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.

Clinical utility of direct application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry and rapid disk diffusion test in presumptive antimicrobial therapy for bacteremia

OBJECTIVE

To study how and to what degree the rapid pathogen identification by MALDI-TOF MS coupled with rapid disk diffusion test improve the current clinical practice of patients with bacteremia in a tertiary teaching hospital with full-time ID consultation service.

PATIENTS AND METHODS

MALDI-TOF MS and 8H disk diffusion tests were directly applied to the positive blood cultures samples and the results were reflected on antimicrobial therapy (n = 119). The appropriateness of antimicrobial selection through these interventions was verified with conventional culture results in comparison with historical control (n = 129). The mortality of patients between the two periods was also compared.

RESULTS

The appropriateness of antimicrobial selection was higher (99.2%) in the intervention than in the control group (93.8%) (p 0.024), but there was no difference in 28-day mortality between the two periods (16.8%, 14.8%) (p 0.668). The duration of presumptive antimicrobial therapy with anti-MRSA agents and carbapenem antibiotics did not differ between the two periods indicating that the intervention was not effective in decreasing the unnecessary antibiotics. On the other hand, some bacteremic patients with pathogens whose drug susceptibilities were invariably sensitive to the standard class of antibiotics definitely benefitted from the intervention.

CONCLUSION

The intervention utilizing MALDI-TOF MS and the rapid disk diffusion test may not demonstrate overall improvement in bacteremia mortality in the institution with full-time infectious disease consultants. Its utility has yet to be evaluated in different setting hospitals.

Expanding Existing Antimicrobial Stewardship Programs in Pediatrics: What Comes Next

The prevalence of pediatric antimicrobial stewardship programs (ASPs) is increasing in acute care facilities across the United States. Over the past several years, the evidence base used to inform effective stewardship practices has expanded, and regulatory interest in stewardship programs has increased. Here, we review approaches for established, hospital-based pediatric ASPs to adapt and report standardized metrics, broaden their reach to specialized populations, expand to undertake novel stewardship initiatives, and implement rapid diagnostics to continue their evolution in improving antimicrobial use and patient outcomes.

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.

A 72-h intervention for improvement of the rate of optimal antibiotic therapy in patients with bloodstream infections

Antimicrobial stewardship programs are implemented to optimize the use of antibiotics and control the spread of antibiotic resistance. Many antimicrobial stewardship interventions have demonstrated significant efficacy in reducing unnecessary prescriptions of antibiotics, the duration of antimicrobial therapy, and mortality. We evaluated the benefits of a combination of rapid diagnostic tests and an active re-evaluation of antibiotic therapy 72 h after the onset of bloodstream infection (BSI). All patients with BSI from November 2015 to November 2016 in a 1100-bed university hospital in Rome, where an Infectious Disease Consultancy Unit (Unità di Consulenza Infettivologica, UDCI) is available, were re-evaluated at the bedside 72 h after starting antimicrobial therapy and compared to two pre-intervention periods: the UDCI was called by the ward physician for patients with BSI and the UDCI was called directly by the microbiologist immediately after a pathogen was isolated from blood cultures. Recommendations for antibiotic de-escalation or discontinuation significantly increased (54%) from the two pre-intervention periods (32% and 27.2%, p < 0.0001). Appropriate escalation also significantly increased (22.5%) from the pre-intervention periods (8.1% and 8.2%, p < 0.0001). The total duration of antibiotic therapy decreased with intervention (from 21.9 days [standard deviation, SD 15.4] in period 1 to 19.3 days [SD 13.3] in period 2 to 17.7 days in period 3 [SD 11.5]; p = 0.002) and the length of stay was significantly shorter (from 29.7 days [SD 29.3] in period 1 to 26.8 days [SD 24.7] in period 2 to 24.2 days in period 3 [SD 20.7]; p = 0.04) than in the two pre-intervention periods. Mortality was similar among the study periods (31 patients died in period 1 (15.7%), 39 (16.7%) in period 2, and 48 (15.3%) in period 3; p = 0.90). Rapid diagnostic tests and 72 h re-evaluation of empirical therapy for BSI significantly correlated with an improved rate of optimal antibiotic therapy and decreased duration of antibiotic therapy and length of stay.

Impact of Matrix-Assisted Laser Desorption and Ionization Time-of-Flight and Antimicrobial Stewardship Intervention on Treatment of Bloodstream Infections in Hospitalized Children

BACKGROUND.

Early definitive identification of infectious pathogens coupled with antimicrobial stewardship interventions allow for targeted and timely administration of antimicrobials. We investigated the combined impact of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) technology and an antimicrobial stewardship program (ASP) in pediatric patients with blood stream infections (BSIs).

METHODS.

This is a single-center study comparing a control group of patients from October 2009 to July 2010 with BSIs to a cohort of patients postimplementation of MALDI-TOF and an ASP, from October 2013 to July 2014. Primary outcome was time to optimal therapy. Secondary outcomes included time to effective therapy, 30-day all-cause mortality, 30-day readmission rate, hospital length of stay, and intensive care admission.

