RESUMO
Non-clinical antibiotic development relies on in vitro susceptibility and infection model studies. Validating the achievement of the targeted drug concentrations is essential to avoid under-estimation of drug effects and over-estimation of resistance emergence. While certain ß-lactams (e.g., imipenem) and ß-lactamase inhibitors (BLIs; clavulanic acid) are believed to be relatively unstable, limited tangible data on their stability in commonly used in vitro media are known. We aimed to determine the thermal stability of 10 ß-lactams and 3 BLIs via LC-MS/MS in cation-adjusted Mueller Hinton broth at 25 and 36°C as well as agar at 4 and 37°C, and in water at -20, 4, and 25°C. Supplement dosing algorithms were developed to achieve broth concentrations close to their target over 24 h. During incubation in broth (pH 7.25)/agar, degradation half-lives were 16.9/21.8 h for imipenem, 20.7/31.6 h for biapenem, 29.0 h for clavulanic acid (studied in broth only), 23.1/71.6 h for cefsulodin, 40.6/57.9 h for doripenem, 46.5/64.6 h for meropenem, 50.8/97.7 h for cefepime, 61.5/99.5 h for piperacillin, and >120 h for all other compounds. Broth stability decreased at higher pH. All drugs were ≥90% stable for 72 h in agar at 4°C. Degradation half-lives in water at 25°C were >200 h for all drugs except imipenem (14.7 h, at 1,000 mg/L) and doripenem (59.5 h). One imipenem supplement dose allowed concentrations to stay within ±31% of their target concentration. This study provides comprehensive stability data on ß-lactams and BLIs in relevant in vitro media using LC-MS/MS. Future studies are warranted applying these data to antimicrobial susceptibility testing and assessing the impact of ß-lactamase-related degradation.
Assuntos
Inibidores de beta-Lactamases , beta-Lactamas , Inibidores de beta-Lactamases/farmacologia , beta-Lactamas/farmacologia , Doripenem , Ágar , Cromatografia Líquida , Espectrometria de Massas em Tandem , Antibacterianos/farmacologia , Penicilinas , Ácido Clavulânico/farmacologia , Imipenem/farmacologia , Água , Testes de Sensibilidade MicrobianaRESUMO
Metallo-ß-lactamase (MBL)-producing Gram-negative bacteria cause infections associated with high rates of morbidity and mortality. Currently, a leading regimen to treat infections caused by MBL-producing bacteria is aztreonam combined with ceftazidime-avibactam. The purpose of the present study was to evaluate and rationally optimize the combination of aztreonam and ceftazidime-avibactam with and without polymyxin B against a clinical Klebsiella pneumoniae isolate producing NDM-1 and CTX-M by use of the hollow fiber infection model (HFIM). A novel de-escalation approach to polymyxin B dosing was also explored, whereby a standard 0-h loading dose was followed by maintenance doses that were 50% of the typical clinical regimen. In the HFIM, the addition of polymyxin B to aztreonam plus ceftazidime-avibactam significantly improved bacterial killing, leading to eradication, including for the novel de-escalation dosing strategy. Serial samples from the growth control and monotherapies were explored in a Galleria mellonella virulence model to assess virulence changes. Weibull regression showed that low-level ceftazidime resistance and treatment with monotherapy resulted in increased G. mellonella mortality (P < 0.05). A neutropenic rabbit pneumonia model demonstrated that aztreonam plus ceftazidime-avibactam with or without polymyxin B resulted in similar bacterial killing, and these combination therapies were statistically significantly better than monotherapies (P < 0.05). However, only the polymyxin B-containing combination therapy produced a statistically significant decrease in lung weights (P < 0.05), indicating a decreased inflammatory process. Altogether, adding polymyxin B to the combination of aztreonam plus ceftazidime-avibactam for NDM- and CTX-M-producing K. pneumoniae improved bacterial killing effects, reduced lung inflammation, suppressed resistance amplification, and limited virulence changes.
