Antibiotic rotation strategies to reduce antimicrobial resistance in Gram-negative bacteria in European intensive care units: study protocol for a cluster-randomized crossover controlled trial

Antibiotic Stewardship and Treatment of Uncomplicated Urinary Tract Infection (UTI) in Children and Adolescents in the Emergency Department of a Community Hospital

A retrospective, cross-sectional study of children with suspected urinary tract infections (UTIs) 3 months to 18 years of age who had a urinalysis and urine culture (UC) during an emergency department (ED) visit between 2019 and 2020 was performed. Chi-square, Fisher exact, and independent samples T tests were used as appropriate. Median age was 6.6 years (interquartile range = 3.3-12.4). Urinalysis positivity was 92.8%, of which 81.9% of children were prescribed a first-line antibiotic. First-line antibiotic use was 82.7%. Positive UC rate was 84.7%, with 84% receiving a first-line antibiotic (P = .025). The correlation between a positive urinalysis and a positive UC was 80.8% (P < .001). Change of antibiotics based on the uropathogen of positive UCs was 6.3% (P < .001). The urinalysis and UC guided the diagnosis and treatment of UTIs. First-line antibiotics can be safely administered in the ED and prescribed for positive urinalyses. Studies are needed to evaluate the discontinuation of antibiotics with negative UCs as part of antibiotic stewardship initiatives.

Antibiotic Prophylaxis in Surgery: Current Insights and Future Directions for Surgical Site Infection Prevention

Surgical site infections (SSIs) remain a significant concern in the field of surgery, contributing to patient morbidity, prolonged hospital stays, and increased healthcare costs. Antibiotic prophylaxis, the administration of antibiotics before surgery, has been a cornerstone in preventing SSIs for decades. This review explores the current state of antibiotic prophylaxis in surgery, offering insights into its effectiveness, challenges, and emerging trends. In this comprehensive analysis, we delve into the historical development of antibiotic prophylaxis, examining its evolution from early practices to modern guidelines. We explore the various classes of antibiotics commonly used, their dosing regimens, and the importance of timing in optimizing prophylactic interventions. Additionally, we investigate the role of patient-specific factors, such as comorbidities and allergies, in tailoring antibiotic prophylaxis to individual needs. While antibiotic prophylaxis has undeniably reduced the incidence of SSIs, concerns about antimicrobial resistance and adverse effects necessitate a reevaluation of current practices. This review presents a critical assessment of the challenges posed by the overuse and misuse of antibiotics in surgery and highlights the urgent need for judicious antibiotic stewardship. Moreover, the future of antibiotic prophylaxis holds promise with the emergence of innovative strategies such as antimicrobial coatings, probiotics, and immunomodulatory agents. We discuss these novel approaches and their potential to enhance SSI prevention while minimizing antibiotic-related risks. In conclusion, antibiotic prophylaxis in surgery has been instrumental in reducing SSIs, but its continued effectiveness requires a multifaceted approach. By addressing current challenges, promoting antibiotic stewardship, and embracing innovative strategies, we can advance the field of SSI prevention and improve patient outcomes in the years to come. This review provides valuable insights and direction for clinicians, researchers, and policymakers as they navigate the evolving landscape of surgical prophylaxis.

Correlation between Antimicrobial Resistance and the Hospital-Wide Diverse Use of Broad-Spectrum Antibiotics by the Antimicrobial Stewardship Program in Japan

Increased antibiotic use and antibiotic homogeneity cause selective pressure. This study investigated the correlation between antibiotic diversity and antimicrobial resistance (AMR) in Gram-negative organisms. The days of therapy/100 patient-days (DOT) for four broad-spectrum antibiotic classes were evaluated for 2015-2022. The antibiotic heterogeneity index (AHI) for the equal use of four classes (25%) and the modified AHI for the equal use of three classes (30%), excluding fluoroquinolones (10%), were measured (target: 1.0). Quarterly antibiotic use markers and the resistance rates against ≥2 anti-Pseudomonas antibiotics were compared. The DOT value was 9.94, and the relative DOT were 34.8% for carbapenems, 32.1% for piperacillin/tazobactam, 24.3% for fourth generation cephalosporins/ceftazidime/aztreonam, and 8.9% for fluoroquinolones. Although no correlation was found between the total DOT and the resistance rate for any bacterium, a significant negative correlation was found between the heterogeneity indices and resistance rates for Pseudomonas aeruginosa and Klebsiella pneumoniae. The significant cutoffs that discriminate the risk of resistance were 0.756 for the AHI and 0.889 for the modified AHI for K. pneumoniae. Antibiotic diversity is more important in preventing AMR than overall antibiotic use. The ideal ratio of broad-spectrum antibiotics should be studied for diversified use to prevent AMR.

