Serio ◽  
K. M. Krause ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Bactericidal Activity ◽  
Minimum Bactericidal Concentration ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Next Generation ◽  
Content Type ◽  
Time Kill

ABSTRACT The next-generation aminoglycoside plazomicin, in development for infections due to multidrug-resistant (MDR) Enterobacteriaceae, was evaluated alongside comparators for bactericidal activity in minimum bactericidal concentration (MBC) and time-kill (TK) assays against MDR Enterobacteriaceae isolates with characterized aminoglycoside and β-lactam resistance mechanisms. Overall, plazomicin and colistin were the most potent, with plazomicin demonstrating an MBC50/90 of 0.5/4 μg/ml and sustained 3-log10 kill against MDR Escherichia coli, Klebsiella pneumoniae, and Enterobacter spp.

scholarly journals WCK 5107 (Zidebactam) and WCK 5153 Are Novel Inhibitors of PBP2 Showing Potent “β-Lactam Enhancer” Activity against Pseudomonas aeruginosa, Including Multidrug-Resistant Metallo-β-Lactamase-Producing High-Risk Clones

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Bartolome Moya ◽  
Isabel M. Barcelo ◽  
Sachin Bhagwat ◽  
Mahesh Patel ◽  
German Bou ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
High Risk ◽  
Bactericidal Activity ◽  
Multidrug Resistant ◽  
Antimicrobial Activities ◽  
Enhancer Activity ◽  
Content Type ◽  
Steady State Kinetics ◽  
Time Kill ◽  
Derivatives Of

ABSTRACT Zidebactam and WCK 5153 are novel β-lactam enhancers that are bicyclo-acyl hydrazides (BCH), derivatives of the diazabicyclooctane (DBO) scaffold, targeted for the treatment of serious infections caused by highly drug-resistant Gram-negative pathogens. In this study, we determined the penicillin-binding protein (PBP) inhibition profiles and the antimicrobial activities of zidebactam and WCK 5153 against Pseudomonas aeruginosa, including multidrug-resistant (MDR) metallo-β-lactamase (MBL)-producing high-risk clones. MIC determinations and time-kill assays were conducted for zidebactam, WCK 5153, and antipseudomonal β-lactams using wild-type PAO1, MexAB-OprM-hyperproducing (mexR), porin-deficient (oprD), and AmpC-hyperproducing (dacB) derivatives of PAO1, and MBL-expressing clinical strains ST175 (bla VIM-2) and ST111 (bla VIM-1). Furthermore, steady-state kinetics was used to assess the inhibitory potential of these compounds against the purified VIM-2 MBL. Zidebactam and WCK 5153 showed specific PBP2 inhibition and did not inhibit VIM-2 (apparent Ki [Ki app] > 100 μM). MICs for zidebactam and WCK 5153 ranged from 2 to 32 μg/ml (amdinocillin MICs > 32 μg/ml). Time-kill assays revealed bactericidal activity of zidebactam and WCK 5153. LIVE-DEAD staining further supported the bactericidal activity of both compounds, showing spheroplast formation. Fixed concentrations (4 or 8 μg/ml) of zidebactam and WCK 5153 restored susceptibility to all of the tested β-lactams for each of the P. aeruginosa mutant strains. Likewise, antipseudomonal β-lactams (CLSI breakpoints), in combination with 4 or 8 μg/ml of zidebactam or WCK 5153, resulted in enhanced killing. Certain combinations determined full bacterial eradication, even with MDR MBL-producing high-risk clones. β-Lactam–WCK enhancer combinations represent a promising β-lactam “enhancer-based” approach to treat MDR P. aeruginosa infections, bypassing the need for MBL inhibition.

scholarly journals γ-Glutamyl Spermine Synthetase PauA2 as a Potential Target of Antibiotic Development against Pseudomonas aeruginosa

2012 ◽  
Vol 56 (10) ◽  
pp. 5309-5314 ◽  
Author(s):  
Xiangyu Yao ◽  
Congran Li ◽  
Jianmei Zhang ◽  
Chung-Dar Lu
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Human Serum ◽  
Parental Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Strong Support ◽  
Uptake System ◽  
Wild Type ◽  
Content Type ◽  
Antibiotic Development

