Treatment Of Serious Bacterial Infections Research Articles

Rapid design of combination antimicrobial therapy against Acinetobacter baumannii

Treatment of serious bacterial infections with antimicrobial agents, such as antibiotics, is a major clinical challenge, because of growing bacterial resistance to multiple agents. Combination therapy (i.e. combined dosing of more than one agent) is often used for the purpose, but its systematic design remains a challenge. To address this, we recently reported a method to mathematically model bacterial response to antimicrobial agents, and to use this model for systematic design of clinically relevant combination therapy. The method relies on (a) longitudinal data of bacterial load, estimated from optical density measurements during time-kill experiments in an automated instrument, and (b) use of these data to fit a mathematical model for combination therapy design. In this work, we studied an application of the proposed method to (a) an important bacterial pathogen (Acinetobacter baumannii) and (b) two cases of antibiotic combinations (ceftazidime / amikacin and ceftazidime / avibactam) in synchronous and asynchronous dosing, not otherwise studied to date. Following the proposed method, optical density based data of bacterial load under antibiotic exposure for 20 h were used to calibrate the mathematical model and subsequently predict outcomes of various dosing regimens with clinically relevant pharmacokinetics. Representative predictions by the mathematical model were tested in vitro in a hollow fiber infection model over 120 h. Test outcomes validated these predictions. Collectively, this study both provides guidance for design of A. baumannii infection treatments with the agents studied and underscores the broader applicability of the proposed method for design of clinically relevant combination therapy.

The Prospect of Biomimetic Immune Cell Membrane-Coated Nanomedicines for Treatment of Serious Bacterial Infections and Sepsis.

Invasive bacterial infections and sepsis are persistent global health concerns, complicated further by the escalating threat of antibiotic resistance. Over the past 40 years, collaborative endeavors to improve the diagnosis and critical care of septic patients have improved outcomes, yet grappling with the intricate immune dysfunction underlying the septic condition remains a formidable challenge. Anti-inflammatory interventions that exhibited promise in murine models failed to manifest consistent survival benefits in clinical studies through recent decades. Novel therapeutic approaches that target bacterial virulence factors, for example with monoclonal antibodies, aim to thwart pathogen-driven damage and restore an advantage to the immune system. A pioneering technology addressing this challenge is biomimetic nanoparticles-a therapeutic platform featuring nanoscale particles enveloped in natural cell membranes. Borne from the quest for a durable drug delivery system, the original red blood cell-coated nanoparticles showcased a broad capacity to absorb bacterial and environmental toxins from serum. Tailoring the membrane coating to immune cell sources imparts unique characteristics to the nanoparticles suitable for broader application in infectious disease. Their capacity to bind both inflammatory signals and virulence factors assembles the most promising sepsis therapies into a singular, pathogen-agnostic therapeutic. This review explores the ongoing work on immune cell-coated nanoparticle therapeutics for infection and sepsis. SIGNIFICANCE STATEMENT: Invasive bacterial infections and sepsis are a major global health problem made worse by expanding antibiotic resistance, meaning better treatment options are urgently needed. Biomimetic cell-membrane-coated nanoparticles are an innovative therapeutic platform that deploys a multifaceted mechanism to action to neutralize microbial virulence factors, capture endotoxins, and bind excessive host proinflammatory cytokines, seeking to reduce host tissue injury, aid in microbial clearance, and improve patient outcomes.

The Anti-Virulence Activities of the Antihypertensive Drug Propranolol in Light of Its Anti-Quorum Sensing Effects against Pseudomonas aeruginosa and Serratia marcescens.