Clinical Laboratory Features of Microbes That Cause Neonatal Sepsis: An 8-Year Retrospective Study

Purpose

To determine the distribution and antibiotic resistance patterns among pathogens that cause neonatal sepsis (NS) and to assess trends in antibiotic resistance.

Patients and methods

A total of 864 patients with sepsis admitted to a neonatal intensive care unit (NICU) between 2014 and 2021 were enrolled. Data on neonate age and sex, pathogenic microbes, and antimicrobial susceptibility were collected. Univariate and linear regression analyses were performed to determine the differences and trends in antibiotic resistance rates.

Results

The overall incidence rate of NS was 4.59 cases per 1000 live births. Of these cases, 255 (29.5%) were early-onset neonatal sepsis (EONS) and 609 (70.5%) were late-onset neonatal sepsis (LONS). A total of 670 (70.5%) gram-positive cocci and 171 (19.8%) gram-negative bacilli were identified. Among the 552 coagulase-negative Staphylococcus (CoNS) strains, the rate of oxacillin resistance was 70.6%, but no strains were resistant to linezolid, vancomycin or tigecycline. Among the antibiotic resistance patterns of the top three gram-negative pathogens, K. pneumoniae showed the highest rates of resistance, with resistance rates of 37.9% and 39.4% to ertapenem and imipenem, respectively, while E. coli and Enterobacter cloacae showed high levels of susceptibility to both. With regard to the trends in resistance among important pathogens, the rates of resistance to rifampicin, ciprofloxacin, levofloxacin, moxifloxacin and clindamycin by Staphylococcus epidermidis significantly decreased (p<0.05) during the study period. E. coli strains exhibited a significant increase in ceftriaxone resistance during the study period (p<0.05).

Conclusion

CoNS was the main microbe that caused NS, followed by E. coli. The bacterial isolates showed varying levels of resistance to the antimicrobial drugs tested. Thus, periodic surveillance in hospital settings to monitor changes in pathogens and antibiotic resistance is important.

Surgical Infection Society Research Priorities: A Narrative Review of Fourteen Years of Progress

Background: In 2006, the Surgical Infection Society (SIS) utilized a modified Delphi approach to define 15 specific priority research questions that remained unanswered in the field of surgical infections. The aim of the current study was to evaluate the scientific progress achieved during the ensuing period in answering each of the 15 research questions and to determine if additional research in these fields is warranted. Methods: For each of the questions, a literature search using the National Center for Biotechnology Information (NCBI) was performed by the Scientific Studies Committee of the SIS to identify studies that attempted to address each of the defined questions. This literature was analyzed and summarized. The data on each question were evaluated by a surgical infections expert to determine if the question was answered definitively or remains unanswered. Results: All 15 priority research questions were studied in the last 14 years; six questions (40%) were definitively answered and 9 questions (60%) remain unanswered in whole or in part, mainly because of the low quality of the studies available on this topic. Several of the 9 unanswered questions were deemed to remain research priorities in 2020 and warrant further investigation. These included, for example, the role of empiric antimicrobial agents in nosocomial infections, the use of inotropes/vasopressors versus volume loading to raise the mean arterial pressure, and the role of increased antimicrobial dosing and frequency in the obese patient. Conclusions: Several surgical infection-related research questions prioritized in 2006 remain unanswered. Further high-quality research is required to provide a definitive answer to many of these priority knowledge gaps. An updated research agenda by the SIS is warranted at this time to define research priorities for the future.

Optimising efficacy of antibiotics against systemic infection by varying dosage quantities and times

