Randomized Trial of Rapid Multiplex Polymerase Chain Reaction-Based Blood Culture Identification and Susceptibility Testing

A single-cell nanocoating of probiotics for enhanced amelioration of antibiotic-associated diarrhea

The gut microbiota represents a large community of microorganisms that play an important role in immune regulation and maintenance of homeostasis. Living bacteria receive increasing interest as potential therapeutics for gut disorders, because they inhibit the colonization of pathogens and positively regulate the composition of bacteria in gut. However, these treatments are often accompanied by antibiotic administration targeting pathogens. In these cases, the efficacy of therapeutic bacteria is compromised by their susceptibility to antibiotics. Here, we demonstrate that a single-cell coating composed of tannic acids and ferric ions, referred to as 'nanoarmor', can protect bacteria from the action of antibiotics. The nanoarmor protects both Gram-positive and Gram-negative bacteria against six clinically relevant antibiotics. The multiple interactions between the nanoarmor and antibiotic molecules allow the antibiotics to be effectively absorbed onto the nanoarmor. Armored probiotics have shown the ability to colonize inside the gastrointestinal tracts of levofloxacin-treated rats, which significantly reduced antibiotic-associated diarrhea (AAD) resulting from the levofloxacin-treatment and improved some of the pre-inflammatory symptoms caused by AAD. This nanoarmor strategy represents a robust platform to enhance the potency of therapeutic bacteria in the gastrointestinal tracts of patients receiving antibiotics and to avoid the negative effects of antibiotics in the gastrointestinal tract.

How to use new antibiotics in the therapy of ventilator-associated pneumonia

PURPOSE OF REVIEW

Ventilator-associated pneumonia (VAP) is a common nosocomial infection in critically ill patients requiring endotracheal intubation and mechanical ventilation. Recently, the emergence of multidrug-resistant Gram-negative bacteria, including carbapenem-resistant Enterobacterales, multidrug-resistant Pseudomonas aeruginosa and Acinetobacter species, has complicated the selection of appropriate antimicrobials and contributed to treatment failure. Although novel antimicrobials are crucial to treating VAP caused by these multidrug-resistant organisms, knowledge of how to optimize their efficacy while minimizing the development of resistance should be a requirement for their use.

RECENT FINDINGS

Several studies have assessed the efficacy of novel antimicrobials against multidrug-resistant organisms, but high-quality studies focusing on optimal dosing, infusion time and duration of therapy in patients with VAP are still lacking. Antimicrobial and diagnostic stewardship should be combined to optimize the use of these novel agents.

SUMMARY

Improvements in diagnostic tests, stewardship practices and a better understanding of dosing, infusion time, duration of treatment and the effects of combining various antimicrobials should help optimize the use of novel antimicrobials for VAP and maximize clinical outcomes while minimizing the development of resistance.

[Diagnosis and treatment of catheter-related bloodstream infection in hemodialysis: 10 years later]

Patients in hemodialysis on central venous catheter as vascular access are at risk of infections. Catheter-related bloodstream infection is one of the most serious catheter-complications in hemodialysis patients. Its clinical and microbiological diagnosis is challenging. The implementation of empiric antibiotic therapy is based on old recommendations proposing the combination of a molecule targeting methicillin-resistant Staphylococcus aureus and a betalactamin active on P. aeruginosa, and also adapting this probabilistic treatment by carrying out a microbiological register on a local scale, which is rarely done. In our hemodialysis center at Bordeaux University Hospital, an analysis of the microorganisms causing all catheter-related bloodstream infection over the period 2018-2020 enabled us to propose, in agreement with the infectious disease specialists, an adapted probabilistic antibiotic therapy protocol. This approach allowed us to observe a low incidence of meticillinoresistance of Staphylococcus. For catheters inserted more than 6 months ago, we observed no Staphylococcus, no multi-resistant Pseudomonas, and only 2% of Enterobacteria resistant to cephalosporins. A frequent updating of the microbiological epidemiology of catheter-related bloodstream infection, in partnership with the infectious diseases team in each hemodialysis center, allowing an adaptation of the probabilistic antibiotic therapy, and seems to have a good feasibility. This strategy might favor the preservation of microbial ecology on an individual and collective scale in maintenance hemodialysis patients.

Multicenter Evaluation of the Acuitas ® AMR Gene Panel for Detection of an Extended Panel of Antimicrobial Resistance Genes among Bacterial Isolates

Background: The Acuitas® AMR Gene Panel is a qualitative, multiplex nucleic acid-based in vitro diagnostic test for detection and differentiation of 28 antimicrobial resistance (AMR) markers associated with not susceptible results (NS, i.e., intermediate or resistant) to one or more antimicrobial agents among cultured isolates of select Enterobacterales, Pseudomonas aeruginosa and Enterococcus faecalis. Methods: This study was conducted at four sites and included testing of 1,224 de-identified stocks created from 584 retrospectively collected isolates and 83 prospectively collected clinical isolates. The Acuitas results were compared with a combined reference standard including whole genome sequencing, organism identification and phenotypic antimicrobial susceptibility testing. Results: Positive percent agreement (PPA) for FDA-cleared AMR targets ranged from 94.4% for MCR-1 to 100% for armA, CTX-M-2, DHA, IMP, OXA-9, SHV, vanA and VEB. The negative percent agreement (NPA) for the majority of targets was ≥99%, except for AAC, AAD, CMY-41, P. aeruginosa gyrA mutant, Sul1, Sul2 and TEM targets (range: 96.5% to 98.5%). Three AMR markers did not meet FDA inclusion criteria (GES, SPM & MCR-2). For each organism, 1 to 22 AMR targets met the minimum reportable PPA/NPA and correlated with ≥80% positive predictive value with associated NS results for at least one agent (i.e., the probability of an organism carrying an AMR marker testing NS to the associated agent). Conclusion: We demonstrate that the Acuitas® AMR Gene Panel is an accurate method to detect a broad array of AMR markers among cultured isolates. The AMR markers were further associated with expected NS results for specific agent-organism combinations.

Direct antimicrobial resistance prediction from clinical MALDI-TOF mass spectra using machine learning

Early use of effective antimicrobial treatments is critical for the outcome of infections and the prevention of treatment resistance. Antimicrobial resistance testing enables the selection of optimal antibiotic treatments, but current culture-based techniques can take up to 72 hours to generate results. We have developed a novel machine learning approach to predict antimicrobial resistance directly from matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectra profiles of clinical isolates. We trained calibrated classifiers on a newly created publicly available database of mass spectra profiles from the clinically most relevant isolates with linked antimicrobial susceptibility phenotypes. This dataset combines more than 300,000 mass spectra with more than 750,000 antimicrobial resistance phenotypes from four medical institutions. Validation on a panel of clinically important pathogens, including Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, resulting in areas under the receiver operating characteristic curve of 0.80, 0.74 and 0.74, respectively, demonstrated the potential of using machine learning to substantially accelerate antimicrobial resistance determination and change of clinical management. Furthermore, a retrospective clinical case study of 63 patients found that implementing this approach would have changed the clinical treatment in nine cases, which would have been beneficial in eight cases (89%). MALDI-TOF mass spectra-based machine learning may thus be an important new tool for treatment optimization and antibiotic stewardship.

Unresolved issues in the epidemiology and diagnosis of bacteremia: an opinion paper

Bacteremia is an important cause of morbidity and mortality worldwide and, despite the diagnostic and therapeutic advances of the last decades, the evidence supporting many diagnostic aspects of bacteremia is scarce. Information on the epidemiological evolution of this entity is limited and many methodological aspects of blood culture collection and analysis are under discussion. Furthermore, the recommendations of the main scientific societies on many of these aspects are variable and, in many cases, have not been updated recently. In this scenario, we have arranged a series of questions on different aspects of bacteremia and reviewed the literature trying to find proper answers for them. We offer our opinion on the topics where the evidence was weak. The topics covered include epidemiological aspects of bacteremia, indications for blood culture extraction, methods for obtaining and incubating samples, or ways of transmitting results from the microbiology laboratory. We do not intend to summarize the current clinical practice guidelines, nor will we deal with the therapeutic management of this entity. The aim of this paper is to review the current perspective on the diagnosis of bacteremia with a critical approach, to point out the gaps in the literature, to offer the opinion of a team dedicated to infectious diseases and clinical microbiology, and to identify some areas of knowledge on which future studies should focus.

