The prevalence of gram-negative bacteria with difficult-to-treat resistance and utilization of novel ß-lactam antibiotics in the southeastern United States.

Objective: To evaluate temporal trends in the prevalence of gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) in the southeastern United States. Secondary objective was to examine the use of novel ß-lactams for GNB with DTR by both antimicrobial use (AU) and a novel metric of adjusted AU by microbiological burden (am-AU). Design: Retrospective, multicenter, cohort. Setting: Ten hospitals in the southeastern United States. Methods: GNB with DTR including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp. from 2015 to 2020 were tracked at each institution. Cumulative AU of novel ß-lactams including ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilastatin/relebactam, and cefiderocol in days of therapy (DOT) per 1,000 patient-days was calculated. Linear regression was utilized to examine temporal trends in the prevalence of GNB with DTR and cumulative AU of novel ß-lactams. Results: The overall prevalence of GNB with DTR was 0.85% (1,223/143,638) with numerical increase from 0.77% to 1.00% between 2015 and 2020 (P = .06). There was a statistically significant increase in DTR Enterobacterales (0.11% to 0.28%, P = .023) and DTR Acinetobacter spp. (4.2% to 18.8%, P = .002). Cumulative AU of novel ß-lactams was 1.91 ± 1.95 DOT per 1,000 patient-days. When comparing cumulative mean AU and am-AU, there was an increase from 1.91 to 2.36 DOT/1,000 patient-days, with more than half of the hospitals shifting in ranking after adjustment for microbiological burden. Conclusions: The overall prevalence of GNB with DTR and the use of novel ß-lactams remain low. However, the uptrend in the use of novel ß-lactams after adjusting for microbiological burden suggests a higher utilization relative to the prevalence of GNB with DTR.

Clindamycin Plus Vancomycin Versus Linezolid for Treatment of Necrotizing Soft Tissue Infection.

Background: Necrotizing soft tissue infections (NSTIs) are life-threatening infections. The aim of this study is to evaluate the safety of clindamycin plus vancomycin versus linezolid as empiric treatment of NSTIs. Methods: This was a retrospective, single-center, quasi-experimental study of patients admitted from 1 June 2018 to 30 June 2019 (preintervention) and 1 May 2020 to 15 October 2021 (postintervention). Patients who received surgical management within 24 hours of NSTI diagnosis and at least 1 dose of linezolid or clindamycin were included. The primary endpoint was death at 30 days. The secondary outcomes included rates of acute kidney injury (AKI) and Clostridioides difficile infection (CDI). Results: A total of 274 patients were identified by admission diagnosis code for NSTI or Fournier gangrene; 164 patients met the inclusion criteria. Sixty-two matched pairs were evaluated. There was no difference in rates of 30-day mortality (8.06% vs 6.45%; hazard ratio [HR], 1.67 [95% confidence interval {CI}, .32-10.73]; P = .65). There was no difference in CDI (6.45% vs 1.61%; HR, Infinite [Inf], [95% CI, .66-Inf]; P = .07) but more AKI in the preintervention group (9.68% vs 1.61%; HR, 6 [95% CI, .73-276]; P = .05). Conclusions: In this small, retrospective, single-center, quasi-experimental study, there was no difference in 30-day mortality in patients receiving treatment with clindamycin plus vancomycin versus linezolid in combination with standard gram-negative and anaerobic therapy and surgical debridement for the treatment of NSTIs. A composite outcome of death, AKI, or CDI within 30 days was more common in the clindamycin plus vancomycin group.