The development of bacterial resistance is an increasing global concern that requires discovering new antibacterial agents and strategies. Bacterial quorum sensing (QS) systems play important roles in controlling bacterial virulence, and their targeting could lead to diminishing bacterial pathogenesis. In this context, targeting QS systems without significant influence on bacterial growth is assumed as a promising strategy to overcome resistance development. This study aimed at evaluating the anti-QS and anti-virulence activities of the β-adrenoreceptor antagonist propranolol at sub-minimal inhibitory concentrations (sub-MIC) against two Gram-negative bacterial models Pseudomonas aeruginosa and Serratia marcescens. The effect of propranolol on the expression of QS-encoding genes was evaluated. Additionally, the affinity of propranolol to QS receptors was virtually attested. The influence of propranolol at sub-MIC on biofilm formation, motility, and production of virulent factors was conducted. The outcomes of the propranolol combination with different antibiotics were assessed. Finally, the in vivo protection assay in mice was performed to assess propranolol's effect on lessening the bacterial pathogenesis. The current findings emphasized the significant ability of propranolol at sub-MIC to reduce the formation of biofilms, motility, and production of virulence factors. In addition, propranolol at sub-MIC decreased the capacity of tested bacteria to induce pathogenesis in mice. Furthermore, propranolol significantly downregulated the QS-encoding genes and showed significant affinity to QS receptors. Finally, propranolol at sub-MIC synergistically decreased the MICs of different antibiotics against tested bacteria. In conclusion, propranolol might serve as a plausible adjuvant therapy with antibiotics for the treatment of serious bacterial infections after further pharmacological and pharmaceutical studies.

Effectiveness and Adverse Events of Generic and Original Imipenem/Cilastatin in Hospitalized Patients: The First Multicenter Non-Inferiority Study in Thailand

Objective: Imipenem/cilastatin, a broad-spectrum antibacterial, is reserved for treatment of serious infections caused by multidrug-resistant Gram-negative bacteria. The present study was aimed to compare the effectiveness and adverse events of generic and original imipenem/cilastatin. Materials and Methods:A retrospective, multicenter, cohort, non-inferiority study of generic imipenem/cilastatin (Sianem®), and original imipenem/cilastatin (Tienam®) was carried on between November 2017 and September 2020. The centers included Srinagarind Hospital, Taksin Hospital, Nakornping Hospital, Nakhonpathom Hospital, and King Chulalongkorn Memorial Hospital. The clinically relevant data were retrieved from the medical records on day 3, 7, and 14 after enrollment. A sample size of 260 patients per arm was needed. Results: There were 214 and 227 medical and surgical patients enrolled in generic and original imipenem/cilastatin groups, respectively. Baseline characteristics of the two groups were not significantly different. Most patients were male and elderly. Comorbidity was observed in 86.6%. The average length of hospital stay was 17 days. At day 14 after enrollment, the favorable outcome in generic and original imipenem/cilastatin groups were 83.1% and 90.0%, respectively, with no statistical difference. The mortality rates were 3.4% and 2.0% in generic and original imipenem/ cilastatin groups, respectively, with no statistic difference. Serious adverse events were also not significantly different between the two groups at 0.9% and 0.4%. Conclusion: The generic imipenem/cilastatin was non-inferior to the original imipenem/cilastatin in terms of effectiveness and adverse events for the treatment of serious bacterial infections in hospitalized adult patients. Keywords: Effectiveness; Safety; Adverse events; Generic drug; Imipenem/cilastatin

Effect of an Antacid (Aluminum Hydroxide/Magnesium Hydroxide/Simethicone) or a Proton Pump Inhibitor (Omeprazole) on the Pharmacokinetics of Tebipenem Pivoxil Hydrobromide (TBP-PI-HBr) in Healthy Adult Subjects.

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is a novel oral carbapenem prodrug being developed for the treatment of serious bacterial infections. This open-label, 3-period, fixed sequence study evaluated the effect of gastric acid-reducing agents, aluminum hydroxide/magnesium hydroxide/simethicone, and omeprazole on the pharmacokinetics (PK) of tebipenem (TBP), the active moiety, following coadministration with immediate release TBP-PI-HBr during fasting. In Period 1, subjects received a single oral dose of TBP-PI-HBr 600 mg (2 × 300 mg tablets). In Period 2, subjects received a single oral dose of aluminum hydroxide 800 mg/magnesium hydroxide 800 mg/simethicone 80 mg suspension co-administered with a single dose of TBP-PI-HBr 600 mg. In Period 3, subjects received a single oral dose of omeprazole 40 mg once daily over 5 days, followed by single dose administration of TBP-PI-HBr 600 mg on day 5. In each period, whole blood samples were obtained prior to, and up to 24 h, following TBP-PI-HBr dose administration in order to characterize TBP PK. A 7-day washout was required between periods. Twenty subjects were enrolled and completed the study. Following co-administration of TBP-PI-HBr with either aluminum hydroxide/magnesium hydroxide/simethicone or omeprazole, total TBP exposure (area under the curve [AUC]) was approximately 11% (geometric mean ratio 89.2, 90% confidence interval: 83,2, 95.7) lower, and Cmax was 22% (geometric mean ratio 78.4, 90% confidence interval: 67.9, 90.6) and 43% (geometric mean ratio 56.9, 90% confidence interval: 49.2, 65.8) lower, respectively, compared to administration of TBP-PI-HBr alone. Mean TBP elimination half-life (t1/2) was generally comparable across treatments (range: 1.0 to 1.5 h). Concomitant administration of TBP-PI-HBr with omeprazole or aluminum hydroxide/magnesium hydroxide/simethicone is not expected to impact the efficacy of TBP-PI-HBr, as there is minimal impact on TBP plasma AUC, which is the pharmacodynamic driver of efficacy. Co-administration was generally safe and well tolerated.

