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Farrington N, Dubey V, Johnson A, Horner I, Stevenson A, Unsworth J, Jimenez-Valverde A, Schwartz J, Das S, Hope W, Darlow CA. Molecular pharmacodynamics of meropenem for nosocomial pneumonia caused by Pseudomonas aeruginosa. mBio 2024; 15:e0316523. [PMID: 38236031 PMCID: PMC10865990 DOI: 10.1128/mbio.03165-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 12/11/2023] [Indexed: 01/19/2024] Open
Abstract
Hospital-acquired pneumonia (HAP) is a leading cause of morbidity and mortality, commonly caused by Pseudomonas aeruginosa. Meropenem is a commonly used therapeutic agent, although emergent resistance occurs during treatment. We used a rabbit HAP infection model to assess the bacterial kill and resistance pharmacodynamics of meropenem. Meropenem 5 mg/kg administered subcutaneously (s.c.) q8h (±amikacin 3.33-5 mg/kg q8h administered intravenously[i.v.]) or meropenem 30 mg/kg s.c. q8h regimens were assessed in a rabbit lung infection model infected with P. aeruginosa, with bacterial quantification and phenotypic/genotypic characterization of emergent resistant isolates. The pharmacokinetic/pharmacodynamic output was fitted to a mathematical model, and human-like regimens were simulated to predict outcomes in a clinical context. Increasing meropenem monotherapy demonstrated a dose-response effect to bacterial kill and an inverted U relationship with emergent resistance. The addition of amikacin to meropenem suppressed the emergence of resistance. A network of porin loss, efflux upregulation, and increased expression of AmpC was identified as the mechanism of this emergent resistance. A bridging simulation using human pharmacokinetics identified meropenem 2 g i.v. q8h as the licensed clinical regimen most likely to suppress resistance. We demonstrate an innovative experimental platform to phenotypically and genotypically characterize bacterial emergent resistance pharmacodynamics in HAP. For meropenem, we have demonstrated the risk of resistance emergence during therapy and identified two mitigating strategies: (i) regimen intensification and (ii) use of combination therapy. This platform will allow pre-clinical assessment of emergent resistance risk during treatment of HAP for other antimicrobials, to allow construction of clinical regimens that mitigate this risk.IMPORTANCEThe emergence of antimicrobial resistance (AMR) during antimicrobial treatment for hospital-acquired pneumonia (HAP) is a well-documented problem (particularly in pneumonia caused by Pseudomonas aeruginosa) that contributes to the wider global antimicrobial resistance crisis. During drug development, regimens are typically determined by their sufficiency to achieve bactericidal effect. Prevention of the emergence of resistance pharmacodynamics is usually not characterized or used to determine the regimen. The innovative experimental platform described here allows characterization of the emergence of AMR during the treatment of HAP and the development of strategies to mitigate this. We have demonstrated this specifically for meropenem-a broad-spectrum antibiotic commonly used to treat HAP. We have characterized the antimicrobial resistance pharmacodynamics of meropenem when used to treat HAP, caused by initially meropenem-susceptible P. aeruginosa, phenotypically and genotypically. We have also shown that intensifying the regimen and using combination therapy are both strategies that can both treat HAP and suppress the emergence of resistance.
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Affiliation(s)
- Nicola Farrington
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Vineet Dubey
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Adam Johnson
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Iona Horner
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Adam Stevenson
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Jennifer Unsworth
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Ana Jimenez-Valverde
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | | | - Shampa Das
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - William Hope
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
| | - Christopher A. Darlow
- Antimicrobial Pharmacodynamics and Therapeutics, Department of Pharmacology, University of Liverpool, Liverpool Health Partners, Liverpool, United Kingdom
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Attwood M, Griffin P, Noel AR, Albur M, Macgowan AP. Antibacterial effect of seven days exposure to ceftolozane-tazobactam as monotherapy and in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa with ceftolozane-tazobactam MICs at or above 4 mg/l in an in vitro pharmacokinetic model. J Antimicrob Chemother 2023; 78:2254-2262. [PMID: 37527369 DOI: 10.1093/jac/dkad230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/21/2023] [Indexed: 08/03/2023] Open
Abstract
OBJECTIVES To use a pre-clinical pharmacokinetic infection model to assess the antibacterial effect of ceftolozane/tazobactam alone or in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa strains with MICs at or higher than the clinical breakpoint (MIC ≥ 4 mg/L). METHODS An in vitro model was used to assess changes in bacterial load and population profiles after exposure to mean human serum concentrations of ceftolozane/tazobactam associated with doses of 2 g/1 g q8h, fosfomycin concentrations associated with doses of 8 g q8h or tobramycin at doses of 7 mg/kg q24 h over 168 h. RESULTS Simulations of ceftolozane/tazobactam at 2 g/1 g q8h alone produced 3.5-4.5 log reductions in count by 6 h post drug exposure for strains with MIC ≤32 mg/L. The antibacterial effect over the first 24 h was related to ceftolozane/tazobactam MIC. There was subsequent regrowth with most strains to bacterial densities of >106 CFU/mL. Addition of either fosfomycin or tobramycin resulted in suppression of regrowth and in the case of tobramycin more rapid initial bacterial killing up to 6 h. These effects could not be related to either fosfomycin or tobramycin MICs. Changes in population profiles were noted with ceftolozane/tazobactam alone often after 96 h exposure but such changes were suppressed by fosfomycin and almost abolished by the addition of tobramycin. CONCLUSIONS The addition of either fosfomycin or tobramycin to ceftolozane/tazobactam at simulated human clinically observed concentrations reduced P. aeruginosa bacterial loads and the risk of resistance to ceftolozane/tazobactam when strains had ceftolozane/tazobactam MIC values at or above the clinical breakpoint.
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Affiliation(s)
- Marie Attwood
- Department of Infection Sciences, Bristol Centre for Antimicrobial Research & Evaluation, Southmead Hospital, Pathology Sciences Building, Phase 2, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Pippa Griffin
- Department of Infection Sciences, Bristol Centre for Antimicrobial Research & Evaluation, Southmead Hospital, Pathology Sciences Building, Phase 2, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Alan R Noel
- Department of Infection Sciences, Bristol Centre for Antimicrobial Research & Evaluation, Southmead Hospital, Pathology Sciences Building, Phase 2, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Maha Albur
- Department of Infection Sciences, Bristol Centre for Antimicrobial Research & Evaluation, Southmead Hospital, Pathology Sciences Building, Phase 2, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Alasdair P Macgowan
- Department of Infection Sciences, Bristol Centre for Antimicrobial Research & Evaluation, Southmead Hospital, Pathology Sciences Building, Phase 2, Westbury-on-Trym, Bristol BS10 5NB, UK
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Kothari A, Kherdekar R, Mago V, Uniyal M, Mamgain G, Kalia RB, Kumar S, Jain N, Pandey A, Omar BJ. Age of Antibiotic Resistance in MDR/XDR Clinical Pathogen of Pseudomonas aeruginosa. Pharmaceuticals (Basel) 2023; 16:1230. [PMID: 37765038 PMCID: PMC10534605 DOI: 10.3390/ph16091230] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/29/2023] Open
Abstract
Antibiotic resistance in Pseudomonas aeruginosa remains one of the most challenging phenomena of everyday medical science. The universal spread of high-risk clones of multidrug-resistant/extensively drug-resistant (MDR/XDR) clinical P. aeruginosa has become a public health threat. The P. aeruginosa bacteria exhibits remarkable genome plasticity that utilizes highly acquired and intrinsic resistance mechanisms to counter most antibiotic challenges. In addition, the adaptive antibiotic resistance of P. aeruginosa, including biofilm-mediated resistance and the formation of multidrug-tolerant persisted cells, are accountable for recalcitrance and relapse of infections. We highlighted the AMR mechanism considering the most common pathogen P. aeruginosa, its clinical impact, epidemiology, and save our souls (SOS)-mediated resistance. We further discussed the current therapeutic options against MDR/XDR P. aeruginosa infections, and described those treatment options in clinical practice. Finally, other therapeutic strategies, such as bacteriophage-based therapy and antimicrobial peptides, were described with clinical relevance.
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Affiliation(s)
- Ashish Kothari
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh 249203, India;
| | - Radhika Kherdekar
- Department of Dentistry, All India Institute of Medical Sciences, Rishikesh 249203, India;
| | - Vishal Mago
- Department of Burn and Plastic Surgery, All India Institute of Medical Sciences, Rishikesh 249203, India;
| | - Madhur Uniyal
- Department of Trauma Surgery, All India Institute of Medical Sciences, Rishikesh 249203, India;
| | - Garima Mamgain
- Department of Biochemistry, All India Institute of Medical Sciences, Rishikesh 249203, India;
| | - Roop Bhushan Kalia
- Department of Orthopaedics, All India Institute of Medical Sciences, Rishikesh 249203, India;
| | - Sandeep Kumar
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA 30912, USA;
| | - Neeraj Jain
- Department of Medical Oncology, All India Institute of Medical Sciences, Rishikesh 249203, India
- Division of Cancer Biology, Central Drug Research Institute, Lucknow 226031, India
| | - Atul Pandey
- Department of Entomology, University of Kentucky, Lexington, KY 40503, USA
| | - Balram Ji Omar
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh 249203, India;
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O'Donnell JP, Bhavnani SM. The Pharmacokinetics/Pharmacodynamic Relationship of Durlobactam in Combination With Sulbactam in In Vitro and In Vivo Infection Model Systems Versus Acinetobacter baumannii-calcoaceticus Complex. Clin Infect Dis 2023; 76:S202-S209. [PMID: 37125469 PMCID: PMC10150273 DOI: 10.1093/cid/ciad096] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Indexed: 05/02/2023] Open
Abstract
Sulbactam-durlobactam is a β-lactam/β-lactamase inhibitor combination currently in development for the treatment of infections caused by Acinetobacter, including multidrug-resistant (MDR) isolates. Although sulbactam is a β-lactamase inhibitor of a subset of Ambler class A enzymes, it also demonstrates intrinsic antibacterial activity against a limited number of bacterial species, including Acinetobacter, and has been used effectively in the treatment of susceptible Acinetobacter-associated infections. Increasing prevalence of β-lactamase-mediated resistance, however, has eroded the effectiveness of sulbactam in the treatment of this pathogen. Durlobactam is a rationally designed β-lactamase inhibitor within the diazabicyclooctane (DBO) class. The compound demonstrates a broad spectrum of inhibition of serine β-lactamase activity with particularly potent activity against class D enzymes, an attribute which differentiates it from other DBO inhibitors. When combined with sulbactam, durlobactam effectively restores the susceptibility of resistant isolates through β-lactamase inhibition. The present review describes the pharmacokinetic/pharmacodynamic (PK/PD) relationship associated with the activity of sulbactam and durlobactam established in nonclinical infection models with MDR Acinetobacter baumannii isolates. This information aids in the determination of PK/PD targets for efficacy, which can be used to forecast efficacious dose regimens of the combination in humans.