Assuntos
Ceftazidima , Klebsiella pneumoniae , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Compostos Azabicíclicos/farmacologia , Compostos Azabicíclicos/uso terapêutico , Aztreonam/farmacologia , Ceftazidima/farmacologia , Ceftazidima/uso terapêutico , Parede Celular/metabolismo , Combinação de Medicamentos , Klebsiella/metabolismo , Testes de Sensibilidade Microbiana , Polimixina B/farmacologia , Coelhos , beta-Lactamases/metabolismoRESUMO
BACKGROUND: Understanding the mechanism of antimicrobial action is critical for improving antibiotic therapy. For the first time, we integrated correlative metabolomics and transcriptomics of Pseudomonas aeruginosa to elucidate the mechanism of synergistic killing of polymyxin-rifampicin combination. METHODS: Liquid chromatography-mass spectrometry and RNA-seq analyses were conducted to identify the significant changes in the metabolome and transcriptome of P. aeruginosa PAO1 after exposure to polymyxin B (1 mg/L) and rifampicin (2 mg/L) alone, or in combination over 24 h. A genome-scale metabolic network was employed for integrative analysis. RESULTS: In the first 4-h treatment, polymyxin B monotherapy induced significant lipid perturbations, predominantly to fatty acids and glycerophospholipids, indicating a substantial disorganization of the bacterial outer membrane. Expression of ParRS, a two-component regulatory system involved in polymyxin resistance, was increased by polymyxin B alone. Rifampicin alone caused marginal metabolic perturbations but significantly affected gene expression at 24 h. The combination decreased the gene expression of quorum sensing regulated virulence factors at 1 h (e.g. key genes involved in phenazine biosynthesis, secretion system and biofilm formation); and increased the expression of peptidoglycan biosynthesis genes at 4 h. Notably, the combination caused substantial accumulation of nucleotides and amino acids that last at least 4 h, indicating that bacterial cells were in a state of metabolic arrest. CONCLUSION: This study underscores the substantial potential of integrative systems pharmacology to determine mechanisms of synergistic bacterial killing by antibiotic combinations, which will help optimize their use in patients.
Assuntos
Polimixina B , Pseudomonas aeruginosa , Humanos , Pseudomonas aeruginosa/genética , Polimixina B/farmacologia , Polimixina B/metabolismo , Rifampina/farmacologia , Rifampina/metabolismo , Transcriptoma , Polimixinas/farmacologia , Polimixinas/metabolismo , Antibacterianos/farmacologia , Testes de Sensibilidade MicrobianaRESUMO
Resistance to polymyxin antibiotics is increasing. Without new antibiotic classes, combination therapy is often required. We systematically investigated bacterial killing with polymyxin-based combinations against multidrug-resistant (including polymyxin-resistant), carbapenemase-producing Klebsiella pneumoniae Monotherapies and double- and triple-combination therapies were compared to identify the most efficacious treatment using static time-kill studies (24 h, six isolates), an in vitro pharmacokinetic/pharmacodynamic model (IVM; 48 h, two isolates), and the mouse thigh infection model (24 h, six isolates). In static time-kill studies, all monotherapies (polymyxin B, rifampin, amikacin, meropenem, or minocycline) were ineffective. Initial bacterial killing was enhanced with various polymyxin B-containing double combinations; however, substantial regrowth occurred in most cases by 24 h. Most polymyxin B-containing triple combinations provided greater and more sustained killing than double combinations. Standard dosage regimens of polymyxin B (2.5 mg/kg of body weight/day), rifampin (600 mg every 12 h), and amikacin (7.5 mg/kg every 12 h) were simulated in the IVM. Against isolate ATH 16, no viable bacteria were detected across 5 to 25 h with triple therapy, with regrowth to â¼2-log10 CFU/ml occurring at 48 h. Against isolate BD 32, rapid initial killing of â¼3.5-log10 CFU/ml at 5 h was followed by a slow decline to â¼2-log10 CFU/ml at 48 h. In infected mice, polymyxin B monotherapy (60 mg/kg/day) generally was ineffective. With triple therapy (polymyxin B at 60 mg/kg/day, rifampin at 120 mg/kg/day, and amikacin at 300 mg/kg/day), at 24 h there was an â¼1.7-log10 CFU/thigh reduction compared to the starting inoculum for all six isolates. Our results demonstrate that the polymyxin B-rifampin-amikacin combination significantly enhanced in vitro and in vivo bacterial killing, providing important information for the optimization of polymyxin-based combinations in patients.
Assuntos
Klebsiella pneumoniae , Polimixinas , Animais , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Polimixina B/farmacologia , Polimixinas/farmacologia , beta-Lactamases/genética , beta-Lactamases/farmacologiaRESUMO
BACKGROUND: MBL-producing strains of Enterobacteriaceae are a major public health concern. We sought to define optimal combination regimens of ceftazidime/avibactam with aztreonam in a hollow-fibre infection model (HFIM) of MBL-producing strains of Escherichia coli and Klebsiella pneumoniae. METHODS: E. coli ARLG-1013 (blaNDM-1, blaCTX-M, blaCMY, blaTEM) and K. pneumoniae ARLG-1002 (blaNDM-1, blaCTXM-15, blaDHA, blaSHV, blaTEM) were studied in the HFIM using simulated human dosing regimens of ceftazidime/avibactam and aztreonam. Experiments were designed to evaluate the effect of staggered versus simultaneous administration, infusion duration and aztreonam daily dose (6 g/day versus 8 g/day) on bacterial killing and resistance suppression. Prospective validation experiments for the most active combination regimens were performed in triplicate to ensure reproducibility. RESULTS: Staggered administration of the combination (ceftazidime/avibactam followed by aztreonam) was found to be inferior to simultaneous administration. Longer infusion durations (2 h and continuous infusion) also resulted in enhanced bacterial killing relative to 30 min infusions. The rate of killing was more pronounced with 8 g/day versus 6 g/day aztreonam combination regimens for both tested strains. In the prospective validation experiments, ceftazidime/avibactam with aztreonam dosed every 8 and 6 h, respectively (ceftazidime/avibactam 2/0.5 g every 8 h + aztreonam 2 g every 6 h), or ceftazidime/avibactam with aztreonam as continuous infusions resulted in maximal bacterial killing and resistance suppression over 7 days. CONCLUSIONS: Simultaneous administration of aztreonam 8 g/day given as a continuous or 2 h infusion with ceftazidime/avibactam resulted in complete bacterial eradication and resistance suppression. Further study of this combination is needed with additional MBL-producing Gram-negative pathogens. The safety of this double ß-lactam strategy also warrants further study in Phase 1 clinical trials.
