Gut microbiome alpha diversity decreases in relation to body weight, antibiotic exposure, and infection with multidrug-resistant organisms

BACKGROUND

The human gastrointestinal tract is home to a dense and diverse microbiome, predominated by bacteria. Despite the conservation of critical functionality across most individuals, the composition of the gut microbiome is highly individualized, leading to differential responses to perturbations such as oral antibiotics or multidrug-resistant organism (MDRO) infection. Herein, subject responses to these perturbations based on their body weight were evaluated.

METHODS

Fecal samples were collected from 45 subjects at the Detroit Medical Center to evaluate the effects of perturbations on subjects' gut microbiome composition. Bacterial profiling was completed using 16S rRNA gene sequencing.

RESULTS

Subjects with multiple MDROs, subjects weighing greater than 80 kg infected with MDRO E coli, and subjects weighing less than 80 kg with exposure to vancomycin and carbapenem antibiotics during hospitalization had significantly decreased gut microbiome richness.

CONCLUSIONS

Both administration of oral antibiotics and MDRO infections decreased gut microbiome alpha diversity, but the magnitude of these gut microbiome perturbations was body weight dependent.

Microbiota-Based Live Biotherapeutic Products for Clostridioides Difficile Infection- The Devil is in the Details

Clostridioides difficile infection (CDI) remains a significant contributor to healthcare costs and morbidity due to high rates of recurrence. Currently, available antibiotic treatment strategies further disrupt the fecal microbiome and do not address the alterations in commensal flora (dysbiosis) that set the stage for CDI. Advances in microbiome-based research have resulted in the development of new agents, classified as live biotherapeutic products (LBPs), for preventing recurrent CDI (rCDI) by restoring eubiosis. Prior to the LBPs, fecal microbiota transplantation (FMT) was available for this purpose; however, lack of large-scale availability and safety concerns have remained barriers to its widespread use. The LBPs are an exciting development, but questions remain. Some are derived directly from human stool while other developmental products contain a defined microbial consortium manufactured ex vivo, and they may be composed of either living bacteria or their spores, making it difficult to compare members of this heterogenous drug class to one another. None have been studied head-to head or against FMT in preventing rCDI. As a class, they have considerable variability in their biologic composition, biopharmaceutic science, route of administration, stages of development, and clinical trial data. This review will start by explaining the role of dysbiosis in CDI, then give the details of the biopharmaceutical components for the LBPs which are approved or in development including how they differ from FMT and from one another. We then discuss the clinical trials of the LBPs currently approved for rCDI and end with the future clinical directions of LBPs beyond C. difficile.

Bacteroides and related species: The keystone taxa of the human gut microbiota

Microbial communities play a significant role in maintaining ecosystems in a healthy homeostasis. Presently, in the human gastrointestinal tract, there are certain taxonomic groups of importance, though there is no single species that plays a keystone role. Bacteroides spp. are known to be major players in the maintenance of eubiosis in the human gastrointestinal tract. Here we review the critical role that Bacteroides play in the human gut, their potential pathogenic role outside of the gut, and their various methods of adapting to the environment, with a focus on data for B. fragilis and B. thetaiotaomicron. Bacteroides are anaerobic non-sporing Gram negative organisms that are also resistant to bile acids, generally thriving in the gut and having a beneficial relationship with the host. While they are generally commensal organisms, some Bacteroides spp. can be opportunistic pathogens in scenarios of GI disease, trauma, cancer, or GI surgery, and cause infection, most commonly intra-abdominal infection. B. fragilis can develop antimicrobial resistance through multiple mechanisms in large part due to its plasticity and fluid genome. Bacteroidota (formerly, Bacteroidetes) have a very broad metabolic potential in the GI microbiota and can rapidly adapt their carbohydrate metabolism to the available nutrients. Gastrointestinal Bacteroidota species produce short-chain fatty acids such as succinate, acetate, butyrate, and occasionally propionate, as the major end-products, which have wide-ranging and many beneficial influences on the host. Bacteroidota, via bile acid metabolism, also play a role in in colonization-resistance of other organisms, including Clostridioides difficile, and maintenance of gut integrity.

Efficacy and Health-Related Quality of Life Impact of Fecal Microbiota, Live-jslm: A Post Hoc Analysis of PUNCH CD3 Patients at First Recurrence of Clostridioides difficile Infection

INTRODUCTION

Clostridioides difficile infection (CDI) causes symptoms of varying severity and negatively impacts patients' health-related quality of life (HRQL). Despite antibiotic treatment, recurrence of CDI (rCDI) is common and imposes clinical and economic burdens on patients. Fecal microbiota, live-jslm (REBYOTA [RBL]) is newly approved in the USA for prevention of rCDI following antibiotic treatments. We analyzed efficacy and HRQL impact of RBL vs. placebo in patients at first rCDI using data from the phase 3 randomized, double-blind placebo-controlled clinical trial, PUNCH CD3.

METHODS

This post hoc analysis included patients at first rCDI fromPUNCH CD3. Treatment success (i.e., absence of diarrhea within 8 weeks post-treatment) was analyzed adjusting for baseline patient characteristics. HRQL was measured using the Clostridioides difficile Quality of Life Survey (Cdiff32); absolute scores and change from baseline in total and domain (physical, mental, and social) scores were summarized and compared between arms. Analyses were conducted for the trial's blinded phase only.