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Affiliation(s)
- John P O'Donnell
- Department of Drug Metabolism and Pharmacokinetics, Entasis Therapeutics, Waltham, Massachusetts, USA
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5
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Koloskoff K, Thirion DJG, Matouk E, Marsot A. New Recommendations of a Height-Based Dosing Regimen of Tobramycin for Cystic Fibrosis in Adults: A Population Pharmacokinetic Analysis. Ther Drug Monit 2023; 45:251-258. [PMID: 36070759 DOI: 10.1097/ftd.0000000000001021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/08/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Acute pulmonary exacerbations (APEs) in patients with adult cystic fibrosis (CF) are treated with a beta-lactam and an aminoglycoside for activity against Pseudomonas aeruginosa (PA). Emerging drug resistance and changing pharmacokinetic profile in an aging population involve a reevaluation of tobramycin dosing recommendations. The objective of this study was to develop a population pharmacokinetic model and establish optimal dosing recommendations for tobramycin using Monte Carlo simulations. METHODS This retrospective clinical study and data collection were performed at the CF center of the McGill University Health Center (MUHC), Canada. Model development and simulations were performed using a nonlinear mixed-effect modeling approach (NONMEM, version 7.4.2). The ratios of maximal concentration (C max ) to the minimal inhibitory concentration (MIC) (C max /MIC ≥8 and ≥10) and area under the curve (AUC) to the MIC (AUC/MIC ≥70 and ≥100) were evaluated. RESULTS Adult patients with CF (n = 51) treated with tobramycin were included in the study. Plasma concentrations of tobramycin were obtained for 699 samples from the MUHC database. The two-compartmental model best described the pharmacokinetics of tobramycin. The association of patient height with the central volume of distribution significantly improved this model. Height, rather than weight, induced the best reduction in objective function. According to simulations, doses between 3.4 mg/cm and 4.4 mg/cm were necessary to achieve C max /MIC values of ≥8 and ≥10, respectively. However, higher doses were required to achieve the AUC/MIC targets. CONCLUSIONS This study demonstrated that height of the patients seems to be more suitable than their weight for dosing adjustments in adult patients with CF. According to this model, initial doses of tobramycin between 3.4 and 4.4 mg/cm should be recommended for patients with a median height of 164 cm and weight of 55 kg to achieve the target plasma concentrations.
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Affiliation(s)
- Kevin Koloskoff
- Faculty of Pharmacy, Université de Montréal
- Laboratoire STP2, Faculty of Pharmacy, Université de Montréal; and
| | - Daniel J G Thirion
- Faculty of Pharmacy, Université de Montréal
- Pharmacy Department, Royal Victoria Hospital, McGill University Health Centre
| | - Elias Matouk
- Adult Cystic Fibrosis Clinic, Montreal Chest Institute, McGill University, Montreal, Quebec, Canada
| | - Amélie Marsot
- Faculty of Pharmacy, Université de Montréal
- Laboratoire STP2, Faculty of Pharmacy, Université de Montréal; and
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Lynch JP, Zhanel GG. Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy. Semin Respir Crit Care Med 2022; 43:191-218. [PMID: 35062038 DOI: 10.1055/s-0041-1740109] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).
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Affiliation(s)
- Joseph P Lynch
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - George G Zhanel
- Department of Medical Microbiology/Infectious Diseases, University of Manitoba, Max Rady College of Medicine, Winnipeg, Manitoba, Canada
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Beta-lactam monotherapy or combination therapy for bloodstream infections or pneumonia due to P. aeruginosa: a meta-analysis. Int J Antimicrob Agents 2021; 59:106512. [PMID: 34971728 DOI: 10.1016/j.ijantimicag.2021.106512] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 12/15/2021] [Accepted: 12/22/2021] [Indexed: 11/22/2022]
Abstract
OBJECTIVES . The aim of the present meta-analysis was to compare the clinical and microbiological outcomes of patients treated with beta-lactam monotherapy or combination therapy for Pseudomonas aeruginosa infections. DATA SOURCES MEDLINE, Google Scholar and the Cochrane Library STUDY ELIGIBILITY CRITERIA AND INTERVENTIONS: . Experimental and observational studies published as full papers up to December 2020 that compared the efficacy of beta-lactams used in monotherapy or in combination with other active agents as empirical or targeted therapy for bloodstream infections or Hospital-Acquired or Ventilator-Associated Pneumonia (HAP/VAP) due to P. aeruginosa. The outcomes evaluated were hospital-mortality, 14-day- or 30-day-mortality rate, microbiological eradication rate and clinical cure rate. RESULTS . Of a total of 8,363 citations screened, 6 Randomized Controlled Trials (RCTs), 6 prospective cohort studies, and 21 retrospective cohort studies were included in the analysis, accounting for a total of 3,861 subjects. Considering the 14 studies evaluating the empirical therapy, no significant difference in mortality rate was observed between the two groups (RR: 1.06; 95% CI 0.86-1.30, p=0.6). Similar findings were obtained among the 18 studies analysing the targeted therapy (RR: 1.04; 95% CI 0.83-1.31, p=0.708); however, grouping the studies according to the design, a higher mortality among patients receiving monotherapy was observed in 5 prospective studies (RR: 1.37; 95% CI 1.06-1.79, p=0.018). Finally, no difference was observed among groups considering the microbiological and the clinical cure. CONCLUSIONS . Our meta-analysis demonstrated no difference in the mortality rate, clinical cure and microbiological cure in patients treated with beta-lactam monotherapy or combination for P. aeruginosa infections.
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A personalised approach to antibiotic pharmacokinetics and pharmacodynamics in critically ill patients. Anaesth Crit Care Pain Med 2021; 40:100970. [PMID: 34728411 DOI: 10.1016/j.accpm.2021.100970] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/26/2021] [Accepted: 08/14/2021] [Indexed: 01/01/2023]
Abstract
Critically ill patients admitted to intensive care unit (ICU) with severe infections, or those who develop nosocomial infections, have poor outcomes with substantial morbidity and mortality. Such patients commonly have suboptimal antibiotic exposures at routinely used antibiotic doses related to an increased volume of distribution and altered clearance due to their underlying altered physiology. Furthermore, the use of extracorporeal devices such as renal replacement therapy and extracorporeal membrane oxygenation in these group of patients also has the potential to alter in vivo drug concentrations. Moreover, ICU patients are likely to be infected with less-susceptible pathogens. Therefore, one potential contributing cause to the poor outcomes observed in critically ill patients may be related to subtherapeutic antibiotic exposures. Newer concepts include the clinician considering optimised dosing based on a blood antibiotic exposure defined by pharmacokinetic modelling and therapeutic drug monitoring, combined with a knowledge of the antibiotic penetration into the site of infection, thereby achieving optimal bacterial killing. Such optimised dosing is likely to improve patient outcomes. The aim of this review is to highlight key aspects of antibiotic pharmacokinetics and pharmacodynamics (PK/PD) in critically ill patients and provide a PK/PD approach to tailor antibiotic dosing to the individual patient.
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Lang Y, Shah NR, Tao X, Reeve SM, Zhou J, Moya B, Sayed ARM, Dharuman S, Oyer JL, Copik AJ, Fleischer BA, Shin E, Werkman C, Basso KB, Lucas DD, Sutaria DS, Mégroz M, Kim TH, Loudon-Hossler V, Wright A, Jimenez-Nieves RH, Wallace MJ, Cadet KC, Jiao Y, Boyce JD, LoVullo ED, Schweizer HP, Bonomo RA, Bharatham N, Tsuji BT, Landersdorfer CB, Norris MH, Shin BS, Louie A, Balasubramanian V, Lee RE, Drusano GL, Bulitta JB. Combating Multidrug-Resistant Bacteria by Integrating a Novel Target Site Penetration and Receptor Binding Assay Platform Into Translational Modeling. Clin Pharmacol Ther 2021; 109:1000-1020. [PMID: 33576025 PMCID: PMC10662281 DOI: 10.1002/cpt.2205] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/08/2021] [Accepted: 02/08/2021] [Indexed: 12/26/2022]
Abstract
Multidrug-resistant bacteria are causing a serious global health crisis. A dramatic decline in antibiotic discovery and development investment by pharmaceutical industry over the last decades has slowed the adoption of new technologies. It is imperative that we create new mechanistic insights based on latest technologies, and use translational strategies to optimize patient therapy. Although drug development has relied on minimal inhibitory concentration testing and established in vitro and mouse infection models, the limited understanding of outer membrane permeability in Gram-negative bacteria presents major challenges. Our team has developed a platform using the latest technologies to characterize target site penetration and receptor binding in intact bacteria that inform translational modeling and guide new discovery. Enhanced assays can quantify the outer membrane permeability of β-lactam antibiotics and β-lactamase inhibitors using multiplex liquid chromatography tandem mass spectrometry. While β-lactam antibiotics are known to bind to multiple different penicillin-binding proteins (PBPs), their binding profiles are almost always studied in lysed bacteria. Novel assays for PBP binding in the periplasm of intact bacteria were developed and proteins identified via proteomics. To characterize bacterial morphology changes in response to PBP binding, high-throughput flow cytometry and time-lapse confocal microscopy with fluorescent probes provide unprecedented mechanistic insights. Moreover, novel assays to quantify cytosolic receptor binding and intracellular drug concentrations inform target site occupancy. These mechanistic data are integrated by quantitative and systems pharmacology modeling to maximize bacterial killing and minimize resistance in in vitro and mouse infection models. This translational approach holds promise to identify antibiotic combination dosing strategies for patients with serious infections.
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Affiliation(s)
- Yinzhi Lang
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Nirav R. Shah
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Present address: Jansen R&D, Johnson & Johnson, Spring House, Pennsylvania, USA
| | - Xun Tao
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Present address: Genentech USA,Inc., South San Francisco, California, USA
| | - Stephanie M. Reeve
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Jieqiang Zhou
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Bartolome Moya
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Alaa R. M. Sayed
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Department of Chemistry, Faculty of Science, Fayoum University, Fayoum, Egypt
| | - Suresh Dharuman
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Jeremiah L. Oyer
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Alicja J. Copik
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Brett A. Fleischer
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Eunjeong Shin
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Carolin Werkman
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Kari B. Basso
- Department of Chemistry, University of Florida, Gainesville, Florida, USA
| | - Deanna Deveson Lucas
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Dhruvitkumar S. Sutaria
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Present address: Genentech USA,Inc., South San Francisco, California, USA
| | - Marianne Mégroz
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Tae Hwan Kim
- College of Pharmacy, Catholic University of Daegu, Gyeongsan, Gyeongbuk, Korea
| | - Victoria Loudon-Hossler
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Amy Wright
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Rossie H. Jimenez-Nieves
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Miranda J. Wallace
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Keisha C. Cadet
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Yuanyuan Jiao
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - John D. Boyce
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Eric D. LoVullo
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Herbert P. Schweizer
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Robert A. Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA
- Department of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
| | - Nagakumar Bharatham
- BUGWORKS Research India Pvt. Ltd., Centre for Cellular & Molecular Platforms, National Centre for Biological Sciences, Bengaluru, Karnataka, India
| | - Brian T. Tsuji
- Laboratory for Antimicrobial Pharmacodynamics, University at Buffalo, Buffalo, New York, USA
| | - Cornelia B. Landersdorfer
- Drug Delivery, Disposition, and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
- Centre for Medicine Use and Safety, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Michael H. Norris
- Spatial Epidemiology and Ecology Research Laboratory, Department of Geography and the Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
| | - Beom Soo Shin
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| | - Arnold Louie
- Institute for Therapeutic Innovation, College of Medicine, University of Florida, Orlando, Florida, USA
| | - Venkataraman Balasubramanian
- BUGWORKS Research India Pvt. Ltd., Centre for Cellular & Molecular Platforms, National Centre for Biological Sciences, Bengaluru, Karnataka, India
| | - Richard E. Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - George L. Drusano
- Institute for Therapeutic Innovation, College of Medicine, University of Florida, Orlando, Florida, USA
| | - Jürgen B. Bulitta
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
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Adembri C, Novelli A, Nobili S. Some Suggestions from PK/PD Principles to Contain Resistance in the Clinical Setting-Focus on ICU Patients and Gram-Negative Strains. Antibiotics (Basel) 2020; 9:E676. [PMID: 33036190 PMCID: PMC7601871 DOI: 10.3390/antibiotics9100676] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 12/18/2022] Open
Abstract
The containment of the phenomenon of resistance towards antimicrobials is a priority, especially in preserving molecules acting against Gram-negative pathogens, which represent the isolates more frequently found in the fragile population of patients admitted to Intensive Care Units. Antimicrobial therapy aims to prevent resistance through several actions, which are collectively known as "antimicrobial stewardship", to be taken together, including the application of pharmacokinetic/pharmacodynamic (PK/PD) principles. PK/PD application has been shown to prevent the emergence of resistance in numerous experimental studies, although a straight translation to the clinical setting is not possible. Individualized antibiotic dosing and duration should be pursued in all patients, and even more especially when treating intensive care unit (ICU) septic patients in whom optimal exposure is both difficult to achieve and necessary. In this review, we report on the available data that support the application of PK/PD parameters to contain the development of resistance and we give some practical suggestions that can help to translate the benefit of PK/PD application to the bedside.
