Dalbavancin as suppressive antibiotic therapy in patients with prosthetic infections: efficacy and safety.

Suppressive antibiotic therapy (SAT) is a strategy to alleviate symptoms and/or to reduce the progression of an infection when other treatment options cannot be used. Dalbavancin, due to its prolonged half-life, enables (bi) weekly dosing. Here, we report our multicenter real-life clinical experience with dalbavancin used as SAT in patients with prosthetic joint or vascular infections. Medical records of all adult patients with documented vascular or orthopedic chronic prosthetic infections, who received dalbavancin as SAT between 2016 and 2018 from four Spanish hospitals were reviewed for inclusion. Descriptive analysis of demographic characteristics, Charlson Comorbidity index, Barthel index, isolated pathogens and indication, concomitant antibiotic use, adverse events, and clinical outcome of SAT were performed. Eight patients were eligible for inclusion, where six patients had prosthetic vascular infections (aortic valve) and two patients had knee prosthetic joint infections. The most common pathogens were methicillin-susceptible Staphylococcus aureus and Enterococcus faecium. All patients had a history of prior antibiotic treatment for the prosthetic infection [median duration of antibiotic days 125 days (IQR, 28-203 days)]. The median number of dalbavancin doses was 29 (IQR, 9-61) and concomitant antibiotic use (n = 5, 62.5%). Clinical success was reported in 75% (n = 6) of patients. Adverse events were reported in two patients (mild renal and hepatic impairment). The median estimated cost savings due to the avoided hospital days was €60185 (IQR, 19,916-94984) per patient. Despite the limitations of our study, this preliminary data provides valuable insight to support further evaluation of dalbavancin for SAT in patients with prosthetic infections in the outpatient setting when alternative treatments are not feasible.

Antifungal Dosing in Critically Ill Patients on Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) is an established advanced life support system, providing temporary cardiac and/or respiratory support in critically ill patients. Fungal infections are associated with increased mortality in patients on ECMO. Antifungal drug dosing for critically ill patients is highly challenging because of altered pharmacokinetics (PK). PK changes during critical illness; in particular, the drug volume of distribution (Vd) and clearance can be exacerbated by ECMO. This article discusses the available literature to inform adequate dosing of antifungals in this patient population. The number of antifungal PK studies in critically ill patients on ECMO is growing; currently available literature consists of case reports and studies with small sample sizes providing inconsistent findings, with scant or no data for some antifungals. Current data are insufficient to provide definitive empirical drug dosing guidance and use of dosing strategies derived from critically patients not on ECMO is reasonable. However, due to high PK variability, therapeutic drug monitoring should be considered where available in critically ill patients receiving ECMO to prevent subtherapeutic or toxic antifungal exposures.

A Systematic Review on Antimicrobial Pharmacokinetic Differences between Asian and Non-Asian Adult Populations.

While the relevance of inter-ethnic differences to the pharmacokinetic variabilities of antimicrobials has been reported in studies recruiting healthy subjects, differences in antimicrobial pharmacokinetics between Asian and non-Asian patients with severe pathologic conditions require further investigation. For the purpose of describing the potential differences in antimicrobial pharmacokinetics between Asian and non-Asian populations, a systematic review was performed using six journal databases and six theses/dissertation databases (PROSPERO record CRD42018090054). The pharmacokinetic data of healthy volunteers and non-critically ill and critically ill patients were reviewed. Thirty studies on meropenem, imipenem, doripenem, linezolid, and vancomycin were included in the final descriptive summaries. In studies recruiting hospitalised patients, inconsistent differences in the volume of distribution (Vd) and drug clearance (CL) of the studied antimicrobials between Asian and non-Asian patients were observed. Additionally, factors other than ethnicity, such as demographic (e.g., age) or clinical (e.g., sepsis) factors, were suggested to better characterise these pharmacokinetic differences. Inconsistent differences in pharmacokinetic parameters between Asian and non-Asian subjects/patients may suggest that ethnicity is not an important predictor to characterise interindividual pharmacokinetic differences between meropenem, imipenem, doripenem, linezolid, and vancomycin. Therefore, the dosing regimens of these antimicrobials should be adjusted according to patients' demographic or clinical characteristics that can better describe pharmacokinetic differences.

