Rapid diagnostics for bloodstream infections: A primer for infection preventionists

A comparative study of a rapid phenotypic antimicrobial susceptibility testing system directly from positive blood cultures to the disk diffusion and VITEK 2 methods

BACKGROUND

Sepsis is a life-threatening condition that impacts 49 million people annually and causes 11 million deaths worldwide. Surviving bloodstream infections (BSIs) depends on the rapid administration of effective antimicrobial treatment, underscoring a need for rapid antimicrobial susceptibility testing (AST).

AIM

To evaluate the performance of Quantamatrix's dRAST v2.5 system (Seoul, South Korea) for AST directly from positive blood cultures as compared to the Disk-Diffusion (DD) and VITEK 2 methods.

METHODS

The study included 191 positive blood cultures from clinical samples and spiked blood culture bottles. Following Gram staining and species-level identification, AST was performed by VITEK 2 and standard DD methods using CLSI (2021) interpretation.

RESULTS

dRAST demonstrated very good AST performance for a Gram-negative isolate, and good performance for Gram-positive isolates, meeting CLSI criteria for the acceptance of a new method. Antimicrobials that were not considered verified compared to VITEK 2 and DD were cefazolin, ceftazidime, meropenem, and trimethoprim/sulfamethoxazole for Gram-negatives and clindamycin, erythromycin, penicillin, and oxacillin for Gram-positives. dRAST ESBL detection results were strongly correlated with the ESBL phenotypes obtained with other methods. Additional resistance mechanisms were in concordance with traditional tests.

CONCLUSIONS

dRAST demonstrated good AST performance, meeting CLSI criteria for most relevant antibiotics. dRAST was associated with a significant reduction in time-to-results, labor, and the subjectivity of result analyses, making it a valuable addition to efforts supporting the treatment of patients with bacteremia. AST (antimicrobial susceptibility test), blood culture, dRAST, rapid methods, sepsis, turnaround time (TAT).

Opportunities to Enhance Diagnostic Testing and Antimicrobial Stewardship: A Qualitative Multinational Survey of Healthcare Professionals

INTRODUCTION

Antimicrobial resistance (AMR) is a global public health challenge. Global efforts to decrease AMR through antimicrobial stewardship (AMS) initiatives include education and optimising the use of diagnostic technologies and antibiotics. Despite this, economic and societal challenges hinder AMS efforts. The objective of this study was to obtain insights from healthcare professionals (HCPs) on current challenges and identify opportunities for optimising diagnostic test utilisation and AMS efforts.

METHODS

Three hundred HCPs from six countries (representing varied gross national incomes per capita, healthcare system structure, and AMR rates) were surveyed between November 2022 through January 2023. A targeted literature review and expert interviews were conducted to inform survey development. Descriptive statistics were used to summarise survey responses.

RESULTS

These findings suggest that the greatest challenges to diagnostic test utilisation were economic in nature; many HCPs reported that AMS initiatives were lacking investment (32.3%) and resourcing (40.3%). High resistance rates were considered the greatest barriers to appropriate antimicrobial use (52.0%). Most HCPs found local and national guidelines to be very useful (≥ 51.0%), but areas for improvement were noted. The importance of AMS initiatives was confirmed; diagnostic practices were acknowledged to have a positive impact on decreasing AMR (70.3%) and improving patient outcomes (81.0%).

CONCLUSION

AMS initiatives, including diagnostic technology utilisation, are pivotal to decreasing AMR rates. Interpretation of these survey results suggests that while HCPs consider diagnostic practices to be important in AMS efforts, several barriers to successful implementation still exist including patient/institutional costs, turnaround time of test results, resourcing, AMR burden, and education. While some barriers differ by country, these survey results highlight areas of opportunities in all countries for improved use of diagnostic technologies and broader AMS efforts, as perceived by HCPs. Greater investment, resourcing, education, and updated guidelines offer opportunities to further strengthen global AMS efforts.