Assuntos
Aztreonam , Ceftazidima , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Compostos Azabicíclicos , Combinação de Medicamentos , Enterobacteriaceae , Escherichia coli , Humanos , Testes de Sensibilidade Microbiana , Estudos Prospectivos , Reprodutibilidade dos Testes , beta-LactamasesRESUMO
There is a great need for efficacious therapies against Gram-negative bacteria. Double ß-lactam combination(s) (DBL) are relatively safe, and preclinical data are promising; however, their clinical role has not been well defined. We conducted a metaanalysis of the clinical and microbiological efficacy of DBL compared to ß-lactam plus aminoglycoside combinations (BLAG). PubMed, Embase, ISI Web of Knowledge, and Cochrane Controlled Trials Register database were searched through July 2018. We included randomized controlled clinical trials that compared DBL with BLAG combinations. Clinical response was used as the primary outcome and microbiological response in Gram-negative bacteria as the secondary outcome; sensitivity analyses were performed for Pseudomonas aeruginosa, Klebsiella spp., and Escherichia coli Heterogeneity and risk of bias were assessed. Safety results were classified by systems and organs. Thirteen studies evaluated 2,771 cases for clinical response and 665 cases for microbiological response in various Gram-negative species. DBL achieved slightly, but not significantly, better clinical response (risk ratio, 1.05; 95% confidence interval [CI], 0.99 to 1.11) and microbiological response in Gram-negatives (risk ratio, 1.11; 95% CI, 0.99 to 1.25) compared with BLAG. Sensitivity analyses by pathogen showed the same trend. No significant heterogeneity across studies was found. DBL was significantly safer than BLAG regarding renal toxicity (6.6% versus 8.8%, P = 0.0338) and ototoxicity (0.7 versus 3.1%, P = 0.0137). Other adverse events were largely comparable. Overall, empirically designed DBL showed comparable clinical and microbiological responses across different Gram-negative species, and were significantly safer than BLAG. Therefore, DBL should be rationally optimized via the latest translational approaches, leveraging mechanistic insights and newer ß-lactams for future evaluation in clinical trials.
Assuntos
Aminoglicosídeos/uso terapêutico , Antibacterianos/uso terapêutico , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , beta-Lactamas/uso terapêutico , Quimioterapia Combinada , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Tobramicina/uso terapêutico , Resultado do TratamentoRESUMO
Combinations of antimicrobial agents are often used in the management of infectious diseases. Antimicrobial agents used as part of combination therapy are often selected empirically. As regrowth and the emergence of polymyxin (either colistin or polymyxin B) resistance has been observed with polymyxin monotherapy, polymyxin combination therapy has been suggested as a possible means by which to increase antimicrobial activity and reduce the development of resistance. This chapter provides an overview of preclinical and clinical investigations of CMS/colistin and polymyxin B combination therapy. In vitro data and animal model data suggests a potential clinical benefit with many drug combinations containing clinically achievable concentrations of polymyxins, even when resistance to one or more of the drugs in combination is present and including antibiotics normally inactive against Gram-negative organisms. The growing body of data on the emergence of polymyxin resistance with monotherapy lends theoretical support to a benefit with combination therapy. Benefits include enhanced bacterial killing and a suppression of polymyxin resistant subpopulations. However, the complexity of the critically ill patient population, and high rates of treatment failure and death irrespective of infection-related outcome make demonstrating a potential benefit for polymyxin combinations extremely challenging. Polymyxin combination therapy in the clinic remains a heavily debated and controversial topic. When combinations are selected, optimizing the dosage regimens for the polymyxin and the combinatorial agent is critical to ensure that the benefits outweigh the risk of the development of toxicity. Importantly, patient characteristics, pharmacokinetics, the site of infection, pathogen and resistance mechanism must be taken into account to define optimal and rational polymyxin combination regimens in the clinic.