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Affiliation(s)
- Chiara Adembri
- Department of Health Sciences, Section of Anesthesiology and IC, University of Florence, 50134 Firenze, Italy;
| | - Andrea Novelli
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, 50139 Firenze, Italy;
| | - Stefania Nobili
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, 50139 Firenze, Italy;
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11
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Noel AR, Bowker KE, Attwood M, MacGowan AP. Antibacterial effect of imipenem/relebactam on aerobic Gram-negative bacilli: in vitro simulations of 7 or 14 day human exposures. J Antimicrob Chemother 2020; 74:1945-1951. [PMID: 31220257 DOI: 10.1093/jac/dkz114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/25/2019] [Accepted: 02/27/2019] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES We assessed the antibacterial effect of human simulations of dosing with imipenem/relebactam (with or without amikacin) on Enterobacteriaceae or Pseudomonas aeruginosa over 7 or 14 day antibiotic exposures. METHODS An in vitro pharmacokinetic model was used to assess changes in bacterial load and population profiles. RESULTS Imipenem/relebactam produced an initial >4 log drop in viable counts followed by suppression for 7 days for Enterobacteriaceae whether the strain was WT, produced KPC enzymes or produced an AmpC enzyme with porin loss. Similarly, with the P. aeruginosa strains, there was an initial >4 log clearance over the first 24 h irrespective of whether the strain was WT, hyperexpressed AmpC or had OprD mutation with porin loss. However, with three of four strains there was modest regrowth over the 7 days. There were no changes in imipenem/relebactam MICs over the 7 days. Addition of amikacin in 7 day simulations resulted in more suppression of pseudomonal growth. In 14 day simulations with P. aeruginosa there was regrowth to 8 log10 by 14 days with imipenem/relebactam alone and associated increases in MICs. Addition of amikacin resulted in clearance from the model and prevented changes in population profiles. CONCLUSIONS Imipenem/relebactam was highly effective at reducing the bacterial load of Enterobacteriaceae and there was no emergence of resistance. Against P. aeruginosa, the initial bacterial burden was also rapidly reduced, but there was subsequent regrowth, especially after 7 days of exposure. Addition of amikacin increased the clearance of P. aeruginosa and prevented emergence of resistance.
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Affiliation(s)
- Alan R Noel
- Bristol Centre for Antimicrobial Research & Evaluation (BCARE), North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building - Phase 2, Science Quarter, Southmead Hospital, Westbury-on-Trym, Bristol, UK
| | - Karen E Bowker
- Bristol Centre for Antimicrobial Research & Evaluation (BCARE), North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building - Phase 2, Science Quarter, Southmead Hospital, Westbury-on-Trym, Bristol, UK
| | - Marie Attwood
- Bristol Centre for Antimicrobial Research & Evaluation (BCARE), North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building - Phase 2, Science Quarter, Southmead Hospital, Westbury-on-Trym, Bristol, UK
| | - Alasdair P MacGowan
- Bristol Centre for Antimicrobial Research & Evaluation (BCARE), North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building - Phase 2, Science Quarter, Southmead Hospital, Westbury-on-Trym, Bristol, UK
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12
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Efficacy of Ceftolozane-Tazobactam in Combination with Colistin against Extensively Drug-Resistant Pseudomonas aeruginosa, Including High-Risk Clones, in an In Vitro Pharmacodynamic Model. Antimicrob Agents Chemother 2020; 64:AAC.02542-19. [PMID: 32041712 DOI: 10.1128/aac.02542-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 01/30/2020] [Indexed: 12/11/2022] Open
Abstract
Combination therapy is an attractive therapeutic option for extensively drug-resistant (XDR) Pseudomonas aeruginosa infections. Colistin has been the only treatment available for these infections for many years, but its results are suboptimal. Ceftolozane-tazobactam (C/T) is a newly available therapeutic option that has shown good antipseudomonal activity, even against a number of XDR P. aeruginosa strains. However, data about combinations containing C/T are scarce. The aim of this study was to analyze the activity of C/T and colistin alone and in combination against a collection of XDR P. aeruginosa strains containing 24 representative clinical isolates from a multicentre Spanish study. Twenty-four time-kill experiments performed over 24 h were conducted in duplicate to determine the effects of colistin and C/T alone and combined. An in vitro pharmacodynamic chemostat model then was used to validate this combination against three selected XDR P. aeruginosa ST175 isolates with different susceptibility levels to C/T. Static time-kill assays demonstrated superior synergistic or additive effect for C/T plus colistin against 21 of the 24 isolates studied. In the in vitro dynamic pharmacokinetic/pharmacodynamic (PK/PD) model, the C/T regimen of 2/1 g every 8 h with a steady-state concentration of 2 mg/liter colistin effectively suppressed the bacterial growth at 24 h. Additive or synergistic interactions were observed for C/T plus colistin against XDR P. aeruginosa strains and particularly against C/T-resistant strains. C/T plus colistin may be a useful treatment for XDR P. aeruginosa infections, including those caused by high risk-clones resistant to C/T.
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13
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Noel AR, Bowker KE, Attwood M, MacGowan AP. Antibacterial effect of ceftolozane/tazobactam in combination with amikacin against aerobic Gram-negative bacilli studied in an in vitro pharmacokinetic model of infection. J Antimicrob Chemother 2019; 73:2411-2417. [PMID: 30020472 DOI: 10.1093/jac/dky225] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/18/2018] [Indexed: 01/18/2023] Open
Abstract
Objectives To use a pre-clinical infection model to assess the antibacterial effect of human simulations of dosing with ceftolozane/tazobactam (with or without amikacin) or meropenem against Enterobacteriaceae and Pseudomonas aeruginosa. Methods An in vitro pharmacokinetic model was used to assess changes in bacterial load and profiles after exposure to mean human serum concentrations over 168 h. Changes in area under the bacterial kill curve (AUBKC; log cfu/mL·h) and growth on 4 × MIC recovery plates were the co-primary outcome measures. Results Simulations of ceftolozane/tazobactam at 1 g/0.5 g or 2 g/1 g q8h or meropenem 2 g q8h all produced a >4 log reduction in bacterial load of Escherichia coli. Meropenem had smaller AUBKC values, indicating greater reduction in bacterial load than ceftolozane/tazobactam. Meropenem was also more effective than ceftolozane/tazobactam against Klebsiella pneumoniae strains. All regimens were equally effective in reducing P. aeruginosa bacterial load measured by AUBKC but growth on 4 × MIC recovery plates and changes in population profiles were only seen with meropenem. Addition of amikacin at 15 mg/kg q24h or 7.5 mg/kg q12h to 2 g/1 g of ceftolozane/tazobactam produced greater reductions in bacterial load but generated changes in amikacin population profiles with the 7.5 mg/kg q12h amikacin simulation. Conclusions The doses of ceftolozane/tazobactam simulated were highly effective in reducing the bacterial load of E. coli (MIC ≤0.25 mg/L), but less so for K. pneumoniae (MIC 4 mg/L). For both species, meropenem produced an overall greater reduction in pathogen load. Ceftolozane/tazobactam and meropenem were equally effective as monotherapy against P. aeruginosa but emergence of resistance occurred with meropenem. Addition of amikacin to ceftolozane/tazobactam reduced the bacterial load of P. aeruginosa at the expense of emergence of resistance to amikacin.
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Affiliation(s)
- Alan R Noel
- Bristol Centre for Antimicrobial Research & Evaluation, North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building Phase 2, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Karen E Bowker
- Bristol Centre for Antimicrobial Research & Evaluation, North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building Phase 2, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Marie Attwood
- Bristol Centre for Antimicrobial Research & Evaluation, North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building Phase 2, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK
| | - Alasdair P MacGowan
- Bristol Centre for Antimicrobial Research & Evaluation, North Bristol NHS Trust, Department of Infection Sciences, Pathology Sciences Building Phase 2, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK
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14
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Horcajada JP, Montero M, Oliver A, Sorlí L, Luque S, Gómez-Zorrilla S, Benito N, Grau S. Epidemiology and Treatment of Multidrug-Resistant and Extensively Drug-Resistant Pseudomonas aeruginosa Infections. Clin Microbiol Rev 2019; 32:32/4/e00031-19. [PMID: 31462403 PMCID: PMC6730496 DOI: 10.1128/cmr.00031-19] [Citation(s) in RCA: 461] [Impact Index Per Article: 92.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
In recent years, the worldwide spread of the so-called high-risk clones of multidrug-resistant or extensively drug-resistant (MDR/XDR) Pseudomonas aeruginosa has become a public health threat. This article reviews their mechanisms of resistance, epidemiology, and clinical impact and current and upcoming therapeutic options. In vitro and in vivo treatment studies and pharmacokinetic and pharmacodynamic (PK/PD) models are discussed. Polymyxins are reviewed as an important therapeutic option, outlining dosage, pharmacokinetics and pharmacodynamics, and their clinical efficacy against MDR/XDR P. aeruginosa infections. Their narrow therapeutic window and potential for combination therapy are also discussed. Other "old" antimicrobials, such as certain β-lactams, aminoglycosides, and fosfomycin, are reviewed here. New antipseudomonals, as well as those in the pipeline, are also reviewed. Ceftolozane-tazobactam has clinical activity against a significant percentage of MDR/XDR P. aeruginosa strains, and its microbiological and clinical data, as well as recommendations for improving its use against these bacteria, are described, as are those for ceftazidime-avibactam, which has better activity against MDR/XDR P. aeruginosa, especially strains with certain specific mechanisms of resistance. A section is devoted to reviewing upcoming active drugs such as imipenem-relebactam, cefepime-zidebactam, cefiderocol, and murepavadin. Finally, other therapeutic strategies, such as use of vaccines, antibodies, bacteriocins, anti-quorum sensing, and bacteriophages, are described as future options.
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Affiliation(s)
- Juan P Horcajada
- Service of Infectious Diseases, Hospital del Mar, Infectious Pathology and Antimicrobials Research Group, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Universitat Autònoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Madrid, Spain
| | - Milagro Montero
- Service of Infectious Diseases, Hospital del Mar, Infectious Pathology and Antimicrobials Research Group, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Universitat Autònoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Madrid, Spain
| | - Antonio Oliver
- Service of Microbiology, Hospital Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Luisa Sorlí
- Service of Infectious Diseases, Hospital del Mar, Infectious Pathology and Antimicrobials Research Group, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Universitat Pompeu Fabra, Barcelona, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Madrid, Spain
| | - Sònia Luque
- Service of Pharmacy, Hospital del Mar, Infectious Pathology and Antimicrobials Research Group, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Silvia Gómez-Zorrilla
- Service of Infectious Diseases, Hospital del Mar, Infectious Pathology and Antimicrobials Research Group, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Universitat Pompeu Fabra, Barcelona, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Madrid, Spain
| | - Natividad Benito
- Infectious Diseases Unit, Hospital de la Santa Creu i Sant Pau, Institut d'Investigació Biomèdica Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Santiago Grau
- Service of Pharmacy, Hospital del Mar, Infectious Pathology and Antimicrobials Research Group, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Universitat Autònoma de Barcelona, Barcelona, Spain
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15
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Comparable Efficacy and Better Safety of Double β-Lactam Combination Therapy versus β‑Lactam plus Aminoglycoside in Gram-Negative Bacteria in Randomized, Controlled Trials. Antimicrob Agents Chemother 2019; 63:AAC.00425-19. [PMID: 30988147 DOI: 10.1128/aac.00425-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 04/08/2019] [Indexed: 01/04/2023] Open
Abstract
There is a great need for efficacious therapies against Gram-negative bacteria. Double β-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 β-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 β-lactams for future evaluation in clinical trials.