Novel Antimicrobial Agents for Gram-Negative Pathogens.

Gram-negative bacterial resistance to antimicrobials has had an exponential increase at a global level during the last decades and represent an everyday challenge, especially for the hospital practice of our era. Concerted efforts from the researchers and the industry have recently provided several novel promising antimicrobials, resilient to various bacterial resistance mechanisms. There are new antimicrobials that became commercially available during the last five years, namely, cefiderocol, imipenem-cilastatin-relebactam, eravacycline, omadacycline, and plazomicin. Furthermore, other agents are in advanced development, having reached phase 3 clinical trials, namely, aztreonam-avibactam, cefepime-enmetazobactam, cefepime-taniborbactam, cefepime-zidebactam, sulopenem, tebipenem, and benapenem. In this present review, we critically discuss the characteristics of the above-mentioned antimicrobials, their pharmacokinetic/pharmacodynamic properties and the current clinical data.

Why is the Implementation of Beta-Lactam Therapeutic Drug Monitoring for the Critically Ill Falling Short? A Multicenter Mixed-Methods Study.

BACKGROUND: Beta-lactam therapeutic drug monitoring (BL TDM; drug level testing) can facilitate improved outcomes in critically ill patients. However, only 10%-20% of hospitals have implemented BL TDM. This study aimed to characterize provider perceptions and key considerations for successfully implementing BL TDM. METHODS: This was a sequential mixed-methods study from 2020 to 2021 of diverse stakeholders at 3 academic medical centers with varying degrees of BL TDM implementation (not implemented, partially implemented, and fully implemented). Stakeholders were surveyed, and a proportion of participants completed semistructured interviews. Themes were identified, and findings were contextualized with implementation science frameworks. RESULTS: Most of the 138 survey respondents perceived that BL TDM was relevant to their practice and improved medication effectiveness and safety. Integrated with interview data from 30 individuals, 2 implementation themes were identified: individual internalization and organizational features. Individuals needed to internalize, make sense of, and agree to BL TDM implementation, which was positively influenced by repeated exposure to evidence and expertise. The process of internalization appeared more complex with BL TDM than with other antibiotics (ie, vancomycin). Organizational considerations relevant to BL TDM implementation (eg, infrastructure, personnel) were similar to those identified in other TDM settings. CONCLUSIONS: Broad enthusiasm for BL TDM among participants was found. Prior literature suggested that assay availability was the primary barrier to implementation; however, the data revealed many more individual and organizational attributes, which impacted the BL TDM implementation. Internalization should particularly be focused on to improve the adoption of this evidence-based practice.

Population Pharmacokinetics and Dosing Simulations of Ampicillin and Sulbactam in Hospitalised Adult Patients.