RESULTS.

One hundred episodes of BSIs were identified in the preintervention period, and 121 episodes were identified in the postintervention period. Time from blood culture collection to organism identification was significantly reduced in the prospective cohort compared with historical controls (18.8 vs 43.7 hours, respectively). A total of 73 ASP interventions were made on the treatment of BSIs in the postintervention period. Combined use of MALDI-TOF and ASP significantly reduced time to optimal therapy (77.0 to 54.2 hours, P < .001). In the subgroup analysis of Gram-negative bacteremia, time to effective and optimal therapy were significantly reduced (2.0 vs 0.7 hours and 146.8 vs 48.0 hours, respectively). There were no significant differences in clinical outcomes.

CONCLUSIONS.

The combined use of MALDI-TOF and ASP allows early optimization of antimicrobial therapy in pediatric inpatients with BSIs.

Antimicrobial Stewardship: How the Microbiology Laboratory Can Right the Ship

Antimicrobial stewardship is a bundle of integrated interventions employed to optimize the use of antimicrobials in health care settings. While infectious-disease-trained physicians, with clinical pharmacists, are considered the main leaders of antimicrobial stewardship programs, clinical microbiologists can play a key role in these programs. This review is intended to provide a comprehensive discussion of the different components of antimicrobial stewardship in which microbiology laboratories and clinical microbiologists can make significant contributions, including cumulative antimicrobial susceptibility reports, enhanced culture and susceptibility reports, guidance in the preanalytic phase, rapid diagnostic test availability, provider education, and alert and surveillance systems. In reviewing this material, we emphasize how the rapid, and especially the recent, evolution of clinical microbiology has reinforced the importance of clinical microbiologists' collaboration with antimicrobial stewardship programs.

Improved Diagnosis of Prosthetic Joint Infection by Culturing Periprosthetic Tissue Specimens in Blood Culture Bottles

Despite known low sensitivity, culture of periprosthetic tissue specimens on agars and in broths is routine. Culture of periprosthetic tissue samples in blood culture bottles (BCBs) is potentially more convenient, but it has been evaluated in a limited way and has not been widely adopted. The aim of this study was to compare the sensitivity and specificity of inoculation of periprosthetic tissue specimens into blood culture bottles with standard agar and thioglycolate broth culture, applying Bayesian latent class modeling (LCM) in addition to applying the Infectious Diseases Society of America (IDSA) criteria for prosthetic joint infection. This prospective cohort study was conducted over a 9-month period (August 2013 to April 2014) at the Mayo Clinic, Rochester, MN, and included all consecutive patients undergoing revision arthroplasty. Overall, 369 subjects were studied; 117 (32%) met IDSA criteria for prosthetic joint infection, and 82% had late chronic infection. Applying LCM, inoculation of tissues into BCBs was associated with a 47% improvement in sensitivity compared to the sensitivity of conventional agar and broth cultures (92.1 versus 62.6%, respectively); this magnitude of change was similar when IDSA criteria were applied (60.7 versus 44.4%, respectively; P = 0.003). The time to microorganism detection was shorter with BCBs than with standard media (P < 0.0001), with aerobic and anaerobic BCBs yielding positive results within a median of 21 and 23 h, respectively. Results of our study demonstrate that the semiautomated method of periprosthetic tissue culture in blood culture bottles is more sensitive than and as specific as agar and thioglycolate broth cultures and yields results faster.

Prosthetic joint infections are a devastating complication of arthroplasty surgery. Despite this, current microbiological techniques to detect and diagnose infections are imperfect. This study examined a new approach to diagnosing infections, through the inoculation of tissue samples from around the prosthetic joint into blood culture bottles. This study demonstrated that, compared to current laboratory practices, this new technique increased the detection of infection. These findings are important for patient care to allow timely and accurate diagnosis of infection.

Considerations About Antimicrobial Stewardship in Settings with Epidemic Extended-Spectrum β-Lactamase-Producing or Carbapenem-Resistant Enterobacteriaceae

Infections caused by gram-negative bacteria (GNB) resistant to multiple classes of antibiotics are increasing in many hospitals. Extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Enterobacteriaceae in particular are now endemic in many parts of the world and represent a serious public health threat. In this era, antimicrobial stewardship programs are essential as targeted and responsible use of antibiotics improves patient outcomes and hopefully limits the selective pressure that drives the further emergence of resistance. However, some stewardship strategies aimed at promoting carbapenem-sparing regimens remain controversial and are difficult to implement when resistance rates to non-carbapenem antibiotics are increasing. Coordinated efforts between stewardship programs and infection control are essential for reversing conditions that favor the emergence and dissemination of multidrug-resistant GNB within the hospital and identifying extra-institutional "feeder reservoirs" of resistant strains such as long-term care facilities, where colonization is common despite limited numbers of serious infections. In settings where ESBL resistance is endemic, the cost-effectiveness of expanded infection control efforts and antimicrobial stewardship is still unknown. Once a patient has been colonized, selective oral or digestive decontamination may be considered, but evidence supporting its effectiveness is limited in patients who are already colonized or in centers with high rates of resistance. Moreover, temporary success at decolonization may be associated with a higher risk of relapse with strains that are resistant to the decolonizing antibiotics.