Retrospective drug utilization review of meropenem and role of infectious disease pharmacist in specialized cancer care hospital.

Carbapenem antimicrobials are considered for the treatment of serious bacterial infections. The objective of this study was to review the use of meropenem in cancer patients and to evaluate the impact of clinical pharmacist's intervention in this practice to reduce possible risks associated with use of meropenem. This retrospective study was conducted among 100 patients who received meropenem at hospital. A structured questionnaire was used to collect data. Descriptive statistics was used to analyze the collected data. A total of 100 patients were included in this retrospective study with aim to review rationality and possible side effects associated with meropenem use in our study population. It was revealed that meropenem used was associated with rise in bilirubin in many of our study patients. Pharmacist were found to be instrumental in placing timely interventions for either de-escalation or switch of meropenem to imipenem/cilastatin to reduce that risk. Interventions were accepted by physicians in most of the cases. De-escalation and switching were performed in accordance with pharmacist recommendations in more than half of study population with empirically started/ study population in which meropenem was used.

Case Report: Subtherapeutic Vancomycin and Meropenem Concentrations due to Augmented Renal Clearance in a Patient With Intracranial Infection Caused by Streptococcus intermedius.

Streptococcus intermedius occasionally causes brain abscesses that can be life-threatening, requiring prompt antibiotic and neurosurgical treatment. The source is often dental, and it may spread to the eye or the brain parenchyma. We report the case of a 34-year-old man with signs of apical periodontitis, endophthalmitis, and multiple brain abscesses caused by Streptococcus intermedius. Initial treatment with meropenem and vancomycin was unsuccessful due to subtherapeutic concentrations, despite recommended dosages. Adequate concentrations could be reached only after increasing the dose of meropenem to 16 g/day and vancomycin to 1.5 g × 4. The patient exhibited high creatinine clearance consistent with augmented renal clearance, although iohexol and cystatin C clearances were normal. Plasma free vancomycin clearance followed that of creatinine. A one-day dose of trimethoprim–sulfamethoxazole led to an increase in serum creatinine and a decrease in both creatinine and urea clearances. These results indicate that increased tubular secretion of the drugs was the cause of suboptimal antibiotic treatment. The patient eventually recovered, but his left eye needed enucleation. Our case illustrates that augmented renal clearance can jeopardize the treatment of serious bacterial infections and that high doses of antibiotics are needed to achieve therapeutic concentrations in such cases. The mechanisms for regulation of kidney tubular transporters of creatinine, urea, vancomycin, and meropenem in critically ill patients are discussed.

Structures of full-length VanR from Streptomyces coelicolor in both the inactive and activated states.

Vancomycin has historically been used as a last-resort treatment for serious bacterial infections. However, vancomycin resistance has become widespread in certain pathogens, presenting a serious threat to public health. Resistance to vancomycin is conferred by a suite of resistance genes, the expression of which is controlled by the VanR-VanS two-component system. VanR is the response regulator in this system; in the presence of vancomycin, VanR accepts a phosphoryl group from VanS, thereby activating VanR as a transcription factor and inducing expression of the resistance genes. This paper presents the X-ray crystal structures of full-length VanR from Streptomyces coelicolor in both the inactive and activated states at resolutions of 2.3 and 2.0 Å, respectively. Comparison of the two structures illustrates that phosphorylation of VanR is accompanied by a disorder-to-order transition of helix 4, which lies within the receiver domain of the protein. This transition generates an interface that promotes dimerization of the receiver domain; dimerization in solution was verified using analytical ultracentrifugation. The inactive conformation of the protein does not appear intrinsically unable to bind DNA; rather, it is proposed that in the activated form DNA binding is enhanced by an avidity effect contributed by the receiver-domain dimerization.