Impact of rapid susceptibility testing on antimicrobial therapy and clinical outcomes in Gram-negative bloodstream infections

Background

Rapid antimicrobial susceptibility testing (rAST) has the potential to improve care of bloodstream infections.

Objectives

The aim of this service evaluation was to assess the impact of rAST on antimicrobial therapy and clinical outcomes in patients with Gram-negative bloodstream infection.

Methods

A prospective service evaluation was conducted from March 2018 to December 2018. A rAST system (Alfred 60AST) was run Monday–Friday before midday and results were communicated to clinicians on the same day as positive blood culture, with subsequent conventional AST performed. Times to antibiotic therapy and clinical outcomes were compared between rAST and conventional AST.

Results

One hundred and ninety-one patients with Gram-negative bacteraemia were included (93 in the rapid group and 98 in the conventional group). Aminoglycoside combination therapy was stopped earlier in the rapid group [32 h (0–795) versus 54 h (4–216), P = 0.002]. The median time to optimal antibiotic based on AST results was significantly shorter than that in the conventional group [50 h (10–339) versus 69.5 h (20–872), P = 0.034]. In the subgroup of patients on ineffective empirical antibiotic, time to effective antibiotic was shorter in the rapid group [39.5 h (32–97) versus 57 h (49–83), P = 0.036]. No differences were found in 28 day mortality or length of stay.

Conclusions

Rapid susceptibility testing resulted in faster discontinuation of aminoglycosides and a shorter time to starting effective and optimal antibiotic when compared with conventional AST results. rAST has potential clinical benefits and points to the need for larger future studies in areas of high antibiotic resistance.

The Impact of the FilmArray-Based Detection of Microbial Pathogens from Positive Blood Culture Vials on the Time to Optimal Antimicrobial Regimen in Intensive Care Units of the Helios University Clinic Wuppertal, Germany

The role of empirical therapy and time to first effective treatment, including the antimicrobial stewardship program, are decisive in patients presenting with bloodstream infections (BSI). The FilmArray^® Blood Culture Identification Panel (FA BCID 1.0) detects 24 bacterial and fungal pathogens as well as 3 resistance genes from positive blood cultures in approximately 70 min. In this paper, we evaluate the impact of the additional FA BCID analysis on the time to an optimal antimicrobial therapy and on the length of stay in the ICU, ICU mortality, and PCT level reduction. This retro-/prospective trial was conducted in BSI patients in the ICU at a German tertiary care hospital. A total of 179 individual patients with 200 episodes of BSI were included in the prospective intervention group, and 150 patients with 170 episodes of BSI in the retrospective control group. In the intervention group, BSI data were analyzed including the MALDI-TOF MS (matrix assisted laser desorption ionization time-of-flight mass spectrometry) and FA BCID results from January 2019 to August 2020; the data from the control group, including the MALDI-TOF results, were collected retrospectively from the year 2018. The effective and appropriate antimicrobial regimen occurred in a median of 17 hours earlier in the intervention versus control group (p = 0.071). Furthermore, changes in the antimicrobial regimens of the intervention group that did not immediately lead to an optimal therapy occurred significantly earlier by a median of 24 hours (p = 0.029). Surrogate markers, indicating an earlier recovery of the patients from the intervention group, such as length of stay at the ICU, duration of mechanical ventilation, or an earlier reduction in PCT level, were not significantly affected. However, mortality did not differ between the patient groups. A postulated reduction of the antimicrobial therapy, in those cases in which coagulase-negative Staphylococcus species were identified, did occur in the control group, but not in the intervention group (p = 0.041). The implementation of FA BCID into the laboratory workflow can improve patient care by optimizing antimicrobial regimen earlier in BSI patients as it provides rapid and accurate results for key pathogens associated with BSI, as well as important antimicrobial resistance markers, e.g., mecA or vanA.

Impact of early antimicrobial stewardship intervention in patients with positive blood cultures: results from a randomized comparative study: Impact of stewardship on BSI outcomes

BACKGROUND

Antimicrobial stewardship intervention (ASI) appears necessary to realize the full benefits of rapid diagnostic technologies in clinical practice. This study aimed to compare clinical outcomes between early ASI paired with MALDI-TOF compared to MALDI-TOF with standard of care (SOC) reporting in patients with positive blood cultures.

METHODS

Adult patients with positive blood cultures and organism speciation via MALDI-TOF admitted between 2/2015 and 9/2015 were randomized to ASI or SOC in a 1:1 fashion. Patients admitted for at least 48 hours following positive culture were included in analyses. ASI was defined as a clinical assessment by a stewardship team member with non-binding treatment recommendations offered to the primary team. The primary outcome was time to definitive therapy. Secondary outcomes included post-culture length of stay (LOS), time to first change in antibiotics, and in-hospital mortality.

RESULTS

A total of 149 patients were included in analyses (76 in the ASI group and 73 in the SOC group). ASI and SOC arms did not differ according to age, sex, comorbidities, or severity of illness. Gram-positive organisms were common in both SOC and ASI arms (74.0 vs 61.8%, p=0.11). Time-to-definitive therapy was reduced, on average, by 30.3 hours in the ASI group (71.6 vs. 41.3 hours, p=0.01). Hospital LOS following the first positive blood culture was significantly shorter in the ASI group (8.7 vs. 11.2 days, p=0.049).

CONCLUSIONS

ASI combined with MALDI-TOF reduced the time to definitive therapy, time to first change in antibiotics, and was associated with a shorter post-culture LOS.

Genome-Wide Mutation Scoring for Machine-Learning-Based Antimicrobial Resistance Prediction

The prediction of antimicrobial resistance (AMR) based on genomic information can improve patient outcomes. Genetic mechanisms have been shown to explain AMR with accuracies in line with standard microbiology laboratory testing. To translate genetic mechanisms into phenotypic AMR, machine learning has been successfully applied. AMR machine learning models typically use nucleotide k-mer counts to represent genomic sequences. While k-mer representation efficiently captures sequence variation, it also results in high-dimensional and sparse data. With limited training data available, achieving acceptable model performance or model interpretability is challenging. In this study, we explore the utility of feature engineering with several biologically relevant signals. We propose to predict the functional impact of observed mutations with PROVEAN to use the predicted impact as a new feature for each protein in an organism’s proteome. The addition of the new features was tested on a total of 19,521 isolates across nine clinically relevant pathogens and 30 different antibiotics. The new features significantly improved the predictive performance of trained AMR models for Pseudomonas aeruginosa, Citrobacter freundii, and Escherichia coli. The balanced accuracy of the respective models of those three pathogens improved by 6.0% on average.

New evidence for managing Gram-negative bloodstream infections

PURPOSE OF REVIEW

Gram-negative bloodstream infections (GNBSI) are common and carry considerable mortality. Treatment is complicated by increasing antimicrobial resistance, posing a challenge for timely appropriate antibiotics and limiting the choices of effective definitive therapy. The present review aims to summarize recent studies addressing the management of GNBSI.

RECENT FINDINGS

New rapid diagnostic tests (RDT) for pathogen identification and antibiotic susceptibility are associated with improved antimicrobial stewardship and reduced length of stay. No mortality benefit or patient-related outcomes are reported. Data regarding the use of new beta-lactam beta-lactamase inhibitors (BLBLIs) for treating multidrug resistance Gram-negative bacteria is supportive, though questions regarding combinations, optimal dosing, mode of administration, and resistance emergence remain to be clarified. Current data regarding cefiderocol necessitates further studies in order to support its use in GNBSI. Shortened (≤7 days) duration of therapy and early oral step down for GNBSI are supported by the literature. The role of repeated blood cultures should be further defined.

SUMMARY

RDTs should be implemented to improve antibiotic stewardship. Clinical implications on patient-related outcomes should be evaluated. New BLBLIs show promise in the treatment of GNBSI. Additional data are needed regarding the use of cefiderocol. Antibiotic therapy should be shortened and early oral step down should be considered.