Assuntos
Antibacterianos/farmacologia , Polimixinas/farmacologia , Colistina , Quimioterapia Combinada , Humanos , Testes de Sensibilidade Microbiana , Polimixina BRESUMO
The pharmacodynamic profile of azithromycin against persistent strains of nontypeable Haemophilus influenzae (NTHi) from chronic obstructive pulmonary disease (COPD) patients was characterized. Azithromycin displayed differential concentration-dependent activities (R2 ≥ 0.988); the pharmacodynamic response was attenuated when we compared the "first" and "last" strains of NTHi that persisted in the airways of the same patient for 819 days (the 50% effective concentration [EC50] increased more than 50 times [0.0821 mg/liter versus 4.23 mg/liter]). In the hollow-fiber infection model, NTHi viability was maintained throughout simulated azithromycin (Zithromax) Z-Pak regimens over 10 days.
Assuntos
Antibacterianos/uso terapêutico , Azitromicina/uso terapêutico , Infecções por Haemophilus/tratamento farmacológico , Haemophilus influenzae/efeitos dos fármacos , Doença Pulmonar Obstrutiva Crônica/microbiologia , Infecções por Haemophilus/microbiologia , Humanos , Sistema Respiratório/microbiologiaRESUMO
Multidrug-resistant Pseudomonas aeruginosa presents a global medical challenge, and polymyxins are a key last-resort therapeutic option. Unfortunately, polymyxin resistance in P. aeruginosa has been increasingly reported. The present study was designed to define metabolic differences between paired polymyxin-susceptible and -resistant P. aeruginosa strains using untargeted metabolomics and lipidomics analyses. The metabolomes of wild-type P. aeruginosa strain K ([PAK] polymyxin B MIC, 1 mg/liter) and its paired pmrB mutant strains, PAKpmrB6 and PAKpmrB12 (polymyxin B MICs of 16 mg/liter and 64 mg/liter, respectively) were characterized using liquid chromatography-mass spectrometry, and metabolic differences were identified through multivariate and univariate statistics. PAKpmrB6 and PAKpmrB12, which displayed lipid A modifications with 4-amino-4-deoxy-l-arabinose, showed significant perturbations in amino acid and carbohydrate metabolism, particularly the intermediate metabolites from 4-amino-4-deoxy-l-arabinose synthesis and the methionine salvage cycle pathways. The genomics result showed a premature termination (Y275stop) in speE (encoding spermidine synthase) in PAKpmrB6, and metabolomics data revealed a decreased intracellular level of spermidine in PAKpmrB6 compared to that in PAKpmrB12 Our results indicate that spermidine may play an important role in high-level polymyxin resistance in P. aeruginosa Interestingly, both pmrB mutants had decreased levels of phospholipids, fatty acids, and acyl-coenzyme A compared to those in the wild-type PAK. Moreover, the more resistant PAKpmrB12 mutant exhibited much lower levels of phospholipids than the PAKpmrB6 mutant, suggesting that the decreased phospholipid level was associated with polymyxin resistance. In summary, this study provides novel mechanistic information on polymyxin resistance in P. aeruginosa and highlights its impacts on bacterial metabolism.
Assuntos
Antibacterianos/farmacologia , Polimixinas/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana , Lipídeo A/metabolismo , Metabolômica , Testes de Sensibilidade Microbiana , Fosfolipídeos/metabolismo , Polimixina B/farmacologia , Infecções por PseudomonasRESUMO
Background: The pharmacokinetic/pharmacodynamic (PK/PD) relationship for polymyxin B against Klebsiella pneumoniae infections is not known. Methods: Dose-fractionation studies with subcutaneous polymyxin B were conducted in neutropenic mice in which infection with three strains of K. pneumoniae had been produced in thighs or lungs. Dosing (thigh infection 0.5-120 mg/kg/day; lung infection 5-120 mg/kg/day) commenced 2 h after inoculation, and bacterial burden was measured 24 h later. Plasma exposure measures for unbound polymyxin B were from population pharmacokinetic analysis of single doses and plasma protein binding by ultracentrifugation. The inhibitory sigmoid dose-effect model was employed to determine the relationship between exposure and efficacy. Antibacterial activities of polymyxin B and colistin against thigh infection were compared at equimolar doses generating exposures resulting in maximal antibacterial activity. Results: The pharmacokinetics of polymyxin B were well described by a model comprising parallel linear and saturable pathways for absorption and elimination. Plasma binding of polymyxin B was constant (P > 0.05) over the range â¼0.9-37 mg/L; average (±SD) percentage bound was 91.4â±â1.65. In thigh infection, antibacterial effect was well correlated with fAUC/MIC (R2 = 0.89). Target values of fAUC/MIC for stasis and 1 log10 kill were 1.22-13.5 and 3.72-28.0, respectively; 2 log10 kill was not achieved for any strain, even at the highest tolerated dose. There was no difference (P > 0.05) in antibacterial activity between polymyxin B and colistin with equimolar doses. It was not possible to achieve stasis in lung infection, even at the highest dose tolerated by mice. Conclusions: The results will assist in the design of optimized dosage regimens of polymyxin B.
