Length of stay and hospital costs associated with a pharmacodynamic-based clinical pathway for empiric antibiotic choice for ventilator-associated pneumonia

The clinical application of beta-lactam antibiotic therapeutic drug monitoring in the critical care setting

Critically ill patients have increased variability in beta-lactam antibiotic (beta-lactam) exposure due to alterations in their volume of distribution and elimination. Therapeutic drug monitoring (TDM) of beta-lactams, as a dose optimization and individualization tool, has been recommended to overcome this variability in exposure. Despite its potential benefit, only a few centres worldwide perform beta-lactam TDM. An important reason for the low uptake is that the evidence for clinical benefits of beta-lactam TDM is not well established. TDM also requires the availability of specific infrastructure, knowledge and expertise. Observational studies and systematic reviews have demonstrated that TDM leads to an improvement in achieving target concentrations, a reduction in potentially toxic concentrations and improvement of clinical and microbiological outcomes. However, a small number of randomized controlled trials have not shown a mortality benefit. Opportunities for improved study design are apparent, as existing studies are limited by their inclusion of heterogeneous patient populations, including patients that may not even have infection, small sample size, variability in the types of beta-lactams included, infections caused by highly susceptible bacteria, and varied sampling, analytical and dosing algorithm methods. Here we review the fundamentals of beta-lactam TDM in critically ill patients, the existing clinical evidence and the practical aspects involved in beta-lactam TDM implementation.

A Comprehensive Analysis of the Impact of Acute Myocardial Infarction in Patients With Celiac Disease

Background and Aims

We aimed to study the impact of acute myocardial infarction (AMI) in patients with celiac disease (CD).

Methods

We used the National Inpatient Sample 2011-2018 to identify patients aged 18 years and older with a history of CD who presented with AMI using International Classification of Disease Nineth and Tenth Revision codes. Primary outcome of interest was mortality differences in AMI patients with and without CD. Secondary outcomes were in-hospital length of stay, hospital costs, and coronary revascularization.

Results

A total of 2,287,840 weighted patients were included in this study with a principal diagnosis of AMI. Among this population, 183,027 weighted patients had a history of CD (0.08%), and 2,286,010 weighted patients had AMI without a history of CD (99.92%). Most AMI patients with and without CD were older (69.57 ± 13.21 vs 67.08 ± 13.87 years, respectively) and white (92.55% vs 75.39%, respectively). Patients with AMI and CD were more likely to be female than patients without CD (53.76% vs 38.47%; P < .05). In our study, we found that the difference in hospital charges (adjusted mean difference $2644.7) was lower among AMI and CD; however, length of stay was higher among patients with CD (adjusted mean difference 0.36 day) although they were not statistically significant (P > .05). Both cohorts had higher number of Medicare recipients and lower number of patients who self-pay. Our study also found that smoking was more prevalent among patients with CD, 12.14%, vs patients without CD, 2.51%. Moreover, patients with CD who developed AMI had a lower adjusted odds of mortality than those without CD (adjusted odds ratio [aOR] 0.41; P < .05). Patients with CD and AMI also had lower odds of coronary revascularization (aOR 0.80; P < .05). In addition, we found that adults with CD had a lower odds of developing AMI (aOR 0.78; P < .05).

Conclusion

CD is a chronic disease leading to chronic inflammation and various nutrition-related problems which can lead to increased morbid conditions. However, we found lower odds of AMI among patients with CD, as well as lower mortality and comorbidities related to AMI, thus contradicting previous assumptions.

The Practical Problem With Carbapenem Testing and Reporting Accurate Bacterial Susceptibilities

Background: Antibiotic resistance is an evolving issue which requires constant review. Susceptibility breakpoints are revised in line with new microbiological and pharmacological data. Susceptibility breakpoints for carbapenems and Enterobacterales were revised in response to the rise in resistance and the potential for standard doses of carbapenems to provide the necessary antibiotic exposure and to accurately identify rates of carbapenem resistance.

Objectives: This review sought to identify real-world implications associated with lack of testing and reporting current carbapenem breakpoints and potential barriers that may impede implementation of these strategies.

