Antimicrobial Stewardship Approaches in the Intensive Care Unit

Antimicrobial Resistance in Ventilator-Associated Pneumonia: Predictive Microbiology and Evidence-Based Therapy

Ventilator-associated pneumonia (VAP) is a serious intensive care unit (ICU)-related infection in mechanically ventilated patients that is frequent, as more than half of antibiotics prescriptions in ICU are due to VAP. Various risk factors and diagnostic criteria for VAP have been referred to in different settings. The estimated attributable mortality of VAP can go up to 50%, which is higher in cases of antimicrobial-resistant VAP. When the diagnosis of pneumonia in a mechanically ventilated patient is made, initiation of effective antimicrobial therapy must be prompt. Microbiological diagnosis of VAP is required to optimize timely therapy since effective early treatment is fundamental for better outcomes, with controversy continuing regarding optimal sampling and testing. Understanding the role of antimicrobial resistance in the context of VAP is crucial in the era of continuously evolving antimicrobial-resistant clones that represent an urgent threat to global health. This review is focused on the risk factors for antimicrobial resistance in adult VAP and its novel microbiological tools. It aims to summarize the current evidence-based knowledge about the mechanisms of resistance in VAP caused by multidrug-resistant bacteria in clinical settings with focus on Gram-negative pathogens. It highlights the evidence-based antimicrobial management and prevention of drug-resistant VAP. It also addresses emerging concepts related to predictive microbiology in VAP and sheds lights on VAP in the context of coronavirus disease 2019 (COVID-19).

Arginine-Rich Peptidomimetic Ampicillin/Gentamicin Conjugate To Tackle Nosocomial Biofilms: A Promising Strategy To Repurpose First-Line Antibiotics

Combined therapy with penicillins and aminoglycosides has been proved beneficial to address many persistent bacterial infections with possible synergistic effects. However, the different pharmacokinetic profiles of these two antibiotic classes may not guarantee a concerted spatio-temporal delivery at the site of action, decreasing the efficacy of this combination and promoting resistance. Herein, we propose a multifunctional antibiotic-polymer conjugate, designed to colocalize ampicillin and gentamicin to tackle persistent biofilm infections. The two antibacterial molecules were grafted along with the amino acid l-arginine to a biocompatible polymer backbone with peptidomimetic hydrophilic structure, obtaining the antimicrobial poly(argilylaspartamide-co-aspartic) acid-ampicillin, gentamicin (PAA-AG) conjugate. The PAA-AG conjugate displayed excellent biocompatibility on human cell lines if compared with free drugs, potentially enlarging their therapeutic window and safety, and suitable mucoadhesive characteristics which may help local treatments of mucosal infections. Studies on planktonic cultures of clinical and reference strains of S. aureus, P. aeruginosa, and E. coli revealed that PAA-AG holds a broad-spectrum antibacterial efficacy, revealing high potency in inhibiting the growth of the tested strains. More interestingly, PAA-AG exhibited excellent antibiofilm activity on both Gram+ and Gram- communities, showing inhibition of their formation at subMIC concentrations as well as inducing the regression of mature biofilms. Given the high biocompatibility and broad antibiofilm efficacy, combined with the opportunity for synchronous co-delivery, the PAA-AG conjugate could be a valuable tool to increase the success of ampicillin/gentamicin-based antibiotic multitherapy.

Clinical prediction models for multidrug-resistant organism colonisation or infection in critically ill patients: a systematic review protocol

INTRODUCTION

Multidrug-resistant organisms (MDROs) are pathogenic bacteria that are the leading cause of hospital-acquired infection which is associated with high morbidity and mortality rates in intensive care units, increasing hospitalisation duration and cost. Predicting the risk of MDRO colonisation or infection for critically ill patients supports clinical decision-making. Several models predicting MDRO colonisation or infection have been developed; however, owing to different disease scenarios, bacterial species and few externally validated cohorts in different prediction models; the stability and applicability of these models for MDRO colonisation or infection in critically ill patients are controversial. In addition, there are currently no standardised risk scoring systems to predict MDRO colonisation or infection in critically ill patients. The aim of this systematic review is to summarise and assess models predicting MDRO colonisation or infection in critically ill patients and to compare their predictive performance.