RESULTS

Among 86 eligible patients (32.8% of the overall trial population, RBL 53 [61.6%], placebo 33 [38.4%]), RBL-treated patients had significantly lower odds of recurrence (i.e., greater probability of treatment success) at week 8 vs. placebo (odds ratio 0.35 [95% confidence interval 0.13, 0.98]). Probability of treatment success at week 8 was 81% for RBL and 60% for placebo, representing 21% absolute and 35% relative increases for RBL (crude proportions 79.2% vs. 60.6%; relative risk 0.53, p = 0.06). Additionally, RBL was associated with significantly higher Cdiff32 total (change score difference 13.5 [standard deviation 5.7], p < 0.05) and mental domain (16.2 [6.0], p < 0.01) scores vs. placebo from baseline to week 8.

CONCLUSION

Compared to placebo, RBL demonstrated a significantly higher treatment success in preventing further rCDI and enhanced HRQL among patients at first recurrence, establishing RBL as an effective treatment to prevent further recurrences in these patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT03244644.

Fecal Microbiota, Live-jslm for the Prevention of Recurrent Clostridioides difficile Infection : Subgroup Analysis of PUNCH CD2 and PUNCH CD3

GOALS

To assess fecal microbiota, live-jslm (REBYOTA, abbreviated as RBL, formerly RBX2660) efficacy and safety in participants grouped by recurrent Clostridioides difficile infection (rCDI) risk factors and treatment-related variables.

BACKGROUND

RBL is the first microbiota-based live biotherapeutic approved by the US Food and Drug Administration for the prevention of rCDI in adults after antibiotic treatment for rCDI.

STUDY

Treatment success rates across subgroups for PUNCH CD3 (NCT03244644) were estimated using a Bayesian hierarchical model, borrowing data from PUNCH CD2 (NCT02299570). Treatment-emergent adverse events were summarized for the double-blind treatment period within 8 weeks.

RESULTS

Treatment differences between RBL and placebo at 8 weeks were similar to the total population for most subgroups. Treatment effect sizes were similar between CDI tests, higher for oral vancomycin courses >14 days versus ≤14 days and higher for antibiotic washout periods of 3 days versus ≤2 days. The largest reductions in the rate of rCDI with RBL versus placebo were observed for participants with a 3-day CDI antibiotic washout period and participants with ≥4 previous CDI episodes. Most RBL-treated participants experienced TEAEs that were mild or moderate in severity and related to preexisting conditions.

CONCLUSION

This analysis provides further evidence of RBL efficacy and safety across subgroups, including those at high risk for rCDI.

Patient Perception of Route of Rectal Administration of Live Biotherapeutic Product for Recurrent Clostridioides difficile Infection

Introduction

CDI is a recurrent disease that is treated with antibiotics, but patients commonly experience repeat infections with significant impacts on hospital budgets and patient health quality. Standard of care management includes the antibiotics, vancomycin and fidaxomicin, which frequently provide clinical response, but do not avoid recurrence of Clostridioides difficile infection (rCDI). These recurrent infections occur due to dysbiosis of the colonic microbiota. One adjunctive therapeutic approach is to restore the deficient gastrointestinal flora using fecal microbiota transplantation (FMT) or live biotherapeutic products (LBP) when given after standard of care antimicrobials, which have been successful in reducing repeat infections with success rates up to 88%. FMT or LBP can be given by various routes.

Methods

Two groups of subjects aged ≥18 years with at least one previous CDI episode within the previous 36 months completed self-administered online surveys to assess the acceptability of an LBP administered rectally. Group 1 consisted of LBP-recipients who had received RBL (REBYOTA) rectally as part of the Phase III PUNCH CD3 clinical trial. Group 2 consisted of LBP-naïve subjects who volunteered to participate and had experienced CDI within the prior 36 months but had no history of receiving FMT or LBP therapy.

Results

LBP-recipients considered rectal administration easy (96%) and quick (94%), while 98% of respondents considered the lack of need for bowel preparation appealing. Most LBP-recipients (96%) wished they had earlier access to RBL. Most LBP-naïve subjects (87%) were likely or somewhat likely to consider a rectally administered treatment and 80% preferred a treatment option that does not require bowel preparation. Many of these subjects (76%) expressed interest in finding out about new treatment options for rCDI.

Discussion

LBP-recipients and LBP-naïve subjects alike felt that rectal delivery of microbiome therapy is not only acceptable but highly interesting as a treatment avenue.

Economic Impact of Recurrent Clostridioides difficile Infection in the USA: A Systematic Literature Review and Cost Synthesis

INTRODUCTION

Up to 35% of patients with a first episode of Clostridioides difficile infection (CDI) develop recurrent CDI (rCDI), and of those, up to 65% experience multiple recurrences. A systematic literature review (SLR) was conducted to review and summarize the economic impact of rCDI in the United States of America.

METHODS

English-language publications reporting real-world healthcare resource utilization (HRU) and/or direct medical costs associated with rCDI in the USA were searched in MEDLINE, MEDLINE In-Process, Embase, and the Cochrane Library databases over the past 10 years (2012-2022), as well as in selected scientific conferences that publish research on rCDI and its economic burden over the past 3 years (2019-2022). HRU and costs identified through the SLR were synthesized to estimate annual rCDI-attributable direct medical costs to inform the economic impact of rCDI from a US third-party payer's perspective.

RESULTS

A total of 661 publications were retrieved, and 31 of them met all selection criteria. Substantial variability was found across these publications in terms of data source, patient population, sample size, definition of rCDI, follow-up period, outcomes reported, analytic approach, and methods to adjudicate rCDI-attributable costs. Only one study reported rCDI-attributable costs over 12 months. Synthesizing across the relevant publications using a component-based cost approach, the per-patient per-year rCDI-attributable direct medical cost was estimated to range from $67,837 to $82,268.

CONCLUSIONS

While real-world studies on economic impact of rCDI in the USA suggested a high-cost burden, inconsistency in methodologies and results reporting warranted a component-based cost synthesis approach to estimate the annual medical cost burden of rCDI. Utilizing available literature, we estimated the average annual rCDI-attributable medical costs to allow for consistent economic assessments of rCDI and identify the budget impact on US payers.