Methods: A literature review was conducted using PubMed and Google Scholar electronic databases.

Results: The failure to adopt revised breakpoints incurs negative clinical outcomes and carries increased cost implications. However, there were several impediments highlighted which are barriers for laboratories to implement breakpoint updates.

Conclusion: Possible practical steps to implement revised breakpoints which apply to carbapenems and Enterobacterales are proposed. The challenge for laboratories is to be aware and implement these changes to provide accurate and relevant susceptibility results for clinicians.

Patterns, price and predictors of successful empiric antibiotic therapy in a real-world setting

WHAT IS KNOWN AND OBJECTIVE

Prompt and appropriate empiric antibiotic therapy (EAT) remains the cornerstone of successful outcomes, while the majority of blood cultures do not identify pathogen. We aimed to report patterns of EAT and its impact on outcomes and associated medical costs, while exploring predictors of its success in a real-world setting.

METHODS

We retrospectively utilized the prospective registry of the medical unit of a tertiary university hospital, including patients admitted with diagnosis of infection between 1st May 2016 and 1st May 2018. Costs of hospitalization and unit of antibiotic regimen were retrieved from a database regarding Greek hospitals containing hospitalization-cost data for each ICD-10 code and the national formulary, respectively.

RESULTS

A total of 489 patients were included in this study. Mean age was 61.3 years, 53% were males, while intra-abdominal infections predominated (55%). The most commonly administered EAT included quinolones (48%), followed by piperacillin/tazobactam (18%), or other regimens alone or in combination. EAT was successful in 67% and failed in 33% of cases. Fourteen patients died of the infection before EAT was switched, while among 55 patients that EAT had to be modified, mortality was 22%. Presence of urinary tract infection and use of quinolones, least predicted for failure of EAT [OR:0.15 (0.07-0.35), p < 0.0001, OR:0.53 (0.32-0.90), p = 0.019, respectively], in contrast to presence of sepsis [OR:3.11 (1.79-5.40), p < 0.0001]. Patients with failure had longer length of stay [7(5-11) versus 4 (3-6) days], higher antibiotic [201.9 (97.8-471.8) vs 104.6 (60.2-187.7) euros] and hospitalization costs [1409.3 (945.4-2311.6) vs 759.4 (516.5-1036.5) euros] (p < 0.0001).

DISCUSSION

We observed significantly increased antibiotic-related, healthcare-related costs and length of stay in patients with failure of EAT. Moreover, in our cohort, absence of sepsis, presence of urinary tract infection and use of quinolones better predicted for success of EAT.

WHAT IS NEW AND CONCLUSIONS

Appropriate selection of EAT is crucial to ensure better outcomes and minimize costs.

Review of methods and study designs of evaluations related to clinical pathways

Objective The HealthPathways program is an online information portal that helps clinicians provide consistent and integrated patient care within a local health system through localised pathways for diagnosis, treatment and management of various health conditions. These pathways are consistent with the definition of clinical pathways. Evaluations of HealthPathways programs have thus far focused primarily on website utilisation and clinical users' experience and satisfaction, with limited evidence on changes to patient outcomes. This lack motivated a literature review of the effects of clinical pathways on patient and economic outcomes to inform a subsequent HealthPathways evaluation. Methods A systematic review was performed to summarise the analytical methods, study designs and results of studies evaluating clinical pathways with an economic outcome component published between 1 January 2000 and 31 August 2017 in four academic literature databases. Results Fifty-five relevant articles were identified for inclusion in this review. The practical pre-post study design with retrospective baseline data extraction and prospective intervention data collection was most commonly used in the evaluations identified. Straightforward statistical methods for comparing outcomes, such as the t-test or χ2 test, were frequently used. Only four of the 55 articles performed a cost-effectiveness analysis. Clinical pathways were generally associated with improved patient outcomes and positive economic outcomes in hospital settings. Conclusions Clinical pathways evaluations commonly use pragmatic study designs, straightforward statistical tests and cost-consequence analyses. More HealthPathways program evaluations focused on patient and economic outcomes, clinical pathway evaluations in a primary care setting and cost-effectiveness analyses of clinical pathways are needed. What is known about the topic? HealthPathways is a web-based program that originated from Canterbury, New Zealand, and has seen uptake elsewhere in New Zealand, Australia and the UK. The HealthPathways program aims to assist the provision of consistent and integrated health services through dedicated, localised pathways for various health conditions specific to the health region. Evaluations of HealthPathways program focused on patient and economic outcomes have been limited. What does this paper add? This review synthesises the academic literature of clinical pathways evaluations in order to inform a subsequent HealthPathways evaluation. The focus of the synthesis was on the analytical methods and study designs used in the previous evaluations. The previous clinical pathway evaluations have been pragmatic in nature with relatively straightforward study designs and analysis. What are the implications for practitioners? There is a need for more economic and patient outcome evaluations for HealthPathways programs. More sophisticated statistical analyses and economic evaluations could add value to these evaluations, where appropriate and taking into consideration the data limitations.