METHODS AND ANALYSIS

We will perform a systematic search of PubMed, Cochrane Library, CINAHL, Embase, Web of science, China National Knowledge Infrastructure and Wanfang databases to identify all studies describing the development and/or external validation of models predicting MDRO colonisation or infection in critically ill patients. Two reviewers will independently extract and review the data using the Data Extraction for Systematic Reviews of Prediction Modelling Studies checklist; they will also assess the risk of bias using the Prediction Model Risk of Bias Assessment Tool. Quantitative data on model predictive performance will be synthesised in meta-analyses, as applicable.

ETHICS AND DISSEMINATION

Ethical permissions will not be required because all data will be extracted from published studies. We intend to publish our results in peer-reviewed scientific journals and to present them at international conferences on critical care.

PROSPERO REGISTRATION NUMBER

CRD42022274175.

The role of the microbiology laboratory in the diagnosis of multidrug-resistant Gram-negative bacilli infections. The importance of the determination of resistance mechanisms

Early diagnosis and treatment has an important impact on the morbidity and mortality of infections caused by multidrug-resistant bacteria. Multidrug-resistant gram-negative bacilli (MR-GNB) constitute the main current threat in hospitals and especially in intensive care units (ICU). The role of the microbiology laboratory is essential in providing a rapid and effective response. This review updates the microbiology laboratory procedures for the rapid detection of BGN-MR and its resistance determinants. The role of the laboratory in the surveillance and control of outbreaks caused by these bacteria, including typing techniques, is also studied. The importance of providing standardized resistance maps that allow knowing the epidemiological situation of the different units is emphasized. Finally, the importance of effective communication systems for the transmission of results and decision making in the management of patients infected by BGN-MR is reviewed.

Effectiveness of a Multifaced Antibiotic Stewardship Program: A Pre-Post Study in Seven Italian ICUs

Multidrug resistance has become a serious threat for health, particularly in hospital-acquired infections. To improve patients’ safety and outcomes while maintaining the efficacy of antimicrobials, complex interventions are needed involving infection control and appropriate pharmacological treatments in antibiotic stewardship programs. We conducted a multicenter pre-post study to assess the impact of a stewardship program in seven Italian intensive care units (ICUs). Each ICU was visited by a multidisciplinary team involving clinicians, microbiologists, pharmacologists, infectious disease specialists, and data scientists. Interventions were targeted according to the characteristics of each unit. The effect of the program was measured with a panel of indicators computed with data from the MargheritaTre electronic health record. The median duration of empirical therapy decreased from 5.6 to 4.6 days and the use of quinolones dropped from 15.3% to 6%, both p < 0.001. The proportion of multi-drug-resistant bacteria (MDR) in ICU-acquired infections fell from 57.7% to 48.8%. ICU mortality and length of stay remained unchanged, indicating that reducing antibiotic administration did not harm patients’ safety. This study shows that our stewardship program successfully improved the management of infections. This suggests that policy makers should tackle multidrug resistance with a multidisciplinary approach based on continuous monitoring and personalised interventions.

Rethinking the ‘Pan-culture’: Clinical Impact of Respiratory Culturing in Patients with Low Pretest Probability of Ventilator-associated Pneumonia

Background

Respiratory cultures are often obtained as part of a “pan-culture” in mechanically ventilated patients in response to new fevers or leukocytosis, despite an absence of clinical or radiographic evidence suggestive of pneumonia.

Methods

This was a propensity score–stratified cohort study of hospitalized mechanically ventilated adult patients between 2014 and 2019, with a new abnormal temperature or serum white blood cell count (NATW), but without radiographic evidence of pneumonia, change in ventilator requirements, or documentation of purulent secretions. Two patient groups were compared: those with respiratory cultures performed within 36 hours after NATW and those without respiratory cultures performed. The co-primary outcomes were the proportion of patients receiving >2 days of total antibiotic therapy and >2 days of broad-spectrum antibiotic therapy within 1 week after NATW.

Results

Of 534 included patients, 113 (21.2%) had respiratory cultures obtained and 421 (78.8%) did not. Patients with respiratory cultures performed were significantly more likely to receive antibiotics for >2 days within 1 week after NATW than those without respiratory cultures performed (total antibiotic: adjusted odds ratio [OR], 2.57; 95% CI, 1.39–4.75; broad-spectrum antibiotic: adjusted OR, 2.47, 95% CI, 1.46–4.20).

Conclusions

Performance of respiratory cultures for fever/leukocytosis in mechanically ventilated patients without increasing ventilator requirements, secretion burden, or radiographic evidence of pneumonia was associated with increased antibiotic use within 1 week after incident abnormal temperature and/or white blood cell count. Diagnostic stewardship interventions targeting performance of unnecessary respiratory cultures in mechanically ventilated patients may reduce antibiotic overuse within intensive care units.