Mass production and use of antibiotics has led to the rise of resistant bacteria, a problem possibly exacerbated by inappropriate and non-optimal application. Antibiotic treatment often follows fixed-dose regimens, with a standard dose of antibiotic administered equally spaced in time. But are such fixed-dose regimens optimal or can alternative regimens be designed to increase efficacy? Yet, few mathematical models have aimed to identify optimal treatments based on biological data of infections inside a living host. In addition, assumptions to make the mathematical models analytically tractable limit the search space of possible treatment regimens (e.g. to fixed-dose treatments). Here, we aimed to address these limitations by using experiments in a Galleria mellonella (insect) model of bacterial infection to create a fully parametrised mathematical model of a systemic Vibrio infection. We successfully validated this model with biological experiments, including treatments unseen by the mathematical model. Then, by applying artificial intelligence, this model was used to determine optimal antibiotic dosage regimens to treat the host to maximise survival while minimising total antibiotic used. As expected, host survival increased as total quantity of antibiotic applied during the course of treatment increased. However, many of the optimal regimens tended to follow a large initial ‘loading’ dose followed by doses of incremental reductions in antibiotic quantity (dose ‘tapering’). Moreover, application of the entire antibiotic in a single dose at the start of treatment was never optimal, except when the total quantity of antibiotic was very low. Importantly, the range of optimal regimens identified was broad enough to allow the antibiotic prescriber to choose a regimen based on additional criteria or preferences. Our findings demonstrate the utility of an insect host to model antibiotic therapies in vivo and the approach lays a foundation for future regimen optimisation for patient and societal benefits.

Research into optimal antibiotic use to improve efficacy is far behind that of cancer care, where personalised treatment is common. The integration of mathematical models with biological observations offers hope to optimise antibiotic use, and in this present study an in vivo insect model of systemic Vibrio infection was used for the first time to determine critical model parameters for optimal antibiotic treatment. By this approach, the optimal regimens tended to result from a large initial ‘loading’ dose followed by subsequent doses of incremental reductions in antibiotic quantity (dose ‘tapering’). The approach and findings of this study opens a new avenue towards optimal application of our precious antibiotic arsenal and may lead to more effective treatment regimens for patients, thus reducing the health and economic burdens associated with bacterial infections. Importantly, it can be argued that until we understand how to use a single antibiotic optimally, it is unlikely we will identify optimal ways to use multiple antibiotics simultaneously.

Effective Antimicrobial StewaRdship StrategIES (ARIES): Cluster Randomized Trial of Computerized Decision Support System and Prospective Review and Feedback

Background

Prospective review and feedback (PRF) of antibiotic prescriptions and compulsory computerized decision support system (CDSS) are 2 strategies of antimicrobial stewardship. There are limited studies investigating their combined effects. We hypothesized that the use of on-demand (voluntary) CDSS would achieve similar patient outcomes compared with automatically triggered (compulsory) CDSS whenever broad-spectrum antibiotics are ordered.

Methods

A parallel-group, 1:1 block cluster randomized crossover study was conducted in 32 medical and surgical wards from March to August 2017. CDSS use for piperacillin-tazobactam or carbapenem in the intervention clusters was at the demand of the doctor, while in the control clusters CDSS use was compulsory. PRF was continued for both arms. The primary outcome was 30-day mortality.

Results

Six hundred forty-one and 616 patients were randomized to voluntary and compulsory CDSS, respectively. There were no differences in 30-day mortality (hazard ratio [HR], 0.87; 95% CI, 0.67–1.12), re-infection and re-admission rates, antibiotic duration, length of stay, or hospitalization cost. The proportion of patients receiving PRF recommendations was not significantly lower in the voluntary CDSS arm (62 [10%] vs 81 [13%]; P = .05). Appropriate indication of antibiotics was high in both arms (351/448 [78%] vs 330/433 [74%]; P = .18). However, in geriatric medicine patients where antibiotic appropriateness was <50%, prescription via compulsory CDSS resulted in a shorter length of stay and lower hospitalization cost.

Conclusions

Voluntary broad-spectrum antibiotics with PRF via CDSS did not result in differing clinical outcomes, antibiotic duration, or length of stay. However, in the setting of low antibiotic appropriateness, compulsory CDSS may be beneficial.

Challenges and opportunities for antimicrobial stewardship in resource-rich and resource-limited countries

Introduction: Inappropriate prescription practices, patient and provider knowledge and attitudes, variable availability of diagnostic and surveillance systems, and the unrestricted use of antimicrobials in animals and plants are contributory factors to the global crisis of antimicrobial resistance (AMR). Areas covered: Notwithstanding that interventions to revert AMR should be tailored to the socio-politico-economic landscape, there is a global consensus for the implementation and enhancement of antimicrobial stewardship strategies. Yet the implementation of Antimicrobial Stewardship Programs (ASPs) remains relatively limited within healthcare settings and faces complex challenges in resource-limited countries. The current review summarizes the limitations of current ASPs, translation challenges in resource-limited countries, and potential solutions. Expert opinion: Suboptimal ASP implementation in hospitals is multifactorial. Restriction of antimicrobial use should be informed by risk-benefit analyses, including the potential for substitute prescribing, and displacement of selection pressures. Thresholds in population use of antibiotics above which AMR increases may provide quantitative targets for ASPs. Horizontal and vertical collaborations involving policymakers and the general public are of paramount importance. While impactful prescribing changes require sustained engagement of the public and health-care professionals, we warn against over-estimating the benefits of behavioral interventions. We advocate for population-level stewardship interventions in addition to investment in structural factors that will aid ASP implementation.

