Use of Total Parenteral Nutrition (TPN) as a Vehicle for Drug Delivery

Total Parenteral Nutrition (TPN) is a method of providing nutrients directly into the bloodstream for individuals who are unable to meet their nutritional needs through the normal digestive process or gastrointestinal system. It provides macronutrients and micronutrients in a single container, reducing handling and contamination risks and making it more cost-effective. TPN has the potential to be used as a drug delivery system, with applications in combination therapies, personalized medicine, and integrating advanced technologies. It can enhance drug dosage precision and provide nutritional assistance, potentially reducing hospitalization and improving patient outcomes. However, implementing new applications requires thorough testing and regulatory approval. TPN could be particularly useful in pediatric and geriatric care and could also contribute to global health by combating malnutrition in areas with limited medical resources. Healthcare professionals prepare a sterile solution tailored to each patient's nutritional needs, and administration involves a central venous catheter. However, the simultaneous administration of medications with PN admixtures can result in pharmacological incompatibility, which can impact the stability of the oil-in-water system. The European Society for Clinical Nutrition and Metabolism and the American Society for Parenteral and Enteral Nutrition recommendations advise against including non-nutrient drugs in PN admixtures due to safety concerns. This review focuses on the utilization of Total Parenteral Nutrition (TPN) as a method for delivering drugs. It discusses the benefits and difficulties associated with its commercial application and offers suggestions for future research endeavors.

Systematic review of room temperature stability of key beta-lactam antibiotics for extended infusions in inpatient settings

BACKGROUND

Extended infusion (EI) of beta-lactam antibiotics may offer clinical benefits aligned with improved probability of target attainment for critical pharmacokinetic/pharmacodynamic parameters that correlate with efficacy. There is much research interest in prolonged and continuous infusions (collectively, extended infusions) of beta-lactams to improve patient outcomes, particularly in critically ill patients in intensive care. While definitive clinical trial data demonstrating beneficial outcomes is awaited, there has been limited focus on the stability of the agents given by EI, which may be an equally critical parameter. EI may allow for savings in nursing time due to reduced need for drug reconstitution. We set out to examine the data for stability for EI at room temperature, consistent with the requirements of 'A Standard Protocol for Deriving and Assessment of Stability- Part 1 Aseptic Preparation (Small Molecules)', which allows a 5% loss of active pharmaceutical ingredient (API) applicable for those territories that use the British Pharmacopoeia also for a 10% loss applicable in much of rest of the world.

METHODS

Searches using preferred reporting items for systematic reviews and meta-analyses (PRISMA) principles for stability data on freshly prepared beta-lactam antimicrobials for extended administration at room temperature (at or above 23°C) were conducted in November 2021 and updated in December 2022.

RESULTS

We found data to support the extension of the shelf life of 12 key beta-lactam antibiotics once reconstituted (aztreonam, amoxicillin, benzylpenicillin, flucloxacillin, piperacillin/tazobactam, cefazolin, cefmetazole, ceftaroline, ceftazidime, ceftriaxone, imipenem and meropenem) compliant with the NHS protocol, and data for five other agents (ticarcillin, cefepime, cefiderocol, cefoxitin and doripenem) which would be acceptable in regions outside the UK beyond that listed in the Summary of Product Characteristics.This review has not been registered under PROSPERO.

Optimizing Antimicrobial Drug Dosing in Critically Ill Patients

A fundamental step in the successful management of sepsis and septic shock is early empiric antimicrobial therapy. However, for this to be effective, several decisions must be addressed simultaneously: (1) antimicrobial choices should be adequate, covering the most probable pathogens; (2) they should be administered in the appropriate dose, (3) by the correct route, and (4) using the correct mode of administration to achieve successful concentration at the infection site. In critically ill patients, antimicrobial dosing is a common challenge and a frequent source of errors, since these patients present deranged pharmacokinetics, namely increased volume of distribution and altered drug clearance, which either increased or decreased. Moreover, the clinical condition of these patients changes markedly over time, either improving or deteriorating. The consequent impact on drug pharmacokinetics further complicates the selection of correct drug schedules and dosing during the course of therapy. In recent years, the knowledge of pharmacokinetics and pharmacodynamics, drug dosing, therapeutic drug monitoring, and antimicrobial resistance in the critically ill patients has greatly improved, fostering strategies to optimize therapeutic efficacy and to reduce toxicity and adverse events. Nonetheless, delivering adequate and appropriate antimicrobial therapy is still a challenge, since pathogen resistance continues to rise, and new therapeutic agents remain scarce. We aim to review the available literature to assess the challenges, impact, and tools to optimize individualization of antimicrobial dosing to maximize exposure and effectiveness in critically ill patients.