BACKGROUND: The pharmacokinetic variability of ampicillin-sulbactam in adults has not been extensively described, particularly in patients with a reduced renal function (i.e., < 60 mL/min). OBJECTIVE: This study investigated the population pharmacokinetics of ampicillin and sulbactam in patients with a wide range of renal functions and sought to define dosing approaches that have a high likelihood for optimising drug exposure. METHODS: Serial blood samples were collected from 16 adult patients receiving intravenous ampicillin-sulbactam in general wards. Total ampicillin and sulbactam concentrations were measured by chromatographic assay and pharmacokinetic parameters were estimated using Pmetrics®. Monte Carlo simulations were used to evaluate the probability of target attainment (PTA) of free ampicillin and sulbactam concentrations exceeding the minimum inhibitory concentration (MIC) for 60% and 100% of the dosing interval. Fractional target attainment (FTA) was calculated against MIC distributions of common hospital pathogens. A threshold of ≥ 90% and ≥ 95% was used to define both optimal PTA and FTA, respectively. RESULTS: The median (range) age, weight, and serum creatinine of the study population was 68 (40-82) years, 62 (40-82) kg, and 1.4 (0.6-6.4) mg/dL, respectively. The pharmacokinetics of ampicillin and sulbactam were best described by a two-compartment model with serum creatinine most closely associated with clearance for both drugs. The estimated ampicillin and sulbactam clearances were 5.58 L/h and 4.79 L/h, respectively, while the volumes of distribution were 12.6 L and 15.36 L, respectively. Approved dosing regimens of ampicillin-sulbactam were sufficient against MICs ≤ 8 and ≤ 4 mg/L, respectively. A 4-h infusion enabled optimal PTA at higher MICs. For both dosing targets, optimal FTAs were obtained against Streptococcus pneumoniae. CONCLUSION: Optimal FTAs were obtained against the susceptible MIC distributions of Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii. Applying a 4-h infusion will enhance PTA and FTA, particularly at higher MICs.

Population pharmacokinetics and dose optimization of intravenous levofloxacin in hospitalized adult patients.

Although levofloxacin has been used for the last 25 years, there are limited pharmacokinetic data to guide levofloxacin dosing in adult patients. This study aimed to develop a population pharmacokinetic model of levofloxacin for adult hospitalized patients and define dosing regimens that attain pharmacokinetic/pharmacodynamic target associated with maximum effectiveness. Blood samples were drawn from 26 patients during one dosing interval. Population pharmacokinetic modelling and dosign simulations were performed using Pmetrics®. Pathogen minimum inhibition concentration (MIC) distribution data from the European Committee on Antimicrobial Susceptibility Testing database was used to analyse fractional target attainment (FTA). A two-compartment model adequately described the data. The final model included estimated glomerular filtration rate (eGFR) to describe clearance. The population estimate for clearance was 1.12 L/h, while the volume of distribution in the central compartment and peripheral compartments were 27.6 L and 28.2 L, respectively. Our simulation demonstrated that an area under free concentration-time curve to MIC ≥ 80 was hardly achieved for pathogens with MIC ≥ 1 mg/L. Low FTA against Pseudomonas aeruginosa and Streptococcus pneumoniae were observed for patients with higher eGFR (≥ 80 mL/min/1.73m2). A daily levofloxacin dose of 1000 mg is suggested to maximise the likelihood of efficacy for adult patients.

Hospital-Based Antimicrobial Stewardship Programs Used in Low- and Middle-Income Countries: A Scoping Review.

The burden of antimicrobial resistance (AMR) is considerable in many low- and middle-income countries (LMICs), and it is important to describe the antimicrobial stewardship program (ASP) activities found in these countries and report their impact. Importantly, as these programs target prescribing behavior, the factors influencing prescription of antimicrobials must also be taken into account. This scoping review aimed to (1) describe hospital-based ASP activities, (2) report methods used to measure the impact of ASPs, and (3) explore factors influencing antimicrobial prescribing behavior in LMICs. PubMed was searched from database inception until April 2021. Factors influencing antimicrobial prescribing behavior were canvassed using the Capability-Opportunity-Motivation and Behavior framework. Most of ASP studies in LMICs were predominantly conducted in tertiary care and university-based hospitals. Audit of antimicrobial prescriptions with feedback and restrictive-based strategies was the main reported activity. Total antimicrobial consumption was the main method used to measure the impact of ASPs. Positive outcomes were observed for both clinical and microbiological outcomes; however, these were measured from nonrandomized controlled trials. Dominant factors identified through the behavioral framework were a limited awareness of AMR as a local problem, a perception that overprescription of antimicrobials had limited consequences and was mainly driven by a motivation to help improve patient outcomes. In addition, antimicrobial prescribing practices were largely influenced by existing hierarchy among prescribers. Our scoping review suggests that LMICs need to evaluate antimicrobial appropriateness as an added measure to assess impact. Furthermore, improvements in the access of microbiology and diagnostic facilities and ensuring ASP champions are recruited from senior prescribers will positively influence antimicrobial prescribing behavior, helping improve stewardship of antimicrobials in these countries.

