Validation of an Antimicrobial Stewardship-Driven Verigene Blood-Culture Gram-Negative Treatment Algorithm to Improve Appropriateness of Antibiotics

Multiplex microarray PCR Unyvero BCU system to accelerate relevant antimicrobial treatment in polymicrobial bloodstream infection

PURPOSE

To evaluate the performance of a rapid multiplex microarray-based method (Unyvero BCU system, BCU) to identify microorganisms and detect antimicrobial resistance directly from positive blood culture (BC) bottles with polymicrobial growth, and to assess relevance of information provided for timely guidance of polymicrobial bloodstream infection treatment.

METHODS

Accuracy, time-to-actionable results and potential impact of BCU on antimicrobial treatment were compared with those of standard of care during a prospective study for the sample analysis (November 2017-November 2018) and a retrospective study for the clinical data analysis and the time-to-result analysis. The study was complemented with an experimental study, based on spiked blood cultures to assess the ability of the method to detect antimicrobial resistance genes.

RESULTS

Sixty-five clinical polymicrobial BC samples (163 total microorganisms) and 30 simulated polymicrobial BC samples (60 strains) were included. BCU reported 84.6% samples as polymicrobial, correctly identified all the bacteria of the mix for 72.3% samples (47/65) and detected bacteria that were missed by the conventional culture for 13.8% samples. All identifications and antimicrobial resistances were accurately detected for 61.5% (40/65) samples. Limitations concerned the detection of anaerobes, enterococci and enterobacterial susceptibility to third generation cephalosporins. BCU results would have guided antimicrobial treatment for 50.8% of the cases (33/65) in a timely and relevant manner, had no impact for 27.7% (18/65) and been misleading for 18.5% (12/65).

CONCLUSIONS

Despite some limitations, the Unyvero BCU system is a rapid and reliable method for polymicrobial BC sample analysis.

Impact of Introducing a Multiplex Polymerase Chain Reaction Blood Culture Panel on Anti-Methicillin-Resistant Staphylococcus aureus (MRSA) and Carbapenem Antimicrobial Agents in a Children's Hospital

BACKGROUND

With the advent of multiplex polymerase chain reaction (PCR) using samples from a positive blood culture, the time required to identify a pathogen has significantly shortened to a few hours. It can help us select appropriate antimicrobial agents more quickly. The present study aimed to assess the impact of using a multiplex PCR blood culture panel on the appropriate administration of antimicrobial agents.

METHODS

Patients aged <16 years with culture-confirmed bacteremia at Tokyo Metropolitan Children's Medical Center were enrolled. A pre-intervention period (period I: December 2016 to December 2018) and a post-intervention period with multiplex PCR use for the confirmation of positive blood cultures (period II: December 2019 to December 2021) were compared for their effect on the use of antimicrobial agents for gram-positive cocci (GPC) and gram-negative rod (GNR) bacteremia. Data on patient background, blood culture results, and antimicrobial use were retrospectively collected from electronic medical records.

RESULTS

Periods I and II had 174 and 154 patients, respectively. The median age at periods I and II was 14 (IQR 2-82) months and 12 (IQR 1-78) months, respectively. GPC bacteremia during periods I and II occurred in 140 and 115 patients, respectively. GNR during periods I and II occurred in 34 and 39 patients, respectively. Neither the vancomycin-resistance genes A/B nor the carbapenem-resistance gene were detected. The use of antimicrobial agents against anti-methicillin-resistant Staphylococcus aureus (MRSA) for GPC bacteremia decreased from 103/140 cases (73%) in period I to 56/115 cases (49%) in period II (p=0.047). The use of carbapenems for GNR bacteremia did not change significantly, at 23/34 (68%) in period I and 34/39 (87%) in period II (p=0.47).

CONCLUSION

Introducing multiplex PCR for pediatric bacteremia decreased the use of anti-MRSA antimicrobial agents but not of carbapenems.