Measurement uncertainty of β-lactam antibiotics results: estimation and clinical impact on therapeutic drug monitoring

Background Despite that measurement uncertainty data should facilitate an appropriate interpretation of measured values, there are actually few reported by clinical laboratories. We aimed to estimate the measurement uncertainty of some β-lactam antibiotics (β-LA), and to evaluate the impact of reporting the measurement uncertainty on clinicians' decisions while guiding antibiotic therapy. Methods Measurement uncertainty of β-LA (aztreonam [ATM], cefepime [FEP], ceftazidime [CAZ], and piperacillin [PIP]) values, obtained by an UHPLC-MS/MS based-method, was estimated using the top-down approach called the single laboratory validation approach (EUROLAB guidelines). Main uncertainty sources considered were related to calibrators' assigned values, the intermediate precision, and the bias. As part of an institutional program, patients with osteoarticular infections are treated with β-LA in continuous infusion and monitored to assure values at least 4 times over the minimal inhibitory concentration (4×MIC). We retrospectively evaluated the impact of two scenarios of laboratory reports on clinicians' expected decisions while monitoring the treatment: reports containing only the β-LA values, or including the β-LA coverage intervals (β-LA values and their expanded measurement uncertainties). Results The relative expanded uncertainties for ATM, FEP, CAZ and PIP were lower than 26.7%, 26.4%, 28.8%, and 25.5%, respectively. Reporting the measurement uncertainty, we identified that clinicians may modify their decision especially in cases where 4×MIC values were within the β-LA coverage intervals. Conclusions This study provides a simple method to estimate the measurement uncertainty of β-LA values that can be easily applied in clinical laboratories. Further studies should confirm the potential impact of reporting measurement uncertainty on clinicians' decision-making while guiding antibiotic therapy.

Clinical and pharmacokinetic/dynamic outcomes of prolonged infusions of beta-lactam antimicrobials: An overview of systematic reviews

OBJECTIVE

This overview of reviews aims to map and compare of objectives, methods, and findings of existing systematic reviews to develop a greater understanding of the information available about prolonged beta-lactam infusions in hospitalized patients with infection.

DESIGN

Overview of systematic reviews.

DATA SOURCES

Medline, Embase, PROSPERO and the Cochrane Library were systematically searched from January, 1990 to June, 2019 using a peer reviewed search strategy. Grey literature was also searched for relevant reviews.

ELIGIBILITY CRITERIA FOR SELECTING REVIEWS

Systematic reviews were sought that compared two or more infusion strategies for intravenous beta-lactam antimicrobials and report clinical cure or mortality. Populations of included reviews were restricted to hospitalized patients with infection, without restrictions on age, infection type, or disease.

DATA EXTRACTION AND ANALYSIS

Abstract screening, data extraction, quality and risk of bias assessment were conducted by two independent reviewers. Overlap between reviews was assessed using a modified corrected covered area. Overview findings are reported in accordance with Cochrane's recommendation for overview conduct. Clinical outcomes extracted included survival, clinical cure, treatment failure, microbiological cure, length of stay, adverse events, cost, and emergence of resistance.

RESULTS

The search strategy identified 3327 unique citations from which 21 eligible reviews were included. Reviews varied by population, intervention and outcomes studied. Between reviews, overlap of primary studies was generally high, methodologic quality generally low and risk of bias variable. Nine of 14 reviews that quantitatively evaluated mortality and clinical cure identified a benefit with prolonged infusions of beta lactams when compared with intermittent infusions. Evidence of mortality and clinical cure benefit was greater among critically ill patients when compared to less sick patients and lower in randomized controlled trials when compared with observational studies.

