Rapid molecular determination of methicillin resistance in staphylococcal bacteraemia improves early targeted antibiotic prescribing: a randomized clinical trial

Clinical impact and cost-consequence analysis of ePlex® blood culture identification panels for the rapid diagnosis of bloodstream infections: a single-center randomized controlled trial

To assess clinical impact and perform cost-consequence analysis of the broadest multiplex PCR panels available for the rapid diagnosis of bloodstream infections (BSI). Single-center, randomized controlled trial conducted from June 2019 to February 2021 at a French University hospital with an institutional antimicrobial stewardship program. Primary endpoint was the percentage of patients with optimized antimicrobial treatment 12 h after transmission of positivity and Gram stain results from the first positive BC. This percentage was significantly higher in the multiplex PCR (mPCR) group (90/105 = 85.7% %, CI95% [77.5 ; 91.8] vs. 68/107 = 63.6%, CI95% [53.7 ; 72.6]; p < 10- 3) at interim analysis, resulting in the early termination of the study after the inclusion of 309 patients. For patients not optimized at baseline, the median time to obtain an optimized therapy was much shorter in the mPCR group than in the control group (6.9 h, IQR [2.9; 17.8] vs. 26.4 h, IQR [3.4; 47.5]; p = 0.001). Early optimization of antibiotic therapy resulted in a non-statistically significant decrease in mortality from 12.4 to 8.8% (p = 0.306), with a trend towards a shorter median length of stay (18 vs. 20 days; p = 0.064) and a non-significant reduction in the average cost per patient of €3,065 (p = 0.15). mPCR identified all the bacteria present in 88% of the samples. Despite its higher laboratory cost, the use of multiplex PCR for BSI diagnosis leads to early-optimised therapy, seems cost-effective and could reduce mortality and length of stay. Their impact could probably be improved if implemented 24/7.

Assessment of the impact of centralized bioMérieux BACT/ALERT® VIRTUO® blood culture system (VIRTUO) implementation on outcomes in patients with gram-negative bacteremia

BACKGROUND

We evaluated pre- and postimplementation of Virtuo on outcome in patients with gram-negative bacteremia using a quasiexperimental time-in-motion design.

METHODS

Becton Dickinson BACTEC™ 9000 series (Bactec) (2018) and Virtuo system (2020) were utilized in a decentralized and centralized process, respectively. Data collected in August-December in 2018 and 2020 were analyzed with SPSS (ver 28).

RESULTS

For 185 patients in each time period, patient age, gender, length of hospitalization were not different. However, blood culture (BC) volume was significantly lower in 2020 (7.1 ± 2.6 mL) compared to 2018 (8.9 ± 1.9 mL). Time from BC draw and time from pathogen identification (ID) to treatment change were both significantly faster in 2020 (52.9 ± 38.3 hours; 15.1 ± 27.4 hours), compared to 2018 (65.0 ± 46.3 hours; 23.8 ± 33.8), respectively.

CONCLUSIONS

Replacement of decentralized Bactec with centralized Virtuo, resulted in significant improvement in management of patients gram-negative bacteremia.

Initial antibiotic therapy for postoperative moderate or severe diabetic foot infections: Broad versus narrow spectrum, empirical versus targeted

AIM

To retrospectively evaluate clinical and microbiological outcomes after combined surgical and medical therapy for diabetic foot infections (DFIs), stratifying between the empirical versus the targeted nature, and between an empirical broad versus a narrow-spectrum, antibiotic therapy.

METHODS

We retrospectively assessed the rate of ultimate therapeutic failures for each of three types of initial postoperative antibiotic therapy: adequate empirical therapy; culture-guided therapy; and empirical inadequate therapy with a switch to targeted treatment based on available microbiological results.

RESULTS

We included data from 332 patients who underwent 716 DFI episodes of surgical debridement, including partial amputations. Clinical failure occurred in 40 of 194 (20.6%) episodes where adequate empirical therapy was given, in 77 of 291 (26.5%) episodes using culture-guided (and correct) therapy from the start, and in 73 of 231 (31.6%) episodes with switching from empirical inadequate therapy to culture-targeted therapy. Equally, a broad-spectrum antibiotic choice could not alter this failure risk. Group comparisons, Kaplan-Meier curves and Cox regression analyses failed to show either statistical superiority or inferiority of any of the initial antibiotic strategies.

CONCLUSIONS

In this study, the microbiological adequacy of the initial antibiotic regimen after (surgical) debridement for DFI did not alter therapeutic outcomes. We recommend that clinicians follow the stewardship approach of avoiding antibiotic de-escalation and start with a narrow-spectrum regimen based on the local epidemiology.