Short DNA-catalyzed formation of quantum dot-DNA hydrogel for enzyme-free femtomolar specific DNA assay

Fast, sensitive, specific, and user-friendly DNA assay is a key technique for the next generation point-of-care molecular diagnosis. However, high-cost, time-consuming, and complicated enzyme-based DNA amplification step is essential to achieve high sensitivity. Herein, a short target DNA-catalyzed formation of quantum dot (QD)-DNA hydrogel is proposed as a new DNA assay platform satisfying the above requirements. A single-stranded target DNA catalyzes the opening cycle of DNA hairpin loops, which are quickly self-assembled with DNA-functionalized QDs to generate QD-DNA hydrogel. The three-dimensional hydrogel network allows efficient resonance energy transfer, dramatically lowering the limit of detection down to ~6 fM without enzymatic DNA amplification. The QD-DNA hydrogel also enables a rapid detection (1 h) with high specificity even for a single-base mismatch. The clinical applicability of the QD-DNA hydrogel is demonstrated for the Klebsiella pneumoniae carbapenemase gene, one of the key targets of drug-resistant pathogenic bacteria.

Opportunities to Improve Antibiotic Appropriateness in U.S. ICUs: A Multicenter Evaluation

OBJECTIVES

To use a standardized tool for a multicenter assessment of antibiotic appropriateness in ICUs and identify local antibiotic stewardship improvement opportunities.

DESIGN

Pilot point prevalence conducted on October 5, 2016; point prevalence survey conducted on March 1, 2017.

SETTING

ICUs in 12 U.S. acute care hospitals with median bed size 563.

PATIENTS

Receiving antibiotics on participating units on March 1, 2017.

INTERVENTIONS

The Centers for Disease Control and Prevention tool for the Assessment of Appropriateness of Inpatient Antibiotics was made actionable by an expert antibiotic stewardship panel and implemented across hospitals. Data were collected by antibiotic stewardship program personnel at each hospital, deidentified and submitted in aggregate for benchmarking. hospital personnel identified most salient reasons for inappropriate use by category and agent.

MEASUREMENTS AND MAIN RESULTS

Forty-seven ICUs participated. Most hospitals (83%) identified as teaching with median licensed ICU beds of 70. On March 1, 2017, 362 (54%) of 667 ICU patients were on antibiotics (range, 8-81 patients); of these, 112 (31%) were identified as inappropriate and administered greater than 72 hours among all 12 hospitals (range, 9-82%). Prophylactic antibiotic regimens and PICU patients demonstrated a statistically significant risk ratio of 1.76 and 1.90 for inappropriate treatment, respectively. Reasons for inappropriate use included unnecessarily broad spectrum (29%), no infection or nonbacterial syndrome (22%), and duration longer than necessary (21%). Of patients on inappropriate antibiotic therapy in surgical ICUs, a statistically significant risk ratio of 2.59 was calculated for noninfectious or nonbacterial reasons for inappropriate therapy.

CONCLUSIONS

In this multicenter point prevalence study, 31% of ICU antibiotic regimens were inappropriate; prophylactic regimens were often inappropriate across different ICU types, particularly in surgical ICUs. Engaging intensivists in antibiotic stewardship program efforts is crucial to sustain the efficacy of antibiotics and quality of infectious diseases care in critical care settings. This study underscores the value of standardized assessment tools and benchmarking to be shared with local leaders for targeted antibiotic stewardship program interventions.

Strategies for implementation of a multidisciplinary approach to the treatment of nosocomial infections in critically ill patients

INTRODUCTION

Intensive Care Units (ICU) are among the hospital wards exhibiting the highest prevalence of antimicrobial resistance (AMR), and resulting impact on patient outcomes. Antimicrobial resistance surveillance and antimicrobial stewardship (AMS) programs play a pivotal role in promoting interventions tailored to optimize infection diagnosis and treatment in the final attempt to limit unnecessary antimicrobial use and development of resistance.

AREAS COVERED

A narrative review of the literature was carried out to summarize the available evidence and develop a set of actions that should be considered for integration into the ICU stewardship framework. Four questions were addressed: how AMR surveillance can inform antibiotic policy in ICU; whether pharmacokinetic and pharmacodynamic (PK/PD) principles and the use of procalcitonin should be incorporated as a standard practice in ICU AMS programs to optimize antibiotic treatment and to drive antibiotic discontinuation; which criteria should drive treatment duration of ICU-associated infections.

