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Background: The SARS-CoV-2 omicron variant has been associated with increased transmissibility and less severe disease than the SARS-CoV-2 delta variant. Low rates of secondary infections and excess empiric antimicrobial use were reported early in the pandemic. Comparisons between later variants are not as well documented. We evaluated outcomes for SARS-CoV-2 delta- and omicron-variant surges with emphases on COVID-19–related treatment, secondary infections, and antimicrobial utilization. Methods: A single-center, observational, retrospective study was conducted for SARS-CoV-2–positive patients admitted to our 548-bed community teaching hospital between November and December 2021 (SARS-CoV-2 delta-variant–predominant phase) and January–February 2022 (SARS-CoV-2 omicron-variant–predominant phase). Demographic and outcome data were obtained from the institutional data warehouse and were compared between groups. Secondary infections were defined as positive blood and respiratory culture results during admission, with likely contaminants excluded. Mann-Whitney U tests were used to evaluate continuous variables, and t tests were used to analyze categorical variables. P ≤ .05 was considered statistically significant. Results: In total, 1,297 patients were included: 787 (60.7%) in SARS-CoV-2 delta-variant–predominant phase and 510 (39.3%) in SARS-CoV-2 omicron-variant–predominant phase. Patients in SARS-CoV-2 omicron-variant–predominant phase were more often vaccinated (37.7% vs 55%; P < .001), required lower rates of ICU care (16.0% vs 11.6%; P = .025), and required less intubation (13% vs 6.3%; P < .001). Utilization of remdesivir (51.0% vs 32.2%; P < .001), dexamethasone (70.8% vs 43.3%; P < .001), and tocilizumab or baricitinib (14.5% vs 5.3%; P < .001) decreased during the SARS-CoV-2 omicron-variant–predominant phase. Length of stay (5 days vs 4 days; P < .001) and 30-day mortality also decreased during this period (16.40% vs 9.8%; P = .001). Infectious diseases consultation increased during the SARS-CoV-2 omicron-variant–predominant phase (39.8% vs 45.5%; P = .042). There was no significant difference in patients with positive blood cultures (3.4% vs 1.8%; P = .074), but there was a significant decrease in positive respiratory cultures (5.8% vs 2.7%; P = .009), combining for an overall reduction (8.4% vs 4.1%; P = .003). The incidence of overall antimicrobial use increased during the omicron-predominant phase (36.1% vs 41.8%; P = .04), and duration was lower (5 days vs 4 days; P < .001). Antimicrobial class-specific duration was unchanged, with the exception of decreased gram-positive agents (3 days vs 2 days; P = .012). Conclusions: Our results confirm previous reports of reduced disease severity during the SARS-CoV-2 omicron-variant–predominant period. The incidence of secondary infections decreased, driven by a reduction in respiratory infections. Antimicrobials were used at increased rates and for shorter durations during the SARS-CoV-2 omicron-variant–predominant period. Disclosures: None

Background: COVID-19 is associated with symptoms, clinical findings, and laboratory abnormalities that raise concern for secondary infections. Excess antimicrobial use despite low rates of secondary infections has been reported and presents a continuing challenge for antimicrobial stewardship programs (ASPs), particularly during COVID-19 surges. The objective of this study was to analyze the appropriateness of antimicrobial use in patients with extended antimicrobial therapy during 2 distinct COVID-19 hospital surges. Methods: We conducted an observational, retrospective, cohort study of COVID-19 patients admitted to our 548-bed community teaching hospital between November and December 2021 (ie, the SARS-CoV-2 delta-variant predominant phase) and January–February 2022 (ie, the SARS-CoV-2 omicron-variant predominant phase) and who received antibiotics for >4 days without positive cultures. Demographic and clinical data were obtained from the institutional data warehouse. Infectious diseases–trained researchers evaluated the appropriateness of antimicrobials based on diagnostic and clinical reporting and institutional antimicrobial stewardship guidelines. Patients were considered to have probable secondary bacterial infection if they had 2 of the following symptoms: fever, unexplained leukocytosis, worsening secretions, or hypoxia and/or imaging. The outcomes of interest included confirmed infections and excess antimicrobial days. Categorical and continuous variables were analyzed using χ 2 tests, Fisher exact tests, and Mann-Whitney U tests, respectively. Statistical significance was defined as P ≤ .05. Results: In total, 87 patients were included in the study. Moreover, 56 patients were identified in the SARS-CoV-2 delta-variant predominant phase and 31 patients were identified in the SARS-CoV-2 omicron-variant predominant phase. The groups were similar, with higher vaccination rates in the SARS-CoV-2 omicron-variant predominant group (37.5% vs 64.5%; P = .016). Patients in the SARS-CoV-2 omicron-variant predominant group required less mechanical ventilation (39.3% vs 16.1%; P = .025). There were no significant differences in infectious diseases consultation, immunomodulator or remdesivir use, antimicrobials classes prescribed, or antimicrobial days of therapy or duration between cohorts. There were no significant differences in length of stay, 30-day mortality, or 30-day readmissions. Infections were confirmed in 78.6% in the delta-variant group versus 83.9% in the omicron-variant group ( P = .55). Pneumonias accounted for 60.7% in the delta-variant group and 40.9%, in the omicron-variant group. Excess antibiotic use occurred in 14.3% of patients in the delta-variant group and in 3.1% of patients in the omicron-variant group ( P = .149). There was no significant difference in the duration of inappropriate antimicrobial use between groups in patients without infections: 5 days in the delta-variant group versus 5 days in the omicron-variant group ( P = .24). Conclusions: Results demonstrated that most antimicrobial use was appropriate in a challenging patient population lacking positive cultures to guide therapy. Inappropriate antimicrobial utilization occurred demonstrating continued opportunities for our institutional ASP. Disclosures: None