The Impact of a Pharmacist-Driven Staphylococcus aureus Bacteremia Initiative in a Community Hospital: A Retrospective Cohort Analysis

Purpose: Staphylococcus aureus is a leading cause of bacteremia with a 30-day mortality of 20%. This study evaluated outcomes after implementation of a pharmacist-driven Staphylococcus aureus bacteremia (SAB) initiative in a community hospital. Methods: This retrospective cohort analysis compared patients admitted with SAB between May 2015 and April 2018 (intervention group) to those admitted between May 2012 and April 2015 (historical control group). Pharmacists were notified of and responded to blood cultures positive for Staphylococcus aureus by contacting provider(s) with a bundle of recommendations. Components of the SAB bundle included prompt source control, selection of appropriate intravenous antibiotics, appropriate duration of therapy, repeat blood cultures, echocardiography, and infectious diseases consult. Demographics (age, gender, and race) were collected at baseline. Primary outcome was in-hospital mortality. Compliance with bundle components was also assessed. Results: Eighty-three patients in the control group and 110 patients in the intervention group were included in this study. Demographics were similar at baseline. In-hospital mortality was lower in the intervention group (3.6% vs. 15.7%; p = 0.0033). Bundle compliance was greater in the intervention group (69.1% vs. 39.8%; p < 0.0001). Conclusions: We observed a significant reduction in in-hospital mortality and increased treatment bundle compliance in the intervention cohort with implementation of a pharmacist-driven SAB initiative. Pharmacists’ participation in the care of SAB patients in the form of recommending adherence to treatment bundle components drastically improved clinical outcomes. Widespread adoption and implementation of similar practice models at other institutions may reduce in-hospital mortality for this relatively common and life-threatening infection.

Diagnostic Stewardship: Appropriate Testing and Judicious Treatments

Diagnostic stewardship encompasses the entire diagnosis-to-treatment paradigm in the intensive care unit (ICU). Initially born of the antimicrobial stewardship movement, contemporary diagnostic stewardship aims to promote timely and appropriate diagnostic testing that directly links to management decisions. In the stewardship framework, excessive diagnostic testing in low probability cases is discouraged due to its tendency to generate false-positive results, which have their own downstream consequences. Though the evidence basis for diagnostic stewardship initiatives in the ICU is nascent and largely limited to retrospective analyses, available literature generally suggests that these initiatives are safe, feasible, and associated with similar patient outcomes. As diagnostic testing of critically ill patients becomes increasingly sophisticated in the ensuing decade, a stewardship mindset will aid bedside clinicians in interpreting and incorporating new diagnostic strategies in the ICU.

Mathematical model of the cost-effectiveness of the BioFire FilmArray Blood Culture Identification (BCID) Panel molecular rapid diagnostic test compared with conventional methods for identification of Escherichia coli bloodstream infections

BACKGROUND

Gram-negative pathogens, such as Escherichia coli, are common causes of bloodstream infections (BSIs) and increasingly demonstrate antimicrobial resistance. Molecular rapid diagnostic tests (mRDTs) offer faster pathogen identification and susceptibility results, but higher costs compared with conventional methods. We determined the cost-effectiveness of the BioFire FilmArray Blood Culture Identification (BCID) Panel, as a type of mRDT, compared with conventional methods in the identification of E. coli BSIs.

METHODS

We constructed a decision analytic model comparing BCID with conventional methods in the identification and susceptibility testing of hospitalized patients with E. coli BSIs from the perspective of the public healthcare payer. Model inputs were obtained from published literature. Cost-effectiveness was calculated by determining the per-patient admission cost, the QALYs garnered and the incremental cost-effectiveness ratios (ICERs) where applicable. Monte Carlo probabilistic sensitivity analyses and one-way sensitivity analyses were conducted to assess the robustness of the model. All costs reflect 2019 Canadian dollars.

RESULTS

The Monte Carlo probabilistic analyses resulted in cost savings ($27 070.83 versus $35 649.81) and improved QALYs (8.65 versus 7.10) in favour of BCID. At a willingness to pay up to $100 000, BCID had a 72.6%-83.8% chance of being cost-effective. One-way sensitivity analyses revealed length of stay and cost per day of hospitalization to have the most substantial impact on costs and QALYs.

CONCLUSIONS

BCID was found to be cost-saving when used to diagnose E. coli BSI compared with conventional testing. Cost savings were most influenced by length of stay and cost per day of hospitalization.

Influence of Antimicrobial Stewardship and Molecular Rapid Diagnostic Tests on Antimicrobial Prescribing for Extended-Spectrum Beta-Lactamase- and Carbapenemase-Producing Escherichia coli and Klebsiella pneumoniae in Bloodstream Infection

The objective of this study was to evaluate whether the addition of the Verigene BC-GN molecular rapid diagnostic test to standard antimicrobial stewardship practices (mRDT + ASP) decreased the time to optimal and effective antimicrobial therapy for patients with extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections (BSI) compared to conventional microbiological methods with ASP (CONV + ASP). This was a multicenter, retrospective cohort study evaluating the time to optimal antimicrobial therapy in 5 years of patients with E. coli or K. pneumoniae BSI determined to be ESBL- or carbapenemase-producing by mRDT and/or CONV. Of the 378 patients included (mRDT + ASP, n = 164; CONV + ASP, n = 214), 339 received optimal antimicrobial therapy (mRDT + ASP, n = 161; CONV + ASP, n = 178), and 360 (mRDT + ASP, n = 163; CONV + ASP, n = 197) received effective antimicrobial therapy. The mRDT + ASP demonstrated a statistically significant decrease in the time to optimal antimicrobial therapy (20.5 h [interquartile range (IQR), 17.0 to 42.2 h] versus 50.1 h [IQR, 27.6 to 77.9 h]; P < 0.001) and the time to effective antimicrobial therapy (15.9 h [IQR, 1.9 to 25.7 h] versus 28.0 h [IQR, 9.5 to 56.7 h]; P < 0.001) compared to CONV + ASP, respectively. IMPORTANCE Our study supports the additional benefit of molecular rapid diagnostic test in combination with timely antimicrobial stewardship program (ASP) intervention on shortening the time to both optimal and effective antimicrobial therapy in patients with ESBL- or carbapenemase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections, compared to conventional microbiological methods and ASP. Gram-negative infections are associated with significant morbidity and mortality, often resulting in life-threatening organ dysfunction. Both resistance phenotypes confer resistance to many of our first-line antimicrobial agents with carbapenemase-producing Enterobacterales requiring novel beta-lactam and beta-lactamase inhibitor combinations or other susceptible non-beta-lactam antibiotics for treatment. National resistance trends in a cohort of hospitalized patients at U.S. hospitals during our study period demonstrate the increasing incidence of both resistance phenotypes, reinforcing the generalizability and timeliness of such analysis.

Real-World Impact of the Accelerate PhenoTest ® BC Kit on patients with bloodstream infections in IOAS (Improving Outcomes and Antimicrobial Stewardship): A Quasi-Experimental Multicenter Study

BACKGROUND

Bloodstream infections (BSI) are a leading cause of morbidity and mortality in hospitalized patients. The IOAS (Improving Outcomes and Antimicrobial Stewardship) study seeks to evaluate the impact of the Accelerate PhenoTest® BC Kit (AXDX) on antimicrobial use and clinical outcomes in BSIs.

METHODS

This multicenter, quasi-experimental study compared clinical and antimicrobial stewardship metrics, prior to and after implementation of AXDX testing, to evaluate the impact this technology has on patients with BSI. Laboratory and clinical data from hospitalized patients with BSI (excluding contaminants) were compared between two arms, one that underwent testing on AXDX (post-AXDX) and one that underwent alternative organism identification and susceptibility testing (pre-AXDX). The primary outcomes were time to optimal therapy (TTOT) within 96 hours of blood culture positivity and 30-day mortality.

RESULTS

A total of 854 patients with BSI (435 pre-AXDX, 419 post-AXDX) were included. Median TTOT was 17.2 hours shorter in the post-AXDX arm (23.7 hours) compared to the pre-AXDX arm (40.9 hours; P<0.0001). Compared with pre-AXDX, median time to first antimicrobial modification (24.2 versus 13.9 hours; P<0.0001) and first antimicrobial de-escalation (36.0 versus 27.2 hours; P=0.0004) were shorter in the post-AXDX arm. Mortality (8.7% pre-AXDX versus 6.0% post-AXDX), length of stay (7.0 pre-AXDX versus 6.5 days post-AXDX), and adverse drug events were not significantly different between arms. Length of stay was shorter in the post-AXDX arm (5.4 versus 6.4 days; P=0.03) among patients with Gram-negative bacteremia.