Effect of multi-lumen perfusion line on catheter-related bacteremia in premature infants: study protocol for a cluster-randomized crossover trial

Background

Catheter-related bacteremia (CRB) is the most frequent nosocomial infection in neonatal intensive care unit (NICU) patients, especially in very low-birth-weight infants. Administration of injectable drugs in premature newborn infants has many particularities and several types of infusion incidents have been reported. The Edelvaiss® Multiline NEO device is a novel multi-lumen access infusion device adapted to the specificities of infusion in neonatology. This multicenter, randomized, controlled study was therefore designed to determine whether or not Edelvaiss® Multiline NEO reduces the risk of CRB in preterm newborn infants in an NICU.

Methods/design

This is a multicenter, randomized, controlled trial, using a cluster-randomized crossover design. Four investigator centers (four clusters) will participate in the study and will be randomized into two groups, corresponding to two different sequences (either the Edelvaiss® Multiline NEO or standard infusion system sequence, then vice versa). A total of 280 patients will be recruited. Infants will be enrolled in the study at the time of placing a single-lumen central venous catheter. Three visits recording specific data are planned in the study protocol. The primary outcome measure is the incidence density (ID) of CRB. For each patient, the total number of catheters and CRB incidents as well as the duration of stay in the NICU will be computed and considered for analysis.

Discussion

The study will provide high-quality evidence to determine whether the Multiline NEO device reduces the risk of CRB in preterm newborns in NICUs or not.

Trial registration

ClinicalTrials.gov, NCT02633124. Registered on 7 December 2015.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3218-6) contains supplementary material, which is available to authorized users.

Surface-attached sulfonamide containing quaternary ammonium antimicrobials for textiles and plastics

With the risks associated with healthcare-associated infections and the rise of antibiotic resistant microorganisms, there is an important need to control the proliferation of these factors in hospitals, retirement homes and other institutions. This work explores the development and application of a novel class of sulfonamide-based quaternary ammonium antimicrobial coatings, anchored to commercially and clinically relevant material surfaces. Synthesized in high yields (60–97%), benzophenone-anchored antimicrobials were spray-coated and UV grafted onto plastic surfaces, while silane-anchored variants were adhered to select textiles via dip-coating. Surface modified samples were characterised by advancing contact angle, anionic dye staining, X-ray photoelectron spectroscopy and atomic force microscopy. After verifying coating quality through the above characterization methods, microbiological testing was performed on batch samples in conditions that simulate the natural inoculation of surfaces and objects (solid/air) and water containers (solid/liquid). Using the previously established Large Drop Inoculum (LDI) protocol at solid/air interfaces, all treated samples showed a full reduction (10⁵–10⁷ CFU) of viable Arthrobacter sp., S. aureus, and E. coli after 3 h of contact time. Additional testing of the walls of plastic LDPE vials treated with a UV-cured sulfonamide antimicrobial at a solid/liquid interface using the newly developed Large Reservoir Inoculum (LRI) protocol under static conditions revealed a complete kill (>10⁶ reduction) of Gram-positive Arthrobacter sp., and a partial kill (>10⁴ reduction) of Gram-negative E. coli within 24–48 h of contact.

A series of surface attached silane or benzophenone sulfonamide quaternary ammonium antimicrobials show potent efficacy at solid/air and solid/liquid interfaces.

The effects of antibiotic cycling and mixing on antibiotic resistance in intensive care units: a cluster-randomised crossover trial

BACKGROUND

Whether antibiotic rotation strategies reduce prevalence of antibiotic-resistant, Gram-negative bacteria in intensive care units (ICUs) has not been accurately established. We aimed to assess whether cycling of antibiotics compared with a mixing strategy (changing antibiotic to an alternative class for each consecutive patient) would reduce the prevalence of antibiotic-resistant, Gram-negative bacteria in European intensive care units (ICUs).