Evaluation of Benzguinols as Next-Generation Antibiotics for the Treatment of Multidrug-Resistant Bacterial Infections.

Our recent focus on the “lost antibiotic” unguinol and related nidulin-family fungal natural products identified two semisynthetic derivatives, benzguinols A and B, with unexpected in vitro activity against Staphylococcus aureus isolates either susceptible or resistant to methicillin. Here, we show further activity of the benzguinols against methicillin-resistant isolates of the animal pathogen Staphylococcus pseudintermedius, with minimum inhibitory concentration (MIC) ranging 0.5–1 μg/mL. When combined with sub-inhibitory concentrations of colistin, the benzguinols demonstrated synergy against Gram-negative reference strains of Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa (MICs of 1–2 μg/mL in the presence of colistin), whereas the benzguinols alone had no activity. Administration of three intraperitoneal (IP) doses of 20 mg/kg benzguinol A or B to mice did not result in any obvious adverse clinical or pathological evidence of acute toxicity. Importantly, mice that received three 20 mg/kg IP doses of benzguinol A or B at 4 h intervals exhibited significantly reduced bacterial loads and longer survival times than vehicle-only treated mice in a bioluminescent S. aureus murine sepsis challenge model. We conclude that the benzguinols are potential candidates for further development for specific treatment of serious bacterial infections as both stand-alone antibiotics and in combination with existing antibiotic classes.

Bacteriophage therapy for challenging bacterial infections: achievements, limitations and prospects for future clinical use by veterinary dermatologists.

Bacteriophages were discovered just over 100 years ago and have been used to treat bacterial infections in animals since the 1920s. The antimicrobial resistance crisis has led to a new surge of interest in the use of bacteriophage therapy as an alternative or supplement to antimicrobial therapy in humans and other animals. To describe the nature of bacteriophages and provide a critical review and update on the clinical use of bacteriophages in the treatment of challenging bacterial infections, with an emphasis on companion animal veterinary applications. The scientific literature on the subject was critically evaluated. Findings from the most pertinent papers have been presented in summary form and critiqued. Over the last 20 years there has been a considerable increase in the volume and quality of publications dealing with bacteriophage therapy. Some recent papers build on excellent work published in the 1980s and describe promising veterinary applications. Challenges related particularly to the registration and approval of phage remedies will need to be overcome before phage therapy can become a mainstream tool for use in veterinary settings. Considerably more research, particularly controlled clinical trials, needs to be done. Bacteriophage therapy is one of the most promising approaches to tackling the looming antimicrobial resistance crisis, yet substantial regulatory challenges will need to be overcome before it enters widespread use. Phage therapy also may, in the future, improve the management of challenging bacterial infections that are not necessarily multidrug-resistant.

Design, synthesis, antibacterial evaluation, and computational studies of hybrid oxothiazolidin-1,2,4-triazole scaffolds.

Bacterial infections are a serious threat to human health due to the development of resistance against the presently used antibiotics. The problem of growing and widespread antibiotic resistance is only getting worse with the shortage of new classes of antibiotics, creating a substantial unmet medical need in the treatment of serious bacterial infections. Therefore, in the present work, we report 18 novel hybrid thiazolidine-1,2,4-triazole derivatives as DNA gyrase inhibitors. The derivatives were synthesized by multistep organic synthesis and characterized by spectroscopic methods (1 H and 13 C nuclear magnetic resonance and mass spectroscopy). The derivatives were tested for DNA gyrase inhibition, and the result emphasized that the synthesized derivatives have a tendency to inhibit the function of DNA gyrase. Furthermore, the compounds were also tested for antibacterial activity against three Gram-positive (Bacillus subtilis [NCIM 2063], Bacillus cereus [NCIM 2156], Staphylococcus aureus [NCIM 2079]) and two Gram-negative (Escherichia coli [NCIM 2065], Proteus vulgaris [NCIM 2027]) bacteria. The derivatives showed a significant-to-moderate antibacterial activity with noticeable antibiofilm efficacy. Quantitative structure-activity relationship (QSAR), ADME (absorption, distribution, metabolism, elimination) calculation, molecular docking, radial distribution function, and 2D fingerprinting were also performed to elucidate fundamental structural fragments essential for their bioactivity. These studies suggest that the derivatives 10b and 10n have lead antibacterial properties with significant DNA gyrase inhibitory efficacy, and they can serve as a starting scaffold for the further development of new broad-spectrum antibacterial agents.