A narrative review of nontuberculous mycobacterial pulmonary disease: microbiology, epidemiology, diagnosis, and management challenges

INTRODUCTION

Nontuberculous mycobacteria (NTM) are a diverse group of mycobacterial species that are ubiquitous in the environment. They are opportunistic pathogens that can cause a range of diseases, especially in individuals with underlying structural lung disease or compromised immune systems.

AREAS COVERED

This paper provides an in-depth analysis of NTM infections, including microbiology, environmental sources and transmission pathways, risk factors for disease, epidemiology, clinical manifestations and diagnostic approaches, guideline-based treatment recommendations, drugs under development, and management challenges.

EXPERT OPINION

Future approaches to the management of NTM pulmonary disease will require therapies that are well tolerated, can be taken for a shorter time period and perhaps less frequently, have few drug-drug interactions, and are active against the various strains of pathogens. As the numbers of infections increase, such therapies will be welcomed by clinicians and patients.

The burden of CDI in the United States: a multifactorial challenge

Clostridioides difficile infection (CDI) affects approximately 500,000 patients annually in the United States, of these around 30,000 will die. CDI carries significant burdens including clinical, social and economic. While healthcare-associated CDI has declined in recent years, community-associated CDI is on the rise. Many patients are also impacted by recurrent C. difficile infections (rCDI); up to 35% of index CDI will recur and of these up to 60% will further recur with multiple recurrences observed. The range of outcomes adversely affected by rCDI is significant and current standard of care does not alter these recurrence rates due to the damaged gut microbiome and subsequent dysbiosis. The clinical landscape of CDI is changing, we discuss the impact of CDI, rCDI, and the wide range of financial, social, and clinical outcomes by which treatments should be evaluated.

Gut microbiota and microbiota-based therapies for Clostridioides difficile infection

Clostridioides difficile infection poses significant clinical challenges due to its recurrent nature. Current antibiotic management does not address the underlying issue, that of a disturbed gastrointestinal microbiome, called dysbiosis. This provides a supportive environment for the germination of C. difficile spores which lead to infection and toxin production as well as an array of other health conditions. The use of microbiome restoration therapies such as live biotherapeutics can reverse dysbiosis and lead to good clinical outcomes. Several such therapies are under clinical investigation.

Microbiota-Based Live Biotherapeutic RBX2660 for the Reduction of Recurrent Clostridioides difficile Infection in Older Adults With Underlying Comorbidities

Background

Advanced age and underlying comorbidities are associated with greater rates of recurrence in patients with Clostridioides difficile infection (CDI). Reducing the likelihood of recurrence through treatment with an antimicrobial followed by a microbiota replacement therapy can decrease the burden of this infection and improve patient outcomes. We report the efficacy and safety of RBX2660, a microbiota-based live biotherapeutic, in older adults with recurrent CDI, grouped by comorbidities.

Methods

In this post hoc subgroup analysis of the PUNCH CD3 trial, we assessed outcomes in older adults (age ≥65 years) grouped by Charlson Comorbidity Index severity scores at screening (moderate [3-4] and severe [≥5]) and by the presence of underlying cardiac, renal, or gastrointestinal disorders.

Results

RBX2660 treatment success rates in older adults with comorbidities were consistent across subgroups and similar to those in the total RBX2660-treated population. A greater percentage of RBX2660-treated older adults remained free of CDI recurrence through 8 weeks following treatment compared with placebo-treated participants in all but 2 subgroups assessed. Across all subgroups, most treatment-emergent adverse events (TEAEs) were mild or moderate in severity and related to a preexisting condition. None of the serious or life-threatening TEAEs that occurred were related to RBX2660 or its administration. Occurrence of TEAEs did not cluster in any subgroup.

Conclusions

RBX2660 is efficacious and safe in older adults with recurrent CDI and underlying comorbidities.

It's about the patients: Practical antibiotic stewardship in outpatient settings in the United States

Antibiotic-resistant pathogens cause over 35,000 preventable deaths in the United States every year, and multiple strategies could decrease morbidity and mortality. As antibiotic stewardship requirements are being deployed for the outpatient setting, community providers are facing systematic challenges in implementing stewardship programs. Given that the vast majority of antibiotics are prescribed in the outpatient setting, there are endless opportunities to make a smart and informed choice when prescribing and to move the needle on antibiotic stewardship. Antibiotic stewardship in the community, or "smart prescribing" as we suggest, should factor in antibiotic efficacy, safety, local resistance rates, and overall cost, in addition to patient-specific factors and disease presentation, to arrive at an appropriate therapy. Here, we discuss some of the challenges, such as patient/parent pressure to prescribe, lack of data or resources for implementation, and a disconnect between guidelines and real-world practice, among others. We have assembled an easy-to-use best practice guide for providers in the outpatient setting who lack the time or resources to develop a plan or consult lengthy guidelines. We provide specific suggestions for antibiotic prescribing that align real-world clinical practice with best practices for antibiotic stewardship for two of the most common bacterial infections seen in the outpatient setting: community-acquired pneumonia and skin and soft-tissue infection. In addition, we discuss many ways that community providers, payors, and regulatory bodies can make antibiotic stewardship easier to implement and more streamlined in the outpatient setting.

