Antibacterial activity of ibezapolstat against antimicrobial-resistant clinical strains of Clostridioides difficile.

Antimicrobial resistance is emerging in clinical strains of Clostridioides difficile. Ibezapolstat (IBZ) is a DNA polymerase IIIC inhibitor that has completed phase II clinical trials. IBZ has potent in vitro activity against wild-type, susceptible strains but its effect on C. difficile strains with reduced susceptibility to metronidazole (MTZ), vancomycin (VAN), or fidaxomicin (FDX) has not been tested. The primary objective of this study was to test the antibacterial properties of IBZ against multidrug-resistant C. difficile strains. The in vitro activity, bactericidal, and time-kill activity of IBZ versus comparators were evaluated against 100 clinical strains of which 59 had reduced susceptibility to other C. difficile antibiotics. Morphologic changes against a multidrug resistance strain were visualized by light and scanning electron microscopy. The overall IBZ MIC50/90 values (µg/mL) for evaluated C. difficile strains were 4/8, compared with 2/4 for VAN, 0.5/1 for FDX, and 0.25/4 for MTZ. IBZ MIC50/90 values did not differ based on non-susceptibility to antibiotic class or number of classes to which strains were non-susceptible. IBZ bactericidal activity was similar to the minimum inhibitory concentration (MIC) and maintained in wild-type and non-susceptible strains. Time-kill assays against two laboratory wild-type and two clinical non-susceptible strains demonstrated sustained IBZ activity despite reduced killing by comparator antibiotics for IBZ and VAN non-susceptible strains. Microscopy visualized increased cell lengthening and cellular damage in multidrug-resistant strains exposed to IBZ sub-MIC concentrations. This study demonstrated the potent antibacterial activity of IBZ against a large collection of C. difficile strains including multidrug-resistant strains. This study highlights the therapeutic potential of IBZ against multidrug-resistant strains of C. difficile.

Reduced Vancomycin Susceptibility in Clostridioides difficile is Associated with Lower Rates of Initial Cure and Sustained Clinical Response.

BACKGROUND: Epidemiologic studies have shown decreasing vancomycin susceptibility among clinical Clostridioides difficile isolates, but the impact on patient outcomes is unknown. We hypothesized that reduced vancomycin susceptibility would be associated with decreased rates of sustained clinical response (SCR). METHODS: This multicenter cohort study included adults with C. difficile infection (CDI) treated with oral vancomycin between 2016-2021. C. difficile isolates underwent agar dilution vancomycin susceptibility testing, ribotyping, and Sanger sequencing of the vancomycin resistance vanR gene. Reduced susceptibility was defined as vancomycin minimum inhibitory concentration (MIC) >2 µg/mL. The primary outcome was 30-day SCR; secondary outcomes were 14-day initial cure, 30-day recurrence, and 30-day mortality. Exploratory analysis assessed the association between the VanR Thr115Ala polymorphism, susceptibility, and outcomes. RESULTS: A high proportion (34%, 102/300) of C. difficile isolates exhibited reduced vancomycin susceptibility (range: 0.5-16 µg/mL, MIC50/90 = 2/4 µg/mL). Ribotype (RT) 027 accounted for the highest proportion (77.4%, 41/53) of isolates with reduced vancomycin susceptibility. Overall, 83% (249) of patients achieved 30-day SCR. Reduced vancomycin susceptibility was associated with lower rates of 30-day SCR (76%, 78/102) than vancomycin susceptible strains (86%, 171/198; P=0.031). A significantly lower rate of 14-day initial cure was also observed among individuals infected with strains with reduced vancomycin susceptibility (89% vs. 96%; P=0.04). Reduced susceptibility remained an independent predictor of 30-day SCR in multivariable modeling (odds ratio, 0.52, 95% confidence interval 0.28-0.97; P=0.04). CONCLUSIONS: Reduced vancomycin susceptibility in C. difficile was associated with decreased odds of 30-day SCR and lower 14-day initial cure rates in the studied patient cohort.

Impact of Hypoalbuminemia on Ceftriaxone Treatment Failure in Patients With Enterobacterales Bacteremia: A Propensity-Matched, Retrospective Cohort Study.