Antimicrobial De-Escalation in Critically Ill Patients

Antimicrobial de-escalation (ADE) is defined as the discontinuation of one or more antimicrobials in empirical therapy, or the replacement of a broad-spectrum antimicrobial with a narrower-spectrum antimicrobial. The aim of this review is to provide an overview of the available literature on the effectiveness and safety of ADE in critically ill patients, with a focus on special conditions such as anti-fungal therapy and high-risk categories. Although it is widely considered a safe strategy for antimicrobial stewardship (AMS), to date, there has been no assessment of the effect of de-escalation on the development of resistance. Conversely, some authors suggest that prolonged antibiotic treatment may be a side effect of de-escalation, especially in high-risk categories such as neutropenic critically ill patients and intra-abdominal infections (IAIs). Moreover, microbiological documentation is crucial for increasing ADE rates in critically ill patients with infections, and efforts should be focused on exploring new diagnostic tools to accelerate pathogen identification. For these reasons, ADE can be safely used in patients with infections, as confirmed by high-quality and reliable microbiological samplings, although further studies are warranted to clarify its applicability in selected populations.

Characterizing Antibiotic Regimen Modification Behavior, Patient Characteristics, and Outcomes for Patients with Gram-Negative Bacterial Infections, A Retrospective Single-Center Study

Few studies describe the frequency of antibiotic regimen modification behaviors in the acute care setting. We sought to ascertain patient and treatment characteristics, details of regimen modification, and clinical outcomes with antibiotic modifications. This retrospective study included patients admitted to Hoag Memorial Hospital from 1 January 2019-31 March 2021 with a complicated infection caused by a Gram-negative organism resistant to extended-spectrum cephalosporins or with the potential for resistance (AmpC producers). A total of 400 patients were included. The predominant sources were bloodstream (33%), urine (26%), and respiratory (24%), including patients with multiple sources. The most isolated organisms were Pseudomonas spp. and ESBL-producing organisms, 38% and 34%, respectively. A total of 72% of patients had antibiotic regimen modifications to their inpatient antibiotic regimens. In patients where modifications occurred, the number ranged from one to six modifications. The most common reasons for modifications included a lack of patient response (14%), additional history reviewed (9%), and decompensation (7%). No difference in clinical outcomes was observed based on antibiotic modifications. The numerous changes in therapy observed may reflect the limitations in identifying patients with resistant organisms early on in admission. This highlights the need for more novel antibiotics and the importance of identifying patients at risk for resistant organisms.

Improving the Efficiency of Antimicrobial Stewardship Action in Acute Care Facilities

Inpatient antimicrobial stewardship (AS) programs are quality improvement programs tasked with improving antibiotic practices by augmenting frontline providers' antibiotic prescription. Prospective audit and feedback (PAF) and preauthorization (PRA) are essential activities in the hospital that can be resource intensive for AS teams. Improving efficiency in AS activities is needed when there are limited resources or when programs are looking to expand tasks beyond PAF and PRA, such as broad education or guideline development. Guidance on the creation and maintenance of alerts for the purpose of PAF reviews, modifications of antibiotic restrictions for PRA polices, and overall initiative prioritization strategies are reviewed. In addition, daily prioritization tools, such as the tiered approach, scoring systems, and regression modeling, are available for stewards to prioritize their daily workflow. Using these tools and guidance, AS programs can be productive and impactful in the face of resource limitation or competing priorities in the hospital.

From bottle to bedside: Implementation considerations and antimicrobial stewardship considerations for bloodstream infection rapid diagnostic testing

Antimicrobial stewardship (AMS) programs have been quick to adopt novel molecular rapid diagnostic technologies (mRDTs) for bloodstream infections (BSIs) to improve antimicrobial management. As such, most of the literature demonstrating the clinical and economic benefits of mRDTs for BSI is in the presence of active AMS intervention. Leveraging mRDTs to improve antimicrobial therapy for BSI is increasingly integral to AMS program activities. This narrative review discusses available and future mRDTs, the relationship between the clinical microbiology laboratory and AMS programs, and practical considerations for optimizing the use of these tools within a health system. Antimicrobial stewardship programs must work closely with their clinical microbiology laboratories to ensure that mRDTs are used to their fullest benefit while remaining cognizant of their limitations. As more mRDT instruments and panels become available and AMS programs continue to expand, future efforts must consider the expansion beyond traditional settings of large academic medical centers and how combinations of tools can further improve patient care.