ABSTRACTPolyamines are absolute requirements for cell growth. When in excess,Pseudomonas aeruginosapossesses six γ-glutamylpolyamine synthetases (GPSs) encoded by thepauA1-pauA7genes to initiate polyamine catabolism. Recently, thepauA2mutant was reported to lose the capability to grow on spermine (Spm) and spermidine (Spd) as sole carbon and nitrogen sources. Although this mutant grew normally in defined minimal medium and LB broth, growth was completely abolished by the addition of Spm or Spd. These two compounds exert a bactericidal effect (Spm > Spd) on the mutants as demonstrated by MIC measurements (over 500-fold reduction) and time-killing curves. Spm toxicity in thepauA2mutant was attenuated when the major uptake system was further deleted from the strain, suggesting cytoplasmic targets of toxicity. In addition, the synergistic effect of Spm and carbenicillin in the wild-type strain PAO1 was diminished in mutants without functional PauA2. Furthermore, Spm MIC was reduced by 8-fold when the Spm uptake system was deleted from the wild-type strain, suggesting a second target of Spm toxicity in the periplasm. Experiments were also conducted to test the hypothesis that native Spm and Spd in human serum may be sufficient to kill thepauA2mutant. Growth of the mutant was completely inhibited by 40% (vol/vol) human serum, whereas the parental strain required 80%. Colony counts indicated that the mutant but not the parent was in fact killed by human plasma. In addition, carbenicillin MIC against the mutant was reduced by 16-fold in the presence of 20% human serum while that of the parental strain remained unchanged. Taking PauA2 as the template, sequence comparison indicates that putative PauA2 homologues are widespread in a variety of Gram-negative bacteria. In summary, this study reveals the importance of GPS in alleviation of polyamine toxicity when in excess, and it provides strong support to the feasibility of GPS as a molecular target for new antibiotic development.

scholarly journals Antimicrobial Activity of Fosfomycin-Tobramycin Combination against Pseudomonas aeruginosa Isolates Assessed by Time-Kill Assays and Mutant Prevention Concentrations

2015 ◽  
Vol 59 (10) ◽  
pp. 6039-6045 ◽  
Author(s):  
María Díez-Aguilar ◽  
María Isabel Morosini ◽  
Ana P. Tedim ◽  
Irene Rodríguez ◽  
Zerrin Aktaş ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Wild Type ◽  
Anaerobic Conditions ◽  
Mutant Selection ◽  
Content Type ◽  
Mutant Prevention Concentration ◽  
Fosfomycin Resistance ◽  
Time Kill ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTThe antibacterial activity of fosfomycin-tobramycin combination was studied by time-kill assay in eightPseudomonas aeruginosaclinical isolates belonging to the fosfomycin wild-type population (MIC = 64 μg/ml) but with different tobramycin susceptibilities (MIC range, 1 to 64 μg/ml). The mutant prevention concentration (MPC) and mutant selection window (MSW) were determined in five of these strains (tobramycin MIC range, 1 to 64 μg/ml) in aerobic and anaerobic conditions simulating environments that are present in biofilm-mediated infections. Fosfomycin-tobramycin was synergistic and bactericidal for the isolates with mutations in themexZrepressor gene, with a tobramycin MIC of 4 μg/ml. This effect was not observed in strains displaying tobramycin MICs of 1 to 2 μg/ml due to the strong bactericidal effect of tobramycin alone. Fosfomycin presented higher MPC values (range, 2,048 to >2,048 μg/ml) in aerobic and anaerobic conditions than did tobramycin (range, 16 to 256 μg/ml). Interestingly, the association rendered narrow or even null MSWs in the two conditions. However, for isolates with high-level tobramycin resistance that harbored aminoglycoside nucleotidyltransferases, time-kill assays showed no synergy, with wide MSWs in the two environments.glpTgene mutations responsible for fosfomycin resistance inP. aeruginosawere determined in fosfomycin-susceptible wild-type strains and mutant derivatives recovered from MPC studies. All mutant derivatives had changes in the GlpT amino acid sequence, which resulted in a truncated permease responsible for fosfomycin resistance. These results suggest that fosfomycin-tobramycin can be an alternative for infections due toP. aeruginosasince it has demonstrated synergistic and bactericidal activity in susceptible isolates and those with low-level tobramycin resistance. It also prevents the emergence of resistant mutants in either aerobic or anaerobic environments.