Impact of Extended- Versus Intermittent-Infusion Cefepime on Clinical Outcomes in Hospitalized Patients

Background: Pharmacodynamic models support potential improved antimicrobial pharmacokinetic and pharmacodynamic goal attainment in patients treated with extended-infusion (EI) versus intermittent-infusion (II) cefepime. Small clinical studies demonstrate inconsistent findings in patient outcomes, necessitating a deeper review of this administration method. Methods: This was a retrospective cohort study comparing patients receiving EI versus II cefepime between September 1, 2017, and March 31, 2018. The primary outcome was in-hospital all-cause mortality. Secondary objectives included length of hospital and ICU stay, time to defervescence, duration of therapy, duration of mechanical ventilation, and readmission rate. Subgroup analyses for the primary objective were conducted based on comorbid burden and isolate susceptibilities. Results: No statistically significant differences were noted in the 645 included patients for the primary outcome between the EI and II groups (7.8% vs 10.4%, P = .32). Median length of stay was 9 days (IQR 12) versus 11 days (IQR 14) (P = .30), respectively. In addition, statistical significance was not seen in any of the subgroups for the primary outcome including patients with APACHE II score ≥ 20 (17.4% vs 30.6%, P = .26) and for infections caused by Pseudomonas aeruginosa (5.9% vs 20.0%, P = .23) or Enterobacteriaceae (11.1% vs 20.0%, P = .13) with minimum inhibitory concentration (MIC) ≥ 4. Conclusion: No statistically significant differences were noted between EI and II groups, although benefits in specific subpopulations may exist when these results are correlated with findings from studies examining alternative antipseudomonal beta lactams.

Antibiotic Breakpoints: How Redefining Susceptibility Preserves Efficacy and Improves Patient Care

Carbapenems are a primary treatment for infections from multidrug-resistant bacterial pathogens. To maintain their efficacy and control the emergence of further resistance, breakpoints that correspond to recommended doses with appropriate PK/PD target attainment are paramount.

Diagnostic efficacy of serum procalcitonin, C-reactive protein concentration and clinical pulmonary infection score in Ventilator-Associated Pneumonia

OBJECTIVE

The aim of this study was to evaluate the diagnostic efficacy of serum procalcitonin (PCT), c-reactive protein (CRP) concentration and clinical pulmonary infection score(CPIS) in ventilator-associated pneumonia(VAP).

METHODS

Forty-nine patients who were admitted to the intensive care unit (ICU) of Zhejiang Hospital with suspected VAP were recruited in this study. The serum level of PCT and CRP of all patients were measured and CPIS was calculated at the time of VAP suspected diagnosis. Of the included 49 patients, 24 were finally confirmed of VAP by microbiology assay. And the other 25 patients were considered as clinical suspected VAP without microbiology confirmation. The diagnostic sensitivity, specificity and area under the receiver operating characteristic (ROC) curve (AUC) were calculated using the serum PCT, CRP concentration and CPIS. The correlation among serum PCT, CRP concentration and CPIS were also evaluated by Spearson correlation test.