CONCLUSIONS

For BSIs, use of AXDX was associated with significant decreases in TTOT, first antimicrobial modification, and time to antimicrobial de-escalation.

A Piece of the Puzzle: The Role of Molecular Testing in Antimicrobial Stewardship

Molecular testing may have an important role in expediting the diagnosis of infectious diseases. Pediatric infectious diseases specialists need to be cognizant of the strengths and limitations of these existing and emerging technologies in order to ensure that they are used and interpreted appropriately.

Core Genome Multilocus Sequence Typing and Prediction of Antimicrobial Susceptibility Using Whole-Genome Sequences of Escherichia coli Bloodstream Infection Isolates

In total, 50 Escherichia coli bloodstream isolates from the clinical laboratory and 12 E. coli isolates referred for pulsed-field gel electrophoresis (PFGE) were sequenced, assessed for clonality using core genome multilocus sequence typing (cgMLST), and evaluated for genomic susceptibility predictions using ARESdb. Results of sequence typing using whole-genome sequencing (WGS)-based MLST and sequence type (ST)-specific PCR were identical. Overall categorical agreement between genotypic (ARESdb) and phenotypic susceptibility testing for 62 isolates and 11 antimicrobial agents was 91%. Among the referred isolates, high major error rates were found for ceftazidime, cefepime, and piperacillin-tazobactam.

Guidelines on Implementing Antimicrobial Stewardship Programs in Korea

These guidelines were developed as a part of the 2021 Academic R&D Service Project of the Korea Disease Control and Prevention Agency in response to requests from healthcare professionals in clinical practice for guidance on developing antimicrobial stewardship programs (ASPs). These guidelines were developed by means of a systematic literature review and a summary of recent literature, in which evidence-based intervention methods were used to address key questions about the appropriate use of antimicrobial agents and ASP expansion. These guidelines also provide evidence of the effectiveness of ASPs and describe intervention methods applicable in Korea.

Desirability of Outcome Ranking for the Management of Antimicrobial Therapy (DOOR MAT) Reveals Improvements in the Treatment of Bloodstream Infections Caused by Escherichia coli and Klebsiella pneumoniae in Patients from the Veterans Health Administration

BACKGROUND

Reductions in the use of broad-spectrum antibiotics is a cornerstone of antimicrobial stewardship. We aim to demonstrate use of the Desirability of Outcome Ranking Approach for the Management of Antimicrobial Therapy (DOOR MAT) to evaluate the treatment of Escherichia coli and Klebsiella pneumoniae bloodstream infections in patients from the Veterans Health Administration (VHA) across a decade.

METHODS

Using electronic records, we determined empiric and definitive antibiotic treatments, clinical characteristics, and 30-day mortality of patients with monomicrobial E. coli and K. pneumoniae bloodstream infections hospitalized in VHA medical centers from 2009 to 2018. Focusing on patients treated with parenteral β-lactams and with available antibiotic susceptibility testing results, we applied a range of DOOR MAT scores that reflect the desirability of antibiotic choices according to spectrum and activity against individual isolates. We report trends in resistance and desirability of empiric and definitive antibiotic treatments.

RESULTS

During the 10-year period analyzed, resistance to expanded-spectrum cephalosporins and fluoroquinolones increased in E. coli but not in K. pneumoniae, while resistance to carbapenems and piperacillin-tazobactam remained unchanged. In 6451 cases analyzed, we observed improvements in DOOR MAT scores consistent with deescalation. Improvement in desirability of definitive treatment compared with empiric treatment occurred in 26% of cases, increasing from 16% in 2009 to 34% in 2018. Reductions in overtreatment were sustained and without negative impact on survival.

CONCLUSIONS

DOOR MAT provides a framework to assess antibiotic treatment of E. coli and K. pneumoniae bloodstream infections and can be a useful metric in antimicrobial stewardship.

Accuracy of a rapid multiplex PCR plus a chromogenic phenotypic test algorithm for detection of ESBL and carbapenemase-producing Gram-negative bacilli in positive blood culture bottles

We studied the performance of an algorithm combining multiplex-PCR with phenotypic detection of ESBLs and carbapenemases directly from positive blood culture bottles in patients with Gram-negative bacteremia and found good concordance with routine cultures. Such an algorithm may be a tool to improve time-to-optimal therapy in patients with Gram-negative bacteremia.

Syndromic diagnostic testing: a new way to approach patient care in the treatment of infectious diseases

Advanced microbiology technologies such as multiplex molecular assays (i.e. syndromic diagnostic tests) are a novel approach to the rapid diagnosis of common infectious diseases. As the global burden of antimicrobial resistance continues to rise, the judicious use of antimicrobials is of utmost importance. Syndromic panels are now being recognized in some clinical practice guidelines as a 'game-changer' in the diagnosis of infectious diseases. These syndromic panels, if implemented thoughtfully and interpreted carefully, have the potential to improve patient outcomes through improved clinical decision making, optimized laboratory workflow, and enhanced antimicrobial stewardship. This paper reviews the potential benefits of and considerations regarding various infectious diseases syndromic panels, and highlights how to maximize impact through collaboration between clinical microbiology laboratory and antimicrobial stewardship programmes.

Blood culture diagnostics: a Nordic multicentre survey comparison of practices in clinical microbiology laboratories

OBJECTIVES

Accurate and rapid microbiological diagnostics are crucial to tailor treatment and improve outcomes in patients with severe infections. This study aimed to assess blood culture diagnostics in the Nordic countries and to compare them with those of a previous survey conducted in Sweden in 2013.

METHODS

An online questionnaire was designed and distributed to the Nordic clinical microbiology laboratories (CMLs) (n = 76) in January 2018.

RESULTS

The response rate was 64% (49/76). Around-the-clock incubation of blood cultures (BCs) was supported in 82% of the CMLs (40/49), although in six of these access to the incubators around the clock was not given to all of the cabinets in the catchment area, and 41% of the sites (20/49) did not assist with satellite incubators. Almost half (49%, 24/49) of the CMLs offered opening hours for ≥10 h during weekdays, more commonly in CMLs with an annual output ≥30 000 BCs. Still, positive BCs were left unprocessed for 60-70% of the day due to restrictive opening hours. Treatment advice was given by 23% of CMLs (11/48) in ≥75% of the phone contacts. Rapid analyses (species identification and susceptibility testing with short incubation), performed on aliquots from positive cultures, were implemented in 18% of CMLs (9/49). Compared to 2013, species identification from subcultured colonies (<6 h) had become more common.

CONCLUSIONS

CMLs have taken action to improve aspects of BC diagnostics, implementing satellite incubators, rapid species identification and susceptibility testing. However, the limited opening hours and availability of clinical microbiologists are confining the advantages of these changes.

Clinical Impact of the Expanded BioFire Blood Culture Identification 2 Panel in a U.S. Children's Hospital

The BioFire blood culture identification (BCID) panel decreases time to pathogen identification and time to optimal antimicrobial therapy. The BioFire blood culture identification 2 (BCID2) panel is an expanded panel with 17 additional targets and resistance genes; however, there are limited data on its impact in pediatric patients. We compared the BioFire BCID2 panel and the BCID panel by assaying BCID2 simultaneously with the current standard of care on 191 consecutive blood culture specimens at Children's Hospital Colorado. The primary outcome was equivalence, measured as percent agreement between the two panels and standard culture. The theoretical reduction in time to optimal therapy was calculated overall, with subanalyses performed on Enterococcus species and Gram-negative resistance genes. The percent agreement was equivalent between the two panels, with BCID at 98% (95% confidence interval [CI], 95 to 100%) and BCID2 at 97% (95% CI, 93 to 99%); the difference was 1.2% (95% CI, -0.8, 3.1%; P < 0.0001). There was not a significant reduction in time to theoretical optimal therapy with BCID2 compared to BCID for all cultures (reduction of 9 h, P = 0.3). Notably, 13 Enterococcus faecalis isolates were detected on BCID2, which would have resulted in a theoretical reduction in time to optimal antimicrobial therapy of 34 h (P = 0.0046). Five CTX-M genes were detected for enteric bacteria. The BioFire BCID2 panel had equal rates of detection compared to the BioFire BCID panel in pediatric patients. It had the advantage of detecting more organisms at the species level, and significantly reducing time to theoretical optimal antimicrobial therapy for Enterococcus faecalis. With the additional resistance genes, it also has the potential to impact care with earlier identification of resistant enteric pathogens. IMPORTANCE The BioFire BCID2 panel is an accurate panel that is equivalent to the BioFire BCID panel compared to standard culture. The BioFire BCID2 panel offers several advantages over the BioFire BCID panel, including enterococcal species identification, Gram-negative resistance gene detection, Salmonella identification, and the added mecA/mecC and SCCmec right extremity junction (MREJ) target for better Staphylococcus aureus and coagulase-negative Staphylococcus (CoNS) differentiation. Most importantly, it provides additional clinical impact with the potential to decrease the time to optimal antimicrobial therapy compared to the BioFire BCID panel, with likely further impact at institutions with a higher prevalence of Gram-negative resistance.