Transitions of care in Clostridioides difficile infection: a need of the hour

Clostridioides difficile infection (CDI) is a complex disease that by virtue of both its initial virulence and proclivity toward recurrent episodes causes a high morbidity, mortality, and financial burden. This burden is felt by patients and their families as well as the U.S. healthcare system. Recurrent CDI episodes can occur in 25-65% of patients, with a cycle of multiple recurrences in a single patient contributing to the complexity of care. Patients with or suspected of having CDI will receive treatment and their care will be managed across multiple healthcare settings and will include many different levels of healthcare workers. The understanding of this infection is essential for all who are involved in the care of these patients. A well-structured and implemented Transition of Care process can ease the burden on the healthcare system, patients, and their families; reduce the cost of care; and improve patient outcomes. We review the development of Transitions of Care processes, resource guides, and their relevance to improving the management of CDI.

Structured patient interview to assess clinical outcomes in complicated urinary tract infections in the APEKS-cUTI study: pilot investigation

Background

The APEKS-cUTI study demonstrated the non-inferiority of cefiderocol to imipenem-cilastatin in the primary endpoint of the composite of clinical and microbiological outcome in patients with complicated urinary tract infections (cUTIs). We piloted a structured patient interview (SPI) to evaluate clinical outcomes based on patient-reported symptoms while conducting this pivotal randomized, double-blind, phase-2 study. The objectives were to assess the value of the SPI, using its performance relative to physician assessment, and also to strengthen the value of patient-reported measures in conducting clinical trials for cUTI treatment.

Methods

In addition to the protocol-defined clinical and microbiological outcomes, patients randomized in the APEKS-cUTI study were interviewed by the investigator or qualified study personnel at screening/baseline, early assessment (EA), end of treatment (EOT), test of cure (TOC), and follow-up (FUP). The 14-element questionnaire graded cUTI symptoms as absent or present, and if present, as mild, moderate, or severe. Changes in post-baseline symptoms based on patients' responses were rated by the interviewer. The overall clinical outcome was evaluated based on the responses provided by patients at each time point.

Results

Among the 371 patients in the modified intention-to-treat population, the rate of SPI completion in each treatment arm exceeded 90% at each time point. SPI-assessed clinical cure rates were 89.7% in the cefiderocol arm and 84.9% in the imipenem-cilastatin arm. There was substantial agreement between SPI evaluation and investigator global assessment of clinical outcome at TOC and FUP, with lower agreement at EA and EOT.

Conclusion

This analysis suggests that patient-reported symptoms can be effectively captured in hospitalized patients with cUTI in a clinical trial setting. Development of a validated patient-reported outcome for use in such a setting is warranted.

Registration

NCT02321800 (registered on 22 December 2014).

The burden of Clostridioides difficile infection in COVID-19 patients: A systematic review and meta-analysis

OBJECTIVES

The main aim of this systematic review and meta-analysis was to assess the proportion of confirmed COVID-19 patients with Clostridioides difficile infection (CDI) and to describe risk factors and outcome of these patients.

METHODS

MEDLINE and Cochrane Central Register of Controlled Trials databases were searched up to July 15, 2021. We included studies reporting data on CDI occurring in patients with a confirmed diagnosis of COVID-19. We pooled proportion of CDI patients using a random effects model (DerSimonian-Laird method) stabilising the variances using the Freeman-Tukey double arcsine transformation.

RESULTS

Thirteen studies were included in the systematic review. All the studies retrospectively collected data between February 2020 and February 2021. The reported CDI incidence rates ranged from 1.4 to 4.4 CDI cases per 10,000 patient-days. Seven studies reported data on the number of COVID-19 patients who developed CDI and the total number of COVID-19 patients in the study period and were included in the meta-analysis, comprising 23,697 COVID-19 patients. The overall pooled proportion of COVID-19 patients who had CDI was 1% [95% confidence interval: 1-2]. Among studies reporting CDI occurrence in patients with and without COVID-19, the majority of them reported reduced or unchanged CDI rates compared to pre-COVID period.

CONCLUSIONS

CDI is a relevant issue for COVID-19 patients. Adherence to infection prevention and control measures and to the antimicrobial stewardship principles is crucial even during the COVID-19 pandemic.

Heterogeneity of Recent Phase 3 Complicated Urinary Tract Infection Clinical Trials

Background

For new antibiotics developed to treat antibiotic-resistant Gram-negative infections, the US Food and Drug Administration (FDA) regulatory pathway includes complicated urinary tract infection (cUTI) clinical trials in which the clinical isolates are susceptible to the active control. This allows for inferential testing in a noninferiority study design. Although complying with regulatory guidelines, individual clinical trials may differ substantially in design and patient population. To determine variables that impacted patient selection and outcome parameters, 6 recent cUTI trials that were pivotal to an new drug application (NDA) submission were reviewed.

Methods

This selective descriptive analysis utilized cUTI trial data, obtained from publicly disclosed information including FDA documents and peer-reviewed publications, from 6 new antibiotics developed to treat multidrug-resistant Gram-negative infections: ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, cefiderocol, plazomicin, and fosfomycin. Eravacycline was not approved for cUTI and is not included.

Results

Microbiologic modified intent-to-treat sample size, age, proportions of female patients, acute pyelonephritis (AP), Escherichia coli and other pathogens at baseline, protocol-specified switch to oral antibiotic, and the noninferiority margin were compared. Outcome data included clinical response, microbiologic eradication, and composite outcomes, including a subset of patients with AP.

Conclusions

A study design can follow regulatory guidelines but still have variable populations. The proportion of AP within a study varied greatly and influenced population demographics (age, gender) and baseline microbiology. A smaller proportion of AP resulted in an older patient population, fewer females, less E coli, and lower proportions of patients achieving success. Fluoroquinolones and piperacillin/tazobactam should be reconsidered as active comparators given the high rates of resistance to these antibiotics.