scholarly journals Bactericidal Effect of Tomatidine-Tobramycin Combination against Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa Is Enhanced by Interspecific Small-Molecule Interactions

2015 ◽  
Vol 59 (12) ◽  
pp. 7458-7464 ◽  
Author(s):  
Simon Boulanger ◽  
Gabriel Mitchell ◽  
Kamal Bouarab ◽  
Éric Marsault ◽  
André Cantin ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Bactericidal Effect ◽  
Methicillin Resistant ◽  
Content Type ◽  
New Treatment ◽  
Molecule Interactions ◽  
Kinetics Of ◽  
Related Compounds ◽  
Respiratory Deficient

ABSTRACTThis study investigated the antibacterial activity of the plant alkaloid tomatidine (TO) againstStaphylococcus aureusgrown in the presence ofPseudomonas aeruginosa. Since theP. aeruginosaexoproduct 4-hydroxy-2-heptylquinoline-N-oxide (HQNO) is known to cause a respiratory deficiency inS. aureusand respiratory-deficientS. aureusare known to be hypersensitive to TO, we assessed kill kinetics of TO (8 μg/ml) againstS. aureusin coculture withP. aeruginosa. Kill kinetics were also assessed usingP. aeruginosamutants deficient in the production of different exoproducts and quorum sensing-related compounds. After 24 h in coculture, TO increased the killing ofS. aureusby 3.4 log10CFU/ml in comparison to that observed in a coculture without TO. The effect of TO was abolished whenS. aureuswas in coculture with thelasRrhlR,pqsA,pqsL, orlasAmutant ofP. aeruginosa. The bactericidal effect of TO againstS. aureusin coculture with thepqsLmutant was restored by supplemental HQNO. In anS. aureusmonoculture, the combination of HQNO and TO was bacteriostatic, indicating that thepqsLmutant produced an additional factor required for the bactericidal effect. The bactericidal activity of TO was also observed against a tobramycin-resistant methicillin-resistantS. aureus(MRSA) in coculture withP. aeruginosa, and the addition of tobramycin significantly suppressed the growth of both microorganisms. TO shows a strong bactericidal effect againstS. aureuswhen cocultured withP. aeruginosa. The combination of TO and tobramycin may represent a new treatment approach for cystic fibrosis patients frequently cocolonized by MRSA andP. aeruginosa.

scholarly journals Role of Iron Uptake Systems in Pseudomonas aeruginosa Virulence and Airway Infection

2016 ◽  
Vol 84 (8) ◽  
pp. 2324-2335 ◽  
Author(s):  
Fabrizia Minandri ◽  
Francesco Imperi ◽  
Emanuela Frangipani ◽  
Carlo Bonchi ◽  
Daniela Visaggio ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mouse Model ◽  
Human Serum ◽  
Iron Uptake ◽  
Lung Infection ◽  
Null Mutant ◽  
Wild Type ◽  
Heme Uptake ◽  
Content Type