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16
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Generating Robust and Informative Nonclinical In Vitro and In Vivo Bacterial Infection Model Efficacy Data To Support Translation to Humans. Antimicrob Agents Chemother 2019; 63:AAC.02307-18. [PMID: 30833428 PMCID: PMC6496039 DOI: 10.1128/aac.02307-18] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In June 2017, the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, organized a workshop entitled “Pharmacokinetics-Pharmacodynamics (PK/PD) for Development of Therapeutics against Bacterial Pathogens.” The aims were to discuss details of various PK/PD models and identify sound practices for deriving and utilizing PK/PD relationships to design optimal dosage regimens for patients. Workshop participants encompassed individuals from academia, industry, and government, including the United States Food and Drug Administration. In June 2017, the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, organized a workshop entitled “Pharmacokinetics-Pharmacodynamics (PK/PD) for Development of Therapeutics against Bacterial Pathogens.” The aims were to discuss details of various PK/PD models and identify sound practices for deriving and utilizing PK/PD relationships to design optimal dosage regimens for patients. Workshop participants encompassed individuals from academia, industry, and government, including the United States Food and Drug Administration. This and the accompanying review on clinical PK/PD summarize the workshop discussions and recommendations. Nonclinical PK/PD models play a critical role in designing human dosage regimens and are essential tools for drug development. These include in vitro and in vivo efficacy models that provide valuable and complementary information for dose selection and translation from the laboratory to human. It is crucial that studies be designed, conducted, and interpreted appropriately. For antibacterial PK/PD, extensive published data and expertise are available. These have been leveraged to develop recommendations, identify common pitfalls, and describe the applications, strengths, and limitations of various nonclinical infection models and translational approaches. Despite these robust tools and published guidance, characterizing nonclinical PK/PD relationships may not be straightforward, especially for a new drug or new class. Antimicrobial PK/PD is an evolving discipline that needs to adapt to future research and development needs. Open communication between academia, pharmaceutical industry, government, and regulatory bodies is essential to share perspectives and collectively solve future challenges.
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17
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Heffernan AJ, Sime FB, Lipman J, Roberts JA. Individualising Therapy to Minimize Bacterial Multidrug Resistance. Drugs 2019; 78:621-641. [PMID: 29569104 DOI: 10.1007/s40265-018-0891-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The scourge of antibiotic resistance threatens modern healthcare delivery. A contributing factor to this significant issue may be antibiotic dosing, whereby standard antibiotic regimens are unable to suppress the emergence of antibiotic resistance. This article aims to review the role of pharmacokinetic and pharmacodynamic (PK/PD) measures for optimising antibiotic therapy to minimise resistance emergence. It also seeks to describe the utility of combination antibiotic therapy for suppression of resistance and summarise the role of biomarkers in individualising antibiotic therapy. Scientific journals indexed in PubMed and Web of Science were searched to identify relevant articles and summarise existing evidence. Studies suggest that optimising antibiotic dosing to attain defined PK/PD ratios may limit the emergence of resistance. A maximum aminoglycoside concentration to minimum inhibitory concentration (MIC) ratio of > 20, a fluoroquinolone area under the concentration-time curve to MIC ratio of > 285 and a β-lactam trough concentration of > 6 × MIC are likely required for resistance suppression. In vitro studies demonstrate a clear advantage for some antibiotic combinations. However, clinical evidence is limited, suggesting that the use of combination regimens should be assessed on an individual patient basis. Biomarkers, such as procalcitonin, may help to individualise and reduce the duration of antibiotic treatment, which may minimise antibiotic resistance emergence during therapy. Future studies should translate laboratory-based studies into clinical trials and validate the appropriate clinical PK/PD predictors required for resistance suppression in vivo. Other adjunct strategies, such as biomarker-guided therapy or the use of antibiotic combinations require further investigation.
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Affiliation(s)
- A J Heffernan
- School of Medicine, Griffith University, Gold Coast, Queensland, Australia
- Centre for Translational Anti-Infective Pharmacodynamics, School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - F B Sime
- Centre for Translational Anti-Infective Pharmacodynamics, School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Building 71/918, Herston Rd, Herston, Queensland, 4029, Australia
| | - J Lipman
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Building 71/918, Herston Rd, Herston, Queensland, 4029, Australia
- Department of Intensive Care Medicine, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
| | - J A Roberts
- Centre for Translational Anti-Infective Pharmacodynamics, School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia.
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Building 71/918, Herston Rd, Herston, Queensland, 4029, Australia.
- Department of Intensive Care Medicine, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
- Pharmacy Department, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
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Perumal S, Mahmud R, Mohamed N. Combination of Epicatechin 3-Gallate from Euphorbia hirta and Cefepime Promotes Potential Synergistic Eradication Action against Resistant Clinical Isolate of Pseudomonas aeruginosa. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2018; 2018:5713703. [PMID: 30108657 PMCID: PMC6077534 DOI: 10.1155/2018/5713703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/02/2018] [Indexed: 11/17/2022]
Abstract
Pseudomonas aeruginosa is naturally resistant to many classes of antipseudomonal antibiotics due to the species ability to easily acquire resistance. Plant-based antibacterial agent in combination with the existing antibiotic proposes an alternative treatment regimen for the eradication of resistant bacterial infections. The antibacterial effects of the isolated epicatechin 3-gallate compound from Euphorbia hirta in combination with cefepime were investigated in vitro against resistant P. aeruginosa. The fractional inhibitory concentration index of the combination was determined using checkerboard broth microdilution method. Epicatechin 3-gallate combined with cefepime had produced synergistic effect against P. aeruginosa (with average FIC index of 0.24). The MIC of epicatechin 3-gallate was effectively reduced to MIC/4, MIC/8, MIC/16, and MIC/32 in the presence of cefepime. Time-kill study of epicatechin 3-gallate combined with cefepime exhibited remarkable bactericidal activity where the eradication of P. aeruginosa occurred within 4 h of treatment. Scanning electron micrographs revealed apparent cell membrane damage and leakage of cytoplasmic contents from P. aeruginosa cells which eventually led to the cell lysis after the combination treatment of epicatechin 3-gallate and cefepime. The potential of epicatechin 3-gallate to act synergistically with cefepime against clinically resistant P. aeruginosa strain possibly will maximize the successful outcomes when choosing empirical antibiotic treatment in hospitals or health care institutions.
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Affiliation(s)
- Shanmugapriya Perumal
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Roziahanim Mahmud
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Nornisah Mohamed
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
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19
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20
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Efficacy of Human-Simulated Exposures of Ceftolozane-Tazobactam Alone and in Combination with Amikacin or Colistin against Multidrug-Resistant Pseudomonas aeruginosa in an In Vitro Pharmacodynamic Model. Antimicrob Agents Chemother 2018; 62:AAC.02384-17. [PMID: 29483119 DOI: 10.1128/aac.02384-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/17/2018] [Indexed: 12/23/2022] Open
Abstract
Combination therapy is an attractive option for the treatment of multidrug-resistant (MDR) Pseudomonas aeruginosa infections; however, limited data are available on combinations with ceftolozane-tazobactam (C-T). The in vitro pharmacodynamic chemostat model was employed to compare human-simulated exposures of C-T at 3 g every 8 h alone or in combination with amikacin at 25 mg/kg of body weight daily or colistin at 360 mg daily against four MDR P. aeruginosa isolates. C-T alone resulted in 24-h changes in the number of CFU of -0.02 ± 0.21, -1.81 ± 0.55, -1.44 ± 0.40, and +0.62 ± 0.05 log10 CFU/ml against isolates with C-T MICs of 4, 4, 8, and 16 μg/ml, respectively. Amikacin and colistin monotherapy displayed various results. The addition of amikacin to C-T resulted in -2.00 ± 0.23 (P < 0.001, additive)-, -1.50 ± 0.83 (P = 0.687, indifferent)-, -2.84 ± 0.08 (P = 0.079, indifferent)-, and -2.67 ± 0.54 (P < 0.001, synergy)-log10 CFU/ml reductions, respectively. The addition of colistin to C-T resulted in -3.02 ± 0.22 (P < 0.001, additive)-, -3.21 ± 0.24 (P > 0.05, indifferent)-, -4.6 ± 0.11 (P = 0.002, synergy)-, and -3.01 ± 0.28 (P < 0.001, synergy)-log10 CFU/ml reductions, respectively, against the MDR P. aeruginosa isolates with these MICs. Greater overall reductions in bacterial burden, including additive or synergistic interactions at 24 h, with C-T plus amikacin or colistin were observed against 3 out of 4 MDR P. aeruginosa strains tested, particularly those strains that were intermediate or resistant to C-T. Further studies assessing combination regimens containing C-T against MDR P. aeruginosa are warranted.
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21
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Owens RC, Bulik CC, Andes DR. Pharmacokinetics-pharmacodynamics, computer decision support technologies, and antimicrobial stewardship: the compass and rudder. Diagn Microbiol Infect Dis 2018; 91:371-382. [PMID: 29776710 DOI: 10.1016/j.diagmicrobio.2018.03.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 03/21/2018] [Accepted: 03/26/2018] [Indexed: 12/19/2022]
Abstract
The first guidelines for conducting antimicrobial stewardship in the hospitalized setting were published in 2007. These guidelines recommend that stewardship programs employ the science of pharmacokinetics-pharmacodynamics (PK-PD) as well as adopting computerized decision support technologies when possible. The United States Food and Drug Administration have adopted PK-PD as a cornerstone in the evaluation of antimicrobial agents during clinical development. The core principles of PK-PD center around describing the relationship between drug exposure indexed to the susceptibility of the infecting bacterial pathogen and patient response. Using such relationships with population pharmacokinetic models and simulation, rational drug and dosing regimens can be selected. But because PK-PD modeling and simulation programs are generally absent in clinical practice, systematic application of this science is missing. Herein we explain advances in technology that allow clinicians to apply PK-PD to optimize the agents and dosing regimens selected for the treatment of hospitalized patients with infection.
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Affiliation(s)
- Robert C Owens
- Institute for Clinical Pharmacodynamics, Schenectady, New York.
| | | | - David R Andes
- University of Wisconsin, School of Medicine, Madison, Wisconsin
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22
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El Chakhtoura NG, Saade E, Iovleva A, Yasmin M, Wilson B, Perez F, Bonomo RA. Therapies for multidrug resistant and extensively drug-resistant non-fermenting gram-negative bacteria causing nosocomial infections: a perilous journey toward 'molecularly targeted' therapy. Expert Rev Anti Infect Ther 2018; 16:89-110. [PMID: 29310479 PMCID: PMC6093184 DOI: 10.1080/14787210.2018.1425139] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/04/2018] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Non-fermenting Gram-negative bacilli are at the center of the antimicrobial resistance epidemic. Acinetobacter baumannii and Pseudomonas aeruginosa are both designated with a threat level to human health of 'serious' by the Centers for Disease Control and Prevention. Two other major non-fermenting Gram-negative bacilli, Stenotrophomonas maltophilia and Burkholderia cepacia complex, while not as prevalent, have devastating effects on vulnerable populations, such as those with cystic fibrosis, as well as immunosuppressed or hospitalized patients. Areas covered: In this review, we summarize the clinical impact, presentations, and mechanisms of resistance of these four major groups of non-fermenting Gram-negative bacilli. We also describe available and promising novel therapeutic options and strategies, particularly combination antibiotic strategies, with a focus on multidrug resistant variants. Expert commentary: We finally advocate for a therapeutic approach that incorporates in vitro antibiotic susceptibility testing with molecular and genotypic characterization of mechanisms of resistance, as well as pharmacokinetics and pharmacodynamics (PK/PD) parameters. The goal is to begin to formulate a precision medicine approach to antimicrobial therapy: a clinical-decision making model that integrates bacterial phenotype, genotype and patient's PK/PD to arrive at rationally-optimized combination antibiotic chemotherapy regimens tailored to individual clinical scenarios.