Knowledge, Attitude, and Practice (KAP) Survey on the Management of Multidrug-Resistant Gram-Negative Infections With Innovative Antibiotics: Focus on Ceftazidime-Avibactam

BACKGROUND

Antimicrobial resistance (AMR) is a major public health dilemma and a chief health concern globally. The rising incidence of resistance against carbapenems, which are considered most effective against gram-negative bacteria, has added to the concern and has limited the number of available treatment options. Newer antibiotic options may be required to tackle the mounting concern of antibiotic resistance. However, only a few antimicrobials are in the pipeline for managing infections instigated by multidrug-resistant (MDR) gram-negative bacteria. This justifies the prudent application of already available antibiotics. Among newer antibiotics available to healthcare professionals (HCPs), ceftazidime-avibactam (CAZ-AVI) has shown good efficacy in the management of MDR gram-negative infections.

METHOD

A cross-sectional survey on the knowledge, attitude, and practices (KAP) among HCPs was carried out using a questionnaire comprising 21 parameters related to AMR patterns on the need for innovative antibiotics to manage MDR gram-negative infections and the usage of CAZ-AVI by HCPs while managing such infections. The KAP scores were calculated to rank respondents' KAP levels.

RESULT

Out of the 204 study respondents, the majority (~80%) (n=160) believed that renewed efforts should be made to seek antimicrobial agents that will add to the armamentarium of treatment options for MDR gram-negative infections. CAZ-AVI is an important treatment alternative for managing MDR gram-negative infections (n=90, 45%). Further, it can be the first choice of definitive therapy for oxacillinases (OXA)-48-producing carbapenem-resistant Enterobacterales (n=84, 42%). HCPs also believed that the use of CAZ-AVI in clinical practice will require high levels of antimicrobial stewardship (n=100, 49%).

CONCLUSION

Novel and innovative antibiotics are the need of the hour in the management of MDR gram-negative infections. CAZ-AVI has established its effectiveness in treating these infections; however, the molecule must be utilized prudently while keeping stewardship principles in mind.

Fast Track Diagnostic Tools for Clinical Management of Sepsis: Paradigm Shift from Conventional to Advanced Methods

Sepsis is one of the deadliest disorders in the new century due to specific limitations in early and differential diagnosis. Moreover, antimicrobial resistance (AMR) is becoming the dominant threat to human health globally. The only way to encounter the spread and emergence of AMR is through the active detection and identification of the pathogen along with the quantification of resistance. For better management of such disease, there is an essential requirement to approach many suitable diagnostic techniques for the proper administration of antibiotics and elimination of these infectious diseases. The current method employed for the diagnosis of sepsis relies on the conventional culture of blood suspected infection. However, this method is more time consuming and generates results that are false negative in the case of antibiotic pretreated samples as well as slow-growing microbes. In comparison to the conventional method, modern methods are capable of analyzing blood samples, obtaining accurate results from the suspicious patient of sepsis, and giving all the necessary information to identify the pathogens as well as AMR in a short period. The present review is intended to highlight the culture shift from conventional to modern and advanced technologies including their limitations for the proper and prompt diagnosing of bloodstream infections and AMR detection.

Recommendations for change in infection prevention programs and practice

Fifty years of evolution in infection prevention and control programs have involved significant accomplishments related to clinical practices, methodologies, and technology. However, regulatory mandates, and resource and research limitations, coupled with emerging infection threats such as the COVID-19 pandemic, present considerable challenges for infection preventionists. This article provides guidance and recommendations in 14 key areas. These interventions should be considered for implementation by United States health care facilities in the near future.

Early appropriate diagnostics and treatment of MDR Gram-negative infections

The term difficult-to-treat resistance has been recently coined to identify Gram-negative bacteria exhibiting resistance to all fluoroquinolones and all β-lactam categories, including carbapenems. Such bacteria are posing serious challenges to clinicians trying to identify the best therapeutic option for any given patient. Delayed appropriate therapy has been associated with worse outcomes including increase in length of stay, increase in total in-hospital costs and ∼20% increase in the risk of in-hospital mortality. In addition, time to appropriate antibiotic therapy has been shown to be an independent predictor of 30 day mortality in patients with resistant organisms. Improving and anticipating aetiological diagnosis through optimizing not only the identification of phenotypic resistance to antibiotic classes/agents, but also the identification of specific resistance mechanisms, would have a major impact on reducing the frequency and duration of inappropriate early antibiotic therapy. In light of these considerations, the present paper reviews the increasing need for rapid diagnosis of bacterial infections and efficient laboratory workflows to confirm diagnoses and facilitate prompt de-escalation to targeted therapy, in line with antimicrobial stewardship principles. Rapid diagnostic tests currently available and future perspectives for their use are discussed. Early appropriate diagnostics and treatment of MDR Gram-negative infections require a multidisciplinary approach that includes multiple different diagnostic methods and further consensus of algorithms, protocols and guidelines to select the optimal antibiotic therapy.