An update on cefepime and its future role in combination with novel β-lactamase inhibitors for MDR Enterobacterales and Pseudomonas aeruginosa.

Cefepime, a wide-spectrum β-lactam antibiotic, has been in use for the treatment of serious bacterial infections for almost 25 years. Since its clinical development, there has been a dramatic shift in its dosing, with 2 g every 8 hours being preferred for serious infections to optimize pharmacokinetic/pharmacodynamic considerations. The advent of ESBLs has become a threat to its ongoing use, although future coadministration with β-lactamase inhibitors (BLIs) under development is an area of intense study. There are currently four new cefepime/BLI combinations in clinical development. Cefepime/zidebactam is generally active against MBL-producing Enterobacterales and Pseudomonas aeruginosa, in vitro and in animal studies, and cefepime/taniborbactam has activity against KPC and OXA-48 producers. Cefepime/enmetazobactam and cefepime/tazobactam are potential carbapenem-sparing agents with activity against ESBLs. Cefepime/enmetazobactam has completed Phase III and cefepime/taniborbactam is in Phase III clinical studies, where they are being tested against carbapenems or piperacillin/tazobactam for the treatment of complicated urinary tract infections. While these combinations are promising, their role in the treatment of MDR Gram-negative infections can only be determined with further clinical studies.

Sequential Multiple Assignment Randomized Trials for COMparing Personalized Antibiotic StrategieS (SMART COMPASS): Design Considerations

Clinical patient management is dynamic. It is not based on a single decision but on a sequence of decisions, with adjustments of therapy overtime, where adjustment are personalized to individual patients. However, strategies allowing for such adjustments are infrequently studied. In the treatment of serious bacterial infections, there are two therapeutic decision points: empirical therapy when the patient is first seen by the clinician, and definitive therapy when drug susceptibility results are available to help guide therapeutic choices. COMparing Personalized Antibiotic StrategieS (COMPASS) is a trial design that compares strategies consistent with clinical practice rather than specific treatments. A strategy is a decision-rule guiding treatments of bacterial infections both at the empirical and at the definitive stages. Sequential multiple assignment randomized (SMART) COMPASS allows evaluation of strategies when there are multiple definitive therapy choices. SMART COMPASS is a pragmatic design, mirroring antibiotic treatment decision-making as they unfold in clinical practice and addressing the most relevant question for treating patients: identification of the patient-management strategy that optimizes ultimate patient outcomes. Complex statistical challenges are encountered during the design of SMART COMPASS including how to: appropriately estimate effects and associated standard errors within the context of sequential randomization, identify the best of several strategies while controlling trial-wise error, and calculate sample size and power when trying to identify the optimal strategy. Design considerations for SMART COMPASS are discussed.

Antimicrobial resistance of Salmonella and generic Escherichia coli isolated from surface water samples used for recreation and a source of drinking water in southwestern Ontario, Canada.

Antimicrobial resistance (AMR) in the aquatic environment represents an important means of introduction and dissemination of resistance genes, and presence of resistant pathogens in surface waters may pose a public health concern to recreational and drinking water users. The purpose of this study was to explore antimicrobial resistance patterns in water samples collected from the Grand River watershed (southwestern Ontario, Canada) to describe the composition, trends and potential risks of AMR in the aquatic environment. As part of FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), stream water samples were collected bi-weekly from sampling sites within the Grand River watershed in the Waterloo, Ontario sentinel site and tested for the presence and antimicrobial susceptibility of Salmonella spp. (2005-2013) and generic Escherichia coli (2012-2013). Of all samples tested, 16% of Salmonella and 22% of E.coli isolates were resistant to at least one antimicrobial, including three Salmonella isolates and two E.coli isolates that were resistant to Category I antimicrobials, which are classified as very high importance for the treatment of serious bacterial infections in humans. The greatest proportion of resistant E.coli isolates were observed from the river site upstream of the drinking water intake, while the greatest proportion of resistant Salmonella isolates were from sites upstream in the watershed, and at one recreational water site. Salmonella resistance trends remained fairly stable between 2007 and 2013, with the exception of streptomycin and tetracycline which increased in 2010 and 2013. Continued surveillance of antimicrobial resistance patterns and exploration of risk factor data will allow for a better understanding of resistance transmission in the aquatic environment.