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Affiliation(s)
- Nadim G. El Chakhtoura
- Medicine Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research Services Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatrics Research, Education and Clinical Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Elie Saade
- Medicine Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research Services Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatrics Research, Education and Clinical Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Medicine, University Hospitals Cleveland Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Alina Iovleva
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Mohamad Yasmin
- Medicine Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research Services Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Medicine, University Hospitals Cleveland Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Brigid Wilson
- Medicine Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research Services Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatrics Research, Education and Clinical Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Federico Perez
- Medicine Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research Services Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatrics Research, Education and Clinical Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Robert A. Bonomo
- Medicine Case Western Reserve University School of Medicine, Cleveland, Ohio
- Research Services Case Western Reserve University School of Medicine, Cleveland, Ohio
- Geriatrics Research, Education and Clinical Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Medicine, University Hospitals Cleveland Medical Center Case Western Reserve University School of Medicine, Cleveland, Ohio
- Departments of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio
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Mensa J, Barberán J, Soriano A, Llinares P, Marco F, Cantón R, Bou G, del Castillo JG, Maseda E, Azanza JR, Pasquau J, García-Vidal C, Reguera JM, Sousa D, Gómez J, Montejo M, Borges M, Torres A, Alvarez-Lerma F, Salavert M, Zaragoza R, Oliver A. Antibiotic selection in the treatment of acute invasive infections by Pseudomonas aeruginosa: Guidelines by the Spanish Society of Chemotherapy. REVISTA ESPANOLA DE QUIMIOTERAPIA : PUBLICACION OFICIAL DE LA SOCIEDAD ESPANOLA DE QUIMIOTERAPIA 2018; 31:78-100. [PMID: 29480677 PMCID: PMC6159363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pseudomonas aeruginosa is characterized by a notable intrinsic resistance to antibiotics, mainly mediated by the expression of inducible chromosomic β-lactamases and the production of constitutive or inducible efflux pumps. Apart from this intrinsic resistance, P. aeruginosa possess an extraordinary ability to develop resistance to nearly all available antimicrobials through selection of mutations. The progressive increase in resistance rates in P. aeruginosa has led to the emergence of strains which, based on their degree of resistance to common antibiotics, have been defined as multidrug resistant, extended-resistant and panresistant strains. These strains are increasingly disseminated worldwide, progressively complicating the treatment of P. aeruginosa infections. In this scenario, the objective of the present guidelines was to review and update published evidence for the treatment of patients with acute, invasive and severe infections caused by P. aeruginosa. To this end, mechanisms of intrinsic resistance, factors favoring development of resistance during antibiotic exposure, prevalence of resistance in Spain, classical and recently appeared new antibiotics active against P. aeruginosa, pharmacodynamic principles predicting efficacy, clinical experience with monotherapy and combination therapy, and principles for antibiotic treatment were reviewed to elaborate recommendations by the panel of experts for empirical and directed treatment of P. aeruginosa invasive infections.
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Affiliation(s)
- José Mensa
- Servicio de Enfermedades Infecciosas, Hospital Clinic, Barcelona, Spain
| | - José Barberán
- Servicio de Medicina Enfermedades infecciosas, Hospital Universitario HM Montepríncipe, Universidad San Pablo CEU. Madrid, Spain
| | - Alex Soriano
- Servicio de Enfermedades Infecciosas, Hospital Clinic, Barcelona, Spain
| | - Pedro Llinares
- Unidad de Enfermedades Infecciosas, Complejo Hospitalario Universitario A Coruña, Spain
| | - Francesc Marco
- Servicio de Microbiología, Hospital Clinic, Barcelona, Spain
| | - Rafael Cantón
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS). Madrid, Spain
| | - German Bou
- Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña, Spain
| | | | - Emilio Maseda
- Servicio de Anestesiología, Hospital Universitario La Paz, Madrid, Spain
| | - José Ramón Azanza
- Servicio de Farmacología, Clínica Universitaria de Navarra, Pamplona, Spain
| | - Juan Pasquau
- Servicio de Enfermedades Infecciosas, Hospital Universitario Virgen de la Nieves, Granada, Spain
| | | | - José María Reguera
- Servicio de Enfermedades Infecciosas, Hospital Universitario Carlos Haya, Málaga, Spain
| | - Dolores Sousa
- Unidad de Enfermedades Infecciosas, Complejo Hospitalario Universitario A Coruña, Spain
| | - Joaquín Gómez
- Servicio de Enfermedades Infecciosas, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Miguel Montejo
- Servicio de Enfermedades Infecciosas, Hospital Universitario Cruces, Bilbao, Spain
| | - Marcio Borges
- Servicio de Medicina Intensiva, Hospital Son Llátzer, Palma de Mallorca, Spain
| | - Antonio Torres
- Departamento de Neumología, Hospital Clinic, Barcelona, Spain
| | | | - Miguel Salavert
- Unidad de Enfermedades Infecciosas. Hospital Univeristario la Fe, Valencia, Spain
| | - Rafael Zaragoza
- Servicio de Medicina Intensiva, Hospital Universitario Dr. Peset, Valencia, Spain
| | - Antonio Oliver
- Servicio de Microbiología, Hospital Universitari Son Espases, Instituto de Investigación Sanitaria Illes Balears (idISBa), Palma de Mallorca, Spain
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Satlin MJ, Walsh TJ. Multidrug-resistant Enterobacteriaceae, Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus: Three major threats to hematopoietic stem cell transplant recipients. Transpl Infect Dis 2017; 19. [PMID: 28815897 DOI: 10.1111/tid.12762] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 04/04/2017] [Accepted: 06/01/2017] [Indexed: 12/13/2022]
Abstract
Hematopoietic stem cell transplant (HSCT) recipients are uniquely threatened by the emergence of multidrug-resistant (MDR) bacteria because these patients rely on immediate active antimicrobial therapy to combat bacterial infections. This review describes the epidemiology and treatment considerations for three challenging MDR bacterial pathogens in HSCT recipients: MDR Enterobacteriaceae, including extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Enterobacteriaceae (CRE), Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus (VRE). These bacteria are common causes of infection in this population and bacteremias caused by these organisms are associated with high mortality rates. Carbapenems remain the treatments of choice for serious infections due to ESBL-producing Enterobacteriaceae in HSCT recipients. Administration of β-lactam agents as an extended infusion is associated with improved outcomes in patients with severe infections caused by P. aeruginosa. Older agents used for the treatment of CRE and MDR P. aeruginosa infections, such as polymyxins and aminoglycosides, have major limitations. Newer agents, such as ceftazidime-avibactam and ceftolozane-tazobactam have great potential for the treatment of Klebsiella pneumoniae carbapemenase-producing CRE and MDR P. aeruginosa, respectively, but more pre-clinical and clinical data are needed to better evaluate their efficacy. Daptomycin dosages ≥8 mg/kg/day are recommended to treat VRE infections in this population, particularly in the setting of increasing daptomycin resistance. Strategies to prevent these infections include strict adherence to recommended infection control practices and multidisciplinary antimicrobial stewardship. Last, gastrointestinal screening to guide empirical therapy and the use of polymerase chain reaction-based rapid diagnostics may decrease the time to administration of appropriate therapy for these infections, thereby leading to improved outcomes.
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Affiliation(s)
- Michael J Satlin
- Transplantation-Oncology Infectious Diseases Program, Division of Infectious Diseases, Weill Cornell Medicine, New York, NY, USA.,Weill Cornell Medical Center, New York-Presbyterian Hospital, New York, NY, USA
| | - Thomas J Walsh
- Transplantation-Oncology Infectious Diseases Program, Division of Infectious Diseases, Weill Cornell Medicine, New York, NY, USA.,Weill Cornell Medical Center, New York-Presbyterian Hospital, New York, NY, USA.,Department of Pediatrics and Microbiology & Immunology, Weill Cornell Medicine, New York, NY, USA
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25
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Drusano GL. Pre-clinical in vitro infection models. Curr Opin Pharmacol 2017; 36:100-106. [DOI: 10.1016/j.coph.2017.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 09/26/2017] [Indexed: 10/18/2022]
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Pseudomonas Endocarditis with an unstable phenotype: the challenges of isolate characterization and Carbapenem stewardship with a partial review of the literature. Antimicrob Resist Infect Control 2017; 6:87. [PMID: 28855980 PMCID: PMC5574246 DOI: 10.1186/s13756-017-0245-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 08/20/2017] [Indexed: 01/11/2023] Open
Abstract
Background Pseudomonas endocarditis is exceedingly rare, especially in patients without predisposing risks. We present such a case that included unexpected switches in antibacterial resistance profiles in two Pseudomonas aeruginosa (PA) strains with the same whole-genome sequence. The case also involved diagnostic and treatment challenges, such as issues with automated testing platforms, choosing the optimal aminoglycoside, minimizing unnecessary carbapenem exposure, and the need for faster, more informative laboratory tests. Case presentation On hospital day one (HD-1) a cefepime and piperacillin-tazobactam (FEP-TZP)-susceptible P. aeruginosa was isolated from the bloodstream of a 62-year-old man admitted for evaluation of possible endocarditis and treated with gentamicin and cefepime. On HD-2, his antibiotic regimen was changed to tobramycin and cefepime. On HD-11, he underwent aortic valve replacement, and P. aeruginosa was isolated from the explanted valve. Unexpectedly, it was FEP-TZP-resistant, so cefepime was switched to meropenem. On HD-14, in preparation for whole-genome sequencing (WGS), valve and blood isolates were removed from cryo-storage, re-cultured, and simultaneously tested with the same platforms, reagents, and inoculations previously used. Curiously, the valve isolate was now FEP-TZP-susceptible. WGS revealed that both isolates were phylogenetically identical, differing by a single nucleotide in a chemotaxis-encoding gene. They also contained the same resistance genes (blaADC35, aph(3′)-II, blaOXA-50, catB7, fosA). Conclusion Repeated testing on alternate platforms and WGS did not definitively determine the resistance mechanism(s), which in this case, is most likely unstable de-repression of a chromosomal AmpC β-lactamase, porin alterations, or efflux upregulation, with reversion to baseline (non-efflux) transcription. Although sub-culture on specialized media to select for less fit (more resistant) colonies, followed by transcriptome analysis, and multiple sequence alignment, might have revealed the mechanism and better informed the optimal choice of β-lactam, such approaches are neither rapid, nor feasible for hospital laboratories. In this era of escalating drug resistance and dwindling antibiotics, use of the most potent anti-pseudomonals must be balanced with stewardship. Clinicians need access to validated genomic correlates of resistance, and faster, more informative diagnostics. Therefore, we placed these isolates and their sequences in the public domain for inclusion in the Pseudomonas pan-genome and database projects for further countermeasure development.
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Substantial Impact of Altered Pharmacokinetics in Critically Ill Patients on the Antibacterial Effects of Meropenem Evaluated via the Dynamic Hollow-Fiber Infection Model. Antimicrob Agents Chemother 2017; 61:AAC.02642-16. [PMID: 28264846 DOI: 10.1128/aac.02642-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/28/2017] [Indexed: 12/15/2022] Open
Abstract
Critically ill patients frequently have substantially altered pharmacokinetics compared to non-critically ill patients. We investigated the impact of pharmacokinetic alterations on bacterial killing and resistance for commonly used meropenem dosing regimens. A Pseudomonas aeruginosa isolate (MICmeropenem 0.25 mg/liter) was studied in the hollow-fiber infection model (inoculum ∼107.5 CFU/ml; 10 days). Pharmacokinetic profiles representing critically ill patients with augmented renal clearance (ARC), normal, or impaired renal function (creatinine clearances of 285, 120, or ∼10 ml/min, respectively) were generated for three meropenem regimens (2, 1, and 0.5 g administered as 8-hourly 30-min infusions), plus 1 g given 12 hourly with impaired renal function. The time course of total and less-susceptible populations and MICs were determined. Mechanism-based modeling (MBM) was performed using S-ADAPT. All dosing regimens across all renal functions produced similar initial bacterial killing (≤∼2.5 log10). For all regimens subjected to ARC, regrowth occurred after 7 h. For normal and impaired renal function, bacterial killing continued until 23 to 47 h; regrowth then occurred with 0.5- and 1-g regimens with normal renal function (fT>5×MIC = 56 and 69%, fCmin/MIC < 2); the emergence of less-susceptible populations (≥32-fold increases in MIC) accompanied all regrowth. Bacterial counts remained suppressed across 10 days with normal (2-g 8-hourly regimen) and impaired (all regimens) renal function (fT>5×MIC ≥ 82%, fCmin/MIC ≥ 2). The MBM successfully described bacterial killing and regrowth for all renal functions and regimens simultaneously. Optimized dosing regimens, including extended infusions and/or combinations, supported by MBM and Monte Carlo simulations, should be evaluated in the context of ARC to maximize bacterial killing and suppress resistance emergence.