Pseudomonas aeruginosais a leading cause of hospital-acquired pneumonia and chronic lung infections in cystic fibrosis patients. Iron is essential for bacterial growth, andP. aeruginosaexpresses multiple iron uptake systems, whose role in lung infection deserves further investigation.P. aeruginosaFe3+uptake systems include the pyoverdine and pyochelin siderophores and two systems for heme uptake, all of which are dependent on the TonB energy transducer.P. aeruginosaalso has the FeoB transporter for Fe2+acquisition. To assess the roles of individual iron uptake systems inP. aeruginosalung infection, single and double deletion mutants were generated inP. aeruginosaPAO1 and characterizedin vitro, using iron-poor media and human serum, andin vivo, using a mouse model of lung infection. The iron uptake-null mutant (tonB1 feoB) and the Fe3+transport mutant (tonB1) did not grow aerobically under low-iron conditions and were avirulent in the mouse model. Conversely, the wild type and thefeoB,hasR phuR(heme uptake), andpchD(pyochelin) mutants grewin vitroand caused 60 to 90% mortality in mice. The pyoverdine mutant (pvdA) and the siderophore-null mutant (pvdA pchD) grew aerobically in iron-poor media but not in human serum, and they caused low mortality in mice (10 to 20%). To differentiate the roles of pyoverdine in iron uptake and virulence regulation, apvdA fpvRdouble mutant defective in pyoverdine production but expressing wild-type levels of pyoverdine-regulated virulence factors was generated. Deletion offpvRin thepvdAbackground partially restored the lethal phenotype, indicating that pyoverdine contributes to the pathogenesis ofP. aeruginosalung infection by combining iron transport and virulence-inducing capabilities.

scholarly journals Hyperbaric Oxygen Sensitizes Anoxic Pseudomonas aeruginosa Biofilm to Ciprofloxacin

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Mette Kolpen ◽  
Christian J. Lerche ◽  
Kasper N. Kragh ◽  
Thomas Sams ◽  
Klaus Koren ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Hyperbaric Oxygen ◽  
Bactericidal Activity ◽  
Host Response ◽  
Polymorphonuclear Leukocytes ◽  
Bactericidal Effect ◽  
Aerobic Respiration ◽  
Hyperbaric Oxygen Treatment ◽  
Content Type ◽  
Oxygen Treatment

ABSTRACT Chronic Pseudomonas aeruginosa lung infection is characterized by the presence of endobronchial antibiotic-tolerant biofilm, which is subject to strong oxygen (O2) depletion due to the activity of surrounding polymorphonuclear leukocytes. The exact mechanisms affecting the antibiotic susceptibility of biofilms remain unclear, but accumulating evidence suggests that the efficacy of several bactericidal antibiotics is enhanced by stimulation of aerobic respiration of pathogens, while lack of O2 increases their tolerance. In fact, the bactericidal effect of several antibiotics depends on active aerobic metabolism activity and the endogenous formation of reactive O2 radicals (ROS). In this study, we aimed to apply hyperbaric oxygen treatment (HBOT) to sensitize anoxic P. aeruginosa agarose biofilms established to mimic situations with intense O2 consumption by the host response in the cystic fibrosis (CF) lung. Application of HBOT resulted in enhanced bactericidal activity of ciprofloxacin at clinically relevant durations and was accompanied by indications of restored aerobic respiration, involvement of endogenous lethal oxidative stress, and increased bacterial growth. The findings highlight that oxygenation by HBOT improves the bactericidal activity of ciprofloxacin on P. aeruginosa biofilm and suggest that bacterial biofilms are sensitized to antibiotics by supplying hyperbaric O2.

scholarly journals Effect of Nitroxides on Swarming Motility and Biofilm Formation, Multicellular Behaviors in Pseudomonas aeruginosa

2013 ◽  
Vol 57 (10) ◽  
pp. 4877-4881 ◽  
Author(s):  
César de la Fuente-Núñez ◽  
Fany Reffuveille ◽  
Kathryn E. Fairfull-Smith ◽  
Robert E. W. Hancock
Keyword(s):  
Nitric Oxide ◽  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Wild Type ◽  
Planktonic Cells ◽  
Swarming Motility ◽  
Content Type ◽  
Exogenous Addition ◽  
Biofilm Dispersion ◽  
Dispersal Activity