RESULTS

A total of 100 bronchoscopic aspiration sputum specimen were examined in bacterial culture. 30 samples were found with suspected pathogenic bacteria. Six samples were found with 2 types of suspected pathogenic bacteria. PCT serum concentration and CPIS score were significantly different (P<0.05) between the patient group [1.4 (0.68 ∼ 2.24), 6.0 (4.25 ∼ 8.00)] and the control group [0.4 (0.17 ∼ 1.39), 3.0 (1.00 ∼ 5.00)] ; However, the serum CRP [102.8(66.75 ∼ 130.90) vs 86.1(66.95 ∼ 110.10)] was not statistically different between the two groups (P>0.05). A significant correlation was found between serum PCT and CRP concentrations (r=0.55, P<0.01), but not between PCT vs CPIS and CRP vs CPIS (p>0.05). The diagnostic sensitivity, specificity and AUC were 72.0%, 75.0%, 0.81 (0.69 ∼ 0.93) for CPIS; 60.0%, 87.5%, 0.76 (0.62 ∼ 0.90) for PCT and 68.0%, 58.3%, 0.59 (0.43 ∼ 0.76) for CRP.

CONCLUSION

PCT serum level and CPIS score are elevated in VAP patients and could therefore represent potential biomarkers for VAP early diagnosis.

β-lactam antibiotic concentrations during continuous renal replacement therapy

Introduction

The use of standard doses of β-lactam antibiotics during continuous renal replacement therapy (CRRT) may result in inadequate serum concentrations. The aim of this study was to evaluate the adequacy of unadjusted drug regimens (i.e., similar to those used in patients with normal renal function) in patients treated with CRRT and the influence of CRRT intensity on drug clearance.

Methods

We reviewed data from 50 consecutive adult patients admitted to our Department of Intensive Care in whom routine therapeutic drug monitoring (TDM) of broad-spectrum β-lactam antibiotics (ceftazidime or cefepime, CEF; piperacillin/tazobactam; TZP; meropenem, MEM) was performed using unadjusted β-lactam antibiotics regimens (CEF = 2 g q8h; TZP = 4 g q6h; MEM = 1 g q8h). Serum drug concentrations were measured twice during the elimination phase by high-performance liquid chromatography (HPLC-UV). We considered therapy was adequate when serum drug concentrations were between 4 and 8 times the minimal inhibitory concentration (MIC) of Pseudomonas aeruginosa during optimal periods of time for each drug (≥70% for CEF; ≥ 50% for TZP; ≥ 40% for MEM). Therapy was considered as early (ET) or late (LT) phase if TDM was performed within 48 hours of antibiotic initiation or later on, respectively.

Results

We collected 73 serum samples from 50 patients (age 58 ± 13 years; Acute Physiology and Chronic Health Evaluation II (APACHE II) score on admission 21 (17–25)), 35 during ET and 38 during LT. Drug concentrations were above 4 times the MIC in 63 (90%), but above 8 times the MIC in 39 (53%) samples. The proportions of patients with adequate drug concentrations during ET and LT were quite similar. We found a weak but significant correlation between β-lactam antibiotics clearance and CRRT intensity.

Conclusions

In septic patients undergoing CRRT, doses of β-lactam antibiotics similar to those given to patients with normal renal function achieved drug levels above the target threshold in 90% of samples. Nevertheless, 53% of samples were associated with very high drug levels and daily drug regimens may need to be adapted accordingly.

Optimal dosing of antibiotics in critically ill patients by using continuous/extended infusions: a systematic review and meta-analysis

Introduction

The aim of this study was to determine whether using pharmacodynamic-based dosing of antimicrobials, such as extended/continuous infusions, in critically ill patients is associated with improved outcomes as compared with traditional dosing methods.

Methods

We searched Medline, HealthStar, EMBASE, Cochrane Clinical Trial Registry, and CINAHL from inception to September 2013 without language restrictions for studies comparing the use of extended/continuous infusions with traditional dosing. Two authors independently selected studies, extracted data on methodology and outcomes, and performed quality assessment. Meta-analyses were performed by using random-effects models.