Biomarkers of infection in the optimization of antibacterial therapy: justified expectations

Despite the continuous improvement of approaches to antimicrobial therapy and the emergence of new highly effective antibiotics, severe bacterial infections being a significant cause of morbidity and mortality remain a top of mind issue for clinicians. Immediate initiation of the effective antibiotic therapy is an essential component of the successful treatment of serious bacterial infections, and therefore, special attention should be paid to the timely diagnosis. Measurements of biomarkers of inflammation (C-reactive protein, procalcitonin, presepsin, proadrenomedullin) in combination with clinical evaluation are important at first for the diagnosis of bacterial infection, and after that these can help to assess the clinical response to therapy and determine the time-point of antibiotics withdrawal. This review presents the characteristics of the main markers of inflammation, discusses the situations when determination of biomarkers is appropriate, and also provides modern clinical recommendations and algorithms regarding the use of these diagnostic markers in the management of patients with bacterial infections.

Antimicrobial Effects on Swine Gastrointestinal Microbiota and Their Accompanying Antibiotic Resistome.

Antimicrobials are the most commonly prescribed drugs in the swine industry. While antimicrobials are an effective treatment for serious bacterial infections, their use has been associated with major adverse effects on health. It has been shown that antimicrobials have substantial direct and indirect impacts on the swine gastrointestinal (GI) microbiota and their accompanying antimicrobial resistome. Antimicrobials have also been associated with a significant public health concern through selection of resistant opportunistic pathogens and increased emergence of antimicrobial resistance genes (ARGs). Since the mutualistic microbiota play a crucial role in host immune regulation and in providing colonization resistance against potential pathogens, the detrimental impacts of antimicrobial treatment on the microbiota structure and its metabolic activity may lead to further health complications later in life. In this review, we present an overview of antimicrobial use in the swine industry and their role in the emergence of antimicrobial resistance. Additionally, we review our current understanding of GI microbiota and their role in swine health. Finally, we investigate the effects of antimicrobial administration on the swine GI microbiota and their accompanying antibiotic resistome. The presented data is crucial for the development of robust non-antibiotic alternative strategies to restore the GI microbiota functionality and guarantee effective continued use of antimicrobials in the livestock production system.

Design, Synthesis, and Biological Evaluation of a New Series of Carvedilol Derivatives That Protect Sensory Hair Cells from Aminoglycoside-Induced Damage by Blocking the Mechanoelectrical Transducer Channel.

Aminoglycosides (AGs) are broad-spectrum antibiotics used for the treatment of serious bacterial infections but have use-limiting side effects including irreversible hearing loss. Here, we assessed the otoprotective profile of carvedilol in mouse cochlear cultures and in vivo zebrafish assays and investigated its mechanism of protection which, we found, may be mediated by a block of the hair cell's mechanoelectrical transducer (MET) channel, the major entry route for the AGs. To understand the full otoprotective potential of carvedilol, a series of 18 analogues were prepared and evaluated for their effect against AG-induced damage as well as their affinity for the MET channel. One derivative was found to confer greater protection than carvedilol itself in cochlear cultures and also to bind more tightly to the MET channel. At higher concentrations, both carvedilol and this derivative were toxic in cochlear cultures but not in zebrafish, suggesting a good therapeutic window under in vivo conditions.

Simultaneous quantification of levofloxacin, pefloxacin, ciprofloxacin and moxifloxacin in microvolumes of human plasma using high-performance liquid chromatography with ultraviolet detection.