Antimicrobial Management of Respiratory Infections in Severe Acute Respiratory Syndrome Coronavirus 2 Patients: Clinical and Antimicrobial Stewardship Programs Conundrums

The role of empirical and even directed antimicrobial management of patients hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is problematic; antibiotics are used frequently among these patients to treat confirmed or suspected coinfection or just the symptoms. In the rapidly changing clinical landscape of SARS-CoV-2, there is minimal guidance for selecting appropriate treatment versus non-antimicrobial treatment, and clinicians are pressed to make daily decisions under the stress of absence of data while watching patients deteriorate. We review current data and patterns of antimicrobial use and the potential approach for antimicrobial stewardship in the context of SARS-CoV-2.

Clinical outcomes after faecal microbiota transplant by retention enema in both immunocompetent and immunocompromised patients with recurrent Clostridioides difficile infections at an academic medical centre

BACKGROUND

Recurrent Clostridioides difficile infection (CDI) is one of the most common and challenging infections to treat in healthcare facilities. Faecal microbiota transplantation (FMT) is recommended as a definitive treatment option.

METHODS

We performed a retrospective review of 50 patients from January 2015 to December 2019 who underwent FMT for recurrent CDI. Primary outcome was recurrence of CDI within 12-weeks of FMT and secondary outcomes were the need for repeat FMT, serious adverse outcomes related to FMT and all-cause mortality.

RESULTS

Fifty charts were reviewed, of which 47 cases comprising 17 immunocompromised patients treated with FMT via retention enema were included in the study. The majority of the patients had ≥3 recurrent CDIs (62%). Nine (19%) patients failed to respond to the first FMT and five underwent repeat FMT within four to 12 weeks. The cure rate was 81% after the first FMT (38/47) and 91% after the second FMT treatment (43/47). Serious adverse events occurred in 2% and all-cause mortality was 2% at 90-day follow up.

CONCLUSION

Our study demonstrated the safety and efficacy of FMT administered via retention enema, a simple bedside procedure, for the treatment and prevention of recurrent non-severe and severe CDI with an overall cure rate of 91%.

Omadacycline: a therapeutic review of use in community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections

Omadacycline is a novel aminomethylcycline antimicrobial, US FDA approved for the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. It is not susceptible to common tetracycline resistance mechanisms, and has demonstrated efficacy against a broad spectrum of pathogens including resistant isolates, which are increasing in prevalence and complexity. It is available in both intravenous and oral formats, and can be administered in single, once daily doses or multiple doses, with no dosing adjustments required for sex, age, hepatic or renal impairment. It can be a good option for patients with low treatment adherence, and oral therapy may be used to reduce length of hospitalization for iv. treatment. This article reviews the in vitro and in vivo activity, PK/PD profile, integrated data from clinical trials including clinical efficacy and safety profile, and looks to future application of omadacycline.

Global travel and Gram-negative bacterial resistance; implications on clinical management

INTRODUCTION

Antimicrobial resistance (AR) is escalating worldwide with the potential for dire consequences, global travel contributes to the dissemination of resistant pathogens from one region to another. The World Health Organization identified the rapid emergence and prevalence of carbapenem-resistant Gram-negative species, including Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa, as an international crisis due to treatment challenges, poor health outcomes, increased mortality, and high economic costs caused by these pathogens.

AREAS COVERED

This review describes key carbapenem-resistant (CR) Gram-negative species, changes in current global and regional trends, AR surveillance and reporting, and identifies drivers of change, specifically travel. Finally, we review clinical implications and challenges of treating CR infections which exist due to widespread dissemination of CR bacteria. A literature search was conducted using PubMed, Google Scholar, Ebsco, and ProQuest (from 2000 to December 2019).

EXPERT OPINION

The level of global travel is increasing, and antimicrobial resistance continues to disseminate worldwide. Healthcare providers risk assessment for AR needs to consider a patient's recent travel history, including pre-travel and intra-travel antimicrobial prescription, and potential exposure based on geography. Patient education, healthcare provider awareness, and access to data and surveillance resources are critical to inform antimicrobial selection and improve health outcomes.

Analysis of Pooled Phase 3 Safety Data for Delafloxacin in Acute Bacterial Skin and Skin Structure Infections

Background

Through improved understanding of the structure-activity relationship attributes of fluoroquinolones, molecule development has improved efficacy, safety, and tolerability of the class. Adverse events (AEs) associated with the fluoroquinolones are well defined and a prospective part of the development process. However, not all fluoroquinolones have the same AE profile with different substitutions on the core molecule resulting in differences in side effects and spectrum of activity. Unique structural attributes of delafloxacin (DLX) may differentiate its AE profile compared to other fluoroquinolones. This analysis compared the incidence of AEs between DLX and vancomycin/aztreonam across two phase 3 ABSSSI studies in order to provide a broader overview of DLX safety.

Methods

Safety events occurring in all subjects in the pivotal phase 3 trials were pooled to provide a broad overview of DLX safety.

Results

DLX was safe and well-tolerated in the pooled phase 3 ABSSSI trial population of 741 subjects. Treatment-emergent AEs (TEAEs) were seen in the DLX group versus the comparator group at 45.1% and 47.7%, respectively. Most were mild or moderate in severity. Treatment-related TEAEs were reported in the DLX group versus the comparator group at rates of 22.1% and 26.1%, respectively.

Conclusions

Available data show DLX is well tolerated in both intravenous and oral formulation for the treatment of ABSSSI and does not appear to be associated with increased risk of AEs associated with other fluoroquinolones. It remains important to monitor for potential AEs that have been observed with other fluoroquinolones.