Results

Of 1,319 citations, 13 randomized controlled trials (RCTs) (n = 782 patients) and 13 cohort studies (n = 2,117 patients) met the inclusion criteria. Compared with traditional non-pharmacodynamic-based dosing, RCTs of continuous/extended infusions significantly reduced clinical failure rates (relative risk (RR) 0.68; 95% confidence interval (CI) 0.49 to 0.94, P = 0.02) and intensive care unit length of stay (mean difference, −1.5; 95% CI, −2.8 to −0.2 days, P = 0.02), but not mortality (RR, 0.87; 95% CI, 0.64 to 1.19; P = 0.38). No significant between-trial heterogeneity was found for these analyses (I² = 0). Reduced mortality rates almost achieved statistical significance when the results of all included studies (RCTs and cohort studies) were pooled (RR, 0.83; 95% CI, 0.69 to 1.00; P = 0.054).

Conclusions

Pooled results from small RCTs suggest reduced clinical failure rates and intensive care unit length-of-stay when using continuous/extended infusions of antibiotics in critically ill patients. Reduced mortality rates almost achieved statistical significance when the results of RCTs were combined with cohort studies. These results support the conduct of adequately powered RCTs to define better the utility of continuous/extended infusions in the era of antibiotic resistance.

Prolonging β-lactam infusion: a review of the rationale and evidence, and guidance for implementation

Given the sparse antibiotic pipeline and the increasing prevalence of resistant organisms, efforts should be made to optimise the pharmacodynamic exposure of currently available agents. Prolonging the infusion duration is a strategy used to increase the percentage of the dosing interval that free drug concentrations remain above the minimum inhibitory concentration (fT>MIC), the pharmacodynamic efficacy driver for time-dependent antibiotics such as β-lactams. β-Lactams, the most commonly prescribed class of antibiotics owing to their efficacy and safety profile, have been the mainstay of therapy since the discovery of penicillin over 60 years ago. Mounting evidence, including the use of population pharmacokinetic modelling and Monte Carlo simulation, suggests that prolonging the infusion time of β-lactam antibiotics may have advantages over standard infusion techniques, including an enhanced probability of achieving requisite fT>MIC exposures, lower mortality and potentially reductions in infection/antibiotic-related costs. As a result of these favourable attributes, clinical practice guidelines support the use of prolonged-infusion β-lactams in the treatment of many severe infections. This article discusses the rationale and evidence for prolonging the infusion of β-lactam antibiotics and provides guidance for the implementation of a prolonged-infusion programme.

Strategies to minimize antibiotic resistance

Antibiotic resistance can be reduced by using antibiotics prudently based on guidelines of antimicrobial stewardship programs (ASPs) and various data such as pharmacokinetic (PK) and pharmacodynamic (PD) properties of antibiotics, diagnostic testing, antimicrobial susceptibility testing (AST), clinical response, and effects on the microbiota, as well as by new antibiotic developments. The controlled use of antibiotics in food animals is another cornerstone among efforts to reduce antibiotic resistance. All major resistance-control strategies recommend education for patients, children (e.g., through schools and day care), the public, and relevant healthcare professionals (e.g., primary-care physicians, pharmacists, and medical students) regarding unique features of bacterial infections and antibiotics, prudent antibiotic prescribing as a positive construct, and personal hygiene (e.g., handwashing). The problem of antibiotic resistance can be minimized only by concerted efforts of all members of society for ensuring the continued efficiency of antibiotics.

Antimicrobial stewardship in hospitals: Does it work and can we do it?

Selection of resistant pathogens by antimicrobial use is probably the most important cause of antimicrobial resistance. Antimicrobial stewardship (AMS) refers to a multifaceted approach to optimise prescribing. The benefits of AMS programmes have been widely demonstrated in terms of reductions in antimicrobial use, mortality, Clostridium difficile and other healthcare-associated infections, hospital length of stay and bacterial resistance. Several kinds of interventions (i.e. restriction of drugs, pre-authorisation of certain antimicrobials, joint clinical rounds with prescribers, implementation of guidelines and education) have shown positive results. Regrettably, in most hospitals in Latin America, Asia and Africa as well as in a significant proportion of institutions in Europe and North America, essential human and material resources are scarce or absent, and teams are neither developed nor well functioning. Despite current or potential barriers, we should start or improve our already ongoing initiatives on AMS by considering the main specific problems and act accordingly with the available human and material resources. From supervising the use of specific classes of drugs to implementing more sophisticated decision support programmes, there is a wide range of possible useful interventions.