Background: Ceftriaxone is frequently prescribed due to its convenience of dosing and robust antimicrobial activity. However, patients with hypoalbuminemia may experience suboptimal ceftriaxone exposure due to the high degree of protein binding. We aimed to evaluate the impact of hypoalbuminemia on treatment failure among hospitalized adults with Enterobacterales bacteremia who received ceftriaxone therapy. Methods: We conducted an observational cohort study among patients with Enterobacterales bacteremia who received >72 hours of ceftriaxone initiated within 48 hours of index culture. A propensity-score model was used to match and compare patients with hypoalbuminemia. The primary outcome was treatment failure, defined as a composite of (1) escalation from ceftriaxone to ertapenem or an intravenous antibacterial agent with activity against Pseudomonas aeruginosa, or (2) inpatient death. Secondary outcomes included hospital length of stay, duration of antibiotic therapy, and time to infection resolution. Results: Of 260 patients included, the majority developed bacteremia from a urinary source (71.5%), and Escherichia coli was the most common pathogen identified (72.3%). Patients with hypoalbuminemia experienced numerically higher rates of treatment failure, although not reaching statistical significance (12.3% vs 7.7%; P = .21). Among patients receiving care in the intensive care unit, the impact of hypoalbuminemia on treatment failure was more pronounced (24.4% vs 7.3%; P = .07). Conclusions: Hypoalbuminemia may not have a significant impact on clinical outcomes among patients with Enterobacterales bacteremia treated with ceftriaxone. However, critically ill patients may be subject to higher incidence of treatment failure in the presence of hypoalbuminemia.

Significant Publications on Infectious Diseases Pharmacotherapy in 2020.

Purpose. To summarize the most highly esteemed, peer-reviewed, infectious diseases (ID) pharmacotherapy articles published in 2020. Summary. Members of the Houston Infectious Diseases Network (HIDN) nominated articles that were deemed to have noteworthy contributions to ID pharmacotherapy in 2020, including those on coronavirus disease 2019 (COVID-19) and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). To select the most significant articles of 2020, a survey was created and distributed to members of the Society of Infectious Diseases Pharmacists (SIDP) to vote on their top 10 articles of general ID and COVID-19 pharmacotherapy and one noteworthy HIV/AIDS publication. A total of 40 articles were nominated by HIDN: 35 articles pertaining to general ID/COVID-19 pharmacotherapy and 5 articles with HIV/AIDS involvement. Of the 247 SIDP members who responded to the survey, 205 and 42 members voted for general ID/COVID-19 pharmacotherapy articles and HIV/AIDS related articles, respectively. The top publications are summarized. Conclusion. In a taxing year of a global pandemic, the abundant and rapid distribution of ID literature has made it challenging for clinicians to stay informed of significant publications across the ID spectrum. This review summarizes significant ID-related publications in 2020 with the goal of aiding clinicians in staying up to date on the most relevant publications in ID pharmacotherapy.

Genetic Mechanisms of Vancomycin Resistance in Clostridioides difficile: A Systematic Review.

Antimicrobial resistance to treatments for Clostridioides difficile infection (CDI) poses a significant threat to global health. C. difficile is widely thought to be susceptible to oral vancomycin, which is increasingly the mainstay of CDI treatment. However, clinical labs do not conduct C. difficile susceptibility testing, presenting a challenge to detecting the emergence and impact of resistance. In this systematic review, we describe gene determinants and associated clinical and laboratory mechanisms of vancomycin resistance in C. difficile, including drug-binding site alterations, efflux pumps, RNA polymerase mutations, and biofilm formation. Additional research is needed to further characterize these mechanisms and understand their clinical impact.

Successful Treatment of Invasive Mucormycosis in Orthotopic Liver Transplant Population.

Mucormycosis is caused by ubiquitous fungi and encompasses a variety of different opportunistic syndromes in humans that disproportionately affect immunocompromised patients. Mortality has been documented to range between 50 and 100%; however, location of infection greatly dictates likelihood of survival. Treatment of mucormycosis involves aggressive surgical intervention and combination therapy of antifungal agents. In solid organ transplant recipients, immunosuppressive agents used to prevent rejection of the transplanted organ pose additional obstacles in the treatment of invasive fungal infections. We report on 3 high models for end-stage liver disease (MELD-Na) score orthotopic liver transplant (OLT) recipients who all were diagnosed with Rhizopus spp. infections with positive, 1-year outcomes after aggressive, individualized treatment.

Role of Rapid Diagnostics in Diagnosis and Management of Patients With Sepsis.

Delayed administration of active anti-infective therapy is associated with increased rates of adverse events, mortality, and costs among sepsis patients. Inherent limitations of conventional culture identification methods and the lengthy turnaround time of antimicrobial susceptibility testing are significant barriers to the timely delivery of life-saving therapy, particularly among antibiotic-resistant infections. Culture-independent diagnostic techniques that detect pathogens and antimicrobial resistance genes within clinical samples present a tremendous benefit to timely diagnosis and management of patients. Improved outcomes for rapid intervention with rapid diagnostics have been documented and include decreased mortality rates, decreased health care delivery costs, and faster delivery of appropriate therapeutics.