Assuntos
Antibacterianos/farmacologia , Antibacterianos/farmacocinética , Infecções por Klebsiella/tratamento farmacológico , Klebsiella pneumoniae/efeitos dos fármacos , Polimixina B/farmacologia , Polimixina B/farmacocinética , Animais , Antibacterianos/administração & dosagem , Carga Bacteriana , Proteínas Sanguíneas/metabolismo , Modelos Animais de Doenças , Feminino , Injeções Subcutâneas , Camundongos , Testes de Sensibilidade Microbiana , Plasma/química , Polimixina B/administração & dosagem , Ligação ProteicaRESUMO
The impact of quorum sensing on polymyxin and azithromycin pharmacodynamics was assessed in Pseudomonas aeruginosa PAO1 and an isogenic rhlR/lasR double knockout. For polymyxin B, greater killing against the rhlR/lasR knockout than against PAO1 was observed at 108 CFU/ml (polymyxin B half-maximal effective concentration [EC50], 5.61 versus 12.5 mg/liter, respectively; P < 0.005). Polymyxin B combined with azithromycin (256 mg/liter) was synergistic against each strain, significantly reducing the respective polymyxin B EC50 compared to those with monotherapy (P < 0.005), and is a promising strategy by which to combat P. aeruginosa.
Assuntos
Azitromicina/farmacologia , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Polimixina B/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Percepção de Quorum/efeitos dos fármacos , Transativadores/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Contagem de Colônia Microbiana , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Sinergismo Farmacológico , Concentração Inibidora 50 , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/metabolismo , Percepção de Quorum/genética , Transativadores/deficiênciaRESUMO
Acinetobacter baumannii is emerging with resistance to polymyxins. In 24-h time-kill experiments, high-dose ampicillin-sulbactam in combination with meropenem and polymyxin B achieved additivity or synergy against 108 CFU/ml of two clinical A. baumannii isolates resistant to all three drugs (maximum reductions, 1.6 and 3.1 logs). In a 14-day hollow-fiber infection model, high-dose ampicillin-sulbactam (8/4 g every 8 h, respectively) in combination with meropenem (2 g every 8 h) and polymyxin B (1.43 mg/kg of body weight every 12 h with loading dose) resulted in rapid (96 h) eradication of A. baumannii.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacocinética , Modelos Estatísticos , Polimixina B/farmacocinética , Tienamicinas/farmacocinética , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/crescimento & desenvolvimento , Ampicilina/sangue , Ampicilina/farmacocinética , Antibacterianos/sangue , Área Sob a Curva , Disponibilidade Biológica , Índice de Massa Corporal , Esquema de Medicação , Combinação de Medicamentos , Cálculos da Dosagem de Medicamento , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Humanos , Meropeném , Testes de Sensibilidade Microbiana , Polimixina B/sangue , Sulbactam/sangue , Sulbactam/farmacocinética , Tienamicinas/sangueRESUMO
Pharmacodynamics of a polymyxin B, meropenem, and rifampin triple combination were examined against Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) ST258. In time-kill experiments against three KPC-Kp isolates, triple combination generated 8.14, 8.19, and 8.29 log10 CFU/ml reductions within 24 h. In the hollow-fiber infection model, the triple combination caused maximal killing of 5.16 log10 CFU/ml at 78 h and the time required for regrowth was more than doubled versus the 2-drug combinations. Remarkably, combinations with a high single-dose polymyxin B burst plus rifampin preserved KPC-Kp polymyxin susceptibility (MIC240 h = 0.5 mg/liter) versus the same combination with traditionally dosed polymyxin B, where resistance was amplified (MIC240 h = 32 mg/liter).