METHODS

In a cluster-randomised crossover study, we randomly assigned ICUs to use one of three antibiotic groups (third-generation or fourth-generation cephalosporins, piperacillin-tazobactam, and carbapenems) as preferred empirical treatment during 6-week periods (cycling) or to change preference after every consecutively treated patient (mixing). Computer-based randomisation of intervention and rotated antibiotic sequence was done centrally. Cycling or mixing was applied for 9 months; then, following a washout period, the alternative strategy was implemented. We defined antibiotic-resistant, Gram-negative bacteria as Enterobacteriaceae with extended-spectrum β-lactamase production or piperacillin-tazobactam resistance, and Acinetobacter spp and Pseudomonas aeruginosa with piperacillin-tazobactam or carbapenem resistance. Data were collected for all admissions during the study. The primary endpoint was average, unit-wide, monthly point prevalence of antibiotic-resistant, Gram-negative bacteria in respiratory and perineal swabs with adjustment for potential confounders. This trial is registered with ClinicalTrials.gov, number NCT01293071.

FINDINGS

Eight ICUs (from Belgium, France, Germany, Portugal, and Slovenia) were randomly assigned and patients enrolled from June 27, 2011, to Feb 16, 2014. 4069 patients were admitted during the cycling periods in total and 4707 were admitted during the mixing periods. Of these, 745 patients during cycling and 853 patients during mixing were present during the monthly point-prevalence surveys, and were included in the main analysis. Mean prevalence of the composite primary endpoint was 23% (168/745) during cycling and 22% (184/853) during mixing (p=0·64), yielding an adjusted incidence rate ratio during mixing of 1·039 (95% CI 0·837-1·291; p=0·73). There was no difference in all-cause in-ICU mortality between intervention periods.

INTERPRETATION

Antibiotic cycling does not reduce the prevalence of carriage of antibiotic-resistant, Gram-negative bacteria in patients admitted to the ICU.

FUNDING

European Union Seventh Framework Programme.

Modeling antimicrobial cycling and mixing: Differences arising from an individual-based versus a population-based perspective

In order to manage bacterial infections in hospitals in the face of antibiotic resistance, the two treatment protocols "mixing" and "cycling" have received considerable attention both from modelers and clinicians. However, the terms are not used in exactly the same way by both groups. This comes because the standard modeling approach disregards the perspective of individual patients. In this article, we investigate a model that comes closer to clinical practice and compare the predictions to the standard model. We set up two deterministic models, implemented as a set of differential equations, for the spread of bacterial infections in a hospital. Following the traditional approach, the first model takes a population-based perspective. The second model, in contrast, takes the drug use of individual patients into account. The alternative model can indeed lead to different predictions than the standard model. We provide examples for which in the new model, the opposite strategy maximizes the number of uninfected patients or minimizes the rate of spread of double resistance. While the traditional models provide valuable insight, care is hence needed in the interpretation of results.

Clinical research in critical care. Difficulties and perspectives

In the field of Intensive Care Medicine, improved survival has resulted from better patient care, the early detection of clinical deterioration, and the prevention of iatrogenic complications, while research on new treatments has been followed by an overwhelming number of disappointments. The origins of these fiascos must be sought in the conjunction of methodological problems - common to other disciplines - and the particularities of critically ill patients. The present article discusses both aspects and suggests some options for progress.

Understanding the cluster randomised crossover design: a graphical illustraton of the components of variation and a sample size tutorial

BACKGROUND

In a cluster randomised crossover (CRXO) design, a sequence of interventions is assigned to a group, or 'cluster' of individuals. Each cluster receives each intervention in a separate period of time, forming 'cluster-periods'. Sample size calculations for CRXO trials need to account for both the cluster randomisation and crossover aspects of the design. Formulae are available for the two-period, two-intervention, cross-sectional CRXO design, however implementation of these formulae is known to be suboptimal. The aims of this tutorial are to illustrate the intuition behind the design; and provide guidance on performing sample size calculations.

METHODS

Graphical illustrations are used to describe the effect of the cluster randomisation and crossover aspects of the design on the correlation between individual responses in a CRXO trial. Sample size calculations for binary and continuous outcomes are illustrated using parameters estimated from the Australia and New Zealand Intensive Care Society - Adult Patient Database (ANZICS-APD) for patient mortality and length(s) of stay (LOS).

RESULTS

The similarity between individual responses in a CRXO trial can be understood in terms of three components of variation: variation in cluster mean response; variation in the cluster-period mean response; and variation between individual responses within a cluster-period; or equivalently in terms of the correlation between individual responses in the same cluster-period (within-cluster within-period correlation, WPC), and between individual responses in the same cluster, but in different periods (within-cluster between-period correlation, BPC). The BPC lies between zero and the WPC. When the WPC and BPC are equal the precision gained by crossover aspect of the CRXO design equals the precision lost by cluster randomisation. When the BPC is zero there is no advantage in a CRXO over a parallel-group cluster randomised trial. Sample size calculations illustrate that small changes in the specification of the WPC or BPC can increase the required number of clusters.