CONCLUSIONS

Findings from our review demonstrate a consistent and reproducible lack of harm with prolonged infusions of beta-lactam antibiotics with variability in effect size and significance of benefits. Despite 21 systematic reviews addressing prolonged infusions of beta-lactams, this overview supports the continued need for a definitive systematic review given variability in populations, interventions and outcomes in the current systematic reviews. Subsequent systematic reviews should have more rigorous and transparent methods, only include RCTs and evaluate the proposed benefits found in various subgroup-analyses-i.e. high risk of mortality.

TRIAL REGISTRATION

Prospero registry, CRD42019117118.

Compatibility of intravenous metronidazole with some all-in-one parenteral nutrition regimens

OBJECTIVES

Supplementation of parenteral nutrition (PN) admixtures with other parenteral drugs may be desired especially in the case of polypharmacy and limited vascular access. Metronidazole (MTZ) is administered in surgical and critically ill patients often requiring concomitant nutritional therapy in the form of parenteral nutrition. The aim of the study was to evaluate the possibility of the concomitant administration of MTZ with PN admixtures from one container.

METHODS

MTZ (1500 mg) was combined with six different PN admixtures and stored for 7 days before the simulation of administration. The mean droplet size (MDS) of the lipid emulsion, zeta potential, color, and pH of the tested samples were determined every 24 h. The content of MTZ was determined by the high-performance liquid chromatography method within the same time frames.

RESULTS

PN admixtures supplemented with MTZ were characterized by a pH range from 6.19 to 6.38 and zeta potential range from -21.6 mV to -8.8 mV. For all samples the pharmacopeial criteria for intravenously administered emulsions were met: The visual inspection showed no sign of emulsion destabilization or precipitation, and the MDS was <500 nm. The MTZ content remained >90% of the initial value throughout the whole study period.

CONCLUSIONS

Results showed the physicochemical compatibility and stability of PN admixtures supplemented with MTZ at the dose of 1500 mg. Such formulations can be stored at a temperature of 5°C for up to 7 d before administration to the patient.

Infections by multidrug-resistant Gram-negative Bacteria: What's new in our arsenal and what's in the pipeline?

The spread of multidrug-resistant bacteria is an ever-growing concern, particularly among Gram-negative bacteria because of their intrinsic resistance and how quickly they acquire and spread new resistance mechanisms. Treating infections caused by Gram-negative bacteria is a challenge for medical practitioners and increases patient mortality and cost of care globally. This vulnerability, along with strategies to tackle antimicrobial resistance development, prompts the development of new antibiotic agents and exploration of alternative treatment options. This article summarises the new antibiotics that have recently been approved for Gram-negative bacterial infections, looks down the pipeline at promising agents currently in phase I, II, or III clinical trials, and introduces new alternative avenues that show potential in combating multidrug-resistant Gram-negative bacteria.

New paradigm for rapid achievement of appropriate therapy in special populations: coupling antibiotic dose optimization rapid microbiological methods

INTRODUCTION

Some special patient populations (e.g. critically ill, burns, hematological malignancy, post-major surgery, post-major trauma) have characteristics that lead to higher rates of failure and mortality associated with infection. Choice of effective antibiotics and optimized doses are challenging in these patients that are commonly infected by multidrug-resistant pathogens. Areas covered: A review of the importance of diagnosis and the place of newer microbiological methods (e.g. whole-genome sequencing) to ensure rapid transition from empiric to directed antibiotic therapy is provided. The effects of pathophysiological changes on antibiotic pharmacokinetics are also provided. Expert opinion: Product information dosing regimens do not address the pharmacokinetic alterations that can occur in special patient populations and increase the likelihood of therapeutic failure and the emergence of bacterial resistance. Altered dosing approaches, supplemented with the use of dosing software and therapeutic drug monitoring, may be needed to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients with severe infection. Dose optimization needs to be coupled with advanced microbiological techniques that enable rapid microbiological identification and characterization of resistance mechanism to ensure that maximally effective directed therapy can be chosen.