Assuntos
Antibacterianos/farmacocinética , Klebsiella pneumoniae/efeitos dos fármacos , Modelos Estatísticos , Polimixina B/farmacocinética , Rifampina/farmacocinética , Tienamicinas/farmacocinética , Antibacterianos/sangue , Antibacterianos/farmacologia , Área Sob a Curva , Disponibilidade Biológica , Contagem de Colônia Microbiana , Esquema de Medicação , Cálculos da Dosagem de Medicamento , Sinergismo Farmacológico , Quimioterapia Combinada , Humanos , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/crescimento & desenvolvimento , Meropeném , Testes de Sensibilidade Microbiana , Polimixina B/sangue , Polimixina B/farmacologia , Rifampina/sangue , Rifampina/farmacologia , Tienamicinas/sangue , Tienamicinas/farmacologiaRESUMO
Objectives: Gram-negative bacteria harbouring the mcr-1 plasmid are resistant to the 'last-line' polymyxins and have been reported worldwide. Our objective was to define the impact of increasing the initial polymyxin B dose intensity against an mcr-1 -harbouring strain to delineate the impact of plasmid-mediated polymyxin resistance on the dynamics of bacterial killing and resistance. Methods: A hollow fibre infection model (HFIM) was used to simulate polymyxin B regimens against an mcr-1 -harbouring Escherichia coli (MIC 8 mg/L) over 10 days. Four escalating polymyxin B 'front-loading' regimens (3.33, 6.66, 13.3 or 26.6 mg/kg for one dose followed by 1.43 mg/kg every 12 h starting 12 h later) simulating human pharmacokinetics were utilized in the HFIM. A mechanism-based, mathematical model was developed using S-ADAPT to characterize bacterial killing. Results: The 3.33 mg/kg 'front-loading' regimen resulted in regrowth mirroring the growth control. The 6.66, 13.3 and 26.6 mg/kg 'front-loading' regimens resulted in maximal bacterial reductions of 1.91, 3.79 and 6.14 log 10 cfu/mL, respectively. Irrespective of the early polymyxin B exposure (24 h AUC), population analysis profiles showed similar growth of polymyxin B-resistant subpopulations. The HFIM data were well described by the mechanism-based model integrating three subpopulations (susceptible, intermediate and resistant). Compared with the susceptible subpopulation of mcr-1 -harbouring E. coli , the resistant subpopulation had an approximately 10-fold lower rate of killing due to polymyxin B treatment. Conclusions: Manipulating initial dose intensity of polymyxin B was not able to overcome plasmid-mediated resistance due to mcr-1 in E. coli . This reinforces the need to develop new combinatorial strategies to combat these highly resistant Gram-negative bacteria.
Assuntos
Antibacterianos/administração & dosagem , Antibacterianos/farmacocinética , Farmacorresistência Bacteriana , Infecções por Escherichia coli/tratamento farmacológico , Proteínas de Escherichia coli/genética , Polimixina B/administração & dosagem , Polimixina B/farmacocinética , Antibacterianos/farmacologia , Infecções por Escherichia coli/microbiologia , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Modelos Teóricos , Polimixina B/farmacologiaRESUMO
OBJECTIVES: The pharmacodynamics of polymyxin/carbapenem combinations against carbapenem-resistant Acinetobacter baumannii (CRAB) are largely unknown. Our objective was to determine whether intensified meropenem regimens in combination with polymyxin B enhance killing and resistance suppression of CRAB. METHODS: Time-kill experiments for meropenem and polymyxin B combinations were conducted against three polymyxin B-susceptible (MIC of polymyxin Bâ=â0.5 mg/L) CRAB strains with varying meropenem MICs (ATCC 19606, N16870 and 03-149-1; MIC of meropenemâ=â4, 16 and 64 mg/L, respectively) at 108 cfu/mL. A hollow-fibre infection model was then used to simulate humanized regimens of polymyxin B and meropenem (2, 4, 6 and 8 g prolonged infusions every 8 h) versus N16870 at 108 cfu/mL over 14 days. New mathematical mechanism-based models were developed using S-ADAPT. RESULTS: Time-kill experiments were well described by the mathematical mechanism-based models, with the presence of polymyxin B drastically decreasing the meropenem concentration needed for half-maximal activity against meropenem-resistant populations from 438 to 82.1 (ATCC 19606), 158 to 93.6 (N16870) and 433 to 76.0 mg/L (03-149-1). The maximum killing effect of combination treatment was similar among all three strains despite divergent meropenem MIC values (Emaxâ=â2.13, 2.08 and 2.15; MIC of meropenemâ=â4, 16 and 64 mg/L, respectively). Escalating the dose of meropenem in hollow-fibre combination regimens from 2 g every 8 h to 8 g every 8 h resulted in killing that progressed from a >2.5 log10 cfu/mL reduction with regrowth by 72 h (2 g every 8 h) to complete eradication by 336 h (8 g every 8 h). CONCLUSION: Intensified meropenem dosing in combination with polymyxin B may offer a unique strategy to kill CRAB irrespective of the meropenem MIC.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Polimixina B/farmacologia , Tienamicinas/farmacologia , Resistência beta-Lactâmica , Antibacterianos/administração & dosagem , Humanos , Meropeném , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Modelos Teóricos , Polimixina B/administração & dosagem , Tienamicinas/administração & dosagemRESUMO
Objectives: KPC-producing Klebsiella pneumoniae are an emerging public health problem around the globe. We defined the combinatorial pharmacodynamics and ability to suppress resistance of two 'old' antibiotics, fosfomycin and colistin, in time-kill experiments and hollow-fibre infection models (HFIM). Methods: Two KPC-2-producing K. pneumoniae isolates were used: one susceptible to both colistin and fosfomycin (KPC 9A: MIC colistin 0.25 mg/L and MIC fosfomycin ≤8 mg/L) and the other resistant to colistin and susceptible to fosfomycin (KPC 5A: MIC colistin 64 mg/L and MIC fosfomycin 32 mg/L). Time-kill experiments assessed an array of colistin and fosfomycin concentrations against both isolates. Colistin and fosfomycin pharmacokinetics from critically ill patients were simulated in the HFIM to define the pharmacodynamic activity of humanized regimens over 5 days against KPC 9A. Results: In time-kill experiments, synergy was demonstrated for all colistin/fosfomycin combinations containing >8 mg/L fosfomycin against the double-susceptible KPC strain, 9A. Synergy versus KPC strain 5A was only achieved at the highest concentrations of colistin (4 mg/L) and fosfomycin (512 mg/L) at 48 h. In the HFIM, colistin or fosfomycin monotherapies resulted in rapid proliferation of resistant subpopulations; KPC 9A regrew by 24 h. In contrast to the monotherapies, the colistin/fosfomycin combination resulted in a rapid 6.15 log 10 cfu/mL reduction of KPC 9A by 6 h and complete suppression of resistant subpopulations until 120 h. Conclusions: Colistin and fosfomycin may represent an important treatment option for KPC-producing K. pneumoniae otherwise resistant to traditional antibiotics.