Clinical characteristics, appropriateness of empiric antibiotic therapy, and outcome of Pseudomonas aeruginosa bacteremia across multiple community hospitals

There is relatively little contemporary information regarding clinical characteristics of patients with Pseudomonas aeruginosa bacteremia (PAB) in the community hospital setting. This was a retrospective, observational cohort study examining the clinical characteristics of patients with PAB across several community hospitals in the USA with a focus on the appropriateness of initial empirical therapy and impact on patient outcomes. Cases of PAB occurring between 2016 and 2019 were pulled from 8 community medical centers. Patients were classified as having either positive or negative outcome at hospital discharge. Several variables including receipt of active empiric therapy (AET) and the time to receiving AET were collected. Variables with a p value of < 0.05 in univariate analyses were included in a multivariable logistic regression model. Two hundred and eleven episodes of PAB were included in the analysis. AET was given to 81.5% of patients and there was no difference in regard to outcome (p = 0.62). There was no difference in the median time to AET in patients with a positive or negative outcome (p = 0.53). After controlling for other variables, age, Pitt bacteremia score ≥ 4, and septic shock were independently associated with a negative outcome. A high proportion of patients received timely, active antimicrobial therapy for PAB and time to AET did not have a significant impact on patient outcome.

Antimicrobial Resistance Trends at a Pediatric Hospital in Guatemala City, 2005-2019

Antimicrobial resistance (AMR) is increasing worldwide. We analyzed AMR rates for bacterial species identified from pediatric blood cultures between 2005 and 2019 at a single institution in Guatemala. We found significantly increased rates in Gram-negative resistance, with a high prevalence of carbapenem-resistant Acinetobacter and Klebsiella harboring the New Delhi metallo-beta-lactamase gene.

Shortening the Time of the Identification and Antimicrobial Susceptibility Testing on Positive Blood Cultures with MALDI-TOF MS

The current processes used in clinical microbiology laboratories take ~24 h for incubation to identify the bacteria after the blood culture has been confirmed as positive and fa further ~24 h to report the results of antimicrobial susceptibility tests (ASTs). Patients with suspected bloodstream infection are treated with empiric broad-spectrum antibiotics but delayed targeted antimicrobial therapy. This study aimed to develop a method with a significantly shortened turnaround time for clinical application by identifying the optimal incubation period of a subculture. A total of 188 positive blood culture samples obtained from Nov. 2019 to Aug. 2020 were included. Compared to the conventional 24-h incubation for bacterial identification, our approach achieved 96.1% and 97.4% identification accuracy after shortening the incubation time to 4.5 and 3.5 h for gram-positive (GP) and gram-negative (GN) bacterial samples, respectively. Samples from short-term incubation without any intermediate step or process were directly subjected to analysis with the Phoenix M50 AST. Compared to the conventional disk diffusion AST, the category agreements for GP (excluding Streptococcus spp.), Streptococcus spp., and GN bacterial samples were 91.8%, 97.5%, and 92.7%, respectively. Our approach significantly reduced the average turnaround time from 48 h to 28 h for reporting bacterial identity and decreased average AST from 72 h to 50.3 h compared to the conventional methods. Accordingly, this approach allows a physician to prescribe the appropriate antibiotic(s) ~21.7 h earlier, thereby improving patient outcomes.

Comparing the Clinical Utility of Rapid Diagnostics for Treatment of Bloodstream Infections Using Desirability of Outcome Ranking Approach for the Management of Antibiotic Therapy (DOOR-MAT)

Decisions regarding which rapid diagnostic test (RDT) for bloodstream infections to implement remain challenging given the diversity of organisms detected by different platforms. We used the desirability of outcome ranking management of antimicrobial therapy (DOOR-MAT) as a framework to compare two RDT platforms on potential desirability of antimicrobial therapy decisions. An observational study was performed at University of Maryland Medical System comparing Verigene blood culture (BC) to GenMark Dx ePlex blood culture ID (BCID) (research use only) panels on blood cultures from adult patients. Positive percent agreement (PPA) between each RDT platform and Vitek MS was calculated for comparison of on-panel targets. Theoretical antimicrobial decisions were made based on RDT results, taking into consideration patient parameters, antimicrobial stewardship practices, and local infectious diseases epidemiology. DOOR-MAT with a partial credit scoring system was applied to these decisions, and mean scores were compared across platforms using a paired t test. The study consisted of 160 unique patients. The Verigene BC PPA was 98.6% (95% confidence interval [CI], 95.1 to 99.8), and ePlex BCID PPA was 98% (95% CI, 94.3 to 99.6). Among the 31 organisms not on the Verigene BC panels, 61% were identified by the ePlex BCID panels. The mean (standard deviation [SD]) DOOR-MAT score for Verigene BC was 86.8 (28.5), while that for ePlex BCID was 91.9 (23.1) (P = 0.01). Both RDT platforms had high PPA for on-panel targets. The ePlex BCID was able to identify more organisms than Verigene, resulting in higher mean DOOR-MAT scores.

No Implementation Without Representation: Real-Time Pharmacist Intervention Optimizes Rapid Diagnostic Tests for Bacteremia at a Small Community Hospital

Background: Rapid diagnostic tests (RDTs) for bacteremia allow for early antimicrobial therapy modification based on organism and resistance gene identification. Studies suggest patient outcomes are optimized when infectious disease (ID)-trained antimicrobial stewardship personnel intervene on RDT results. However, data are limited regarding RDT implementation at small community hospitals, which often lack access to on-site ID clinicians. Methods: This study evaluated the impact of RDTs with and without real-time pharmacist intervention (RTPI) at a small community hospital with local pharmacist training and asynchronous support from a remote ID Telehealth pharmacist. Time to targeted therapy (TTT) in patients with bacteremia was compared retrospectively across 3 different time periods: a control without RDT, RDT-only, and RDT with RTPI. Results: Median TTT was significantly faster in both the RDT with RTPI and RDT-only groups compared with the control group (2 vs 25 vs 51 hours respectively; P < .001). TTT was numerically faster for RDT with RTPI compared with RDT-only but did not reach statistical significance ( P = .078). Median time to any de-escalation was significantly shorter for RDT with RTPI compared with both RDT-only (14 vs 33 hours; P = .012) and the control group (14 vs 45 hours; P < .001). Median length of stay was also significantly shorter in both RDT groups compared with the control group (4.0 vs 4.1 vs 5.5 hours; P = .013). Conclusion: This study supports RDT use for bacteremia in a small community hospital with ID Telehealth support, suggesting additional benefit with RTPI.

The state of antibiotic stewardship programs in 2021: The perspective of an experienced steward

Recognition of antibiotic stewardship programs (ASPs) as essential components of quality health care has dramatically increased in the past decade. The value of ASPs has been further reinforced during the coronavirus disease 2019 (COVID-19) pandemic because these programs were instrumental in monitoring antibiotic use, assessing emerging COVID-19 therapies, and coordinating implementation of monoclonal antibody infusions and vaccinations. ASPs are now required across hospital settings as a condition of participation for the Centers for Medicare and Medicaid Services and for accreditation by The Joint Commission. In the 2019 National Healthcare Safety Network annual survey, almost 89% of hospitals met the Seven Core Elements for ASPs defined by the Centers for Disease Control and Prevention. More than 61% of programs were co-led by physicians and pharmacists, evidence of the leadership role of both groups. ASPs employ many strategies to improve prescribing. Core interventions of preauthorization for targeted antibiotics, prospective audit and feedback, and development of local treatment guidelines have been supplemented with numerous emerging strategies. Diagnostic stewardship, optimizing duration of therapy, promoting appropriate conversion from intravenous to oral therapy, monitoring at transitions of care and hospital discharge, implementing stewardship initiatives in the outpatient setting, and increasing use of telemedicine are approaches being adopted across hospital settings. As a core function for medical facilities, ASP leaders must ensure that antibiotic use and ASP interventions promote optimal and equitable care. The urgency of success becomes progressively greater as complex patterns of antibiotic resistance continue to emerge, exacerbated by unpredictable factors such as a worldwide pandemic.