Optimisation of antimicrobial dosing based on pharmacokinetic and pharmacodynamic principles

While suboptimal dosing of antimicrobials has been attributed to poorer clinical outcomes, clinical cure and mortality advantages have been demonstrated when target pharmacokinetic (PK) and pharmacodynamic (PD) indices for various classes of antimicrobials were achieved to maximise antibiotic activity. Dosing optimisation requires a good knowledge of PK/PD principles. This review serves to provide a foundation in PK/PD principles for the commonly prescribed antibiotics (β-lactams, vancomycin, fluoroquinolones and aminoglycosides), as well as dosing considerations in special populations (critically ill and obese patients). PK principles determine whether an appropriate dose of antimicrobial reaches the intended pathogen(s). It involves the fundamental processes of absorption, distribution, metabolism and elimination, and is affected by the antimicrobial's physicochemical properties. Antimicrobial pharmacodynamics define the relationship between the drug concentration and its observed effect on the pathogen. The major indicator of the effect of the antibiotics is the minimum inhibitory concentration. The quantitative relationship between a PK and microbiological parameter is known as a PK/PD index, which describes the relationship between dose administered and the rate and extent of bacterial killing. Improvements in clinical outcomes have been observed when antimicrobial agents are dosed optimally to achieve their respective PK/PD targets. With the rising rates of antimicrobial resistance and a limited drug development pipeline, PK/PD concepts can foster more rational and individualised dosing regimens, improving outcomes while simultaneously limiting the toxicity of antimicrobials.

Overview of systematic reviews assessing the evidence for shorter versus longer duration antibiotic treatment for bacterial infections in secondary care

Our objective was to assess the clinical effectiveness of shorter versus longer duration antibiotics for treatment of bacterial infections in adults and children in secondary care settings, using the evidence from published systematic reviews. We conducted electronic searches in MEDLINE, Embase, Cochrane, and Cinahl. Our primary outcome was clinical resolution. The quality of included reviews was assessed using the AMSTAR criteria, and the quality of the evidence was rated using the GRADE criteria. We included 6 systematic reviews (n = 3,162). Four reviews were rated high quality, and two of moderate quality. In adults, there was no difference between shorter versus longer duration in clinical resolution rates for peritonitis (RR 1.03, 95% CI 0.98 to 1.09, I² = 0%), ventilator-associated pneumonia (RR 0.93; 95% CI 0.81 to 1.08, I² = 24%), or acute pyelonephritis and septic UTI (clinical failure: RR 1.00, 95% CI 0.46 to 2.18). The quality of the evidence was very low to moderate. In children, there was no difference in clinical resolution rates for pneumonia (RR 0.98, 95% CI 0.91 to 1.04, I² = 48%), pyelonephritis (RR 0.95, 95% CI 0.88 to 1.04) and confirmed bacterial meningitis (RR 1.02, 95% CI 0.93 to 1.11, I² = 0%). The quality of the evidence was low to moderate. In conclusion, there is currently a limited body of evidence to clearly assess the clinical benefits of shorter versus longer duration antibiotics in secondary care. High quality trials assessing strategies to shorten antibiotic treatment duration for bacterial infections in secondary care settings should now be a priority.

Antibiotic dosing for multidrug-resistant pathogen pneumonia

PURPOSE OF REVIEW

Nosocomial pneumonia caused by multidrug-resistant pathogens is increasing in the ICU, and these infections are negatively associated with patient outcomes. Optimization of antibiotic dosing has been suggested as a key intervention to improve clinical outcomes in patients with nosocomial pneumonia. This review describes the recent pharmacokinetic/pharmacodynamic data relevant to antibiotic dosing for nosocomial pneumonia caused by multidrug-resistant pathogens.

RECENT FINDINGS

Optimal antibiotic treatment is challenging in critically ill patients with nosocomial pneumonia; most dosing guidelines do not consider the altered physiology and illness severity associated with severe lung infections. Antibiotic dosing can be guided by plasma drug concentrations, which do not reflect the concentrations at the site of infection. The application of aggressive dosing regimens, in accordance to the antibiotic's pharmacokinetic/pharmacodynamic characteristics, may be required to ensure rapid and effective drug exposure in infected lung tissues.