Assuntos
Antibacterianos/farmacologia , Colistina/farmacologia , Fosfomicina/farmacologia , Klebsiella pneumoniae/efeitos dos fármacos , Modelos Biológicos , beta-Lactamases/biossíntese , Adulto , Idoso , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Feminino , Humanos , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-IdadeRESUMO
Objectives: The emergence of polymyxin resistance threatens to leave clinicians with few options for combatting drug-resistant Acinetobacter baumannii . The objectives of the current investigation were to define the in vitro emergence of polymyxin resistance and identify a combination regimen capable of eradicating A. baumannii with no apparent drug susceptibilities. Methods: Two clonally related, paired, A. baumannii isolates collected from a critically ill patient who developed colistin resistance while receiving colistin methanesulfonate in a clinical population pharmacokinetic study were evaluated: an A. baumannii isolate collected before (03-149.1, polymyxin-susceptible, MIC 0.5â mg/L) and an isolate collected after (03-149.2, polymyxin-resistant, MIC 32â mg/L, carbapenem-resistant, ampicillin/sulbactam-resistant). Using the patient's unique pharmacokinetics, the patient's actual regimen received in the clinic was recreated in a hollow-fibre infection model (HFIM) to track the emergence of polymyxin resistance against 03-149.1. A subsequent HFIM challenged the pan-resistant 03-149.2 isolate against polymyxin B, meropenem and ampicillin/sulbactam alone and in two-drug and three-drug combinations. Results: Despite achieving colistin steady-state targets of an AUC 0-24 >60â mg·h/L and C avg of >2.5â mg/L, colistin population analysis profiles confirmed the clinical development of polymyxin resistance. During the simulation of the patient's colistin regimen in the HFIM, no killing was achieved in the HFIM and amplification of polymyxin resistance was observed by 96â h. Against the polymyxin-resistant isolate, the triple combination of polymyxin B, meropenem and ampicillin/sulbactam eradicated the A. baumannii by 96â h in the HFIM, whereas monotherapies and double combinations resulted in regrowth. Conclusions: To combat polymyxin-resistant A. baumannii , the triple combination of polymyxin B, meropenem and ampicillin/sulbactam holds great promise.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Colistina/farmacologia , Farmacorresistência Bacteriana Múltipla , Polimixina B/farmacologia , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Adulto , Antibacterianos/uso terapêutico , Colistina/farmacocinética , Colistina/uso terapêutico , Sinergismo Farmacológico , Quimioterapia Combinada , Humanos , Meropeném , Testes de Sensibilidade Microbiana , Polimixina B/uso terapêutico , Tienamicinas/farmacologia , Tienamicinas/uso terapêuticoRESUMO
Little is known about the effect of antibiotics on eradication of carriage and development of resistance in Haemophilus influenzae in individuals with chronic obstructive pulmonary disease (COPD). Our goals were to assess antibiotic susceptibilities, prevalence of resistance genes, and development of resistance in H. influenzae and to evaluate the effect of macrolide and fluoroquinolone administration on H. influenzae eradication. Data were from a 15-year longitudinal study of COPD. Genome sequence data were used to determine genotype and identify resistance genes. MICs of antibiotics were determined by reference broth microdilution. Generalized linear mixed models were used to evaluate associations between antibiotic use and H. influenzae eradication. We examined 267 H. influenzae isolates from 77 individuals. All newly acquired H. influenzae isolates were susceptible to azithromycin. Five of 27 (19%) strains developed 4-fold increases in azithromycin MICs and reached or exceeded the susceptibility breakpoint (≤4 µg/ml) during exposure. H. influenzae isolates were uniformly susceptible to ciprofloxacin, levofloxacin, and moxifloxacin (MIC90s of 0.015, 0.015, and 0.06, respectively); there were no mutations in quinolone resistance-determining regions. Fluoroquinolone administration was associated with increased H. influenzae eradication compared to macrolides (odds ratio [OR], 16.67; 95% confidence interval [CI], 2.67 to 104.09). There was no difference in H. influenzae eradication when comparing macrolide administration to no antibiotic (OR, 1.89; 95% CI, 0.43 to 8.30). Fluoroquinolones are effective in eradicating H. influenzae in individuals with COPD. Macrolides are ineffective in eradicating H. influenzae, and their use in COPD patients may lead to decreased macrolide susceptibility and resistance.