Inappropriate antibiotic use due to decreased compliance with a ventilator-associated pneumonia computerized clinical pathway: implications for continuing education and prospective feedback

STUDY OBJECTIVE

To assess the impact of noncompliance with a ventilator-associated pneumonia (VAP) computerized clinical pathway (CCP) on antibiotic use after removal of prospective antibiotic stewardship resources.

DESIGN

Retrospective, observational, quasi-experimental study.

SETTING

Three intensive care units (medical, surgical, and neurotrauma) in a large, tertiary care hospital.

PATIENTS

A total of 136 patients with culture-positive VAP; 72 were treated from September 2006-August 2007 (period 1), during which use of the CCP was mandatory along with aggressive stewardship support, and 64 were treated from September 2009-April 2010 (period 2), during which use of the CCP was voluntary.

MEASUREMENTS AND MAIN RESULTS

Compliance with use of the CCP was 100% during period 1 and 44% (28/64 patients) during period 2. For the 36 patients (56%) whose antibiotic selection did not comply with the CCP, empiric antibiotics were selected by provider discretion. Most patients had late-onset VAP and were similar with respect to age, sex, and comorbidities between the two periods. Staphylococcus aureus (11-17% methicillin-resistant S. aureus) and Pseudomonas aeruginosa were the most common pathogens during both periods. The proportion of patients with appropriate antibiotics within 24 hours of VAP identification was not significantly different between period 1 (70.8%) and period 2 (56.3%, p=0.112). During period 2, patients who were treated according to the CCP were more likely to receive appropriate antibiotic therapy compared with patients treated according to provider discretion (82.1% vs 36.1%, p ≤ 0.001). Time to appropriate therapy was also shorter for patients treated according to the CCP (mean ± SD 0.43 ± 1.14 vs 1.29 ± 1.36 days, p=0.003). Treatment with the CCP was the only variable significantly associated with appropriate antibiotic therapy (odds ratio 4.8, 95% confidence interval 2.1-10.9). Mortality was not significantly different between period 1 and period 2, and only Acute Physiology and Chronic Health Evaluation II score and admission with a head injury were predictive of death. Finally, a greater proportion of patients treated with the CCP were de-escalated from anti- Pseudomonas β-lactams (85.0% vs 33.3%, p=0.006) when they were not necessary.

CONCLUSION

These data highlight the importance of continued stewardship resources after CCP implementation to ensure compliance and to maximize antibiotic stewardship outcomes.

Implementation and outcomes of a critical pathway for lumbar laminectomy or microdiscectomy

Objective

The aim of this study is to implement a critical pathway (CP) for patients undergoing lumbar laminectomy or microdiscectomy and describe the results before and after the CP in terms of length of hospital stay and cost.

Methods

From March 2008 to February 2009, 61 patients underwent lumbar laminectomy or microdiscectomy due to stenosis or one- or two-level disc herniation in our department and were included in the prepathway group. After development and implementation of the CP in March 2009, 58 patients were applicable for the CP, and these were classified as the postpathway group.

Results

The CP, which established a 6-day hospital stay (5 bed-days), was fulfilled by 42 patients (72.4%) in the postpathway group. The mean length of stay was 5.4 days in the postpathway group compared to 6.9 days in the prepathway group, demonstrating a 20% reduction, which was a statistically significant difference (p≤0.000). There was a statistically significant reduction in charges for bed and nursing care (p=0.002).

Conclusion

Implementation of a CP for lumbar laminectomy or microdiscectomy produced significant decreases in length of hospitalization and charges for bed and nursing care. We believe that this CP reduces the unnecessary use of hospital resources without increasing risk of adverse events.