SUMMARY

Conventional antibiotic dosing increases the likelihood of therapeutic failure in critically ill patients with nosocomial pneumonia. Alternative dosing strategies, which exploit the pharmacokinetic/pharmacodynamic properties of an antibiotic, should be strongly considered to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients.

Activity of cefiderocol (S-649266) against carbapenem-resistant Gram-negative bacteria collected from inpatients in Greek hospitals

Background

Cefiderocol (S-649266), a siderophore cephalosporin, utilizes a novel mechanism of entry into the periplasmic space of Gram-negative bacteria and is broadly stable to ESBLs and carbapenemases.

Methods

A collection of carbapenem-resistant Gram-negative bacteria isolated from clinical specimens in 18 Greek hospitals was tested for susceptibility to cefiderocol, meropenem, ceftazidime, cefepime, ceftazidime/avibactam, ceftolozane/tazobactam, aztreonam, amikacin, ciprofloxacin, colistin and tigecycline. Broth microdilution plates were used to determine MICs.

Results

In total 189 non-fermentative Gram-negative bacteria (107 Acinetobacter baumannii and 82 Pseudomonas aeruginosa ) and 282 Enterobacteriaceae (including 244 Klebsiella pneumoniae , 14 Enterobacter cloacae and 11 Providencia stuartii ) were studied. For both A. baumannii and P. aeruginosa the MIC 90 of cefiderocol was 0.5 mg/L. For K. pneumoniae , E. cloacae and P. stuartii the MIC 90 of cefiderocol was 1, 1 and 0.5 mg/L, respectively. Tigecycline was the second most active antibiotic, followed by colistin.

Conclusions

Cefiderocol exhibited greater antimicrobial activity in vitro against carbapenem-resistant Gram-negative bacteria than comparator antibiotics.

Continuous and Prolonged Intravenous β-Lactam Dosing: Implications for the Clinical Laboratory

Beta-lactam antibiotics serve as a cornerstone in the management of bacterial infections because of their wide spectrum of activity and low toxicity. Since resistance rates among bacteria are continuously on the rise and the pipeline for new antibiotics does not meet this trend, an optimization of current beta-lactam treatment is needed. This review provides an overview of optimization through use of prolonged- and continuous-infusion dosing strategies compared with more traditional intermittent infusions. Included is an overview of the scientific basis for using these nontraditional prolonged- and continuous-infusion-based regimens, with a focus on major areas in which the clinical laboratory can support the clinical use of these regimens.

Development and validation of a measurement procedure based on ultra-high performance liquid chromatography-tandem mass spectrometry for simultaneous measurement of β-lactam antibiotic concentration in human plasma

BACKGROUND

The administration of β-lactam antibiotics in continuous infusion could let optimize the pharmacokinetic/pharmacodynamic parameters, especially in the treatment of serious bacterial infections. In this context, and also due to variability in their plasmatic concentrations, therapeutic drug monitoring (TDM) may be useful to optimize dosing and, therefore, be useful for the clinicians.

MATERIAL AND METHODS

We developed and validated a measurement procedure based on ultra-high performance liquid chromatography-tandem mass spectrometry for simultaneous measurement of amoxicillin, ampicillin, cloxacillin, piperacillin, cefepime, ceftazidime, cefuroxime, aztreonam and meropenem concentrations in plasma. The chromatographic separation was achieved using an Acquity®-UPLC® BEH™ (2.1×100mm id, 1.7μm) reverse-phase C₁₈ column, with a water/acetonitrile linear gradient containing 0.1% formic acid at a 0.4mL/min flow rate. β-Lactam antibiotics and their internal standards were detected by electrospray ionization mass spectrometry in multiple reaction monitoring mode.

RESULTS

Chromatography run time was 7.0min and β-lactam antibiotics eluted at retention times ranging between 1.08 and 1.91min. The lower limits of quantification were between 0.50 and 1.00mg/L. Coefficients of variation and relative bias absolute values were <13.3% and 14.7%, respectively. Recovery values ranged from 55.7% to 84.8%. Evaluation of the matrix effect showed ion enhancement for all antibiotics. No interferences or carry-over were observed.

CONCLUSIONS

Our measurement procedure could be applied to daily clinical laboratory practice to measure the concentration of β-lactam antibiotics in plasma, for instance in patients with bone and joint infections and critically ill patients.