Early and Appropriate Use of Ceftazidime-Avibactam in the Management of Multidrug-Resistant Gram-Negative Bacterial Infections in the Indian Scenario

The increasing prevalence of antibiotic-resistant pathogens exerts a substantial burden on the healthcare infrastructure worldwide. The World Health Organization (WHO) has declared that multidrug-resistant (MDR) Gram-negative pathogens, especially, carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii, and Pseudomonas aeruginosa as the topmost priority while developing newer antimicrobials. The increasing prevalence of infectious diseases caused by MDR Gram-negative bacteria also poses a challenge when choosing the empiric antimicrobial therapy for seriously ill hospitalized patients. The infections caused by MDR Gram-negative organisms ultimately result in increased mortality, morbidity, prolonged hospital stay, and increased cost of management. To tackle these challenges, newer antimicrobials like ceftazidime-avibactam were explored. The article also discusses the in vitro activity and therapeutic efficacy of ceftazidime-avibactam along with its pharmacokinetic properties and the role it will play in the management of MDR Gram-negative organisms in the Indian setting. Several studies have highlighted the role of early and appropriate antibiotic use in the reduction of mortality in patients with Gram-negative infections. Timely initiation of appropriate antibiotic therapy for serious infections leads to favorable clinical outcomes. Early and appropriate use of ceftazidime-avibactam while treating MDR Gram-negative infections has been associated with improved clinical outcomes. The aim of this review is to highlight the efficacy of ceftazidime-avibactam in the treatment of MDR Gram-negative infections. We have also summarized the information on outcomes achieved by early and appropriate use of ceftazidime-avibactam.

Performance Evaluation of the Quantamatrix QMAC-dRAST System for Rapid Antibiotic Susceptibility Testing Directly from Blood Cultures

Objectives: Rapid antibiotic susceptibility testing (AST) for positive blood cultures can improve patient clinical outcomes if the time to an effective antimicrobial therapy is shortened. In this study, we tested the Quantamatrix dRAST system (QMAC-dRAST), a rapid AST system based on time-lapse microscopic imagery of bacterial colony formation in agarose. Methods: Evaluation of the QMAC-dRAST was performed from 250 monobacterial blood cultures including 130 Enterobacterales, 20 non-fermentative Gram-negative bacteria, 69 staphylococci and 31 enterococci. Blood cultures were recovered from anonymous patients or from spiking experiments to enrich our study with bacterial species and resistant strains. Categorical agreement (CA), minor errors (me), major errors (ME) and very major errors (VME) were calculated in comparison to the results obtained from the BD Phoenix™ M50. Discrepancies between the Phoenix™ M50 and QMAC-dRAST results were investigated using the gradient strip method. The repeatability and reproducibility performance of the QMAC-dRAST was assessed for 16 strains, each strain being tested five times from a spiked blood culture. Results: The overall CAs for Enterobacterales, non-fermentative Gram-negative bacteria, staphylococci and enterococci were 95.1%, 91.2%, 93.4% and 94.5%, respectively. The VME percentage was below 4% for all the groups except for staphylococci, which showed a VME rate of 7%. The median time to result was 6.7 h (range: 4.7–7.9). Repeatability and reproducibility assays showed a high reliability of AST results with best and worst ratios of 98.8% and 99.6% and 95.0% and 98.3%, respectively. Conclusions: The QMAC-dRAST is a fast and reliable system to determine AST directly from monobacterial blood cultures with a major TAT reduction compared to conventional AST testing.