Antibiotic use in US hospitals: quantification, quality measures and stewardship

A majority of patients hospitalized in the US hospitals receive an antibiotic during their hospitalization. Furthermore, up to half of antibiotics prescribed in hospitals are inappropriate. In the setting of continued emergence of antibiotic-resistant pathogens and a limited pipeline of new antimicrobials, attention to optimizing antibiotic use in healthcare settings is essential. We review the measures of antibiotic consumption in the USA, the evolving metrics for comparing antibiotic use (known as benchmarking), trends in antibiotic use, the structure and outcome measures of Antimicrobial Stewardship Programs and interventions to optimize antimicrobial use.

Use of electronic health records and clinical decision support systems for antimicrobial stewardship

Electronic health records (EHRs) and clinical decision support systems (CDSSs) have the potential to enhance antimicrobial stewardship. Numerous EHRs and CDSSs are available and have the potential to enable all clinicians and antimicrobial stewardship programs (ASPs) to more efficiently review pharmacy, microbiology, and clinical data. Literature evaluating the impact of EHRs and CDSSs on patient outcomes is lacking, although EHRs with integrated CDSSs have demonstrated improvements in clinical and economic outcomes. Both technologies can be used to enhance existing ASPs and their implementation of core ASP strategies. Resolution of administrative, legal, and technical issues will enhance the acceptance and impact of these systems. EHR systems will increase in value when manufacturers include integrated ASP tools and CDSSs that do not require extensive commitment of information technology resources. Further research is needed to determine the true impact of current systems on ASP and the ultimate goal of improved patient outcomes through optimized antimicrobial use.

High burden of extended-spectrum β-lactamase-positive Escherichia coli in geriatric patients

Few studies have described how an expanding elderly population influences the burden of antimicrobial resistance in micro-organisms. This study aimed to investigate trends in age-stratified extended-spectrum β-lactamase (ESBL)-positive Escherichia coli metrics in relation to an ageing population. The antimicrobial resistance database of E. coli from a healthcare region in Hong Kong from 2003 to 2012 was retrospectively reviewed. Future trends in age-stratified ESBL metrics were predicted up to 2022. Susceptibility results of clinical E. coli isolates from patients aged 0–74 years (n = 17 853) and aged ≥75 years (n = 17 047) were analysed. For the period 2003–2012, 23.7 % of the hospital admissions were of patients aged ≥75 years. However, approximately half of the annual ESBL-positive E. coli isolates were recovered from patients aged ≥75 years, being 55.0 % (233/424) in 2003 and 56.0 % (639/1142) in 2012. During this period of time, the annual prevalence and cumulative incidence of ESBL-positive E. coli in patients aged ≥75 years were significantly higher than in patients aged 0–74 years. From 2012–2022, it is predicted that ESBL-positive E. coli prevalence among patients aged 0–74 years and ≥75 years would increase from 25.4 % to 50.2 % and from 30.8 % to 70.0 %, respectively. In 2022, the predicted ESBL-positive E. coli cumulative incidence would be 63.7 per 10 000 admissions and 178.7 per 10 000 admissions among patients aged 0–74 years and ≥75 years, respectively. In conclusion, a rapidly expanding elderly population would substantially add to the burden of ESBL.

Better tests, better care: improved diagnostics for infectious diseases

In this IDSA policy paper, we review the current diagnostic landscape, including unmet needs and emerging technologies, and assess the challenges to the development and clinical integration of improved tests. To fulfill the promise of emerging diagnostics, IDSA presents recommendations that address a host of identified barriers. Achieving these goals will require the engagement and coordination of a number of stakeholders, including Congress, funding and regulatory bodies, public health agencies, the diagnostics industry, healthcare systems, professional societies, and individual clinicians.

The role of the microbiology laboratory in antimicrobial stewardship programs

One of the impediments to the success of antimicrobial stewardship is the lack of availability of rapid and sensitive laboratory tests. The last decade has seen an explosion in new technologies that permit, in less than 4 hours, the identification of organisms and their resistance markers. In addition, the use of biomarkers has been explored in algorithms to distinguish infections that require antimicrobial agents. Clinical microbiology laboratories also contribute to the success of stewardship programs through compilation of aggregate antimicrobial susceptibility data. This article reviews rapid diagnostics, the use of biomarkers, and antibiogram development to antimicrobial stewardship activities and the subsequent impact on patient outcomes.