Extended infusion compared to standard infusion cefepime as empiric treatment of febrile neutropenia

Background Extended infusion (EI) dosing provides a longer time above the minimum inhibitory concentration, which is important for the clinical success of β-lactam antibiotics, especially for patients with impaired immunity. The aim of this study was to determine the feasibility and clinical impact of administering cefepime by EI as treatment of febrile neutropenia. Methods This was a prospective, randomized, comparative pilot study. All patients received cefepime 2 g IV every 8 h, with the first dose administered using a 30-min infusion. After the first dose, patients were randomized to receive cefepime over 30 min as a standard infusion (SI) or 3 h (EI). Patients were >18 years old with febrile neutropenia (neutrophil count <500 cells/mm³ and temperature >38.0ºC) and received chemotherapy or stem cell transplant as treatment for malignancy. Patients were excluded for the following: allergy to a cephalosporin, creatinine clearance (CrCl) < 50 mL/min, receipt of concurrent Gram-negative antimicrobial, sepsis, or solid tumor malignancy. The primary outcome was defervescence by 72 h. Secondary outcomes included time to defervescence, clinical success, in-hospital mortality, hospital length of stay, and need for additional antimicrobials. Main results Sixty-three patients were enrolled: 33 in the SI arm and 30 in the EI arm. The groups were similar with regard to age, gender, weight, estimated creatinine clearance, and duration of neutropenia. None of the patients in the EI arm withdrew due to practical complications of receiving EI cefepime. Twenty-three patients in the SI arm and 20 patients in the EI arm defervesced by 72 h ( p = 0.99). There were no differences in secondary outcome measures; however, patients in the EI arm appeared to have defervesced more rapidly (median 19 vs. 41 h, p = 0.305). Conclusion Administration of cefepime by EI for the treatment of febrile neutropenia is feasible. Larger clinical trials are necessary to determine if EI cefepime imparts a clinical benefit in the treatment of febrile neutropenia.

Colistin loading dose: evaluation of the published pharmacokinetic and clinical data

Colistin (polymyxin E) has been widely used since the beginning of the century as a last-option antibiotic for the treatment of patients with multidrug-resistant and extensively-drug resistant bacterial infections. However, colistin dosing is troublesome because each batch of the drug contains a mixture of components and because it is administered as the inactive pro-drug colistimethate sodium (CMS), which has different pharmacokinetic (PK) properties from the active drug. Significant inter-individual and intra-individual variability in colistin plasma concentrations have been observed in all available studies. Low plasma concentrations of the drug during the first hours from initiation of administration suggested that a loading dose would be appropriate. However, other PK studies challenge this approach. Clinical data from randomised controlled trials are not available, whilst data from observational studies do not support higher effectiveness of a loading dose. In this review, we summarise the available data regarding the administration of a loading dose and discuss the issues surrounding the potential advantages and disadvantages as well as the context within which such an approach could be beneficial to patients.

Continuous versus short-term infusion of cefuroxime: assessment of concept based on plasma, subcutaneous tissue, and bone pharmacokinetics in an animal model

The relatively short half-lives of most β-lactams suggest that continuous infusion of these time-dependent antimicrobials may be favorable compared to short-term infusion. Nevertheless, only limited solid-tissue pharmacokinetic data are available to support this theory. In this study, we randomly assigned 12 pigs to receive cefuroxime as either a short-term or continuous infusion. Measurements of cefuroxime were obtained every 30 min in plasma, subcutaneous tissue, and bone. For the measurements in solid tissues, microdialysis was applied. A two-compartment population model was fitted separately to the drug concentration data for the different tissues using a nonlinear mixed-effects regression model. Estimates of the pharmacokinetic parameters and time with concentrations above the MIC were derived using Monte Carlo simulations. Except for subcutaneous tissue in the short-term infusion group, the tissue penetration was incomplete for all tissues. For short-term infusion, the tissue penetration ratios were 0.97 (95% confidence interval [CI], 0.67 to 1.39), 0.61 (95% CI, 0.51 to 0.73), and 0.45 (95% CI, 0.36 to 0.56) for subcutaneous tissue, cancellous bone, and cortical bone, respectively. For continuous infusion, they were 0.53 (95% CI, 0.33 to 0.84), 0.38 (95% CI, 0.23 to 0.57), and 0.27 (95% CI, 0.13 to 0.48) for the same tissues, respectively. The absolute areas under the concentration-time curve were also lower in the continuous infusion group. Nevertheless, a significantly longer time with concentrations above the MIC was found for continuous infusion up until MICs of 4, 2, 2, and 0.5 μg/ml for plasma and the same three tissues mentioned above, respectively. For drugs with a short half-life, like cefuroxime, continuous infusion seems to be favorable compared to short-term infusion; however, incomplete tissue penetration and high MIC strains may jeopardize the continuous infusion approach.