Indonesian healthcare providers' perceptions and attitude on antimicrobial resistance, prescription and stewardship programs.

Background: A successful antimicrobial stewardship program (ASP) is sustained through improving antimicrobial prescribing by changing prescribing behavior. This requires a better understanding of hospital stakeholders' views regarding antimicrobial resistance (AMR), antimicrobial use and participation in ASP activities. Objectives: Identify perceptions and attitudes among physicians and pharmacists in a public hospital toward AMR, prescription and ASP. Methods: A questionnaire consisting of 45 items was distributed to physicians and pharmacists in a 320-bed public hospital. All responses were formatted into the Likert scale. Results: A total of 78 respondents (73% response rate) completed the questionnaire. The majority of the respondents perceived AMR within hospital as less of a severe problem, and factors outside hospital were considered to be greater contributors to AMR. In addition, interprofessional conflict was identified as a serious concern in relation to implementing ASP. Conclusion: This finding indicates the need to address existing perceptions and attitudes toward ASP activities that may hamper its successful implementation in Indonesia.

Provider perspectives on beta-lactam therapeutic drug monitoring programs in the critically ill: a protocol for a multicenter mixed-methods study.

BACKGROUND: Beta-lactams (i.e., penicillins, cephalosporins, carbapenems, monobactams) are the most widely used class of antibiotics in critically ill patients. There is substantial interpatient variability in beta-lactam pharmacokinetics which renders their effectiveness and safety largely unpredictable. One strategy to ensure achievement of therapeutic concentrations is drug level testing ("therapeutic drug monitoring"; TDM). While studies have suggested promise with beta-lactam TDM, it is not yet widely available or implemented. This protocol presents a mixed-methods study designed to examine healthcare practitioners' perspectives on the use and implementation of beta-lactam TDM in the critically ill. METHODS: An explanatory sequential mixed-methods design will be used [QUANT → qual]. First, quantitative data will be collected through a web-based questionnaire directed at clinicians at three academic medical centers at different phases of beta-lactam TDM implementation (not yet implemented, partially implemented, fully implemented). The sampling frame will include providers from a variety of disciplines that interact with drug level testing and interpretation in the critical care environment including pharmacists, intensivists, infectious diseases experts, medical/surgical trainees, and advanced practice providers. Second, approximately 30 individuals will be purposively sampled from survey respondents to conduct in-depth qualitative interviews to explain and expand upon the results from the quantitative strand. Normalization Process Theory and the Consolidated Framework for Implementation Science will be used to guide data analysis. DISCUSSION: These data will be used to answer two specific questions: "What are ICU practitioners' perspectives on implementing beta-lactam TDM?" and "What factors contribute to the success of beta-lactam TDM program implementation?" Results of this study will be used to design future implementation strategies for beta-lactam TDM programs in the critically ill. TRIAL REGISTRATION: NCT04755777 .

A case report: Community-acquired Pseudomonas aeruginosa necrotizing fasciitis in a morbidly obese diabetic young man can be fatal.

We present a case study of a 26-year-old morbidly obese man with a three-day history of right leg pain and swelling. The swelling was associated with low grade fever. He was alert and conscious upon presentation to the hospital. His physical examination showed gross swelling of the entire right lower limb with no systemic manifestations. There was no discharge and bullae from the swelling area of the leg. He had high blood sugar and was newly diagnosed with type 2 diabetes mellitus. He was diagnosed with necrotizing fasciitis. An intravenous imipenem-cilastatin 500 mg every 6 h together with clindamycin 900 mg every 8 h was started empirically. Extensive wound debridement was performed. The swab culture obtained intraoperatively grew Pseudomonas aeruginosa. He required an above knee amputation due to worsening infection despite wound debridement. Post-operatively, he developed acute kidney injury with severe metabolic acidosis, which required daily hemodialysis. However, the patient deteriorated due to septic shock with multi-organ failure, resulting in his death.