Impact of the FilmArray Rapid Multiplex PCR Assay on Clinical Outcomes of Patients with Bacteremia

Bacteremia is a serious disease with a reported mortality of 30%. Appropriate antibiotic use with a prompt blood culture can improve patient survival. However, when bacterial identification tests based on conventional biochemical properties are used, it takes 2 to 3 days from positive blood culture conversion to reporting the results, which makes early intervention difficult. Recently, FilmArray (FA) multiplex PCR panel for blood culture identification was introduced to the clinical setting. In this study, we investigated the clinical impact of the FA system on decision making for treating septic diseases and its association with patients' survival. Our hospital introduced the FA multiplex PCR panel in July 2018. In this study, blood-culture-positive cases submitted between January and October 2018 were unbiasedly included, and clinical outcomes before and after the introduction of FA were compared. The outcomes included (i) the duration of use of broad-spectrum antibiotics, (ii) the time until the start of anti-MRSA therapy to MRSA bacteremia, and (iii) sixty-day overall survival. In addition, multivariate analysis was used to identify prognostic factors. In the FA group, overall, 122 (87.8%) microorganisms were concordantly retrieved with the FA identification panel. The duration of ABPC/SBT use and the start-up time of anti-MRSA therapy to MRSA bacteremia were significantly shorter in the FA group. Sixty-day overall survival was significantly improved by utilizing FA compared with the control group. In addition, multivariate analysis identified Pitt score, Charlson score, and utilization of FA as prognostic factors. In conclusion, FA can lead to the prompt bacterial identification of bacteremia and its effective treatment, thus significantly improving survival in patients with bacteremia.

Detection of Methicillin-Resistant Staphylococcus aureus Infections Using Molecular Methods

The application of molecular detection methods for bacterial pathogens has dramatically improved the outcomes of septic patients, including those with methicillin-resistant Staphylococcus aureus (MRSA) infections. Molecular methods can be applied to a variety of clinical specimens including nasal swabs, growth in blood culture bottles, and wounds. While data show that the overall accuracy of molecular tests for MRSA is high, results can be confounded by the presence of multiple staphylococcal species in a specimen, insertions and deletions of DNA in and around the Staphylococcal Cassette Chromosome mec (SCCmec) element, and point mutations in mecA. Herein, we explore the complexities of molecular approaches to MRSA detection and the instances where phenotypic methods should be pursued to resolve discrepancies between genotypic and phenotypic results.

Antimicrobial susceptibility testing for Gram positive cocci towards vancomycin using scanning electron microscopy

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SEM-based method can be applied for rapid phenotypic AST on Gram-positive cocci towards 2 vancomycin based on morphological changes 3.

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The ratio of septa as a marker of bacterial division and size of grape-like clusters enabled the 4 profiling of E. faecalis, E. faecium and S. aureus after brief incubation with vancomycin 5.

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SEM-AST strategy showed the feasibility of detecting antibiotic susceptibility or 6 resistance on Gram-positive cocci within one hour of exposition to vancomycin 7.

The rapid detection of resistant bacteria has become a challenge for microbiologists worldwide. Numerous pathogens that cause nosocomial infections are still being treated empirically and have developed resistance mechanisms against key antibiotics. Thus, one of the challenges for researchers has been to develop rapid antimicrobial susceptibility testing (AST) to detect resistant isolates, ensuring better antibiotic stewardship. In this study, we established a proof-of-concept for a new strategy of phenotypic AST on Gram-positive cocci towards vancomycin using scanning electron microscopy (SEM). Our study evaluated the profiling of Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus after brief incubation with vancomycin. Sixteen isolates were analysed aiming to detect ultrastructural modifications at set timepoints, comparing bacteria with and without vancomycin. After optimising slides preparation and micrographs acquisition, two analytical strategies were used. The high magnification micrographs served to analyse the division of cocci based on the ratio of septa, along with the bacterial size. Susceptible strains with vancomycin showed a reduced septa percentage and the average surface area was consequently double that of the controls. The resistant bacteria revealed multiple septa occurring at advanced timepoints. Low magnification micrographs made it possible to quantify the pixels at different timepoints, confirming the profiling of cocci towards vancomycin. This new phenotypic AST strategy proved to be a promising tool to discriminate between resistant and susceptible cocci within an hour of contact with vancomycin. The analysis strategies applied here would potentially allow the creation of artificial intelligence algorithms for septa detection and bacterial quantification, subsequently creating a rapid automated SEM-AST assay.