Impact of an Antimicrobial Stewardship Program Intervention Associated with the Rapid Identification of Microorganisms by MALDI-TOF and Detection of Resistance Genes in ICU Patients with Gram-Negative Bacteremia

Combination of strategies for rapid diagnostics tests (RDT) with real-time intervention could improve patient outcomes. We aimed to assess the impact on clinical outcomes, antimicrobial consumption, and costs in patients with gram-negative bacteremia. We designed a quasi-experimental study among 216 episodes of gram-negative bacteremia using RDT (MALDI-TOF and detection of resistance genes) directly from blood culture bottles combined with real-time communication of results. Our study did not demonstrate impact on 30-day mortality (25% vs. 35%; p = 0.115). Hospital and ICU length of stay were significantly lower in the intervention period ((44 days vs. 39 days; p = 0.005) and (17 days vs. 13 days; p = 0.033)), respectively. The antimicrobial consumption was 1381 DOT/1000 days in the pre-intervention period compared to 1262 DOT/1000 days in the intervention period (p = 0.032). Antimicrobials against gram-positive and carbapenems had a significantly reduced consumption in the intervention period. Our intervention showed no impact on 30 days-mortality, but demonstrated an impact on hospital and ICU length of stay, as well as antimicrobials consumption and costs. Knowledge of resistance genes adds value and information for safe decision making that can result in direct and indirect benefits related to the economic burden of antibiotic overuse and bacterial resistance.

Diagnosis and Management of Bloodstream Infections With Rapid, Multiplexed Molecular Assays

Bloodstream infection is a major health concern, responsible for considerable morbidity and mortality across the globe. Prompt identification of the responsible pathogen in the early stages of the disease allows clinicians to implement appropriate antibiotic therapy in a timelier manner. Rapid treatment with the correct antibiotic not only improves the chances of patient survival, but also significantly reduces the length of hospital stay and associated healthcare costs. Although culture has been the gold standard and most common method for diagnosis of bloodstream pathogens, it is being enhanced or supplanted with more advanced methods, including molecular tests that can reduce the turnaround time from several days to a few hours. In this article, we describe two rapid, molecular bloodstream infection panels that identify the most common pathogens and associated genetic determinants of antibiotic resistance – the Luminex^® VERIGENE^® Gram-Positive Blood Culture Test and the VERIGENE^® Gram-Negative Blood Culture Test. We conducted a search on PubMed to retrieve articles describing the performance and impact of these tests in the clinical setting. From a total of 48 articles retrieved, we selected 15 for inclusion in this review based on the type and size of the study and so there would be minimum of three articles describing performance and three articles describing the impact post-implementation for each assay. Here we provide a comprehensive review of these publications illustrating the performance and clinical utility of these assays, demonstrating how genotypic tests can benefit diagnostic and antimicrobial stewardship efforts.

Performance of the eazyplex® BloodScreen GN as a simple and rapid molecular test for identification of Gram-negative bacteria from positive blood cultures

The LAMP-based eazyplex® BloodScreen GN was evaluated for the detection of frequent Gram-negatives directly from positive blood culture (BC) bottles. A total of 449 BCs were analyzed. Sensitivities and specificities were 100% and 100% for Escherichia coli, 95.7% and 100% for Klebsiella pneumoniae, 100% and 100% for bla_CTX-M, 100% and 100% for Klebsiella oxytoca, 100% and 99% for Proteus mirabilis, and 100% and 99.8% for Pseudomonas aeruginosa, respectively. The time to result ranged from 8 to 16 min, plus about 6 min for sample preparation. The eazyplex® BloodScreen GN is a reliable molecular assay for rapid BC testing.

Impact of Pharmacist Involvement on the Utility of a Gram-Negative Blood Culture Identification Panel on Antimicrobial Usage

Background: A rapid molecular diagnostic test (MDT) is a test used to identify several different species of gram-negative bacteria and their genetic resistance markers. However, the impact of rapid MDT has not been established when combined with pharmacist involvement. Objective: To determine the impact of pharmacy involvement on patient outcomes when using rapid MDT. The primary outcome is the time from gram stain result to the first dose of the targeted antibiotic. Methods: This is a single-center, quasi-experimental, 1-group pretest-posttest design study of patients with gram-negative bacteremia in a community hospital. Hospitalized patients 18 years or older were included if they had a gram-negative blood culture. Patients were excluded if they were discharged or expired prior to culture results. Outcomes were compared between patients prior to and after implementation of the automated MDT. This research was determined to be exempt from institutional review board oversight consistent with West Florida Healthcare and in accordance with institutional policy. Results: The use of rapid MDT combined with pharmacist intervention resulted in a statistically significant decrease in the time to targeted antibiotic therapy (pre-intervention group, n = 77, 44.8 ± 17.8 hours versus post-intervention group, n= 80, 4.4 ± 5.8 hours; P ≤.001). There was no significant difference found between secondary outcomes. Limitations included small sample size as well as inconsistent documentation. Conclusions: The use of rapid MDT combined with pharmacist intervention resulted in a statistically significant decrease in the time to targeted antibiotic therapy.