Analysis of Blood Culture Data Influences Future Epidemiology of Bloodstream Infections: A 5-year Retrospective Study at a Tertiary Care Hospital in India

Background

Blood cultures are the most significant samples received in a microbiology laboratory. Good quality control of pre-analytic, analytic, and post-analytic stages can have a significant impact on patient outcomes. Here, we present the improvements brought about by reviewing blood culture data with clinicians at a tertiary care institute in India.

Methods

Four-year blood culture data (phase I—February 2014–February 2018) were shared with clinicians in the clinical grand round. Several take-home messages were discussed in a quiz format, and a number of holistic quality control measures were implemented at different levels. Based on observable changes in blood culture reports, another dataset was analyzed and compared in phase II (April 2018–April 2019).

Results

In phase II, the blood culture contamination rate improved from 6 to 2% along with four times reduction in ICU isolates and three times increased isolation of salmonellae and pneumococci. The development of resistance in Klebsiella pneumoniae to carbapenems and piperacillin–tazobactam was reduced. Colistin resistance in ICU isolates hovered around 15%. Vaccine-preventable pneumococcal serotypes were predominant in the under-five age-group. Typhoidal salmonellae were more commonly isolated from adults with 50% showing sensitivity to pefloxacin and 97% to ampicillin, chloramphenicol, and cotrimoxazole. Candida parapsilosis was the leading non-albicans Candida (NAC). Fluconazole resistance was observed in 50% of NAC.

Conclusion

Reviewing blood culture data with clinicians mutually helped us to improve the overall quality of blood culture reports. It had a major impact on epidemiological trends and thus, found to be superior to just sharing an antibiogram with the clinicians.

How to cite this article

Sharma A, Samaddar A, Maurya A, Hada V, Narula H, Shrimali T, et al. Analysis of Blood Culture Data Influences Future Epidemiology of Bloodstream Infections: A 5-year Retrospective Study at a Tertiary Care Hospital in India. Indian J Crit Care Med 2021;25(11):1258–1262.

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.

A multiplexed nanoliter array-based microfluidic platform for quick, automatic antimicrobial susceptibility testing

Antimicrobial resistance stemming from indiscriminate usage of antibiotics has emerged as a global healthcare issue with substantial economic implications. The inefficacy of commonly used antibiotics combined with superfluous consumption has worsened the issue. Rapid antimicrobial susceptibility testing (AST) to antibiotics can be advantageous in thwarting bacterial infections. Therefore, this study developed a simple nanoliter array-based microfluidic platform for performing rapid AST, which can handle and manipulate liquids both in nanoliter and microliter volumes. The platform consisted of two microfluidic devices, one for performing AST and another for diluting antibiotics and these two were suitably integrated. The microfluidic device used for generating microarrays for AST experiments is single-layered (no air layer) and has no active microvalves and air hole, which makes the device easy to fabricate and use. The loading process ensures uniform distribution of bacteria and relies on displacing the air from microarrays through porous polydimethylsiloxane membranes. Furthermore, the chip for dilution consisted of active microfluidic components, and could prepare and test seven different concentrations of antibiotics, which make the platform multiplexed and be capable of evaluating minimum inhibitory concentrations (MICs), a clinically relevant parameter. MIC determination requires less number of bacteria (∼2000) and hence shortens the pre-culture step, i.e. bacteria culture in blood and urine. This automated system demonstrated AST and evaluated MICs using Escherichia coli and two antibiotics, including ampicillin and streptomycin, and the results were ascertained using a gold standard method. It only took 8-9 h to perform AST, which is substantially less compared to a conventional process and hence is of high clinical utility.

Antimicrobial Resistance in a Tertiary Care Hospital in Armenia: 2016-2019

Antimicrobial resistance (AMR) is the acquired ability of pathogens to withstand antimicrobial treatment. To bridge the gap in knowledge for implementing effective and targeted interventions in relation to the AMR in Armenia, we designed this study to explore the performance of AMR diagnostics and the profile of AMR in the Nork Infection Clinical Hospital (NICH) for the period of 2016-2019, particularly to (i) determine the proportions of antimicrobial resistance among all samples tested at the hospital laboratory, (ii) determine the proportion of resistance against specific antimicrobials, and (iii) identify factors associated with AMR. A cross-sectional study was conducted with a secondary data analysis that included all the patients tested for AMR in the laboratory of the NICH for the period of 2016-2019. For this period, only 107 (0.3%) patients out of 36,528 had their AMR test results available and of them, 87 (81%) had resistance at least to one tested antimicrobial. This study has provided some valuable information on the AMR situation in Armenia. The results call for immediate actions to control the access to and the use of antimicrobials, strengthen AMR surveillance, and improve laboratory capacity for the proper and fast identification of drug resistance through a comprehensive system.