Clostridioides difficile in COVID-19 Patients, Detroit, Michigan, USA, March-April 2020

We describe 9 patients at a medical center in Detroit, Michigan, USA, with severe acute respiratory syndrome coronavirus 2 and Clostridioides difficile. Both infections can manifest as digestive symptoms and merit screening when assessing patients with diarrhea during the coronavirus disease pandemic. These co-infections also highlight the continued importance of antimicrobial stewardship.

The Burden of Bloodstream Infections due to Stenotrophomonas Maltophilia in the United States: A Large, Retrospective Database Study

Background

Stenotrophomonas maltophilia is an opportunistic pathogen observed in both nosocomial and community-onset infections. S. maltophilia is intrinsically resistant to many currently available broad-spectrum antibiotics and is often not included in antimicrobial resistance surveillance studies or stewardship programs’ guidelines.

Methods

A retrospective cohort study of patients with S. maltophilia bloodstream infection (BSI) in the United States was conducted using the 2010–2015 US Premier Healthcare Database. This study described patient characteristics, infection characteristics, antibiotic treatment, and discharge status.

Results

S. maltophilia was the most common carbapenem-resistant, gram-negative pathogen causing BSIs in this database. Of 486 unique patients with S. maltophilia BSI, 44.6% were assessed as community-onset, 95% of cultures were susceptible to trimethoprim-sulfamethoxazole (TMP-SMX), and 84% were susceptible to fluoroquinolones; 39.1% of patients received a potentially effective antibiotic (fluoroquinolone, doxycycline, ceftazidime, minocycline, or TMP-SMX) during the empiric treatment period (≤3 days post–index culture date), whereas 85.8% received a potential effective antibiotics during the definitive treatment period. The most common antibiotic received as definitive treatment was levofloxacin (48.9%). TMP-SMX was used infrequently empirically (10.5%) and in 38.3% during the definitive period. Compared with BSIs caused by other carbapenem-resistant gram-negative pathogens, S. maltophilia BSIs were more likely to be community-onset, and were more likely to be discharged to home and to have a lower mortality rate.

Conclusions

This study demonstrated that patients at risk for S. maltophilia BSI are highly variable and that standard of care is not clearly defined, leading to questions regarding the appropriateness of antibiotic treatment among patients. Further efforts are needed to better recognize and treat S. maltophilia BSI.

Antibiotic Treatment Failure and Associated Outcomes Among Adult Patients With Community-Acquired Pneumonia in the Outpatient Setting: A Real-world US Insurance Claims Database Study

Background

Antibiotic treatment failure is common among patients with community-acquired pneumonia (CAP) who are managed in the outpatient setting and is associated with higher mortality and increased health care costs. This study's objectives were to quantify the occurrence of antibiotic treatment failure (ATF) and to evaluate clinical and economic outcomes between CAP patients who experienced ATF relative to those who did not.

Methods

Retrospective analysis of the MarketScan Commercial & Medicare Supplemental Databases was performed, identifying patients ≥18 years old, with a pneumonia diagnosis in the outpatient setting, and who received a fluoroquinolone, macrolides, beta-lactam, or tetracycline. ATF was defined as any of the following events within 30 days of initial antibiotic: antibiotic refill, antibiotic switch, emergency room visit, or hospitalization. Outcomes included 30-day all-cause mortality and CAP-related health care costs.

Results

During the study period, 251 947 unique patients met inclusion criteria. The mean age was 52.2 years, and 47.7% were male. The majority of patients received a fluoroquinolone (44.4%) or macrolide (43.6%). Overall, 22.1% were classified as ATFs. Among 18-64-year-old patients, 21.2% experienced treatment failure, compared with 25.7% in those >65 years old. All-cause mortality was greater in the antibiotic failure group relative to the non-antibiotic failure group (18.1% vs 4.6%, respectively), and the differences in 30-day mortality between antibiotic failure groups increased as a function of age. Mean 30-day CAP-related health care costs were also higher in the patients who experienced treatment failure relative to those who did not ($2140 vs $54, respectively).

Conclusions

Treatment failure and poor outcomes from outpatient CAP are common with current guideline-concordant CAP therapies. Improvements in clinical management programs and therapeutic options are needed.

Antibiotic Breakpoints: How Redefining Susceptibility Preserves Efficacy and Improves Patient Care

Carbapenems are a primary treatment for infections from multidrug-resistant bacterial pathogens. To maintain their efficacy and control the emergence of further resistance, breakpoints that correspond to recommended doses with appropriate PK/PD target attainment are paramount.

Physicians' attitude and knowledge regarding antibiotic use and resistance in ambulatory settings

BACKGROUND

The aim of this survey was to assess the attitudes of physicians toward antibiotic prescribing and explore their knowledge about antimicrobial resistance (AMR) in ambulatory care settings.

METHODS

We conducted a cross-sectional survey that was administered to physicians who work primarily in ambulatory care settings in the United States. The survey was self-administered, voluntary, and anonymous, and was delivered through electronic mail and online forums using a 35-item questionnaire.

RESULTS

The survey was completed by 323 physicians. Ninety-nine percent of respondents agreed that AMR is a national problem, but only 63% agreed that AMR is a local problem within their own facilities. Ninety-four percent of the respondents reported that each antibiotic prescription can impact AMR; however, 23% still believed that aggressive prescribing is necessary to avoid clinical failures. Factor perceived to have a low to moderate impact on the physicians' choice of antibiotic was the presence of prescription guidelines (54%). Top measures reported to be effective in reducing the emergence of AMR were institution specific guidelines (94%), institution specific antibiogram (92%), educating health care providers (87%), and regular audits and feedback on antibiotic prescribing (86%).

CONCLUSIONS

AMR awareness campaigns and antibiotic stewardships incorporating interactive education and feedback, along with input of local experts, are critically needed to address the problem of AMR in both inpatient and ambulatory settings.