Immunohistochemistry in the Postmortem Diagnosis of Sepsis: A Systematic Review

It is not uncommon for the forensic pathologist to question whether a deceased person had experienced sepsis that could have either been the cause of or contributed to the person's death. Often, the missing typical pathologic factors or lack of clinical and circumstantial information on the death render the autopsy of a sepsis-related death a difficult task for the forensic pathologist. Several authors emphasize on how an immunohistochemical analysis could help in diagnosing death related to sepsis. The research we carried out analyzes the main scientific studies in the literature, primarily the tracing of 21 immunohistochemical antigens evaluated to help diagnose death related to sepsis. The purpose of this review was to analyze and summarize the markers studied until now and to consider the limitations of immunohistochemistry that currently exist with regard to this particular field of forensic pathology. Immunohistochemistry provided interesting and promising results, but further studies are needed in order for them to be confirmed, so that they may be applied in standard forensic practice.

Evaluation and Management of Well-Appearing Febrile Infants 8 to 60 Days Old

This guideline addresses the evaluation and management of well-appearing, term infants, 8 to 60 days of age, with fever ≥38.0°C. Exclusions are noted. After a commissioned evidence-based review by the Agency for Healthcare Research and Quality, an additional extensive and ongoing review of the literature, and supplemental data from published, peer-reviewed studies provided by active investigators, 21 key action statements were derived. For each key action statement, the quality of evidence and benefit-harm relationship were assessed and graded to determine the strength of recommendations. When appropriate, parents' values and preferences should be incorporated as part of shared decision-making. For diagnostic testing, the committee has attempted to develop numbers needed to test, and for antimicrobial administration, the committee provided numbers needed to treat. Three algorithms summarize the recommendations for infants 8 to 21 days of age, 22 to 28 days of age, and 29 to 60 days of age. The recommendations in this guideline do not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.

Randomized Trial Evaluating Clinical Impact of RAPid IDentification and Susceptibility Testing for Gram-negative Bacteremia: RAPIDS-GN

BACKGROUND

Rapid blood culture diagnostics are of unclear benefit for patients with gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, randomized, controlled trial comparing outcomes of patients with GNB BSIs who had blood culture testing with standard-of-care (SOC) culture and antimicrobial susceptibility testing (AST) vs rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno System (RAPID).

METHODS

Patients with positive blood cultures with Gram stains showing GNB were randomized to SOC testing with antimicrobial stewardship (AS) review or RAPID with AS. The primary outcome was time to first antibiotic modification within 72 hours of randomization.

RESULTS

Of 500 randomized patients, 448 were included (226 SOC, 222 RAPID). Mean (standard deviation) time to results was faster for RAPID than SOC for organism ID (2.7 [1.2] vs 11.7 [10.5] hours; P < .001) and AST (13.5 [56] vs 44.9 [12.1] hours; P < .001). Median (interquartile range [IQR]) time to first antibiotic modification was faster in the RAPID arm vs the SOC arm for overall antibiotics (8.6 [2.6-27.6] vs 14.9 [3.3-41.1] hours; P = .02) and gram-negative antibiotics (17.3 [4.9-72] vs 42.1 [10.1-72] hours; P < .001). Median (IQR) time to antibiotic escalation was faster in the RAPID arm vs the SOC arm for antimicrobial-resistant BSIs (18.4 [5.8-72] vs 61.7 [30.4-72] hours; P = .01). There were no differences between the arms in patient outcomes.

CONCLUSIONS

Rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for gram-negative BSIs.

CLINICAL TRIALS REGISTRATION

NCT03218397.

Antibiotic Stewardship Implementation and Antibiotic Use at Hospitals With and Without On-site Infectious Disease Specialists

BACKGROUND

Many US hospitals lack infectious disease (ID) specialists, which may hinder antibiotic stewardship efforts. We sought to compare patient-level antibiotic exposure at Veterans Health Administration (VHA) hospitals with and without an on-site ID specialist, defined as an ID physician and/or ID pharmacist.

METHODS

This retrospective VHA cohort included all acute-care patient admissions during 2016. A mandatory survey was used to identify hospitals' antibiotic stewardship processes and their access to an on-site ID specialist. Antibiotic use was quantified as days of therapy per days present and categorized based on National Healthcare Safety Network definitions. A negative binomial regression model with risk adjustment was used to determine the association between presence of an on-site ID specialist and antibiotic use at the level of patient admissions.

RESULTS

Eighteen of 122 (14.8%) hospitals lacked an on-site ID specialist; there were 525 451 (95.8%) admissions at ID hospitals and 23 007 (4.2%) at non-ID sites. In the adjusted analysis, presence of an ID specialist was associated with lower total inpatient antibacterial use (odds ratio, 0.92; 95% confidence interval, .85-.99). Presence of an ID specialist was also associated with lower use of broad-spectrum antibacterials (0.61; .54-.70) and higher narrow-spectrum β-lactam use (1.43; 1.22-1.67). Total antibacterial exposure (inpatient plus postdischarge) was lower among patients at ID versus non-ID sites (0.92; .86-.99).

CONCLUSIONS

Patients at hospitals with an ID specialist received antibiotics in a way more consistent with stewardship principles. The presence of an ID specialist may be important to effective antibiotic stewardship.

Optimizing rapid diagnostics and diagnostic stewardship in Gram-negative bacteremia

Antimicrobial resistance remains a high global concern, as it is associated with prolonged hospitalizations, increased morbidity and mortality, and escalating healthcare-related costs. Rapid diagnostic technology (RDT) has become the cornerstone in achieving prompt blood culture results providing a quicker initiation of optimal therapy, decreased mortality, and decreased spread of resistance. To maximize the benefits of RDTs, antimicrobial stewardship programs must implement a diagnostic stewardship (DS) subgroup to optimize communication, education, and interpretation of RDT results within the healthcare system. The DS subgroup is necessary to evaluate the technologies available, better integrate the selected technologies into the healthcare system, and develop innovative and appropriate use to improve patient outcomes.

New Microbiological Techniques for the Diagnosis of Bacterial Infections and Sepsis in ICU Including Point of Care

Purpose of Review

The aim of this article is to review current and emerging microbiological techniques that support the rapid diagnosis of bacterial infections in critically ill patients, including their performance, strengths and pitfalls, as well as available data evaluating their clinical impact.

Recent Findings

Bacterial infections and sepsis are responsible for significant morbidity and mortality in patients admitted to the intensive care unit and their management is further complicated by the increase in the global burden of antimicrobial resistance. In this setting, new diagnostic methods able to overcome the limits of traditional microbiology in terms of turn-around time and accuracy are highly warranted. We discuss the following broad themes: optimisation of existing culture-based methodologies, rapid antigen detection, nucleic acid detection (including multiplex PCR assays and microarrays), sepsis biomarkers, novel methods of pathogen detection (e.g. T2 magnetic resonance) and susceptibility testing (e.g. morphokinetic cellular analysis) and the application of direct metagenomics on clinical samples. The assessment of the host response through new “omics” technologies might also aid in early diagnosis of infections, as well as define non-infectious inflammatory states.

Summary

Despite being a promising field, there is still scarce evidence about the real-life impact of these assays on patient management. A common finding of available studies is that the performance of rapid diagnostic strategies highly depends on whether they are integrated within active antimicrobial stewardship programs. Assessing the impact of these emerging diagnostic methods through patient-centred clinical outcomes is a complex challenge for which large and well-designed studies are awaited.

Improving outcomes and antibiotic stewardship (IOAS) for patients with Gram-positive bloodstream infections through use of rapid testing: a quasi-experimental multicentre study of the Accelerate PhenoTest™ BC Kit

BACKGROUND

Data from the Improving Outcomes and Antibiotic Stewardship for Patients with Bloodstream Infections: Accelerate PhenoTest™ BC Kit (AXDX) Registry Study were analysed to determine the impact of rapid organism identification and antimicrobial susceptibility testing (AST) for Gram-positive bacteraemia.