Systematic Review: A Comparison between Vancomycin and Daptomycin for Sepsis Infection Antibiotic Therapy

BACKGROUND: Sepsis is a dangerous condition that threatens life because of immune system dysregulation caused by an infection resulting in organ failure. One of the most common resistant strain bacteria that can cause sepsis is Methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin is the first-line therapy for treating sepsis infection caused by MRSA, but recently there have been some MRSA strains that are resistant to vancomycin therapy. AIM: This study aimed to review comparison between vancomycin and daptomycin for sepsis infection antibiotics therapy. MATERIALS AND METHODS: This research was a systematic review using three databases such as PubMed, ProQuest, and ScienceDirect. The journal articles included in this study were about randomized controlled trial (RCT) studies published from 2011 to 2020. RESULTS: This research included seven RCT studies, but none of them discuss the usage of daptomycin for sepsis treatment caused by MRSA. They discuss more the effect of dose, method of administration, and side effects of vancomycin therapy in relation to the outcome of the patient. CONCLUSIONS: Because of the lack of RCT articles that conducted experiments of daptomycin usage for sepsis treatment caused by MRSA infection, this research could not compare the effectiveness between vancomycin and daptomycin. However, from some case reports included in this research, there was evidence that the usage of daptomycin base after vancomycin treatment failure will cause another treatment failure.

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.

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.

Optimal and responsible use of antibiotics

PURPOSE OF REVIEW

In this review, we focus on the dual face of antibiotic therapy in the critically ill that must harmonize the need for early, appropriate and adequate antibiotic therapy in the individual-infected patient with the obligation to limit antibiotic selection pressure as much as possible to preserve its future potential.

RECENT FINDINGS

Recent articles have highlighted and detailed the various aspects, which determine antibiotic efficacy, and have identified adjunctive treatments, such as source control, which impact outcome. In addition, settings and indications where antibiotics do not improve outcome and may cause harm have been identified.

SUMMARY

Reconciling antibiotic efficacy with the limitations of their use is feasible but requires a dedicated and sustained effort throughout the whole process of clinical decision-making, from initial suspicion of sepsis to its definitive treatment.

Rapid Diagnostics for Blood Cultures: Supporting Decisions for Antimicrobial Therapy and Value-Based Care

Bacteremia and sepsis are critically important syndromes with high mortality, morbidity, and associated costs. Bloodstream infections and sepsis are among the top causes of mortality in the US, with >600 deaths each day. Most septic patients can be found in emergency medicine departments or critical care units, settings in which rapid administration of targeted antibiotic therapy can reduce mortality. Unfortunately, routine blood cultures are not rapid enough to aid in the decision of therapeutic intervention at the onset of bacteremia. As a result, empiric, broad-spectrum treatment is common-a costly approach that may fail to target the correct microbe effectively, may inadvertently harm patients via antimicrobial toxicity, and may contribute to the evolution of drug-resistant microbes. To overcome these challenges, laboratorians must understand the complexity of diagnosing and treating septic patients, focus on creating algorithms that rapidly support decisions for targeted antibiotic therapy, and synergize with existing emergency department and critical care clinical practices put forth in the Surviving Sepsis Guidelines.

Influence of GeneXpert MRSA/SA test implementation on clinical outcomes of Staphylococcus aureus bacteremia - a before-after retrospective study

Use of GeneXpert MRSA/SA in diagnostic algorithms of Staphylococcus aureus bacteremia may influence both patients' clinical outcomes and antibiotic stewardship. We evaluated these outcomes in a retrospective cohort before (1/6/2015-31/5/2016) and after (1/6/2016-31/8/2017) the introduction of the test in adult patients with Gram-positive cocci in clusters in blood cultures. We included 254 patients (125 preintervention, 129 postintervention). No significant difference in 30-day mortality or clinical success was demonstrated between periods. Appropriate antibiotic therapy rates were significantly higher in the postintervention group, and vancomycin use was significantly reduced (80.6% vs 53.6%, P < 0.01; 2.3±0.38 vs 2.98±1.02 defined daily doses/100 patient days, P = 0.026, respectively). Appropriate beta-lactam use was also significantly higher (56.7% postintervention vs 23.1% preintervention, P < 0.01). Use of GeneXpert MRSA/SA test has a positive effect on antibiotic stewardship measures, though it has no significant effect on clinical outcomes including mortality in this fatal infection.

Comparison of Methicillin-resistant Versus Susceptible Staphylococcus aureus Pediatric Osteomyelitis

BACKGROUND

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) pediatric osteomyelitis has risen and been associated with a more severe clinical course than methicillin-susceptible Staphylococcus aureus (MSSA) infections. National databases have been underutilized to describe these trends. We compared demographics, clinical course, and outcomes for patients with MRSA versus MSSA osteomyelitis.

METHODS

We queried the 2009 and 2012 Healthcare Cost and Utilization Project Kids Inpatient Database for discharge records with diagnosis codes for osteomyelitis and S. aureus. We explored demographics predicting MRSA and evaluated MRSA versus MSSA as predictors of clinical outcomes including surgery, sepsis, thrombophlebitis, length of stay, and total charges.