CONCLUSIONS

By illustrating how the parameters required for sample size calculations arise from the CRXO design and by providing guidance on both how to choose values for the parameters and perform the sample size calculations, the implementation of the sample size formulae for CRXO trials may improve.

A Concise Set of Structure and Process Indicators to Assess and Compare Antimicrobial Stewardship Programs Among EU and US Hospitals: Results From a Multinational Expert Panel

OBJECTIVES To develop common indicators, relevant to both EU member states and the United States, that characterize and allow for meaningful comparison of antimicrobial stewardship programs among different countries and healthcare systems. DESIGN Modified Delphi process. PARTICIPANTS A multinational panel of 20 experts in antimicrobial stewardship. METHODS Potential indicators were rated on the perceived feasibility to implement and measure each indicator and clinical importance for optimizing appropriate antimicrobial prescribing. RESULTS The outcome was a set of 33 indicators developed to characterize the infrastructure and activities of hospital antimicrobial stewardship programs. Among them 17 indicators were considered essential to characterize an antimicrobial stewardship program and therefore were included in a core set of indicators. The remaining 16 indicators were considered optional indicators and included in a supplemental set. CONCLUSIONS The integration of these indicators in public health surveillance and special studies will lead to a better understanding of best practices in antimicrobial stewardship. Additionally, future studies can explore the association of hospital antimicrobial stewardship programs to antimicrobial use and resistance. Infect Control Hosp Epidemiol 2016:1-11.

Evaluation of a Mixing versus a Cycling Strategy of Antibiotic Use in Critically-Ill Medical Patients: Impact on Acquisition of Resistant Microorganisms and Clinical Outcomes

Objective

To compare the effect of two strategies of antibiotic use (mixing vs. cycling) on the acquisition of resistant microorganisms, infections and other clinical outcomes.

Methods

Prospective cohort study in an 8-bed intensive care unit during 35- months in which a mixing-cycling policy of antipseudomonal beta-lactams (meropenem, ceftazidime/piperacillin-tazobactam) and fluoroquinolones was operative. Nasopharyngeal and rectal swabs and respiratory secretions were obtained within 48h of admission and thrice weekly thereafter. Target microorganisms included methicillin-resistant S. aureus, vancomycin-resistant enterococci, third-generation cephalosporin-resistant Enterobacteriaceae and non-fermenters.

Results

A total of 409 (42%) patients were included in mixing and 560 (58%) in cycling. Exposure to ceftazidime/piperacillin-tazobactam and fluoroquinolones was significantly higher in mixing while exposure to meropenem was higher in cycling, although overall use of antipseudomonals was not significantly different (37.5/100 patient-days vs. 38.1/100 patient-days). There was a barely higher acquisition rate of microorganisms during mixing, but this difference lost its significance when the cases due to an exogenous Burkholderia cepacia outbreak were excluded (19.3% vs. 15.4%, OR 0.8, CI 0.5–1.1). Acquisition of Pseudomonas aeruginosa resistant to the intervention antibiotics or with multiple-drug resistance was similar. There were no significant differences between mixing and cycling in the proportion of patients acquiring any infection (16.6% vs. 14.5%, OR 0.9, CI 0.6–1.2), any infection due to target microorganisms (5.9% vs. 5.2%, OR 0.9, CI 0.5–1.5), length of stay (median 5 d for both groups) or mortality (13.9 vs. 14.3%, OR 1.03, CI 0.7–1.3).

Conclusions

A cycling strategy of antibiotic use with a 6-week cycle duration is similar to mixing in terms of acquisition of resistant microorganisms, infections, length of stay and mortality.

Improved Designs for Cluster Randomized Trials

Studies in which clusters of individuals are randomized to conditions are increasingly common in public health research. However, the designs utilized for such studies are often suboptimal and inefficient. We review strategies to improve the design of cluster randomized trials. We discuss both older but effective design concepts that are underutilized, such as stratification and factorial designs, as well as emergent ideas including fractional factorial designs and cluster randomized crossover studies. We draw examples from the recent literature and provide resources for sample size and power planning. Given the inherent inefficiencies of cluster randomized trials, these design strategies merit wider consideration and can lead to studies that are more cost-effective and potentially more rigorous than traditional approaches.