The role of antibiotic pharmacokinetic studies performed post-licensing.

Post-licensing pharmacometric studies can provide a better understanding of the pharmacokinetic (PK) alterations in special patient populations and may lead to better clinical outcomes. Some patient populations exhibit markedly different pathophysiology to general ward patients or healthy individuals. This may be developmental (paediatric patients), a manifestation of an underlying disease pathology (patients with obesity or haematological malignancies) or due to medical interventions (critically ill patients receiving extracorporeal therapies). This paper outlines the factors that affect the PK of special patient populations and describes some novel methods of antimicrobial administration that may increase antimicrobial concentrations at the site of infection and improve treatment of severe infection.

Prolonged Versus Intermittent Infusion of ß-Lactam Antibiotics: A Systematic Review and Meta-Regression of Bacterial Killing in Preclinical Infection Models.

BACKGROUND: Administering ß-lactam antibiotics via prolonged infusions for critically ill patients is mainly based on preclinical evidence. Preclinical data on this topic have not been systematically reviewed before. OBJECTIVES: The aim of this study was to describe the pharmacokinetic/pharmacodynamic (PK/PD) indices and targets reported in preclinical models and to compare the bactericidal efficacy of intermittent and prolonged infusions of ß-lactam antibiotics. METHODS: The MEDLINE and EMBASE databases were searched. To compare the bactericidal action of ß-lactam antibiotics across different modes of infusion, the reported PK/PD outcomes, expressed as the percentage of time (T) that free (f) ß-lactam antibiotic concentrations remain above the minimal inhibitory concentration (MIC) (%fT>MIC) or trough concentration (Cmin)/MIC of individual studies, were recomputed relative to the area under the curve of free drug to MIC ratio (fAUC24/MIC). A linear mixed-effects meta-regression was performed to evaluate the impact of the ß-lactam class, initial inoculum, Gram stain, in vivo or in vitro experiment and mode of infusion on the reduction of bacterial cells (in colony-forming units/mL). RESULTS: Overall, 33 articles were included for review, 11 of which were eligible for meta-regression. For maximal bactericidal activity, intermittent experiments reported a PK/PD target of 40-70% fT>MIC, while continuous experiments reported a steady-state concentration to MIC ratio of 4-8. The adjusted effect of a prolonged as opposed to intermittent infusion on bacterial killing was small (coefficient 0.66, 95% confidence interval - 0.78 to 2.11). CONCLUSIONS: Intermittent and prolonged infusions of ß-lactam antibiotics require different PK/PD targets to obtain the same level of bacterial cell kill. The additional effect of a prolonged infusion for enhancing bacterial killing could not be demonstrated.

Knowledge, Perception, and Antibiotic Prescribing Practice in the Intensive Care Unit: Findings from the Malaysian Public Setting.

INTRODUCTION: Approach to managing infection in the intensive care unit (ICU) often varies between institutions and not many readily adapt to available local guidelines despite it was constructed to suite local clinical scenario. Malaysia already has two published guidelines on managing infection in the ICU but data on its compliance are largely unknown. OBJECTIVES: A cross-sectional survey was carried out and sent to a total of 868 specialists working primarily in the ICU. The aim of this study was to explore knowledge, perception, and the antibiotic prescribing practice among specialists and advanced trainees in Malaysian ICU. MATERIALS AND METHODS: A cross-sectional survey was used, consisted of three sections: knowledge, perception, and antibiotic prescribing practice in ICU. Three case vignettes on hospital-acquired pneumonia (HAP), infected necrotizing pancreatitis (INP), and catheter-related bloodstream infection (CRBSI) were used to explore antibiotic prescribing practice. RESULTS: A total of 868 eligible subjects were approached with 104 responded to the survey. Three hundred eighty-nine antibiotics were chosen from seven different classes in the case vignettes. All respondents acknowledged the importance of pharmacokinetic/pharmacodynamic (PK/PD) in antibiotic optimization and majority (97.2%) perceived that current dosing is inadequate to achieve optimal PK/PD target in ICU patients. Majority (85.6%) believed that antibiotic dose should be streamlined to the organisms' minimum inhibitory concentration (MIC). In terms of knowledge, only 64.4% provided the correct correlations between antibiotics and their respective PK/PD targets. Compliance rates in terms of antibiotic choices were at 79.8%, 77.8%, and 27.9% for HAI, INP, and CRBSI, respectively. CONCLUSION: Malaysian physicians are receptive to use PK/PD approach to optimize antibiotic dosing in ICU patients. Nonetheless, there are still gaps in the knowledge of antibiotic PK/PD as well as its application in the critically ill, especially for ß-lactams.