Validation of neonatal and paediatric antimicrobial stewardship treatment algorithms in rapid diagnostic-detected bacteraemia

OBJECTIVES

Blood culture rapid diagnostic testing (RDT) aids in early organism identification and resistance gene detection. This information allows quicker transition to tailored antimicrobial therapy, improved patient outcomes and prevention of antimicrobial resistance. An antimicrobial treatment algorithm based on RDT results and local antibiograms can serve as a valuable clinical decision-support tool. This study assessed the proportion of appropriate antibiotic therapy recommendations using a novel paediatric RDT-guided treatment algorithm compared with standard care (SC) in paediatric bacteraemia.

METHODS

This was a retrospective, observational study of admitted paediatric patients who received antibiotics for RDT-confirmed bacteraemia. Appropriateness of SC was compared with algorithm-recommended treatment. Antimicrobial appropriateness was defined as in vitro susceptibility to the organism identified through traditional microbiology. Clinical appropriateness took into consideration the ability to tailor therapy within 12 h of RDT results. Appropriateness was evaluated by two blinded, independent reviewers.

KEY FINDINGS

Eighty-six blood cultures were included with 15 unique Gram-positive and Gram-negative species or genus identified. Comparative antimicrobial appropriateness of SC and algorithm-recommended treatment was 94.2% (81/86) and 100% (86/86), respectively (P = 0.06). Clinical assessment determined 39.5% (34/86) of SC patients were on appropriate therapy within 12 h of RDT result. Algorithm-recommended therapy was clinically appropriate in 97.7% (84/86) of patients (P < 0.001). There was a median time savings of 42.7 h (IQR 40.6, 49.4) for the patients able to be de-escalated as compared with waiting on final sensitivities.

CONCLUSIONS

Algorithm-guided treatment may allow most patients to be de-escalated to organism-tailored therapy earlier in their therapeutic course.

An antibiotic stewardship program in a surgical ICU of a resource-limited country: financial impact with improved clinical outcomes

Background

Antibiotic resistance (ABX-R) is alarming in lower/middle-income countries (LMICs). Nonadherence to antibiotic guidelines and inappropriate prescribing are significant contributing factors to ABX-R. This study determined the clinical and economic impacts of antibiotic stewardship program (ASP) in surgical intensive care units (SICU) of LMIC.

Method

We conducted this pre and post-test analysis in adult SICU of Aga Khan University Hospital, Pakistan, and compared pre-ASP (September–December 2017) and post-ASP data (April–July 2018). January–March 2018 as an implementation/training phase, for designing standard operating procedures and training the team. We enrolled all the patients admitted to adult SICU and prescribed any antibiotic. ASP-team daily reviewed antibiotics prescription for its appropriateness. Through prospective-audit and feedback-mechanism changes were made and recorded. Outcome measures included antibiotic defined daily dose (DDDs)/1000 patient-days, prescription appropriateness, antibiotic duration, readmission, mortality, and cost-effectiveness.

Result

123 and 125 patients were enrolled in pre-ASP and post-ASP periods. DDDs/1000 patient-days of all the antibiotics reduced in the post-ASP period, ceftriaxone, cefazolin, metronidazole, piperacillin/tazobactam, and vancomycin showed statistically significant (p < 0.01) reduction. The duration of all antibiotics use reduced significantly (p < 0.01). Length of SICU stays, mortality, and readmission reduced in the post-ASP period. ID-pharmacist interventions and source-control-documentation were observed in 62% and 50% cases respectively. Guidelines adherence improved significantly (p < 0.01). Net cost saving is 6360US$ yearly, mainly through reduced antibiotics consumption, around US$ 18,000 (PKR 2.8 million) yearly.