Delafloxacin: an improved fluoroquinolone developed through advanced molecular engineering

The emergence of antimicrobial resistance threatens current clinical practice across a range of infection types. Delafloxacin, a non-zwitterionic fluoroquinolone recently approved by the US FDA for the treatment of acute bacterial skin and skin structure infections, has been developed to address some of these challenges. Uniquely delafloxacin has increased intracellular penetration and enhanced antibacterial activity under acidic conditions, an environment seen in many infection sites including abscesses. Delafloxacin is active against a wide range of Gram-positive and -negative species including methicillin-resistant Staphylococcus aureus and many fluoroquinolone-resistant strains. Additionally, according to preclinical and clinical trial data, well-known adverse events related to fluoroquinolone class do not appear to occur with this new molecule. Delafloxacin has been studied in acute bacterial skin and skin structure infections with >1400 patients exposed to both intravenous and oral formulation for up to 14 days and has shown noninteriority to vancomycin with or without aztreonam. For its interesting microbiological and pharmacokinetic/pharmacodynamics characteristics and for its safety profile, delafloxacin represents a very promising option for the treatment of infections caused by multidrug-resistant pathogens.

Ridinilazole: a novel therapy for Clostridium difficile infection

Clostridium difficile infection (CDI) is the leading cause of infectious healthcare-associated diarrhoea. Recurrent CDI increases disease morbidity and mortality, posing a high burden to patients and a growing economic burden to the healthcare system. Thus, there exists a significant unmet and increasing medical need for new therapies for CDI. This review aims to provide a concise summary of CDI in general and a specific update on ridinilazole (formerly SMT19969), a novel antibacterial currently under development for the treatment of CDI. Owing to its highly targeted spectrum of activity and ability to spare the normal gut microbiota, ridinilazole provides significant advantages over metronidazole and vancomycin, the mainstay antibiotics for CDI. Ridinilazole is bactericidal against C. difficile and exhibits a prolonged post-antibiotic effect. Furthermore, treatment with ridinilazole results in decreased toxin production. A phase 1 trial demonstrated that oral ridinilazole is well tolerated and specifically targets clostridia whilst sparing other faecal bacteria. Phase 2 and 3 trials will hopefully further our understanding of the clinical utility of ridinilazole for the treatment of CDI.

A randomised phase 1 study to investigate safety, pharmacokinetics and impact on gut microbiota following single and multiple oral doses in healthy male subjects of SMT19969, a novel agent for Clostridium difficile infections

BACKGROUND

Clostridium difficile infection (CDI) is a leading cause of diarrhoea in health care settings with symptoms ranging from mild and self-limiting to life threatening. SMT19969 is a novel, non-absorbable antibiotic currently under development for the treatment of CDI. Here we report the results from a Phase I study.

METHODS

A double-blind, randomized, placebo-controlled study assessing safety and tolerability of single and multiple oral doses of SMT19969 in healthy volunteers. Pharmacokinetic assessments included blood and faecal sampling. The effect of food on systemic exposure and analysis of the gut microbiota were also included.

RESULTS

Fifty-six healthy male subjects were enrolled. Following single oral doses of up to 2,000 mg in the fasted state, plasma concentrations of SMT19969 were generally below the lower limit of quantification. In the fed state levels ranged from 0.102 to 0.296 ng/mL after single dosing and after repeat dosing at Day 10 from 0.105 to 0.305 ng/mL. Following single and multiple oral doses of SMT19969, mean daily faecal concentrations increased with increasing dose level and were significantly above the typical MIC range for C. difficile (0.06-0.5 μg/mL). At 200 mg BID, mean (± SD) faecal concentrations of 1,466 (±547) μg/g and 1,364 (±446) μg/g were determined on days 5 and 10 of dosing respectively. No notable metabolites were detected in faeces. Overall, all doses of SMT19969 were well tolerated both as single oral doses or BID oral doses for 10 days. The majority (88%) of adverse events (AEs) were classified as gastrointestinal disorders and were mild in severity, resolving without treatment. The gut microbiota was analysed in the multiple dose groups with minimal changes observed in the bacterial groups analysed except for total clostridia which were reduced to below the limit of detection by day 4 of dosing.

CONCLUSIONS

Oral administration of SMT19969 was considered safe and well tolerated and was associated with negligible plasma concentrations after single and multiple doses. In addition, minimal disruption of normal gut microbiota was noted, confirming the highly selective spectrum of the compound. These results support the further clinical development of SMT19969 as an oral therapy for CDI.

TRIAL REGISTRATION

Current Controlled Trials. ISRCTN10858225 .

Gemifloxacin for the Management of Community-Acquired Respiratory Tract Infections

Community-acquired lower respiratory tract infections (LRTIs) exert a growing clinical and financial burden on healthcare systems and employers. In addition, antimicrobial resistance among pathogens, such as Streptococcus pneumoniae, has compromised the use of commonly prescribed antimicrobial compounds. Newer fluoroquinolones have been developed to meet these emerging demands. Gemifloxacin is a potent, dual-acting fluoroquinolone with excellent activity against S. pneumoniae (MIC(90)0.03-0.06 microg/ml) including those strains demonstrating resistance to other classes of antibiotics. Gemifloxacin demonstrated excellent clinical success in community-acquired lower respiratory infections, has an acceptable safety profile, and is a cost-effective alternative in the management of LRTIs including those caused by resistant pathogens.