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.

Optimising drug dosing in patients receiving extracorporeal membrane oxygenation.

Optimal pharmacological management during extracorporeal membrane oxygenation (ECMO) involves more than administering drugs to reverse underlying disease. ECMO is a complex therapy that should be administered in a goal-directed manner to achieve therapeutic endpoints that allow reversal of disease and ECMO wean, minimisation of complications (treatment of complications when they do occur), early interruption of sedation and rehabilitation, maximising patient comfort and minimising risks of delirium. ECMO can alter both the pharmacokinetics (PK) and pharmacodynamics (PD) of administered drugs and our understanding of these alterations is still evolving. Based on available data it appears that modern ECMO circuitry probably has a less significant impact on PK when compared with critical illness itself. However, these findings need further confirmation in clinical population PK studies and such studies are underway. The altered PD associated with ECMO is less understood and more research is indicated. Until robust dosing guidelines become available, clinicians will have to rely on the principles of drug dosing in critically ill and known PK alterations induced by ECMO itself. This article summarises the PK alterations and makes preliminary recommendations on possible dosing approaches.

Prolonged administration of ß-lactam antibiotics - a comprehensive review and critical appraisal.

Prolonged infusion of ß-lactam antibiotics as either extended (over at least 2 hours) or continuous infusion is increasingly applied in intensive care units around the world in an attempt to optimise treatment with this most commonly used class of antibiotics, whose effectiveness is challenged by increasing resistance rates. The pharmacokinetics of ß-lactam antibiotics in critically ill patients is profoundly altered secondary to an increased volume of distribution and the presence of altered renal function, including augmented renal clearance. This may lead to a significant decrease in plasma concentrations of ß-lactam antibiotics. As a consequence, low pharmacokinetic/pharmacodynamic (PK/PD) target attainment, which is described as the percentage of time that the free drug concentration is maintained above the minimal inhibitory concentration (MIC) of the causative organism (fT>MIC), has been documented for ß-lactam treatment in these patients when using standard intermittent bolus dosing, even for the most conservative target (50% fT>MIC). Prolonged infusion of ß-lactams has consistently been shown to improve PK/PD target attainment, particularly in patients with severe infections. However, evidence regarding relevant patient outcomes is still limited. Whereas previous observational studies have suggested a clinical benefit of prolonged infusion, results from two recent randomised controlled trials of continuous infusion versus intermittent bolus administration of ß-lactams are conflicting. In particular, the larger, double-blind placebo-controlled randomised controlled trial including 443 patients did not demonstrate any difference in clinical outcomes. We believe that a personalised approach is required to truly optimise ß-lactam treatment in critically ill patients. This may include therapeutic drug monitoring with real-time adaptive feedback, rapid MIC determination and the use of antibiotic dosing software tools that incorporate patient parameters, dosing history, drug concentration and site of infection. Universal administration of ß-lactam antibiotics as prolonged infusion, even if supported by therapeutic drug monitoring, is not yet ready for "prime time", as evidence for its clinical benefit is modest. There is a need for prospective randomised controlled trials that assess patient-centred outcomes (e.g. mortality) of a personalised approach in selected critically ill patients including prolonged infusion of ß-lactams compared with the current standard of care.

