Assessing Clinician Utilization of Next-Generation Antibiotics Against Resistant Gram-Negative Infections in U.S. Hospitals : A Retrospective Cohort Study.

BACKGROUND: The U.S. antibiotic market failure has threatened future innovation and supply. Understanding when and why clinicians underutilize recently approved gram-negative antibiotics might help prioritize the patient in future antibiotic development and potential market entry rewards. OBJECTIVE: To determine use patterns of recently U.S. Food and Drug Administration (FDA)-approved gram-negative antibiotics (ceftazidime-avibactam, ceftolozane-tazobactam, meropenem-vaborbactam, plazomicin, eravacycline, imipenem-relebactam-cilastatin, and cefiderocol) and identify factors associated with their preferential use (over traditional generic agents) in patients with gram-negative infections due to pathogens displaying difficult-to-treat resistance (DTR; that is, resistance to all first-line antibiotics). DESIGN: Retrospective cohort. SETTING: 619 U.S. hospitals. PARTICIPANTS: Adult inpatients. MEASUREMENTS: Quarterly percentage change in antibiotic use was calculated using weighted linear regression. Machine learning selected candidate variables, and mixed models identified factors associated with new (vs. traditional) antibiotic use in DTR infections. RESULTS: Between quarter 1 of 2016 and quarter 2 of 2021, ceftolozane-tazobactam (approved 2014) and ceftazidime-avibactam (2015) predominated new antibiotic usage whereas subsequently approved gram-negative antibiotics saw relatively sluggish uptake. Among gram-negative infection hospitalizations, 0.7% (2551 [2631 episodes] of 362 142) displayed DTR pathogens. Patients were treated exclusively using traditional agents in 1091 of 2631 DTR episodes (41.5%), including "reserve" antibiotics such as polymyxins, aminoglycosides, and tigecycline in 865 of 1091 episodes (79.3%). Patients with bacteremia and chronic diseases had greater adjusted probabilities and those with do-not-resuscitate status, acute liver failure, and Acinetobacter baumannii complex and other nonpseudomonal nonfermenter pathogens had lower adjusted probabilities of receiving newer (vs. traditional) antibiotics for DTR infections, respectively. Availability of susceptibility testing for new antibiotics increased probability of usage. LIMITATION: Residual confounding. CONCLUSION: Despite FDA approval of 7 next-generation gram-negative antibiotics between 2014 and 2019, clinicians still frequently treat resistant gram-negative infections with older, generic antibiotics with suboptimal safety-efficacy profiles. Future antibiotics with innovative mechanisms targeting untapped pathogen niches, widely available susceptibility testing, and evidence demonstrating improved outcomes in resistant infections might enhance utilization. PRIMARY FUNDING SOURCE: U.S. Food and Drug Administration; NIH Intramural Research Program.

Association between minimum inhibitory concentration values and mortality risk in patients with Stenotrophomonas maltophilia infections: a retrospective cohort study of electronic health records from 148 US hospitals.

Background: Clinical data informing antimicrobial susceptibility breakpoints for Stenotrophomonas maltophilia infections are lacking. We sought to leverage real-world data to identify MIC values within the currently defined susceptible range that could discriminate mortality risk for patients with S. maltophilia infections and guide future breakpoint revisions. Methods: Inpatients with S. maltophilia infection who received single-agent targeted therapy with levofloxacin or trimethoprim/sulfamethoxazole were identified in the Cerner HealthFacts electronic health record database. Encounters were restricted to those with MIC values reported to be in the susceptible range for both agents. Curation for exact (non-range) MIC values yielded sequentially granular model populations. Logistic regression was used to calculate adjusted OR (aOR) of mortality or hospice discharge associated with different susceptible-range MICs, controlling for patient- and centre-related factors, and infection site, polymicrobial infection and receipt of empirical therapy. Results: Seventy-three of 851 levofloxacin-treated patients had levofloxacin MIC of exactly 2 mg/L (current Clinical and Laboratory Standards Institute (CLSI) susceptibility breakpoint) and served as the reference category for levofloxacin breakpoint models. In breakpoint model I (n = 501), aOR of mortality associated with infection due to isolates with levofloxacin MIC of ≤1 versus 2 mg/L were similar [aOR = 1.79 (95% CI 0.88-3.62), P = 0.11]. In breakpoint model IIa (n = 358), aOR of mortality associated with MIC ≤0.5 versus 2 mg/L were also similar [aOR 0.1.36 (95% CI 0.65-2.83), P = 0.41]. However, breakpoint model IIb (n = 297) displayed higher aOR of mortality associated with an MIC of 1 versus 2 mg/L [aOR 2.36 (95% CI 1.14-4.88), P = 0.02]. Only 9/645 trimethoprim/sulfamethoxazole-treated patients had trimethoprim/sulfamethoxazole MIC of exactly 2/38 mg/L precluding informative models for this agent. Conclusions: In this retrospective study of real-world patients with S. maltophilia infection, risk-adjusted survival data do not appear to stratify patients clinically within current susceptible-range MIC breakpoint for levofloxacin (≤2 mg/L) by mortality.