Assuntos
Antibacterianos/farmacologia , Fluoroquinolonas/farmacologia , Haemophilus influenzae/efeitos dos fármacos , Macrolídeos/farmacologia , Doença Pulmonar Obstrutiva Crônica/microbiologia , Ciprofloxacina/farmacologia , Levofloxacino/farmacologia , Testes de Sensibilidade Microbiana , MoxifloxacinaRESUMO
Infections caused by multidrug-resistant Acinetobacter baumannii are a major public health problem, and polymyxins are often the last line of therapy for recalcitrant infections by such isolates. The pharmacokinetics of the two clinically used polymyxins, polymyxin B and colistin, differ considerably, since colistin is administered as an inactive prodrug that undergoes slow conversion to colistin. However, the impact of these substantial pharmacokinetic differences on bacterial killing and resistance emergence is poorly understood. We assessed clinically relevant polymyxin B and colistin dosage regimens against one reference and three clinical A. baumannii strains in a dynamic one-compartment in vitro model. A new mechanism-based pharmacodynamic model was developed to describe and predict the drug concentrations and viable counts of the total and resistant populations. Rapid attainment of target concentrations was shown to be critical for polymyxin-induced bacterial killing. All polymyxin B regimens achieved peak concentrations of at least 1 mg/liter within 1 h and caused ≥4 log10 killing at 1 h. In contrast, the slow rise of colistin concentrations to 3 mg/liter over 48 h resulted in markedly reduced bacterial killing. A significant (4 to 6 log10 CFU/ml) amplification of resistant bacterial populations was common to all dosage regimens. The developed mechanism-based model explained the observed bacterial killing, regrowth, and resistance. The model also implicated adaptive polymyxin resistance as a key driver of bacterial regrowth and predicted the amplification of preexisting, highly polymyxin-resistant bacterial populations following polymyxin treatment. Antibiotic combination therapies seem the most promising option for minimizing the emergence of polymyxin resistance.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Colistina/farmacologia , Polimixina B/farmacologia , Algoritmos , Antibacterianos/farmacocinética , Colistina/farmacocinética , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana , Polimixina B/farmacocinéticaRESUMO
Despite a dearth of new agents currently being developed to combat multidrug-resistant Gram-negative pathogens, the combination of ceftolozane and tazobactam was recently approved by the Food and Drug Administration to treat complicated intra-abdominal and urinary tract infections. To characterize the activity of the combination product, time-kill studies were conducted against 4 strains ofEscherichia colithat differed in the type of ß-lactamase they expressed. The four investigational strains included 2805 (no ß-lactamase), 2890 (AmpC ß-lactamase), 2842 (CMY-10 ß-lactamase), and 2807 (CTX-M-15 ß-lactamase), with MICs to ceftolozane of 0.25, 4, 8, and >128 mg/liter with no tazobactam, and MICs of 0.25, 1, 4, and 8 mg/liter with 4 mg/liter tazobactam, respectively. All four strains were exposed to a 6 by 5 array of ceftolozane (0, 1, 4, 16, 64, and 256 mg/liter) and tazobactam (0, 1, 4, 16, and 64 mg/liter) over 48 h using starting inocula of 10(6)and 10(8)CFU/ml. While ceftolozane-tazobactam achieved bactericidal activity against all 4 strains, the concentrations of ceftolozane and tazobactam required for a ≥3-log reduction varied between the two starting inocula and the 4 strains. At both inocula, the Hill plots (R(2)> 0.882) of ceftolozane revealed significantly higher 50% effective concentrations (EC50s) at tazobactam concentrations of ≤4 mg/liter than those at concentrations of ≥16 mg/liter (P< 0.01). Moreover, the EC50s at 10(8)CFU/ml were 2.81 to 66.5 times greater than the EC50s at 10(6)CFU/ml (median, 10.7-fold increase;P= 0.002). These promising results indicate that ceftolozane-tazobactam achieves bactericidal activity against a wide range of ß-lactamase-producingE. colistrains.