PATIENTS AND METHODS

This multicentre, quasi-experimental study evaluated clinical and antimicrobial stewardship metrics following the implementation of AXDX. Data from hospitalized patients with bacteraemia were compared between groups, one that underwent testing on AXDX (post-AXDX) and one that underwent traditional identification and AST (pre-AXDX). An analysis of patients with Gram-positive bacteraemia was performed. The primary outcome was time to optimal therapy (TTOT). Secondary outcomes included time to first antibiotic modification (overall and Gram-positive), duration of unnecessary MRSA coverage, incidence of adverse events, length of stay and mortality.

RESULTS

A total of 219 (109 pre-AXDX, 110 post-AXDX) patients with Gram-positive bacteraemia were included. Median TTOT was 36.3 h (IQR, 16.9-56.7) in the pre-AXDX group and 20.4 h (IQR, 7.5-36.7) in the post-AXDX group (P = 0.01). Compared with pre-AXDX, median time to first antibiotic modification (29.1 versus 15.9 h; P = 0.002), time to first Gram-positive antibiotic modification (33.2 versus 17.2 h; P = 0.003) and median duration of unnecessary MRSA coverage (58.4 versus 29.7 h; P = 0.04) were reduced post-AXDX. A trend towards decreased acute kidney injury (24% versus 13%; P = 0.06) was observed in the post-AXDX group. Groups did not differ in other secondary outcomes.

CONCLUSIONS

Implementation of AXDX testing for patients with Gram-positive bacteraemia shortened the TTOT and reduced unnecessary antibiotic exposure due to faster antibiotic modifications.

Predictive Value of Direct Disk Diffusion Testing from Positive Blood Cultures in a Children's Hospital and Its Utility in Antimicrobial Stewardship

Accurate and early susceptibility results could reduce overuse of broad-spectrum antibiotics for empirical treatment of bacteremia. Direct disk diffusion testing (dDD) using nonstandardized inocula directly from blood cultures could facilitate earlier narrowing of antibiotics. To determine the predictive value of dDD compared with standardized antimicrobial susceptibility testing (AST), we performed a retrospective cohort study of 582 blood cultures from 495 pediatric patients with bacteremia. Positive and negative predictive value (PPV: number of isolates susceptible by both dDD and AST divided by the total number of isolates susceptible by dDD; NPV: number of isolates not susceptible [either intermediate or resistant] by both dDD and AST divided by the total number of isolates not susceptible by dDD), sensitivity, specificity, and 95% confidence interval were calculated for each bacterium-antibiotic combination. We evaluated the Antibiotic Spectrum Index of prescribed antibiotics to assess change in antibiotic prescribing after availability of Gram stain, dDD, and AST results. dDD results were available a median of 21 h before AST results. dDD had PPVs of ≥96% for most organism-antibiotic pairs, including 100% (CI 96 to 100%) for Staphylococcus aureus with oxacillin and 99% (CI 93 to 100%) for Enterobacterales with ceftriaxone. NPVs of dDD were variable and frequently lower than the PPV. Very major errors and major errors occurred in 31/5,454 (0.6%) and 231/5,454 (4.2%) organism-antibiotic combinations, respectively. Antibiotics were narrowed in 30% of cases after a dDD result and a further 25% of cases after AST result. dDD is highly predictive of susceptibility for many common organism-antibiotic combinations and provides actionable information one day earlier than standard susceptibility approaches. dDD has the potential to facilitate earlier deescalation to narrow-spectrum antibiotic treatment.

The Genotype-to-Phenotype Dilemma: How Should Laboratories Approach Discordant Susceptibility Results?

Traditional culture-based methods for identification and antimicrobial susceptibility testing (AST) of bacteria take 2 to 3 days on average. Syndromic molecular diagnostic panels have revolutionized clinical microbiology laboratories as they can simultaneously identify an organism and detect some of the most significant antimicrobial resistance (AMR) genes directly from positive blood culture broth or from various specimen types (e.g., whole blood, cerebrospinal fluid, and respiratory specimens). The presence or absence of an AMR marker associated with a particular organism can be used to predict the phenotypic AST results to more rapidly guide therapy. Numerous studies have shown that genotypic susceptibility predictions by syndromic panels can improve patient outcomes. However, an important limitation of AMR marker detection to predict phenotype is the potential discrepancies that may arise upon performing phenotypic AST of the recovered organism in culture. The focus of this minireview is to address how clinical laboratories should interpret rapid molecular results from commercial platforms in relation to phenotypic AST. Stepwise approaches and solutions are provided to resolve discordant results between genotypic and phenotypic susceptibility results.

Antibiotic stewardship implementation at hospitals without on-site infectious disease specialists: A qualitative study

BACKGROUND

Hospitals are required to have antibiotic stewardship programs (ASPs), but there are few models for implementing ASPs without the support of an infectious disease (ID) specialist, defined as an ID physician and/or ID pharmacist.

OBJECTIVE

In this study, we sought to understand ASP implementation at hospitals that lack on-site ID support within the Veterans' Health Administration (VHA).

METHODS

Using a mandatory VHA survey, we identified acute-care hospitals that lacked an on-site ID specialist. We conducted semistructured interviews with personnel involved in ASP activities.

SETTING

The study was conducted across 7 VHA hospitals.

PARTICIPANTS

In total, 42 hospital personnel were enrolled in the study.

RESULTS

The primary responsibility for ASPs fell on the pharmacist champions, who were typically assigned multiple other non-ASP responsibilities. The pharmacist champions were more successful at gaining buy-in when they had established rapport with clinicians, but at some sites, the use of contract physicians and frequent staff turnover were potential barriers. Some sites felt that having access to an off-site ID specialist was important for overcoming institutional barriers and improving the acceptance of their stewardship recommendations. In general, stewardship champions struggled to mobilize institutional resources, which made it difficult to advance their programmatic goals.

CONCLUSION

In this study of 7 hospitals without on-site ID support, we found that ASPs are largely a pharmacy-driven process. Remote ID support, if available, was seen as helpful for implementing stewardship interventions. These findings may inform the future implementation of ASPs in settings lacking local ID expertise.

Diagnostic stewardship based on patient profiles: differential approaches in acute versus chronic infectious syndromes

Introduction: New diagnostics may be useful in clinical practice, especially in contexts of high prevalence of multidrug-resistant organisms (MDRO). However, misuse of diagnostic tools may lead to increased costs and worse patient outcome. Conventional and new techniques should be appropriately positioned in diagnostic algorithms to guide an appropriate use of antimicrobial therapy.Areas covered: A panel of experts identified 4 main areas in which the implementation of diagnostic stewardship is needed. Among chronic infections, bone and prosthetic joint infections and subacute-chronic intravascular infections and endocarditis represent common challenges for clinicians. Among acute infections, bloodstream infections and community-acquired pneumonia may be associated with high mortality and require appropriate diagnostic approach.Expert opinion: Diagnostic stewardship aims to improve the appropriate use of microbiological diagnostics to guide therapeutic decisions through appropriate and timely diagnostic testing. Here, diagnostic algorithms based on different patient profiles are proposed for chronic and acute clinical syndromes. In each clinical scenario, combining conventional and new diagnostic techniques is crucial to make a rapid and accurate diagnosis and to guide the selection of antimicrobial therapy. Barriers related to the implementation of new rapid diagnostic tools, such as high initial costs, may be overcome through their rational and structured use.

Educational Case: Staphylococcus aureus Bacteremia: Utilization of Rapid Diagnostics for Bloodstream Pathogen Identification and Prediction of Antimicrobial Susceptibility

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040. ¹

Rapid versus standard antimicrobial susceptibility testing to guide treatment of bloodstream infection

BACKGROUND

Rapid antimicrobial susceptibility tests are expected to reduce the time to clinically important results of a blood culture. This might enable clinicians to better target therapy to a person's needs, and thereby, improve health outcomes (mortality, length of hospital stay), and reduce unnecessary prescribing of broad-spectrum antibiotics; thereby reducing antimicrobial resistance rates.

OBJECTIVES

To assess the effects of rapid susceptibility testing versus standard susceptibility testing for bloodstream infections (BSIs).