Performance evaluation of Alfred60AST rapid susceptibility testing directly from positive blood cultures in the routine laboratory workflow

The aim of this study was to evaluate the performance of the new automated system Alfred⁶⁰AST which is based on light scattering technology for rapid susceptibility testing directly from positive blood cultures as well as its applicability in the routine laboratory workflow. We evaluated 176 significant episodes of bacteremia due to 92 Gram-negative and 84 Gram-positive bacteria. The antimicrobial agents tested were ceftriaxone, ciprofloxacin, gentamicin, meropenem, piperacillin-tazobactam, and colistin for Gram negatives and cefoxitin, vancomycin, linezolid, and daptomycin for Gram positives. Concordance assessment was performed in comparison with our routine method, Vitek2 (bioMérieux). Discrepancies were resolved with MICRONAUT-S (Merlin) or E-test (bioMérieux). Out of 690 susceptibility determinations, 94.05% showed categorical agreement (CA) with the routine method and this percentage increased to 94.49 after discrepancy analysis. There were 1.45% very major errors, 3.33% major errors, and 1.16% minor errors (decreased to 1.45, 3.04, and 1.01 after discrepancy analysis). The CA for most of the antibiotics was above 90% except for daptomycin for Gram positives (87.30%) and ceftriaxone for Gram negatives (88.23%). The concordance was slightly better for Gram negative than for Gram-positive bacteria (94.30 versus 93.70%, respectively). The total turnaround time for a complete Alfred⁶⁰AST result was 6-6.5h. The evaluated method gave rapid and reliable results in a few hours, versus 48h for the conventional one. Implementing this technology in routine workflow allows clinicians to optimize the treatment on the same day of blood culture positivity with potential positive clinical benefits and impact on antibiotic stewardship.

Impact of Incremental Delays in Appropriate Therapy on the Outcomes of Hospitalized Adult Patients with Gram-negative Bloodstream Infections: "Every day matters"

BACKGROUND

Serious bloodstream infections (BSIs) are often caused by Gram-negative (GN) bacteria in hospitalized patients. Treatment of these infections has been further complicated by the continued rise and spread of drug-resistant pathogens, including carbapenem resistant (CR) strains of Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa.

METHODS

This retrospective cohort analysis used real-world data from a large United States hospital-based database to examine the association between key clinical outcomes and different lengths of time to appropriate treatment between October 2010 and September 2015.

RESULTS

Of 40,549 patients with GN-BSIs who were identified, 1117 (2.8%) had a CR GN-BSI. Overall, outcomes of hospitalized adult patients with GN-BSIs incrementally worsened the longer appropriate therapy was delayed. Patients with CR GN-BSIs had a median infection-associated length of stay (LOS) of 8, 9, 10, and 13 days, whereas patients with CS GN-BSIs had a median infection-associated LOS of 6, 7, 8, and 11 days for patients with days to appropriate therapy of 0, 1-2, 3-4, and ≥ 5 days, respectively. Among patients with CR GN-BSIs, the percentage of patients discharged home was 38%, 33%, 35%, and 31%, whereas in patients with CS GN-BSIs, the percentage of patients discharged home was 58%, 53%, 48%, and 43% for patients with days to appropriate therapy of 0, 1-2, 3-4, and ≥ 5 days, respectively.

CONCLUSION

The findings from this study highlight the clear need to deliver appropriate therapy more expeditiously in patients with CS and CR GN-BSIs.