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Zavascki AP, Klee BO, Bulitta JB. Aminoglycosides against carbapenem-resistant Enterobacteriaceae in the critically ill: the pitfalls of aminoglycoside susceptibility. Expert Rev Anti Infect Ther 2017; 15:519-526. [PMID: 28375030 DOI: 10.1080/14787210.2017.1316193] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The emergence of carbapenem-resistant Enterobacteriaceae (CRE) has brought aminoglycosides to the frontline since an aminoglycoside may be the only antimicrobial to which CRE isolates show in vitro susceptibility. The appropriateness of aminoglycoside-based therapies for severe infections by CRE is discussed considering the current breakpoints and recent pharmacokinetic (PK) studies in critically ill patients. Areas covered: Many aminoglycoside-susceptible CRE isolates present minimal inhibitory concentrations (MICs) at or slightly below the breakpoint of amikacin or gentamicin. However, recent PK studies with these aminoglycosides in critically ill have invariably shown that the PK/pharmacodynamic (PD) target is very unlikely attained even when high doses are administered, if the MICs are near the breakpoint. Expert commentary: While new antimicrobials are not widely available, the authors forecast an increasing use of aminoglycosides as backbone antibiotics against CRE isolates. However, the altered PK of aminoglycosides in critically ill patients severely impairs their predicted efficacy in these patients. Aminoglycoside breakpoints may hide 'aminoglycoside-susceptible' CRE isolates for that aminoglycosides will unlikely be effective if used in monotherapy. Therefore, these breakpoints may need to be revised due to the increasing use of aminoglycosides as backbone antibiotics to treat severe infections by CRE isolates in critically ill patients.
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Affiliation(s)
- Alexandre P Zavascki
- a Infectious Diseases Service , Hospital de Clinicas de Porto Alegre , Porto Alegre , Brazil.,b Department of Internal Medicine, Medical School , Universidade Federal do Rio Grande do Sul , Porto Alegre , Brazil
| | - Brandon O Klee
- c Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics , College of Pharmacy, University of Florida , Orlando , FL , USA
| | - Jürgen B Bulitta
- c Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics , College of Pharmacy, University of Florida , Orlando , FL , USA
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Bacterial Replication Rate Modulation in Combination with Antimicrobial Therapy: Turning the Microbe against Itself. Antimicrob Agents Chemother 2016; 61:AAC.01605-16. [PMID: 27821440 DOI: 10.1128/aac.01605-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 10/11/2016] [Indexed: 01/21/2023] Open
Abstract
A major clinical challenge for treating infectious diseases is the duration of antimicrobial therapy required to eradicate the pathogen. We hypothesized that modulation of the bacterial replication rate in the context of an antimicrobial exposure is coupled with the rate and extent of bactericidal effects. Herein we describe results from in vitro infection model (one compartment, 24-h model; hollow fiber, 10-day model) studies designed to probe the relationship between the bacterial replication rate and the rate and extent of bactericidal effects in the context of an effective antibiotic exposure. The bacterial replication rate was modulated by adjusting the sodium chloride concentration (0 to 8%) in the growth media (Mueller-Hinton II broth). The study drug selected was levofloxacin, and the challenge isolate was Staphylococcus aureus ATCC 29213 (levofloxacin MIC, 0.125 mg/liter). Within each in vitro infection model, human levofloxacin concentration-time profiles (half-life, 7 h) were simulated and the challenge isolate was subjected to an effective exposure (free-drug area under the concentration-time curve over 24 h divided by the MIC [AUC/MIC ratio], 65; administered as a single dose or daily for 10 days). Over the course of each study, samples were taken from each model for bacterial density determinations and drug concentration assay using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the 24-h one-compartment in vitro infection model studies, as the bacterial replication rate increased, so too did the rate (slope, 0 to 4 h) and extent (24-h CFU count per milliliter) of bacterial killing. In the 10-day hollow-fiber infection model studies, the times until a reduction of bacterial density to 1 × 102 CFU/ml occurred were 10 days in the media in which the challenge isolate grew slowly and approximately 2 days in the media in which the challenge isolate grew rapidly. Together, these data provide a proof of concept for new adjunctive therapeutic options with respect to the use of antimicrobial agents alone that reduce treatment durations. Such adjunctive therapies hold promise for marked reductions in the tonnage of antimicrobial agents administered to patient populations and selection pressure toward antimicrobial resistance.
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Baker TM, Satlin MJ. The growing threat of multidrug-resistant Gram-negative infections in patients with hematologic malignancies. Leuk Lymphoma 2016; 57:2245-58. [PMID: 27339405 PMCID: PMC5027842 DOI: 10.1080/10428194.2016.1193859] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Prolonged neutropenia and chemotherapy-induced mucositis render patients with hematologic malignancies highly vulnerable to Gram-negative bacteremia. Unfortunately, multidrug-resistant (MDR) Gram-negative bacteria are increasingly encountered globally, and current guidelines for empirical antibiotic coverage in these patients may not adequately treat these bacteria. This expansion of resistance, coupled with traditional culturing techniques requiring 2-4 days for bacterial identification and antimicrobial susceptibility results, have grave implications for these immunocompromised hosts. This review characterizes the epidemiology, risk factors, resistance mechanisms, recommended treatments, and outcomes of the MDR Gram-negative bacteria that commonly cause infections in patients with hematologic malignancies. We also examine the infection prevention strategies in hematology patients, such as infection control practices, antimicrobial stewardship, and targeted decolonization. Finally, we assess the strategies to improve outcomes of the infected patients, including gastrointestinal screening to guide empirical antibiotic therapy, new rapid diagnostic tools for expeditious identification of MDR pathogens, and use of two new antimicrobial agents, ceftolozane/tazobactam and ceftazidime/avibactam.
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Affiliation(s)
- Thomas M. Baker
- Division of Infectious Diseases, Weill Cornell Medicine, New York, NY, USA
| | - Michael J. Satlin
- Transplantation-Oncology Infectious Diseases Program, Weill Cornell Medicine, New York, NY, USA
- Division of Infectious Diseases, Weill Cornell Medicine, New York, NY, USA
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Onufrak NJ, Forrest A, Gonzalez D. Pharmacokinetic and Pharmacodynamic Principles of Anti-infective Dosing. Clin Ther 2016; 38:1930-47. [PMID: 27449411 PMCID: PMC5039113 DOI: 10.1016/j.clinthera.2016.06.015] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/09/2016] [Accepted: 06/23/2016] [Indexed: 12/29/2022]
Abstract
PURPOSE An understanding of the pharmacokinetic (PK) and pharmacodynamic (PD) principles that determine response to antimicrobial therapy can provide the clinician with better-informed dosing regimens. Factors influential on antibiotic disposition and clinical outcome are presented, with a focus on the primary site of infection. Techniques to better understand antibiotic PK and optimize PD are acknowledged. METHODS PubMed (inception-April 2016) was reviewed for relevant publications assessing antimicrobial exposures within different anatomic locations and clinical outcomes for various infection sites. FINDINGS A limited literature base indicates variable penetration of antibiotics to different target sites of infection, with drug solubility and extent of protein binding providing significant PK influences in addition to the major clearing pathway of the agent. PD indices derived from in vitro studies and animal models determine the optimal magnitude and frequency of dosing regimens for patients. PK/PD modeling and simulation has been shown an efficient means of assessing these PD endpoints against a variety of PK determinants, clarifying the unique effects of infection site and patient characteristics to inform the adequacy of a given antibiotic regimen. IMPLICATIONS Appreciation of the PK properties of an antibiotic and its PD measure of efficacy can maximize the utility of these life-saving drugs. Unfortunately, clinical data remain limited for a number of infection site-antibiotic exposure relationships. Modeling and simulation can bridge preclinical and patient data for the prescription of optimal antibiotic dosing regimens, consistent with the tenets of personalized medicine.
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Affiliation(s)
- Nikolas J Onufrak
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Alan Forrest
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Daniel Gonzalez
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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Relationship between Fosfomycin Exposure and Amplification of Escherichia coli Subpopulations with Reduced Susceptibility in a Hollow-Fiber Infection Model. Antimicrob Agents Chemother 2016; 60:5141-5. [PMID: 27270274 DOI: 10.1128/aac.00355-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/27/2016] [Indexed: 01/21/2023] Open
Abstract
Understanding the relationship between antibiotic exposure and amplification of bacterial subpopulations with reduced drug susceptibility over time is important for evaluating the adequacy of dosing regimens. We utilized a hollow-fiber infection model to identify the fosfomycin intravenous dosing regimens that prevented the amplification of Escherichia coli bacterial subpopulations with reduced fosfomycin susceptibility. The challenge isolate was E. coli ATCC 25922 (agar MIC with glucose-6-phosphate, 1 mg/liter; agar MIC without glucose-6-phosphate, 32 mg/liter). The fosfomycin dosing regimens studied were 1 to 12 g every 8 h for 10 days to approximate that planned for clinical use. The studies included a no-treatment control regimen. Two bacterial subpopulations were identified, one with reduced susceptibility with agar MIC values ranging from 32 to 128 mg/liter and the other resistant with agar MIC values of 256 to >1,024 mg/liter on plates containing 5× and 256× the baseline MIC value, respectively. An inverted-U-shaped function best described the relationship between the amplification of the two bacterial subpopulations and drug exposure. The lowest fosfomycin dosing regimen that did not amplify a bacterial subpopulation with reduced susceptibility was 4 g administered every 8 h. Nearly immediate amplification of bacterial subpopulations with reduced susceptibility was observed with fosfomycin dosing regimens consisting of 1 to 2 g every 8 h. These data will be useful to support the selection of fosfomycin dosing regimens that minimize the potential for on-therapy amplification of bacterial subpopulations with reduced susceptibility.
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Paradoxical Effect of Polymyxin B: High Drug Exposure Amplifies Resistance in Acinetobacter baumannii. Antimicrob Agents Chemother 2016; 60:3913-20. [PMID: 27067330 DOI: 10.1128/aac.02831-15] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Accepted: 04/05/2016] [Indexed: 11/20/2022] Open
Abstract
Administering polymyxin antibiotics in a traditional fashion may be ineffective against Gram-negative ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens. Here, we explored increasing the dose intensity of polymyxin B against two strains of Acinetobacter baumannii in the hollow-fiber infection model. The following dosage regimens were simulated for polymyxin B (t1/2 = 8 h): non-loading dose (1.43 mg/kg of body weight every 12 h [q12h]), loading dose (2.22 mg/kg q12h for 1 dose and then 1.43 mg/kg q12h), front-loading dose (3.33 mg/kg q12h for 1 dose followed by 1.43 mg/kg q12h), burst (5.53 mg/kg for 1 dose), and supraburst (18.4 mg/kg for 1 dose). Against both A. baumannii isolates, a rapid initial decline in the total population was observed within the first 6 h of polymyxin exposure, whereby greater polymyxin B exposure resulted in greater maximal killing of -1.25, -1.43, -2.84, -2.84, and -3.40 log10 CFU/ml within the first 6 h. Unexpectedly, we observed a paradoxical effect whereby higher polymyxin B exposures dramatically increased resistant subpopulations that grew on agar containing up to 10 mg/liter of polymyxin B over 336 h. High drug exposure also proliferated polymyxin-dependent growth. A cost-benefit pharmacokinetic/pharmacodynamic relationship between 24-h killing and 336-h resistance was explored. The intersecting point, where the benefit of bacterial killing was equal to the cost of resistance, was an fAUC0-24 (area under the concentration-time curve from 0 to 24 h for the free, unbound fraction of drug) of 38.5 mg · h/liter for polymyxin B. Increasing the dose intensity of polymyxin B resulted in amplification of resistance, highlighting the need to utilize polymyxins as part of a combination against high-bacterial-density A. baumannii infections.