SEARCH METHODS

To identify studies with selected outcomes, we searched the Cochrane Infectious Diseases Group Specialised Register, CENTRAL, MEDLINE, LILACS, and two trials registries, between 1987 and October 2020. We used 'bloodstream infection' and 'antimicrobial susceptibility tests' as search terms. We had no language or publication status limitations.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing rapid antimicrobial susceptibility testing (with a time-to-result of ≤ 8 hours) versus conventional antimicrobial susceptibility testing in people with a BSI caused by any bacteria, as identified by a positive blood culture.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened references, full-text reports of potentially relevant studies, extracted data from the studies, and assessed risk of bias. Any disagreement was discussed and resolved with a third review author. For mortality, a dichotomous outcome, we extracted the number of events in each arm, and presented a risk ratio (RR) with 95% confidence interval (CI) to compare rapid susceptibility testing to conventional methods. We used Review Manager 5.4 to meta-analyse the data. For other outcomes, which are time-to-event outcomes (time-to-discharge from hospital, time-to-first appropriate antibiotic change), we conducted qualitative narrative synthesis, due to heterogeneity of outcome measures.  MAIN RESULTS: We included six trials, with 1638 participants. For rapid antimicrobial susceptibility testing compared to conventional methods, there was little or no difference in mortality between groups (RR 1.10, 95% CI 0.82 to 1.46; 6 RCTs, 1638 participants; low-certainty evidence). In subgroup analysis, for rapid genotypic or molecular antimicrobial susceptibility testing compared to conventional methods, there was little or no difference in mortality between groups (RR 1.02, 95% CI 0.69 to 1.49; 4 RCTs, 1074 participants; low-certainty evidence). For phenotypic rapid susceptibility testing compared to conventional methods, there was little or no difference in mortality between groups  (RR 1.37, 95% CI 0.80 to 2.35; 2 RCTs, 564 participants; low-certainty evidence). In qualitative analysis, rapid susceptibility testing may make little or no difference in time-to-discharge (4 RCTs, 1165 participants; low-certainty evidence). In qualitative analysis, rapid genotypic susceptibility testing compared to conventional testing may make little or no difference in time-to-appropriate antibiotic (3 RCTs, 929 participants; low-certainty evidence). In subgroup analysis, rapid phenotypic susceptibility testing compared to conventional testing may improve time-to-appropriate antibiotic (RR -17.29, CI -45.05 to 10.47; 2 RCTs, 564 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: The theoretical benefits of rapid susceptibility testing have not been demonstrated to directly improve mortality, time-to-discharge, or time-to-appropriate antibiotic in these randomized studies. Future large prospective studies should be designed to focus on the most clinically meaningful outcomes, and aim to optimize blood culture pathways.

Management of Pediatric Nonpathogenic Blood Cultures After Introduction of PCR Technology

BACKGROUND

The rapid identification of organisms reported in positive blood cultures via polymerase chain reaction (PCR) can accurately identify a nonpathogenic bacterium and decrease time to definitive identification, as compared with traditional microbiologic methods. How this technology effects clinical and antimicrobial management in children with nonpathogenic bacteria identified in a blood culture without decision support has not been evaluated.

METHODS

A retrospective study of the management of children with positive blood culture results for nonpathogenic organisms before and after implementation of PCR technology. Each cohort's antibiotic management, frequency of repeat cultures, and return visits to an emergency department (ED) were compared.

RESULTS

A total 136 patients during this time (49% [n = 67] pre-PCR and 51% [n = 69] post-PCR) had a blood culture positive for nonpathogenic bacterium. Admitted patients had a second specimen sent for testing on fewer occasions (P = .04); however, total antibiotic exposure did not differ significantly (P = .3) after introduction of PCR technology. There was no significant difference in length of stay postintervention (P = .12). Patients discharged directly from the ED had fewer return visits (P = .02) and received fewer repeat blood cultures (P = .04), and antibiotics were administered on fewer occasions after return (P = .04) postintroduction of PCR technology.

CONCLUSIONS

With the addition of PCR technology, patients with blood cultures positive for nonpathogenic bacteria received less antibiotics, fewer repeat blood cultures, and fewer repeat ED evaluations.

Impact of a Rapid Blood Culture Diagnostic Panel on Time to Optimal Antimicrobial Therapy at a Veterans Affairs Medical Center

PURPOSE

Utilization of rapid diagnostic testing alongside intensive antimicrobial stewardship interventions improves patient outcomes. We sought to determine the clinical impact of a rapid blood culture identification (BCID) panel in an established Antimicrobial Stewardship Program (ASP) with limited personnel resources.

METHODS

A single center retrospective pre- and post-intervention cohort study was performed following the implementation of a BCID panel on patients admitted with at least 1 positive blood culture during the study period. The primary outcome was time to optimal therapy from blood culture collection. Secondary outcomes included days of therapy (DOT), length of stay, and 30-day mortality and readmission rates.

RESULTS

277 patients were screened with 180 patients included, with 82 patients in the pre-BCID and 98 in the post-BCID arms. Median time to optimal therapy was 73.8 hours (IQR; 1.1-79.6) in the pre-BCID arm and 34.7 hours (IQR; 10.9-71.6) in the post-BCID arm (p ≤ 0.001). Median DOT for vancomycin was 4 and 3 days (p ≤ 0.001), and for piperacillin-tazobactam was 3.5 and 2 days (p ≤ 0.007), for the pre-BCID and post-BCID arms, respectively. Median length of hospitalization was decreased from 11 to 9 days (p = 0.031). No significant change in 30-day readmission rate was noted, with a trend toward lower mortality (12% vs 5%; p = 0.086).

CONCLUSION

Introduction of BCID into the daily workflow resulted in a significant reduction in time to optimal therapy for bloodstream infections and DOT for select broad-spectrum antibiotics, highlighting the potential benefits of rapid diagnostics even in settings with limited personnel resources.

Impact of a Best Practice Advisory for Pediatric Patients With Staphylococcus aureus Bacteremia

BACKGROUND

Infectious diseases (ID) consultation and optimal antibiotic therapy improve outcomes in Staphylococcus aureus bacteremia (SAB). Data on strategies to improve adherence to these practices in children are limited.

METHODS

This was a quasi-experimental study evaluating the impact of an electronic medical record (EMR)-based best practice advisory (BPA) for SAB, recommending ID consult and optimal antibiotic therapy based on rapid mecA gene detection. Inpatients < 21 years old with SAB before (January 2015-July 2017) and after (August 2017-December 2018) BPA implementation were included. Primary outcome was receipt of ID consult. Secondary outcomes included receipt of optimal therapy, time to ID consult and optimal therapy, recurrent SAB, and 30-day all-cause mortality. ID consultation rates pre- and postimplementation were compared using interrupted time series (ITS) analysis. Hazard ratios (HRs) and 95% confidence intervals (CIs) for time to optimal therapy were calculated using Cox regression.

RESULTS

We included 99 SAB episodes (70 preintervention, 29 postintervention). Preintervention, 48 (68.6%) patients received an ID consult compared to 27 (93.1%) postintervention, but this was not statistically significant on ITS analysis due to a preexisting trend of increasing consultation. Median hours to optimal therapy decreased from 26.1 to 5.5 (P = .03), most notably in patients with methicillin-sensitive S. aureus (MSSA) (42.2 to 10.8; P < .01). On Cox regression, BPA implementation was associated with faster time to optimal therapy (HR, 3.22 [95% CI, 1.04-10.01]).

CONCLUSIONS

Implementation of an EMR-based BPA for SAB resulted in faster time to optimal antibiotic therapy, particularly for patients with MSSA. ID consultation increased throughout the study period and was not significantly impacted by the BPA.

Day at the Races: Comparing BioFire FilmArray Blood Culture ID Panels to Verigene Blood Culture in Gram-negative Bloodstream Infections using DOOR-MAT Analysis

Three rapid diagnostic test panels (Verigene BC-GN, BioFire BCID, and BCID 2 [RUO]) were compared using the Desirability of Outcome Ranking Management of Antimicrobial Therapy (DOOR-MAT) to evaluate potential downstream antimicrobial prescribing decisions resulting from the panels’ different organism and resistance detection. BioFire BCID 2 (RUO) had the best mean DOOR-MAT scores.