Collection, transport and storage procedures for blood culture specimens in adult patients: recommendations from a board of Italian experts

Bloodstream infections (BSIs) remain a potentially life-threatening condition. The gold standard for the diagnosis of BSI is still blood cultures (BCs), and the diagnostic yield depends on clinical and technical factors that have an impact on collection and transportation. Hence, monitoring of the entire pre-analytical process from blood collection to transportation to the microbiology laboratory is critical. To optimize the clinical impact of the diagnostic and therapeutic procedures, a multidisciplinary approach and univocal protocols are mandatory. A board of specialists discussed the available evidence on the pre-analytical process and produced the present document to guide physicians and nurses on the ideal execution of BC: (1) timing and preparation for blood collection; (2) skin antisepsis; (3) blood volume; (4) sampling method and safety; (5) medium to be used; (6) time to BC transportation; and (7) quality assurance and quality management.

Antimicrobial Peptides as Probes in Biosensors Detecting Whole Bacteria: A Review

Bacterial resistance is becoming a global issue due to its rapid growth. Potential new drugs as antimicrobial peptides (AMPs) are considered for several decades as promising candidates to circumvent this threat. Nonetheless, AMPs have also been used more recently in other settings such as molecular probes grafted on biosensors able to detect whole bacteria. Rapid, reliable and cost-efficient diagnostic tools for bacterial infection could prevent the spread of the pathogen from the earliest stages. Biosensors based on AMPs would enable easy monitoring of potentially infected samples, thanks to their powerful versatility and integrability in pre-existent settings. AMPs, which show a broad spectrum of interactions with bacterial membranes, can be tailored in order to design ubiquitous biosensors easily adaptable to clinical settings. This review aims to focus on the state of the art of AMPs used as the recognition elements of whole bacteria in label-free biosensors with a particular focus on the characteristics obtained in terms of threshold, volume of sample analysable and medium, in order to assess their workability in real-world applications.

Rapid multiplex detection of the resistance genes mecA, vanA and vanB from Gram-positive cocci-positive blood cultures using a PCR-dipstick technique

Introduction. Among the causative agents of bloodstream infections (BSIs), methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) are the key causative pathogens. Their rapid detection directly from Gram-positive cocci-positive blood culture specimens will promote timely treatment and help to implement effective infection control measures.Aim. We aim to develop a PCR-dipstick technique for the rapid detection of MRSA and VRE directly from positive blood culture specimens.Methodology. PCR-dipstick is a PCR-based multiplex detection technique where DNA-DNA hybridization is employed, and the results are interpreted with the naked eye. It was designed to target three drug resistance genes: mecA in MRSA and vanA/vanB in VRE from positive blood culture specimens. A total of 120 clinical isolates were used to evaluate the sensitivity and specificity of PCR-dipstick. Then, PCR-dipstick was examined for MRSA and VRE detection directly from positive blood cultures.Results. PCR-dipstick showed 100 % sensitivity and specificity in detecting mecA, vanA and vanB genes directly from bacterial colonies in comparison with multiplex PCR for genomic DNA followed by agarose gel electrophoresis. Further, it could differentially detect multiple resistant genes in pooled bacterial colonies (n=10). Ultimately, PCR-dipstick could detect MRSA and VRE in positive blood cultures in ~3 h.Conclusion. The results of the current study substantiate that PCR-dipstick can be used as an efficient detection system for MRSA and VRE directly from Gram-positive cocci-positive blood cultures. Its affordability and rapidity indicate that PCR-dipstick can be an effective tool for controlling nosocomial pathogens.

Molecular Diagnostic Advances in Transplant Infectious Diseases

PURPOSE OF REVIEW

The infectious complications of transplantation can have devastating consequences for patients. Early and accurate diagnosis is essential to good outcomes. This review describes recent advances in pathogen-directed diagnostic testing and discusses the role of new methods for transplant infectious diseases.

RECENT FINDINGS

Several molecular assays have been introduced into clinical practice in recent years. When the results of rapid testing are linked to patient-specific interventions, improved outcomes can be realized. Syndromic testing along with metagenomic next-generation sequencing (mNGS) represents novel approaches to infection diagnosis. However, the optimal use of these tests for transplant patients along with an overall assessment of cost-effectiveness demands further study. Molecular diagnostics are revolutionizing transplant care. Clinicians need to be aware of the current diagnostic landscape and have a working knowledge of the nuances related to test performance, result interpretation, and cost.