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Bergen PJ, Bulitta JB, Kirkpatrick CMJ, Rogers KE, McGregor MJ, Wallis SC, Paterson DL, Lipman J, Roberts JA, Landersdorfer CB. Effect of different renal function on antibacterial effects of piperacillin against Pseudomonas aeruginosa evaluated via the hollow-fibre infection model and mechanism-based modelling. J Antimicrob Chemother 2016; 71:2509-20. [PMID: 27231278 DOI: 10.1093/jac/dkw153] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/05/2016] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Pathophysiological changes in critically ill patients can cause severely altered pharmacokinetics and widely varying antibiotic exposures. The impact of altered pharmacokinetics on bacterial killing and resistance has not been characterized in the dynamic hollow-fibre in vitro infection model (HFIM). METHODS A clinical Pseudomonas aeruginosa isolate (piperacillin MIC 4 mg/L) was studied in the HFIM (inoculum ∼10(7) cfu/mL). Pharmacokinetic profiles of three piperacillin dosing regimens (4 g 8-, 6- and 4-hourly, 30 min intravenous infusion) as observed in critically ill patients with augmented renal clearance (ARC), normal renal function or impaired renal function (creatinine clearances of 250, 110 or 30 mL/min, respectively) were simulated over 7 days. The time courses of total and less-susceptible populations and MICs were determined. Mechanism-based modelling was performed in S-ADAPT. RESULTS For all regimens with ARC and regimens with 8- or 6-hourly dosing with normal renal function, initial killing of ≤∼2 log10 was followed by regrowth to 10(8)-10(9) cfu/mL at 48 h. For 8- and 6-hourly dosing at normal renal function, the proportion of less-susceptible colonies increased ∼10-100-fold above those in ARC and control arms. Regimens achieving an fCmin of ≥5× MIC resulted in bacterial killing of 3-4 log10 without regrowth and suppressed less-susceptible populations to ≤∼2 log10. The mechanism-based model successfully quantified the time course of bacterial growth, killing and regrowth. CONCLUSIONS Only high piperacillin concentrations prevented regrowth of P. aeruginosa. Individualized dosing regimens that account for altered pharmacokinetics and aim for higher-than-standard antibiotic exposures to achieve an fCmin of ≥5× MIC were required to maximize bacterial killing and suppress emergence of resistance.
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Affiliation(s)
- Phillip J Bergen
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Jürgen B Bulitta
- Center for Pharmacometrics and Systems Pharmacology, College of Pharmacy, University of Florida, Orlando, FL, USA
| | - Carl M J Kirkpatrick
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Kate E Rogers
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Megan J McGregor
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Steven C Wallis
- Burns, Trauma and Critical Care Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - David L Paterson
- The University of Queensland Center for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
| | - Jeffrey Lipman
- Burns, Trauma and Critical Care Research Centre, The University of Queensland, Brisbane, Queensland, Australia Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
| | - Jason A Roberts
- Burns, Trauma and Critical Care Research Centre, The University of Queensland, Brisbane, Queensland, Australia Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Cornelia B Landersdorfer
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
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Optimization of Polymyxin B in Combination with Doripenem To Combat Mutator Pseudomonas aeruginosa. Antimicrob Agents Chemother 2016; 60:2870-80. [PMID: 26926641 DOI: 10.1128/aac.02377-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/20/2016] [Indexed: 02/07/2023] Open
Abstract
Development of spontaneous mutations in Pseudomonas aeruginosa has been associated with antibiotic failure, leading to high rates of morbidity and mortality. Our objective was to evaluate the pharmacodynamics of polymyxin B combinations against rapidly evolving P. aeruginosa mutator strains and to characterize the time course of bacterial killing and resistance via mechanism-based mathematical models. Polymyxin B or doripenem alone and in combination were evaluated against six P. aeruginosa strains: wild-type PAO1, mismatch repair (MMR)-deficient (mutS and mutL) strains, and 7,8-dihydro-8-oxo-deoxyguanosine system (GO) base excision repair (BER)-deficient (mutM, mutT, and mutY) strains over 48 h. Pharmacodynamic modeling was performed using S-ADAPT and facilitated by SADAPT-TRAN. Mutator strains displayed higher mutation frequencies than the wild type (>600-fold). Exposure to monotherapy was followed by regrowth, even at high polymyxin B concentrations of up to 16 mg/liter. Polymyxin B and doripenem combinations displayed enhanced killing activity against all strains where complete eradication was achieved for polymyxin B concentrations of >4 mg/liter and doripenem concentrations of 8 mg/liter. Modeling suggested that the proportion of preexisting polymyxin B-resistant subpopulations influenced the pharmacodynamic profiles for each strain uniquely (fraction of resistance values are -8.81 log10 for the wild type, -4.71 for the mutS mutant, and -7.40 log10 for the mutM mutant). Our findings provide insight into the optimization of polymyxin B and doripenem combinations against P. aeruginosa mutator strains.
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Suppression of Emergence of Resistance in Pathogenic Bacteria: Keeping Our Powder Dry, Part 2. Antimicrob Agents Chemother 2015; 60:1194-201. [PMID: 26711766 DOI: 10.1128/aac.02231-15] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We are in a crisis of bacterial resistance. For economic reasons, most pharmaceutical companies are abandoning antimicrobial discovery efforts, while, in health care itself, infection control and antibiotic stewardship programs have generally failed to prevent the spread of drug-resistant bacteria. At this point, what can be done? The first step has been taken. Governments and international bodies have declared there is a worldwide crisis in antibiotic drug resistance. As discovery efforts begin anew, what more can be done to protect newly developing agents and improve the use of new drugs to suppress resistance emergence? A neglected path has been the use of recent knowledge regarding antibiotic dosing as single agents and in combination to minimize resistance emergence, while also providing sufficient early bacterial kill. In this review, we look at the data for resistance suppression. Approaches include increasing the intensity of therapy to suppress resistant subpopulations; developing concepts of clinical breakpoints to include issues surrounding suppression of resistance; and paying attention to the duration of therapy, which is another important issue for resistance suppression. New understanding of optimizing combination therapy is of interest for difficult-to-treat pathogens like Pseudomonas aeruginosa, Acinetobacter spp., and multidrug-resistant (MDR) Enterobacteriaceae. These lessons need to be applied to our old drugs as well to preserve them and to be put into national and international antibiotic resistance strategies. As importantly, from a regulatory perspective, new chemical entities should have a resistance suppression plan at the time of regulatory review. In this way, we can make the best of our current situation and improve future prospects.
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Two mechanisms of killing of Pseudomonas aeruginosa by tobramycin assessed at multiple inocula via mechanism-based modeling. Antimicrob Agents Chemother 2015; 59:2315-27. [PMID: 25645838 DOI: 10.1128/aac.04099-14] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial resistance is among the most serious threats to human health globally, and many bacterial isolates have emerged that are resistant to all antibiotics in monotherapy. Aminoglycosides are often used in combination therapies against severe infections by multidrug-resistant bacteria. However, models quantifying different antibacterial effects of aminoglycosides are lacking. While the mode of aminoglycoside action on protein synthesis has often been studied, their disruptive action on the outer membrane of Gram-negative bacteria remains poorly characterized. Here, we developed a novel quantitative model for these two mechanisms of aminoglycoside action, phenotypic tolerance at high bacterial densities, and adaptive bacterial resistance in response to an aminoglycoside (tobramycin) against three Pseudomonas aeruginosa strains. At low-intermediate tobramycin concentrations (<4 mg/liter), bacterial killing due to the effect on protein synthesis was most important, whereas disruption of the outer membrane was the predominant killing mechanism at higher tobramycin concentrations (≥8 mg/liter). The extent of killing was comparable across all inocula; however, the rate of bacterial killing and growth was substantially lower at the 10(8.9) CFU/ml inoculum than that at the lower inocula. At 1 to 4 mg/liter tobramycin for strain PAO1-RH, there was a 0.5- to 6-h lag time of killing that was modeled via the time to synthesize hypothetical lethal protein(s). Disruption of the outer bacterial membrane by tobramycin may be critical to enhance the target site penetration of antibiotics used in synergistic combinations with aminoglycosides and thereby combat multidrug-resistant bacteria. The two mechanisms of aminoglycoside action and the new quantitative model hold great promise to rationally design novel, synergistic aminoglycoside combination dosage regimens.
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Winkler ML, Papp-Wallace KM, Hujer AM, Domitrovic TN, Hujer KM, Hurless KN, Tuohy M, Hall G, Bonomo RA. Unexpected challenges in treating multidrug-resistant Gram-negative bacteria: resistance to ceftazidime-avibactam in archived isolates of Pseudomonas aeruginosa. Antimicrob Agents Chemother 2015; 59:1020-9. [PMID: 25451057 PMCID: PMC4335889 DOI: 10.1128/aac.04238-14] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 11/22/2014] [Indexed: 01/20/2023] Open
Abstract
Pseudomonas aeruginosa is a notoriously difficult-to-treat pathogen that is a common cause of severe nosocomial infections. Investigating a collection of β-lactam-resistant P. aeruginosa clinical isolates from a decade ago, we uncovered resistance to ceftazidime-avibactam, a novel β-lactam/β-lactamase inhibitor combination. The isolates were systematically analyzed through a variety of genetic, biochemical, genomic, and microbiological methods to understand how resistance manifests to a unique drug combination that is not yet clinically released. We discovered that avibactam was able to inactivate different AmpC β-lactamase enzymes and that blaPDC regulatory elements and penicillin-binding protein differences did not contribute in a major way to resistance. By using carefully selected combinations of antimicrobial agents, we deduced that the greatest barrier to ceftazidime-avibactam is membrane permeability and drug efflux. To overcome the constellation of resistance determinants, we show that a combination of antimicrobial agents (ceftazidime/avibactam/fosfomycin) targeting multiple cell wall synthetic pathways can restore susceptibility. In P. aeruginosa, efflux, as a general mechanism of resistance, may pose the greatest challenge to future antibiotic development. Our unexpected findings create concern that even the development of antimicrobial agents targeted for the treatment of multidrug-resistant bacteria may encounter clinically important resistance. Antibiotic therapy in the future must consider these factors.
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Affiliation(s)
- Marisa L Winkler
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, USA Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA
| | - Krisztina M Papp-Wallace
- Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Andrea M Hujer
- Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - T Nicholas Domitrovic
- Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA
| | - Kristine M Hujer
- Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Kelly N Hurless
- Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA
| | - Marion Tuohy
- Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Geraldine Hall
- Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Robert A Bonomo
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, USA Research Service, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
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Drusano GL, Liu W, Fikes S, Cirz R, Robbins N, Kurhanewicz S, Rodriquez J, Brown D, Baluya D, Louie A. Interaction of drug- and granulocyte-mediated killing of Pseudomonas aeruginosa in a murine pneumonia model. J Infect Dis 2014; 210:1319-24. [PMID: 24760199 DOI: 10.1093/infdis/jiu237] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Killing of bacterial pathogens by granulocytes is a saturable process, as previously demonstrated. There is virtually no quantitative information about how granulocytes interact with antimicrobial chemotherapy to kill bacterial cells. METHODS We performed a dose-ranging study with the aminoglycoside plazomicin against Pseudomonas aeruginosa ATCC27853 in a granulocyte-replete murine pneumonia model. Plazomicin was administered in a humanized fashion (ie, administration of decrementing doses 5 times over 24 hours, mimicking a human daily administration profile). Pharmacokinetic profiling was performed in plasma and epithelial lining fluid. All samples were simultaneously analyzed with a population model. Mouse cohorts were treated for 24 hours; other cohorts treated with the same therapy were observed for another 24 hours after therapy cessation, allowing delineation of the therapeutic effect necessary to reduce the bacterial burden to a level below the half-saturation point. RESULTS The mean bacterial burden (±SD) at which granulocyte-mediated kill was half saturable was 2.45 × 10(6) ± 6.84 × 10(5) colony-forming units of bacteria per gram of tissue (CFU/g). Higher levels of plazomicin exposure reduced the bacterial burden to <5 log10 CFU/g, allowing granulocytes to kill an additional 1.0-1.5 log CFU/g over the subsequent 24 hours. CONCLUSIONS For patients with large bacterial burdens (eg, individuals with ventilator-requiring hospital-acquired pneumonia), it is imperative to kill ≥2 log10 CFU/g early after treatment initiation, to allow the granulocytes to contribute optimally to bacterial clearance.