Continuous versus Intermittent ß-Lactam Infusion in Severe Sepsis. A Meta-analysis of Individual Patient Data from Randomized Trials.

RATIONALE: Optimization of ß-lactam antibiotic dosing for critically ill patients is an intervention that may improve outcomes in severe sepsis. OBJECTIVES: In this individual patient data meta-analysis of critically ill patients with severe sepsis, we aimed to compare clinical outcomes of those treated with continuous versus intermittent infusion of ß-lactam antibiotics. METHODS: We identified relevant randomized controlled trials comparing continuous versus intermittent infusion of ß-lactam antibiotics in critically ill patients with severe sepsis. We assessed the quality of the studies according to four criteria. We combined individual patient data from studies and assessed data integrity for common baseline demographics and study endpoints, including hospital mortality censored at 30 days and clinical cure. We then determined the pooled estimates of effect and investigated factors associated with hospital mortality in multivariable analysis. MEASUREMENTS AND MAIN RESULTS: We identified three randomized controlled trials in which researchers recruited a total of 632 patients with severe sepsis. The two groups were well balanced in terms of age, sex, and illness severity. The rates of hospital mortality and clinical cure for the continuous versus intermittent infusion groups were 19.6% versus 26.3% (relative risk, 0.74; 95% confidence interval, 0.56-1.00; P = 0.045) and 55.4% versus 46.3% (relative risk, 1.20; 95% confidence interval, 1.03-1.40; P = 0.021), respectively. In a multivariable model, intermittent ß-lactam administration, higher Acute Physiology and Chronic Health Evaluation II score, use of renal replacement therapy, and infection by nonfermenting gram-negative bacilli were significantly associated with hospital mortality. Continuous ß-lactam administration was not independently associated with clinical cure. CONCLUSIONS: Compared with intermittent dosing, administration of ß-lactam antibiotics by continuous infusion in critically ill patients with severe sepsis is associated with decreased hospital mortality.

What is the effect of obesity on piperacillin and meropenem trough concentrations in critically ill patients?

OBJECTIVES: The objectives of this study were to determine the effects of obesity on unbound trough concentrations and on the achievement of pharmacokinetic (PK)/pharmacodynamic (PD) targets of piperacillin and meropenem in critically ill patients. METHODS: This study retrospectively analysed therapeutic-drug-monitoring data from ICU databases in Australia, Germany and Spain, as well as from a large PK study. The presence of obesity was defined as a BMI ≥30 kg/m(2), and patients were also categorized based on level of renal function. The presence of obesity was compared with unbound piperacillin and meropenem trough concentrations. We also used logistic regression to describe factors associated with the achievement of the PK/PD targets, an unbound concentration maintained above the MIC breakpoint (100% fT>MIC and 100% fT>4×MIC) of Pseudomonas aeruginosa. RESULTS: In all, 1400 patients were eligible for inclusion in the study. The median age and weight were 67 years (IQR 52-76 years) and 79 kg (69-90 kg), respectively, and 65% of participants were male. Significantly lower median piperacillin trough concentrations [29.4 mg/L (IQR 17.0-58.0 mg/L)] were found in obese patients compared with non-obese patients [42.0 mg/L (21.5-73.5 mg/L)] (P = 0.001). There was no difference for meropenem trough concentrations [obese 10.3 mg/L (IQR 4.8-16.0 mg/L) versus non-obese 11.0 mg/L (4.3-18.5 mg/L); P = 0.296]. Using logistic regression, we found that the presence of obesity was not associated with achievement of 100% fT>MIC, but the use of prolonged infusion, a creatinine clearance ≤100 mL/min, increasing age and female gender were for various PK/PD targets for both piperacillin and meropenem (P < 0.05). CONCLUSIONS: This large dataset has shown that the presence of obesity in critically ill patients may affect piperacillin, but not meropenem, unbound trough concentrations.