Vaccination Ameliorates Cellular Inflammatory Responses in SARS-CoV-2 Breakthrough Infections.

BACKGROUND: Data on cellular immune responses in persons with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection following vaccination are limited. The evaluation of these patients with SARS-CoV-2 breakthrough infections may provide insight into how vaccinations limit the escalation of deleterious host inflammatory responses. METHODS: We conducted a prospective study of peripheral blood cellular immune responses to SARS-CoV-2 infection in 21 vaccinated patients, all with mild disease, and 97 unvaccinated patients stratified based on disease severity. RESULTS: We enrolled 118 persons (aged 50 years [SD 14.5 years], 52 women) with SARS-CoV-2 infection. Compared to unvaccinated patients, vaccinated patients with breakthrough infections had a higher percentage of antigen-presenting monocytes (HLA-DR+), mature monocytes (CD83+), functionally competent T cells (CD127+), and mature neutrophils (CD10+); and lower percentages of activated T cells (CD38+), activated neutrophils (CD64+), and immature B cells (CD127+CD19+). These differences widened with increased disease severity in unvaccinated patients. Longitudinal analysis showed that cellular activation decreased over time but persisted in unvaccinated patients with mild disease at 8-month follow-up. CONCLUSIONS: Patients with SARS-CoV-2 breakthrough infections exhibit cellular immune responses that limit the progression of inflammatory responses and suggest mechanisms by which vaccination limits disease severity. These data may have implications for developing more effective vaccines and therapies. Clinical Trials Registration. NCT04401449.

Trimethoprim-Sulfamethoxazole Versus Levofloxacin for Stenotrophomonas maltophilia Infections: A Retrospective Comparative Effectiveness Study of Electronic Health Records from 154 US Hospitals.

BACKGROUND: Trimethoprim-sulfamethoxazole (TMP-SMX) is considered first-line therapy for Stenotrophomonas maltophilia infections based on observational data from small studies. Levofloxacin has emerged as a popular alternative due to tolerability concerns related to TMP-SMX. Data comparing levofloxacin to TMP-SMX as targeted therapy are lacking. METHODS: Adult inpatient encounters January 2005 through December 2017 with growth of S maltophilia in blood and/or lower respiratory cultures were identified in the Cerner Healthfacts database. Patients included received targeted therapy with either levofloxacin or TMP-SMX. Overlap weighting was used followed by downstream weighted regression. The primary outcome was adjusted odds ratio (aOR) for in-hospital mortality or discharge to hospice. The secondary outcome was number of days from index S maltophilia culture to hospital discharge. RESULTS: Among 1581 patients with S maltophilia infections, levofloxacin (n = 823) displayed statistically similar mortality risk (aOR, 0.76 [95% confidence interval {CI}, .58-1.01]; P = .06) compared to TMP-SMX (n = 758). Levofloxacin (vs TMP-SMX) use was associated with a lower aOR of death in patients with lower respiratory tract infection (n = 1452) (aOR, 0.73 [95% CI, .54-.98]; P = .03) and if initiated empirically (n = 89) (aOR, 0.16 [95% CI, .03-.95]; P = .04). The levofloxacin cohort had fewer hospital days between index culture collection and discharge (weighted median [interquartile range], 7 [4-13] vs 9 [6-16] days; P < .0001). CONCLUSIONS: Based on observational evidence, levofloxacin is a reasonable alternative to TMP-SMX for the treatment of bloodstream and lower respiratory tract infections caused by S maltophilia.

Structure-based design of N-substituted 1-hydroxy-4-sulfamoyl-2-naphthoates as selective inhibitors of the Mcl-1 oncoprotein.

Structure-based drug design was utilized to develop novel, 1-hydroxy-2-naphthoate-based small-molecule inhibitors of Mcl-1. Ligand design was driven by exploiting a salt bridge with R263 and interactions with the p2 pocket of the protein. Significantly, target molecules were accessed in just two synthetic steps, suggesting further optimization will require minimal synthetic effort. Molecular modeling using the Site-Identification by Ligand Competitive Saturation (SILCS) approach was used to qualitatively direct ligand design as well as develop quantitative models for inhibitor binding affinity to Mcl-1 and the Bcl-2 relative Bcl-xL as well as for the specificity of binding to the two proteins. Results indicated hydrophobic interactions in the p2 pocket dominated affinity of the most favourable binding ligand (3bl: Ki = 31 nM). Compounds were up to 19-fold selective for Mcl-1 over Bcl-xL. Selectivity of the inhibitors was driven by interactions with the deeper p2 pocket in Mcl-1 versus Bcl-xL. The SILCS-based SAR of the present compounds represents the foundation for the development of Mcl-1 specific inhibitors with the potential to treat a wide range of solid tumours and hematological cancers, including acute myeloid leukemia.