ABSTRACTThe ability of nitric oxide (NO) to induce biofilm dispersion has been well established. Here, we investigated the effect of nitroxides (sterically hindered nitric oxide analogues) on biofilm formation and swarming motility inPseudomonas aeruginosa. A transposon mutant unable to produce nitric oxide endogenously (nirS) was deficient in swarming motility relative to the wild type and the complemented strain. Moreover, expression of thenirSgene was upregulated by 9.65-fold in wild-type swarming cells compared to planktonic cells. Wild-type swarming levels were substantially restored upon the exogenous addition of nitroxide containing compounds, a finding consistent with the hypothesis that NO is necessary for swarming motility. Here, we showed that nitroxides not only mimicked the dispersal activity of NO but also prevented biofilms from forming in flow cell chambers. In addition, anirStransposon mutant was deficient in biofilm formation relative to the wild type and the complemented strain, thus implicating NO in the formation of biofilms. Intriguingly, despite its stand-alone action in inhibiting biofilm formation and promoting dispersal, a nitroxide partially restored the ability of anirSmutant to form biofilms.

scholarly journals Efficacy of Antibiotic Combinations against Multidrug-Resistant Pseudomonas aeruginosa in Automated Time-Lapse Microscopy and Static Time-Kill Experiments

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Anna Olsson ◽  
Pikkei Wistrand-Yuen ◽  
Elisabet I. Nielsen ◽  
Lena E. Friberg ◽  
Linus Sandegren ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Time Lapse ◽  
Polymyxin B ◽  
Multidrug Resistant ◽  
Positive Interactions ◽  
Synergistic Activity ◽  
Content Type ◽  
Time Lapse Microscopy ◽  
Time Kill ◽  
Antibiotic Combination

ABSTRACT Antibiotic combination therapy is used for severe infections caused by multidrug-resistant (MDR) Gram-negative bacteria, yet data regarding which combinations are most effective are lacking. This study aimed to evaluate the in vitro efficacy of polymyxin B in combination with 13 other antibiotics against four clinical strains of MDR Pseudomonas aeruginosa. We evaluated the interactions of polymyxin B in combination with amikacin, aztreonam, cefepime, chloramphenicol, ciprofloxacin, fosfomycin, linezolid, meropenem, minocycline, rifampin, temocillin, thiamphenicol, or trimethoprim by automated time-lapse microscopy using predefined cutoff values indicating inhibition of growth (≤106 CFU/ml) at 24 h. Promising combinations were subsequently evaluated in static time-kill experiments. All strains were intermediate or resistant to polymyxin B, antipseudomonal β-lactams, ciprofloxacin, and amikacin. Genes encoding β-lactamases (e.g., blaPAO and blaOXA-50) and mutations associated with permeability and efflux were detected in all strains. In the time-lapse microscopy experiments, positive interactions were found with 39 of 52 antibiotic combination/bacterial strain setups. Enhanced activity was found against all four strains with polymyxin B used in combination with aztreonam, cefepime, fosfomycin, minocycline, thiamphenicol, and trimethoprim. Time-kill experiments showed additive or synergistic activity with 27 of the 39 tested polymyxin B combinations, most frequently with aztreonam, cefepime, and meropenem. Positive interactions were frequently found with the tested combinations, against strains that harbored several resistance mechanisms to the single drugs, and with antibiotics that are normally not active against P. aeruginosa. Further study is needed to explore the clinical utility of these combinations.

scholarly journals Activity of ACHN-490 Tested Alone and in Combination with Other Agents against Pseudomonas aeruginosa

2011 ◽  
Vol 55 (5) ◽  
pp. 2463-2465 ◽  
Author(s):  
Glenn A. Pankuch ◽  
Gengrong Lin ◽  
Aya Kubo ◽  
Eliana S. Armstrong ◽  
Peter C. Appelbaum ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Content Type ◽  
Time Kill

ABSTRACTACHN-490 was tested alone and in combination with cefepime, doripenem, imipenem, or piperacillin-tazobactam in a synergy time-kill analysis against 25Pseudomonas aeruginosastrains with different resistance phenotypes. Each combination was synergistic against most isolates at 24 h, and antagonism was not observed. Combinations of ACHN-490 with cefepime, doripenem, imipenem, or piperacillin-tazobactam yielded synergies in ≥70% and ≥80% of strains at 6 and 12 h, respectively, and in ≥68% at 24 h.

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