Combating resistance while maintaining innovation: the future of antimicrobial stewardship

Antimicrobial resistance represents a significant global health threat. However, a commercial model that does not offer a return on investment resulting in a lack of investment in antibiotic R&D, means that the current pipeline of antibiotics lacks sufficient innovation to meet this challenge. Those responsible for defining, promoting and monitoring the rationale use of antibiotics (the antimicrobial stewardship programme) are key to addressing current shortcomings. In this personal perspective, we discuss the future role stewardship can play in stimulating innovation, a need to move away from a pharmacy budget dominated view of antibiotic use, and the impact of the ever-increasing sophistication and interdisciplinary nature of antimicrobial control programs. Changes are needed to optimize clinical outcomes for patients.

Development of a bedside tool to predict the probability of drug-resistant pathogens among hospitalized adult patients with gram-negative infections

Background

We developed a clinical bedside tool to simultaneously estimate the probabilities of third-generation cephalosporin-resistant Enterobacteriaceae (3GC-R), carbapenem-resistant Enterobacteriaceae (CRE), and multidrug-resistant Pseudomonas aeruginosa (MDRP) among hospitalized adult patients with Gram-negative infections.

Methods

Data were obtained from a retrospective observational study of the Premier Hospital that included hospitalized adult patients with a complicated urinary tract infection (cUTI), complicated intra-abdominal infection (cIAI), hospital-acquired/ventilator-associated pneumonia (HAP/VAP), or bloodstream infection (BSI) due to Gram-negative bacteria between 2011 and 2015. Risk factors for 3GC-R, CRE, and MDRP were ascertained by multivariate logistic regression, and separate models were developed for patients with community-acquired versus hospital-acquired infections for each resistance phenotype (N = 6). Models were converted to a singular user-friendly interface to estimate the probabilities of a patient having an infection due to 3GC-R, CRE, or MDRP when ≥ 1 risk factor was present.

Results

Overall, 124,068 patients contributed to the dataset. Percentages of patients admitted for cUTI, cIAI, HAP/VAP, and BSI were 61.6, 4.6, 16.5, and 26.4%, respectively (some patients contributed > 1 infection type). Resistant infection rates were 1.90% for CRE, 12.09% for 3GC-R, and 3.91% for MDRP. A greater percentage of the resistant infections were community-acquired relative to hospital-acquired (CRE, 1.30% vs 0.62% of 1.90%; 3GC-R, 9.27% vs 3.42% of 12.09%; MDRP, 2.39% vs 1.59% of 3.91%). The most important predictors of having an 3GC-R, CRE or MDRP infection were prior number of antibiotics; infection site; infection during the previous 3 months; and hospital prevalence of 3GC-R, CRE, or MDRP. To enable application of the six predictive multivariate logistic regression models to real-world clinical practice, we developed a user-friendly interface that estimates the risk of 3GC-R, CRE, and MDRP simultaneously in a given patient with a Gram-negative infection based on their risk (Additional file 1).

Conclusions

We developed a clinical prediction tool to estimate the probabilities of 3GC-R, CRE, and MDRP among hospitalized adult patients with confirmed community- and hospital-acquired Gram-negative infections. Our predictive model has been implemented as a user-friendly bedside tool for use by clinicians/healthcare professionals to predict the probability of resistant infections in individual patients, to guide early appropriate therapy.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4363-y) contains supplementary material, which is available to authorized users.

Perceived differences between intensivists and infectious diseases consultants facing antimicrobial resistance: a global cross-sectional survey