RESULTS

A total of 4214 discharge records were included. Of those, 2602 (61.7%) had MSSA and 1612 (38.3%) had MRSA infections. Patients at Southern and Midwestern hospitals were more likely to have MRSA than those at Northeastern hospitals. Medicaid patients' odds of MRSA were higher than those with private insurance, and black patients were more likely to have MRSA compared with white patients. MRSA patients were more likely to undergo multiple surgeries compared with MSSA patients and were more likely to have complications including severe sepsis, thrombophlebitis, and pulmonary embolism. Patients with MRSA had longer lengths of stay than those with MSSA and higher total charges after controlling for length of stay.

CONCLUSION

Review of a national database demonstrates MRSA is more prevalent in the South and Midwest regions and among black patients. MRSA patients have more surgeries, complications, and longer lengths of stay.

LEVEL OF EVIDENCE

Level III.

New paradigm for rapid achievement of appropriate therapy in special populations: coupling antibiotic dose optimization rapid microbiological methods

INTRODUCTION

Some special patient populations (e.g. critically ill, burns, hematological malignancy, post-major surgery, post-major trauma) have characteristics that lead to higher rates of failure and mortality associated with infection. Choice of effective antibiotics and optimized doses are challenging in these patients that are commonly infected by multidrug-resistant pathogens. Areas covered: A review of the importance of diagnosis and the place of newer microbiological methods (e.g. whole-genome sequencing) to ensure rapid transition from empiric to directed antibiotic therapy is provided. The effects of pathophysiological changes on antibiotic pharmacokinetics are also provided. Expert opinion: Product information dosing regimens do not address the pharmacokinetic alterations that can occur in special patient populations and increase the likelihood of therapeutic failure and the emergence of bacterial resistance. Altered dosing approaches, supplemented with the use of dosing software and therapeutic drug monitoring, may be needed to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients with severe infection. Dose optimization needs to be coupled with advanced microbiological techniques that enable rapid microbiological identification and characterization of resistance mechanism to ensure that maximally effective directed therapy can be chosen.

Optimization of antimicrobial therapy in vancomycin-resistant enterococcal bacteraemia using a rapid detection Gram-positive blood culture assay

Rapid molecular blood culture Gram-positive (BC-GP) assay can promptly identify vancomycin-resistant enterococcal (VRE) bloodstream infections (BSIs). We sought to evaluate patients with VRE BSI following the pre (N = 44) and post (N = 20) implementation of Verigene BC-GP assay. The average time to detection of VRE was 25.9 ± 4.1h (95% confidence interval (CI): 17.6-34.1; P < 0.001) earlier with Verigene BC-GP assay. Compared to patients in the pre-Verigene BC-GP period, the mean adjusted difference in time to administration of anti-VRE therapy was 18.2 ± 7.8h (95% CI: 2.5-33.8; P = 0.024) earlier among patients in the post-Verigene BC-GP period.

Advances in Rapid Identification and Susceptibility Testing of Bacteria in the Clinical Microbiology Laboratory: Implications for Patient Care and Antimicrobial Stewardship Programs

Early availability of information on bacterial pathogens and their antimicrobial susceptibility is of key importance for the management of infectious diseases patients. Currently, using traditional approaches, it usually takes at least 48 hours for identification and susceptibility testing of bacterial pathogens. Therefore, the slowness of diagnostic procedures drives prolongation of empiric, potentially inappropriate, antibacterial therapies. Over the last couple of years, the improvement of available techniques (e.g. for susceptibility testing, DNA amplification assays), and introduction of novel technologies (e.g. MALDI-TOF) has fundamentally changed approaches towards pathogen identification and characterization. Importantly, these techniques offer increased diagnostic resolution while at the same time shorten the time-to-result, and are thus of obvious importance for antimicrobial stewardship. In this review, we will discuss recent advances in medical microbiology with special emphasis on the impact of novel techniques on antimicrobial stewardship programs.

[Advances in diagnostic microbiology : Opportunities and limitations]

In the light of ever increasing problems related to the emergence of multidrug-resistant bacteria, rapid microbiological diagnostics are of growing importance. Timely pathogen detection and availability of susceptibility data are essential for optimal treatment, but are even more crucial for de-escalation of broad spectrum empiric therapies. Medical microbiology is, thus, an integral part of antimicrobial stewardship programs. Traditional microbiological techniques for species identification and susceptibility testing rely on bacterial growth and are, thus, characterized by inherent slowness. Time-to-report is usually 48 h or longer, and typically delays optimization of therapeutic regimens. Constant improvement of available techniques (e. g., molecular methods) and introduction of novel methods (e. g., matrix-assisted laser desorption ionization time-of-flight [MALDI-ToF] mass spectrometry) have fundamentally changed diagnostic procedures. As a consequence, sensitivity and specificity as well as time-to-report have been dramatically improved. In this manuscript, key methodological advances in medical microbiology are discussed, emphasizing consequences for daily management of infectious disease patients.