Conclusion

ASP implementation with supplemental efforts can improve the appropriateness of antibiotic prescriptions and the optimum duration of use. The approach is cost-effective mainly due to the reduced cost of antibiotics with rational use. Better source-control-documentation may further minimize the ABX-R in SICU.

Management of Gram-Negative Bloodstream Infections in the Era of Rapid Diagnostic Testing: Impact With and Without Antibiotic Stewardship

Background

Verigene Blood-Culture Gram-Negative is a rapid diagnostic test (RDT) that detects gram-negatives (GNs) and resistance within hours from gram stain. The majority of the data support the use of RDTs with antimicrobial stewardship (AMS) intervention in gram-positive bloodstream infection (BSI). Less is known about GN BSI.

Methods

This was a retrospective quasi-experimental (nonrandomized) study of adult patients with RDT-target GN BSI comparing patients pre-RDT/AMS vs post-RDT/pre-AMS vs post-RDT/AMS. Optimal therapy was defined as appropriate coverage with the narrowest spectrum, accounting for source and co-infecting organisms. Time to optimal therapy was analyzed using Kaplan-Meier and multivariable Cox proportional hazards regression.

Results

Eight-hundred thirty-two patients were included; 237 pre-RDT/AMS vs 308 post-RDT/pre-AMS vs 237 post-RDT/AMS, respectively. The proportion of patients on optimal antibiotic therapy increased with each intervention (66.5% vs 78.9% vs 83.2%; P < .0001). Time to optimal therapy (interquartile range) decreased with introduction of RDT: 47 (7.9–67.7) hours vs 24.9 (12.4–55.2) hours vs 26.5 (10.3–66.5) hours (P = .09). Using multivariable modeling, infectious diseases (ID) consult was an effect modifier. Within the ID consult stratum, controlling for source and ICU stay, compared with the pre-RDT/AMS group, both post-RDT/pre-AMS (adjusted hazard ratio [aHR], 1.34; 95% CI, 1.04–1.72) and post-RDT/AMS (aHR, 1.28; 95% CI, 1.01–1.64), improved time to optimal therapy. This effect was not seen in the stratum without ID consult.

Conclusions

With the introduction of RDT and AMS, both proportion and time to optimal antibiotic therapy improved, especially among those with an existing ID consult. This study highlights the beneficial role of RDTs in GN BSI.

Acute Acalculous Cholecystitis-Associated Bacteremia Has Worse Outcome

Background: Acute acalculous cholecystitis (AAC) is an inflammation of the gallbladder without gallstones in the setting of critical illness. It represents 2%-15% of acute cholecystitis (AC) cases. Bacteremia is associated with increased morbidity and mortality rates in patients in the intensive care unit (ICU). The incidence of bacteremia in acute calculous cholecystitis (ACC) has been described; however, the incidence of bacteremia in AAC has not been reported. We hypothesized that patients with AAC have higher bacteremia rates, leading to worse outcomes than in those with ACC. Methods: A prospectively collected acute care surgery (ACS) institutional database of patients treated from 2008 through 2018 was queried for patients having ACC using International Classification of Diseases (ICD) 9 and 10 codes. Demographics, microbiology findings, and outcomes were extracted. Only patients with positive blood cultures were included in the study. We defined two cohorts: AAC with bacteremia and ACC with bacteremia. The Student t-test was used for continuous variables and the χ² and Fisher exact tests for categorical variables. Multivariable regression was applied, and statistical significance was set at p < 0.05. Results: Of 323 patients with AC, 57 (17.6%) had AAC and 266 (82.4%) had ACC. Of the 19 patients who had a blood culture, 11 (57.8%) were positive. Patients with positive blood cultures had a mean age of 56.7 ± 15.3 years and a mean Body Mass Index (BMI) of 26.7 ± 4.9. The incidence of bacteremia was significantly higher in AAC (n = 6; 10.5% versus n = 5; 1.9 %; p = 0.005), although the time between admission and diagnosis of bacteremia was similar in the two groups (1.2 ± 1.1 versus 0.2 ± 0.5 days; p = 0.128). The patients with AAC and bacteremia were younger (53.8 ± 19.2 versus 60.2 ± 8 years; p = 0.021) and had a longer ICU length of stay (LOS) (12.6 ± 7.2 versus 1.3 ± 2.1 days; p = 0.030). However, there was no difference in the mortality rate in the groups (n = 2; 33.3% versus 1; 20.0%; p = 1.000). After adjusting for age, gender, BMI, and Charlson Comorbidity Index, bacteremia in AAC patients was found to be an independent variable for longer ICU LOS (odds ratio 8.8; 95% confidence interval 1.7-15.9; p = 0.024). Conclusions: The incidence of bacteremia in patients with AAC is five-fold higher and the ICU stay eight days longer than in patients with ACC.