EXPERT OPINION

In this review we aim to highlight that the ICU must be considered in its own right. Each ICU has its own characteristics depending on the country, on the local antibiotic resistance profile, on the patients feature and the severity of infection.

Intravenous-to-oral antibiotic switch therapy: a cross-sectional study in critical care units

BACKGROUND

This study aimed to evaluate the oral switch (OS) stewardship intervention in the intensive care unit (ICU).

METHODS

This was a retrospective study with a convenience sample in two Brazilian ICUs from different hospitals in patients with sepsis receiving antibiotic therapy. The stewardship intervention included OS in patients diagnosed with sepsis when clinical stability was achieved. The primary outcome was overall mortality. Other variables evaluated were as follows: cost of antimicrobial treatment, daily costs of intensive care, acute kidney injury, and length of stay.

RESULTS

There was no difference in mortality between the OS and non-OS groups (p = 0.06). Length of stay in the ICU (p = 0.029) was shorter and acute kidney injury incidence (p = 0.032) and costs of antimicrobial therapy (p < 0.001) were lower in the OS group.

CONCLUSION

OS stewardship programs in the ICU may be considered a safe strategy. Switch therapy reduced the cost and shortened the length of stay in ICUs.

Rationalizing antimicrobial therapy in the ICU: a narrative review

The massive consumption of antibiotics in the ICU is responsible for substantial ecological side effects that promote the dissemination of multidrug-resistant bacteria (MDRB) in this environment. Strikingly, up to half of ICU patients receiving empirical antibiotic therapy have no definitively confirmed infection, while de-escalation and shortened treatment duration are insufficiently considered in those with documented sepsis, highlighting the potential benefit of implementing antibiotic stewardship programs (ASP) and other quality improvement initiatives. The objective of this narrative review is to summarize the available evidence, emerging options, and unsolved controversies for the optimization of antibiotic therapy in the ICU. Published data notably support the need for better identification of patients at risk of MDRB infection, more accurate diagnostic tools enabling a rule-in/rule-out approach for bacterial sepsis, an individualized reasoning for the selection of single-drug or combination empirical regimen, the use of adequate dosing and administration schemes to ensure the attainment of pharmacokinetics/pharmacodynamics targets, concomitant source control when appropriate, and a systematic reappraisal of initial therapy in an attempt to minimize collateral damage on commensal ecosystems through de-escalation and treatment-shortening whenever conceivable. This narrative review also aims at compiling arguments for the elaboration of actionable ASP in the ICU, including improved patient outcomes and a reduction in antibiotic-related selection pressure that may help to control the dissemination of MDRB in this healthcare setting.

The Burden of Viruses in Pneumonia Associated With Acute Respiratory Failure: An Underappreciated Issue

BACKGROUND

Pneumonia associated with mechanical ventilation (MV) results in substantial mortality and represents a leading reason for the use of antibiotics. The role of viruses in this setting is unclear. Identifying a viral cause in such instances could facilitate antibiotic stewardship.

METHODS

We performed a secondary analysis of a prospective cohort with pneumonia requiring MV. We included both cases occurring in the community and hospital-onset cases and classified patients according to the cause of the pneumonia. The prevalence of viral pathogens represented the primary end point. We identified variables independently associated with isolation of a viral organism as the sole pathogen.

RESULTS

The cohort included 364 patients, and a virus was the sole pathogen in 79 cases (21.7%). The most common viruses included rhinovirus/enterovirus (n = 20), influenza A (n = 12), and respiratory syncytial virus (n = 11). The rate of in-hospital death was high (37.2%) and did not differ from that seen in other patients (36.5%). The duration of MV, hospital length of stay, and 30-day readmission rates also did not differ based on the cause of pneumonia. Two variables were independently associated with recovery of a virus: an Acute Physiology and Health Evaluation II score of < 26 (adjusted odds ratio [AOR], 0.51; 95% CI, 0.28-0.93; P = .027) and stem cell transplantation (SCT) (AOR, 4.39; 95% CI, 2.03-9.50; P = .001). A sensitivity analysis excluding patients who underwent SCT did not substantially alter our observations.

CONCLUSIONS

Viruses represent a major cause of pneumonia in critically ill patients requiring MV. Identifying such subjects presents an opportunity for discontinuing antibiotics. Clinicians should consider systematically evaluating patients with pneumonia requiring MV for viral pathogens.