Descriptive epidemiology of hereditary angioedema emergency department visits in the United States, 2006-2007

Hereditary angioedema (HAE) is a rare inherited disorder of complement factor C1 inhibitor. In 2007 there were over 2000 HAE-related emergency department (ED) visits, nearly one-half of which culminated in a hospitalization. This study examines epidemiology and outcomes of hospital ED visits among HAE patients. We evaluated epidemiology, resource use, and discharge destinations of HAE (International Classification of Diseases, Version 9, clinical modification [ICD-9-CM] code 277.6) ED visits within the Nationwide Emergency Department Sample, part of Agency for Healthcare Research and Quality Healthcare Costs and Utilization Project, in 2006 and 2007. In 2006-2007, there were 5040 ED visits with HAE, of which 2705 (53.7%) had HAE as the principal diagnosis (HAE-PD). The mean age for all HAE visits was 38.2 years, and women accounted for 56.5% of all HAE visits. When HAE was not the primary reason for the visit, abdominal pain was the most prevalent (10%) presenting diagnosis. Two thousand fifty-nine (40.9%) resulted in a hospitalization. Although of all HAE ED visits that did not require a hospitalization, the vast majority was discharged routinely home, further care either at a skilled nursing facility or at home was required after 45 (0.9%) of all the HAE visits and 10 (0.4%) of the HAE-PD visits. Mean HAE ED visits costs were $1479 (95% confidence interval, $1028-1929). HAE ED visit volume is substantial. Although likely representing a fraction of the entire HAE population, prevention and acute treatment strategies aimed at those at risk for frequent exacerbations and disproportionate resource use need to be examined.

Descriptive epidemiology of hereditary angioedema hospitalizations in the United States, 2004-2007

Hereditary angioedema (HAE) is a rare inherited disorder of complement factor C1 inhibitor. There are ∼6000 HAE cases in the United States, nearly one-half of whom suffer a monthly exacerbation. Little is known about hospital use patterns by patients with HAE attacks in the United States. This study was designed to examine burden, epidemiology, and outcomes of hospitalizations among HAE patients. We evaluated epidemiology, resource use, and discharge destinations of HAE (ICD-9-CM code 277.6) hospitalizations within the NIS, part of Agency's for Healthcare Research and Quality Healthcare Costs and Utilization Project in 2004 through 2007. There were 10,125 hospitalizations with HAE, of which 3216 (31.8%) had HAE as the principal diagnosis (HAE-PD). Two-thirds of all HAE hospitalizations were among women, and 60% were white. Hypertension was the most common comorbidity (26.9%, all HAE, and 28.0%, HAE-PD). Mortality was 1.4% in HAE and 0.3% in the HAE-PD group. Mean hospital length of stay (3.7, 95% CI 3.0-4.4 days vs. 5.0, 95% CI 4.6-5.4 days) and costs ($4,760, 95% CI $3,612-$5,907 vs. $8,383, 95% CI $7,432-$9,334) were lower in HAE-PD than in the HAE cohort. Although >80% in each group were discharged home routinely, 15.9% of HAE and 4.9% of HAE-PD required either home health care or a transfer to another short-term hospital or a skilled nursing facility. HAE hospitalization volume is substantial. Because diagnostic uncertainty is likely, HAE and its related resource use may be underestimated. HAE prevention strategies need to be examined in the context of these outcomes.

The burden of hospitalizations and emergency department visits with hereditary angioedema and angioedema in the United States, 2007

Hereditary angioedema (HAE) is a rare inherited disorder of complement factor C1 inhibitor. HAE is frequently confused with angioedema (AE), and little is known about emergency department (ED) or hospital utilization by patients with attacks in the United States. We examined hospitalizations and ED utilization for HAE and AE in two large nationally representative databases. We evaluated annual rate and resource use of HAE (International Classification of Diseases, Version 9, Clinical Modification [ICD-9-CM] code 277.6) and AE (ICD-9-CM code 995.1) hospitalizations within Nationwide Inpatient Sample (NIS), part of the Agency of Healthcare Research and Quality's Healthcare Costs and Utilization Project (AHRQ-HCUP), for 2007. We also used AHRQ-HCUP's 2007 Nationwide Emergency Department Sample (NEDS) to study annual rates of ED visits and subsequent hospitalizations with these conditions. There were 1691 hospitalizations with HAE and 22,572 with AE (4.25 HAE and 57.08 AE cases/100,000 hospitalizations). HAE was the principal diagnosis (PD) in 46.0% and AE in 62.5%. In aggregate, HAE and AE PD hospitalizations accrued 35,000 hospital days and hospital costs of $63 million. There were 2282 ED visits with HAE and 112,105 ED visits with AE (1.87 HAE and 91.64 AE cases/100,000 ED visits). HAE occurred as a PD in 51.2% and AE occurred as a PD in 80.0%. Forty-five percent of HAE patients and 18.3% of AE patients required hospitalization. HAE and AE ED use and hospitalization burden are substantial. Because diagnostic uncertainty is likely, HAE-related proportion of patients and resource use are probably underestimated. Clinical validation of current case definition would be useful, because administrative data may present an attractive source for investigating these populations.

Assessing the economic merits of managing cytomegalovirus infection in organ and stem cell transplantation

Two preventative approaches exist to manage cytomegalovirus (CMV), a common infection in recipients of organ and stem cell transplants: prophylaxis--the prevention of viraemia--and pre-emptive therapy--the prevention of manifestation of disease in patients who have viraemia. Economic evaluation may provide a helpful framework to inform the choice between these two approaches. However, several issues arise. Direct comparisons of prophylaxis and pre-emptive therapy are rare and there are few epidemiological data that depict the full natural history of CMV infection and disease. There is a need for large, prospective randomised trials that directly compare these two strategies and are of sufficient duration to assess their overall impact on direct and indirect effects of CMV as well as patient quality of life. These methodological issues are relevant to the economic evaluation of preventative measures in other clinical settings and highlight the need for a rigorous evaluative framework to best inform decision making about the optimal strategy for patients.