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Affiliation(s)
- George Louis Drusano
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - Weiguo Liu
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - Steven Fikes
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | | | - Nichole Robbins
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - Stephanie Kurhanewicz
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - Jaime Rodriquez
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - David Brown
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - Dodge Baluya
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
| | - Arnold Louie
- Institute for Therapeutic Innovation, Department of Medicine, College of Medicine, University of Florida Research and Academic Center, Lake Nona
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Bacteriostatic antimicrobial combination: antagonistic interaction between epsilon-viniferin and vancomycin against methicillin-resistant Staphylococcus aureus. BIOMED RESEARCH INTERNATIONAL 2014; 2014:461756. [PMID: 24783205 PMCID: PMC3982270 DOI: 10.1155/2014/461756] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 02/25/2014] [Indexed: 01/23/2023]
Abstract
Stilbenoids have been considered as an alternative phytotherapeutic treatment against methicillin-resistant Staphylococcus aureus (MRSA) infection. The combined effect of ε-viniferin and johorenol A with the standard antibiotics, vancomycin and linezolid, was assessed against MRSA ATCC 33591 and HUKM clinical isolate. The minimum inhibitory concentration (MIC) value of the individual tested compounds and the fractional inhibitory concentration index (FICI) value of the combined agents were, respectively, determined using microbroth dilution test and microdilution checkerboard (MDC) method. Only synergistic outcome from checkerboard test will be substantiated for its rate of bacterial killing using time-kill assay. The MIC value of ε-viniferin against ATCC 33591 and johorenol A against both strains was 0.05 mg/mL whereas HUKM strain was susceptible to 0.1 mg/mL of ε-viniferin. MDC study showed that only combination between ε-viniferin and vancomycin was synergistic against ATCC 33591 (FICI 0.25) and HUKM (FICI 0.19). All the other combinations (ε-viniferin-linezolid, johorenol A-vancomycin, and johorenol A-linezolid) were either indifferent or additive against both strains. However, despite the FICI value showing synergistic effect for ε-viniferin-vancomycin, TKA analysis displayed antagonistic interaction with bacteriostatic action against both strains. As conclusion, ε-viniferin can be considered as a bacteriostatic stilbenoid as it antagonized the bactericidal activity of vancomycin. These findings therefore disputed previous report that ε-viniferin acted in synergism with vancomycin but revealed that it targets similar site in close proximity to vancomycin's action, possibly at the bacterial membrane protein. Hence, this combination has a huge potential to be further studied and developed as an alternative treatment in combating MRSA in future.
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Santos DAFD, Nascimento MMP, Vitali LH, Martinez R. In vitro activity of antimicrobial combinations against multidrug-resistant Pseudomonas aeruginosa. Rev Soc Bras Med Trop 2014; 46:299-303. [PMID: 23856877 DOI: 10.1590/0037-8682-0012-2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 05/15/2013] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Pseudomonas aeruginosa isolates related to nosocomial infections are often resistant to multiple antibacterial agents. In this study, antimicrobial combinations were evaluated to detect in vitro synergy against clinical isolates of P. aeruginosa. METHODS Four clinical P. aeruginosa isolates were selected at random among other isolates from inpatients treated at the public University hospital in Ribeirão Preto, SP, Brazil. Two isolates were susceptible to imipenem (IPM-S) and several other antimicrobials, while the other two isolates were imipenem and multidrug resistant (IPM-R). The checkerboard method was used to assess the interactions between antimicrobials. RESULTS Combinations of imipenem or other anti-Pseudomonas drugs with complementary antibiotics, such as aminoglycosides, fosfomycin and rifampin, reached synergy rates of 20.8%, 50%, 62.5% and 50% for the two IPM-S and two IPM-R Pseudomonas isolates, respectively. Imipenem, piperacillin-tazobactam and ceftazidime yielded a greater synergy rate than cefepime or ciprofloxacin. Synergist combinations were more commonly observed when the complementary drug was tobramycin (65%) or fosfomycin (57%). CONCLUSIONS Some antibacterial combinations led to significant reductions of the minimum inhibitory concentrations of both drugs, suggesting that they could be clinically applied to control infections caused by multidrug-resistant P. aeruginosa.
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Alexander EL, Satlin MJ, Gamaletsou MN, Sipsas NV, Walsh TJ. Worldwide challenges of multidrug-resistant bacteria in patients with hematologic malignancies. Int J Hematol Oncol 2013. [DOI: 10.2217/ijh.13.46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
SUMMARY The emergence of infections due to multidrug-resistant (MDR) bacteria poses a major public health threat to all patients, but patients with hematologic malignancies are especially at risk. A common thread across all classes of bacteria is that increased reliance on and usage of broad-spectrum antibacterial agents, combined with the intrinsic ability of bacteria to develop and transmit resistance-conferring mutations, has led to the widespread dissemination of MDR organisms. In this article, we summarize the most worrisome MDR bacteria, assess their clinical impact on patients with hematologic malignancies and outline measures that are required to mitigate this impact.
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Affiliation(s)
| | - Michael J Satlin
- Division of Infectious Diseases, Weill Cornell Medical Center, New York, NY, USA
- Transplantation–Oncology Infectious Diseases Program, Department of Medicine, Weill Cornell Medical Center, New York, NY, USA
| | - Maria N Gamaletsou
- University of Athens School of Medicine & Laikon Hospital, Athens, Greece
| | - Nikolaos V Sipsas
- University of Athens School of Medicine & Laikon Hospital, Athens, Greece
| | - Thomas J Walsh
- Department of Pediatrics, Weill Cornell Medical Center, New York, NY, USA
- Department of Microbiology & Immunology, Weill Cornell Medical Center, New York, NY, USA
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Impact of Bolus dosing versus continuous infusion of Piperacillin and Tazobactam on the development of antimicrobial resistance in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2013; 57:5811-9. [PMID: 24002098 PMCID: PMC3837869 DOI: 10.1128/aac.00867-13] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Management of nosocomial pneumonia is frequently complicated by bacterial resistance. Extended infusions of beta-lactams are increasingly being used to improve clinical outcomes. However, the impact of this strategy on the emergence of antimicrobial resistance is not known. A hollow-fiber infection model with Pseudomonas aeruginosa (PAO1) was used. Pharmacokinetic (PK) profiles of piperacillin-tazobactam similar to those in humans were simulated over 5 days. Three dosages of piperacillin-tazobactam were administered over 0.5 h or 4 h, with redosing every 8 h. Two initial bacterial densities were investigated (∼104 CFU/ml and ∼107 CFU/ml). The time courses of the total bacterial population and the resistant subpopulation were determined. All data were described using a mathematical model, which was then used to define the relationship between drug concentrations, bacterial killing, and emergence of piperacillin resistance. There was logarithmic growth in controls in the initial 24 h, reaching a plateau of ∼9 log10 CFU/ml. Bacterial killing following administration of piperacillin via bolus dosing and that after extended infusions were similar. For the lower initial bacterial density, trough total plasma piperacillin concentration/MIC ratios of 3.4 and 10.4 for bolus and extended-infusion regimens, respectively, were able to suppress the emergence of piperacillin resistance. For the higher initial bacterial density, all regimens were associated with progressive growth of a resistant subpopulation. A stratified approach, according to bacterial density, is required to treat patients with nosocomial pneumonia. Antimicrobial monotherapy may be sufficient for some patients. However, for patients with a high bacterial burden, alternative therapeutic strategies are required to maximize bacterial killing and prevent antimicrobial resistance.
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Nielsen EI, Friberg LE. Pharmacokinetic-pharmacodynamic modeling of antibacterial drugs. Pharmacol Rev 2013; 65:1053-90. [PMID: 23803529 DOI: 10.1124/pr.111.005769] [Citation(s) in RCA: 231] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Pharmacokinetic-pharmacodynamic (PKPD) modeling and simulation has evolved as an important tool for rational drug development and drug use, where developed models characterize both the typical trends in the data and quantify the variability in relationships between dose, concentration, and desired effects and side effects. In parallel, rapid emergence of antibiotic-resistant bacteria imposes new challenges on modern health care. Models that can characterize bacterial growth, bacterial killing by antibiotics and immune system, and selection of resistance can provide valuable information on the interactions between antibiotics, bacteria, and host. Simulations from developed models allow for outcome predictions of untested scenarios, improved study designs, and optimized dosing regimens. Today, much quantitative information on antibiotic PKPD is thrown away by summarizing data into variables with limited possibilities for extrapolation to different dosing regimens and study populations. In vitro studies allow for flexible study designs and valuable information on time courses of antibiotic drug action. Such experiments have formed the basis for development of a variety of PKPD models that primarily differ in how antibiotic drug exposure induces amplification of resistant bacteria. The models have shown promise for efficacy predictions in patients, but few PKPD models describe time courses of antibiotic drug effects in animals and patients. We promote more extensive use of modeling and simulation to speed up development of new antibiotics and promising antibiotic drug combinations. This review summarizes the value of PKPD modeling and provides an overview of the characteristics of available PKPD models of antibiotics based on in vitro, animal, and patient data.
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Affiliation(s)
- Elisabet I Nielsen
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
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Lamers RP, Cavallari JF, Burrows LL. The efflux inhibitor phenylalanine-arginine beta-naphthylamide (PAβN) permeabilizes the outer membrane of gram-negative bacteria. PLoS One 2013; 8:e60666. [PMID: 23544160 PMCID: PMC3609863 DOI: 10.1371/journal.pone.0060666] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 03/01/2013] [Indexed: 11/19/2022] Open
Abstract
Active efflux of antimicrobial agents is a primary mechanism by which bacterial pathogens can become multidrug resistant. The combined use of efflux pump inhibitors (EPIs) with pump substrates is under exploration to overcome efflux-mediated multidrug resistance. Phenylalanine-arginine β-naphthylamide (PAβN) is a well-studied EPI that is routinely combined with fluoroquinolone antibiotics, but few studies have assessed its utility in combination with β-lactam antibiotics. The initial goal of this study was to assess the efficacy of β-lactams in combination with PAβN against the opportunistic pathogen, Pseudomonas aeruginosa. PAβN reduced the minimal inhibitory concentrations (MICs) of several β-lactam antibiotics against P. aeruginosa; however, the susceptibility changes were not due entirely to efflux inhibition. Upon PAβN treatment, intracellular levels of the chromosomally-encoded AmpC β-lactamase that inactivates β-lactam antibiotics were significantly reduced and AmpC levels in supernatants correspondingly increased, potentially due to permeabilization of the outer membrane. PAβN treatment caused a significant increase in uptake of 8-anilino-1-naphthylenesulfonic acid, a fluorescent hydrophobic probe, and sensitized P. aeruginosa to bulky antibiotics (e.g. vancomycin) that are normally incapable of crossing the outer membrane, as well as to detergent-like bile salts. Supplementation of growth media with magnesium to stabilize the outer membrane increased MICs in the presence of PAβN and restored resistance to vancomycin. Thus, PAβN permeabilizes bacterial membranes in a concentration-dependent manner at levels below those typically used in combination studies, and this additional mode of action should be considered when using PAβN as a control for efflux studies.
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Affiliation(s)
- Ryan P. Lamers
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Joseph F. Cavallari
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Lori L. Burrows
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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