Impact of a Rapid Blood Culture Diagnostic Test in a Children's Hospital Depends on Gram-Positive versus Gram-Negative Organism and Day versus Night Shift

Rapid diagnostic tests (RDTs) for bloodstream infections (BSIs) decrease the time to organism identification and resistance detection. RDTs are associated with early deescalation of therapy for Gram-positive BSIs. However, it is less clear how RDTs influence antibiotic management for Gram-negative BSIs and whether RDT results are acted on during off-hours. We performed a single-center, retrospective review of children with BSI and Verigene (VG) testing at a children's hospital. Of the 301 positive cultures included in the study (196 Gram-positive, 44 Gram-negative, 32 polymicrobial, and 29 non-VG targets), the VG result had potential to impact antibiotic selection in 171 cases; among these, antibiotic changes occurred in 119 (70%) cases. For Gram-negative cultures, the Verigene result correlated with unnecessary antibiotic escalation and exposure to broader-spectrum antibiotics than needed. In contrast, for Gram-positive cultures, the VG results correlated with appropriate antibiotic selection. VG results permitted early deescalation for methicillin-susceptible Staphylococcus aureus (MSSA) (19/24 [79%]) and avoidance of antibiotics for skin contaminants (30/85 [35%]). Antibiotic changes occurred more quickly during the day than at night (4.6 versus 11.7 h, respectively; P < 0.05), and antibiotic escalations occurred more quickly than did deescalations (4.1 versus 10.1 h, P < 0.01). In a pediatric institution with a low prevalence of Gram-negative resistance, the VG RDT facilitated antibiotic optimization for Gram-positive BSIs but led to unnecessary escalation of antibiotics for Gram-negative BSIs. The time to action was slower for RDT results reported at night than during the day. Laboratories should consider these factors when implementing blood culture RDTs.

Antimicrobial de-escalation in critically ill patients: a position statement from a task force of the European Society of Intensive Care Medicine (ESICM) and European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Critically Ill Patients Study Group (ESGCIP)

BACKGROUND

Antimicrobial de-escalation (ADE) is a strategy of antimicrobial stewardship, aiming at preventing the emergence of antimicrobial resistance (AMR) by decreasing the exposure to broad-spectrum antimicrobials. There is no high-quality research on ADE and its effects on AMR. Its definition varies and there is little evidence-based guidance for clinicians to use ADE in the intensive care unit (ICU).

METHODS

A task force of 16 international experts was formed in November 2016 to provide with guidelines for clinical practice to develop questions targeted at defining ADE, its effects on the ICU population and to provide clinical guidance. Groups of 2 experts were assigned 1-2 questions each within their field of expertise to provide draft statements and rationale. A Delphi method, with 3 rounds and an agreement threshold of 70% was required to reach consensus.

RESULTS

We present a comprehensive document with 13 statements, reviewing the evidence on the definition of ADE, its effects in the ICU population and providing guidance for clinicians in subsets of clinical scenarios where ADE may be considered.

CONCLUSION

ADE remains a topic of controversy due to the complexity of clinical scenarios where it may be applied and the absence of evidence to the effects it may have on antimicrobial resistance.

A Baker's Dozen of Top Antimicrobial Stewardship Intervention Publications in 2018

With an increasing number of antimicrobial stewardship-related articles published each year, attempting to stay current is challenging. The Southeastern Research Group Endeavor (SERGE-45) identified antimicrobial stewardship-related peer-reviewed literature that detailed an actionable intervention for 2018. The top 13 publications were selected using a modified Delphi technique. These manuscripts were reviewed to highlight the actionable intervention used by antimicrobial stewardship programs to provide key stewardship literature for teaching and training as well as to identify potential intervention opportunities within one's institution.