To identify differences in perception on multi-drug-resistant (MDR) organisms and their management at intensive care units (ICU). A cross-sectional survey was conducted. A proposal addressing a pathogen priority list (PPL) for ICU, arising from the TOTEM study, was compared with a sample of global experts in infections in critically ill patients. The survey was responded by 129 experts. Globally, ESBL Enterobacteriaceae, followed by carbapenem-resistant Acinetobacter baumannii and carbapenem-resistant Klebsiella pneumoniae, were the main concerns. Some differences in opinion were identified between 63 (49%) ICU physicians (ICU/anesthesiology) and 43 (33%) infectious disease consultants (ID physicians/microbiologists). The pathogens most concerning in the ICU for intensivists were ESBL Enterobacteriaceae (38%) versus carbapenem-resistant A. baumannii (48.3%) for ID consultants, (p < 0.05). Increasing number of ID consultants over intensivists (26% vs 14%) reported difficulty in choosing initial therapy for carbapenem-resistant A. baumannii. For intensivists, the urgent measures to limit development of antibiotic resistance were headed by cohort measures (26.3%) versus increasing nurse/patient ratio (32.5%) for ID consultants, (p < 0.05). Regarding effectiveness to prevent MDR development and spread, education programs (42.4%) were the priority for intensivists versus external consultation (35.7%) for ID consultants. Finally, both groups agreed that carbapenem resistance was the most pressing concern (> 70%) regarding emerging resistance. Differences in priorities regarding organisms, infection control practices, and educational priorities were visualized between ID/clinical microbiologists and ICU/anesthesiologists. Multi-disciplinary collaboration is required to achieve best care for ICU patients with severe infections.

Emerging Analytical Techniques for Rapid Pathogen Identification and Susceptibility Testing

In the face of looming threats from multi-drug resistant microorganisms, there is a growing need for technologies that will enable rapid identification and drug susceptibility profiling of these pathogens in health care settings. In particular, recent progress in microfluidics and nucleic acid amplification is pushing the boundaries of timescale for diagnosing bacterial infections. With a diverse range of techniques and parallel developments in the field of analytical chemistry, an integrative perspective is needed to understand the significance of these developments. This review examines the scope of new developments in assay technologies grouped by key enabling domains of research. First, we examine recent development in nucleic acid amplification assays for rapid identification and drug susceptibility testing in bacterial infections. Next, we examine advances in microfluidics that facilitate acceleration of diagnostic assays via integration and scale. Lastly, recentdevelopments in biosensor technologies are reviewed. We conclude this review with perspectives on the use of emerging concepts to develop paradigm-changing assays.

Valuing antibiotics: The role of the hospital clinician

The global public health threat of antibiotic-resistant infections as well as the lack of new treatments in clinical development is a critical issue. Reasons for this include diminished commercial incentives for pharmaceutical companies to develop new antibiotics, which part-reflects a shift in antibiotic marketing paradigm from broad deployment to targeted therapy in relatively small patient populations. Such changes are encouraged by antimicrobial stewardship (AMS). Other factors include a lack of recognition in the traditional assessment of new antibiotics by regulators, health technology assessors and payers of the broad range of benefits of new agents, particularly their value to health care, economies and society. Recognising the seriousness of the situation, there have been recent changes and proposals by regulators for modification of the assessment process to accommodate a broader range of acceptable data supporting new drug applications. There is also increasing recognition by some payers of the societal benefit of new antibiotics and the need for financial incentives for those developing high-priority antibiotics. However, progress is slow, with recent publications focusing on industry and strategic perspectives rather than clinical implications. In this opinion piece, we therefore focus on clinicians and the practical steps they can take to drive and contribute to increasing awareness and understanding of the value of antibiotics. This includes identifying and gathering appropriate alternative data sources, educating on AMS and prescribing habits, and contributing to international antibiotic susceptibility surveillance models.

Chromobacterium violaceum in Northern Australia: A Sheep in Wolf's Clothing?

In many parts of the world, the case-fatality rate of Chromobacterium violaceum infection approaches 60%. To evaluate the spectrum of disease associated with C. violaceum in Far North Queensland (FNQ), Australia, we reviewed all culture-confirmed isolates from 1997 to 2017. There were 28 isolates, 15 represented infection, 11 were contaminants, and two charts were destroyed preventing detailed evaluation of these cases. The most common sites of infection were the skin and soft tissue and the urinary tract; there were two cases of bacteremia without focus. There were no deaths attributable to C. violaceum during the study period and only two cases required intensive care unit support, although in both patients this was not for the C. violaceum infection, but for the management of other health issues. Globally, C. violaceum has a reputation as a deadly pathogen, but in FNQ, Australia, infections usually follow a relatively benign course.