Effect of meropenem administration in extended infusion on the clinical outcome of febrile neutropenia: a retrospective observational study

OBJECTIVES

Information on the efficacy of extended meropenem administration in neutropenic patients is scarce. Our objective was to determine whether the administration of meropenem in a 4 h extended infusion (EI) leads to a better clinical outcome in patients with febrile neutropenia than the conventional short infusion (SI).

METHODS

This was a retrospective observational study. The subjects were neutropenic patients who presented with fever after receiving haematopoietic stem-cell transplantation or induction chemotherapy for acute myeloid leukaemia. The primary endpoint was the success of treatment after 5 days of meropenem therapy, defined as follows: the disappearance of fever leading to a maintained (≥ 24 h) feverless state; the resolution or improvement of the clinical signs and symptoms of infection; the absence of persistent or breakthrough bacteraemia; and no additional antibiotics prescribed because of an unsatisfactory clinical evolution.

RESULTS

Eighty-eight patients received meropenem (1 g/8 h) in SI and 76 received the same dose in EI. Treatment success on day 5 was superior in the EI group [52/76 (68.4%) versus 36/88 (40.9%); P<0.001]. Meropenem administered in EI was independently associated with success (OR 3.13, 95% CI 1.61-6.10). Fewer additional antibiotics were prescribed in the EI group during the first 5 days of treatment [20/76 (26.3%) versus 44/88 (50.0%); P=0.002]. Using Kaplan-Meier survival analysis a more prompt defervescence and a faster decrease in C-reactive protein concentration were observed in the EI group (P=0.021 and P=0.037, respectively). There were no significant differences in the length of hospital stay and in the mortality rate.

CONCLUSIONS

Meropenem administration in EI results in a better clinical outcome for febrile neutropenia episodes, with fewer additional antibiotics needed.

Prolonged infusion versus intermittent boluses of β-lactam antibiotics for treatment of acute infections: a meta-analysis

The clinical advantages of prolonged (extended/continuous) infusion remain controversial. Previous studies and reviews have failed to show consistent clinical benefits of extending the infusion time. This meta-analysis sought to determine whether prolonged β-lactam infusions were associated with a reduction in mortality and improvement in clinical success. A search of PubMed, EMBASE and The Cochrane Library for randomised controlled trials (RCTs) and observational studies comparing prolonged infusion with intermittent bolus administration of the same antibiotic in hospitalised adult patients was conducted. Primary outcomes evaluated were mortality and clinical success. A total of 29 studies with 2206 patients (18 RCTs and 11 observational studies) were included in the meta-analysis. Compared with intermittent boluses, use of prolonged infusion appeared to be associated with a significant reduction in mortality [pooled relative risk (RR) = 0.66, 95% confidence interval (CI) 0.53-0.83] and improvement in clinical success (RR = 1.12, 95% CI 1.03-1.21). Statistically significant benefit was supported by non-randomised studies (mortality, RR = 0.57, 95% CI 0.43-0.76; clinical success, RR = 1.34, 95% CI 1.02-1.76) but not by RCTs (mortality, RR = 0.83, 95% CI 0.57-1.21; clinical success, RR = 1.05, 95% CI 0.99-1.12). The positive results from observational studies, especially in the face of increasing antibiotic resistance, serve to justify the imperative need to conduct a large-scale, well-designed, multicentre RCT involving critically ill patients infected with high minimum inhibitory concentration pathogens to clearly substantiate this benefit.