Current challenges in the management of the infected patient

PURPOSE OF REVIEW

Management of hospital-associated infections (HAIs) has been made more challenging by the increasing proportion of immunocompromised or otherwise severely ill patients and increasing prevalence of antibiotic-resistant pathogens in this environment. This review examines strategies to optimize clinical outcomes and lower healthcare costs for patients with HAIs by focusing on patient-related, pathogen-related, and drug-related factors.

RECENT FINDINGS

Factors have converged to increase the risk of infection with antibiotic-resistant pathogens in the current hospital environment, including the increasing prevalence of resistant species and number of hospitalized patients with conditions increasingly susceptible to infection with drug-resistant bacteria. Although the list of bacterial pathogens associated with HAIs has been fairly constant over time, the prevalence and resistance profile of these individual species continues to evolve. Periodic antibiograms should be utilized to access local patterns of resistance within the different hospital wards. Outcomes for patients with HAIs are optimized with early empiric treatment with an appropriate regimen, selected on the basis of patient characteristics and local resistance patterns. Dosing strategies should be utilized to ensure that the efficacy of an appropriate antibiotic is optimized, by achieving the pharmacodynamic target predictive of its efficacy. Using these strategies improves quality of care and is associated with lower overall healthcare costs.

SUMMARY

Bacterial resistance is an increasing problem in the hospital environment, and has been associated with poorer clinical outcomes and elevated healthcare costs. By using patient characteristics, local antibiograms, and dosing strategies to achieve an optimal pharmacodynamic profile, early appropriate empiric therapy can be utilized to improve clinical outcomes, minimize the development of resistance, and reduce healthcare costs.

Hydrogen peroxide enhances phagocytosis of Pseudomonas aeruginosa in hyperoxia

Mechanical ventilation with hyperoxia is a necessary treatment for patients with respiratory distress. However, patients on mechanical ventilation have increased susceptibility to infection. Studies including ours have shown that reactive oxygen species (ROS), generated by exposure to prolonged hyperoxia, can cause a decrease in the phagocytic activity of alveolar macrophages. Hydrogen peroxide (H₂O₂) is a form of ROS generated under hyperoxic conditions. In this study, we examined whether treatment with H₂O₂ directly affects macrophage phagocytic ability in RAW 264.7 cells that were exposed to either 21% O₂ (room air) or 95% O₂ (hyperoxia). Moderate concentrations (ranging from 10 to 250 μM) of H₂O₂ significantly enhanced macrophage phagocytic activity and restored hyperoxia-suppressed phagocytosis through attenuation of hyperoxia-induced disorganization of actin cytoskeleton and actin oxidation. These results indicate that H₂O₂ at low-moderate concentrations can be beneficial to host immune responses by improving macrophage phagocytic activity.

Use of pharmacodynamic principles to inform β-lactam dosing: "S" does not always mean success

Dose optimization is one of the key strategies for enhancing antimicrobial stewardship. There have been tremendous strides in our understanding of antibiotic exposure-response relationships over the past 25 years. For many antibiotics, the "pharmacodynamic" or the exposure variable associated with outcome has been identified. With advances in mathematical modeling, it is possible to apply our understanding of antimicrobial pharmacodynamics (PD) into clinical practice and design empirical regimens that have a high probability of achieving the PD target linked to effect. By optimizing antibiotic doses to achieve PD targets predictive of efficacy, clinicians can improve care and minimize drug toxicity. For β-lactams, the PD parameter most predictive of maximal bactericidal activity is the duration of time free drug concentrations remain above the minimum inhibitory concentration (MIC) during the dosing interval (fT > MIC). Unfortunately, the conventional intermittent β-lactam dosing schemes often used in practice have suboptimal PD profiles. Prolonging the infusion time of β-lactams is one method to maximize the probability of achieving concentrations in excess of the MIC for the majority of the dosing interval, especially against pathogens with elevated MIC values. Prolonged infusions of intravenous β-lactams are not only associated with improved probability of target attainment (PTA) profiles but offer possible cost savings and greater potential for reducing emergence of resistance relative to intermittent infusions.