Levofloxacin, pefloxacin, ciprofloxacin and moxifloxacin are four fluoroquinolones used in the treatment of serious bacterial infections. The antibacterial activity of fluoroquinolones is concentration dependent. Therefore, therapeutic drug monitoring in daily clinical practice is warranted to ensure the therapy's efficacy and prevent bacterial resistance. The purpose of the present study was to develop a method using high-pressure liquid chromatography with an ultraviolet detector for simultaneous quantification of these four fluoroquinolones in human plasma. A 50 μL aliquot of plasma was precipitated by 200 μL of methanol using gatifloxacin as internal standard. The chromatographic separation was performed on a Kinetex XB-C18 column using a mobile phase composed of a mixture of orthophosphoric acid 0.4% (v/v), acetonitrile and methanol at a flow rate of 1.2 mL/min. Dual UV wavelength mode was used, with levofloxacin and moxifloxacin monitored at 293 nm, and pefloxacin and ciprofloxacin monitored at 280 nm. The calibration was linear over the ranges of 0.125-25 mg/L for levofloxacin, 0.1-20mg/L for moxifloxacin and 0.05-10 mg/L for both pefloxacin and ciprofloxacin. Inter- and intra-day trueness and precision were <13% for all the compounds under study. The proposed method was simple, reliable, cost-effective and suitable for therapeutic drug monitoring or pharmacokinetics studies.

Aminoglycoside Revival: Review of a Historically Important Class of Antimicrobials Undergoing Rejuvenation.

Aminoglycosides are cidal inhibitors of bacterial protein synthesis that have been utilized for the treatment of serious bacterial infections for almost 80 years. There have been approximately 15 members of this class approved worldwide for the treatment of a variety of infections, many serious and life threatening. While aminoglycoside use declined due to the introduction of other antibiotic classes such as cephalosporins, fluoroquinolones, and carbapenems, there has been a resurgence of interest in the class as multidrug-resistant pathogens have spread globally. Furthermore, aminoglycosides are recommended as part of combination therapy for empiric treatment of certain difficult-to-treat infections. The development of semisynthetic aminoglycosides designed to overcome common aminoglycoside resistance mechanisms, and the shift to once-daily dosing, has spurred renewed interest in the class. Plazomicin is the first new aminoglycoside to be approved by the FDA in nearly 40 years, marking the successful start of a new campaign to rejuvenate the class.

1371. Safety, Tolerability, and Pharmacokinetics of Multiple Doses of TP-6076, a Novel, Fully Synthetic Tetracycline, in a Phase 1 Study

BackgroundTP-6076 is a novel, fully synthetic tetracycline being developed for the treatment of serious bacterial infections, including those caused by multidrug-resistant Acinetobacter baumannii. TP-6076 has demonstrated potent activity in vitro against carbapenem-resistant strains of A. baumannii, with MIC90 64 times lower compared with tigecycline and 256 times lower compared with minocycline. We now report the results of a multiple ascending dose study in normal healthy volunteers.MethodsThis was a phase 1, single-site, randomized, double-blind, placebo-controlled dose-escalating, multiple dose study in healthy adults who met the inclusion/exclusion criteria and provided informed consent prior to any study procedure. Cohorts of eight subjects each (six active and two placebo) received daily doses of 6.0 to 40.0 mg TP-6076 or placebo for 7 days. Plasma and urine samples for pharmacokinetic (PK) analyses were collected starting immediately prior to dosing until 96 hours after the last dose. Safety was assessed through collection of adverse events (AEs), clinical laboratories, vital signs, ECG, and physical examination data.ResultsThe geometric mean derived PK parameters for TP-6076 were:TP-6076 Dose (mg)AUC0-tau (ng hours/mL) T 1/2 (hours)Day 1Day 7Day 76.01043162121.220.04871713927.730.063821014928.435.078421082528.840.094331269825.8There were no serious or severe AEs reported. The most frequently reported AEs were gastrointestinal events, including nausea and vomiting, and localized infusion site reactions. There were no clinically significant changes in clinical laboratory values, ECG parameters, or physical examination findings.ConclusionFollowing multiple IV doses of TP-6076, plasma exposure increased as dose increased. Multiple IV doses of TP-6076 were generally well tolerated, with higher gastrointestinal adverse event rates in the higher dose groups.Disclosures L. Tsai, Tetraphase Pharmaceuticals: Employee and Shareholder, Salary. A. Moore, Tetraphase Pharmaceuticals: Employee, Salary.