Maimonides Evening of Research

Fellow Winner

Jessica Chung, MD, MPH

Department of Medicine, Division of Infectious Diseases

Incidence and Outcomes of Community Onset MethicillinSusceptible Staphylococcus Aureus Bloodstream Infections in the Post-Pandemic Era

Background

Methicillin-susceptible Staphylococcus aureus (MSSA) is a prevalent pathogen linked to significant morbidity and mortality. The CDC reported that the incidence of MSSA bloodstream infections (MSSABSI) significantly increased from 2012 to 2017, although mortality rates were unchanged. The COVID-19 pandemic may affect the incidence and mortality of MSSA-BSI due to the use of dexamethasone, delay in diagnosis because of quarantine, or the misdiagnosis of BSI as COVID-19. Our objective was to compare the incidence and outcomes of community-onset MSSA-BSI pre-and post-COVID-19 pandemic. We conducted a retrospective cohort study on hospitalized patients with community-onset MSSA-BSI, defined as a positive blood culture within 72 hours of the index admission. The study population was divided into the pre-pandemic group (June 1, 2018 to December 31, 2019) and the post-pandemic group (January 1, 2022 to June 30, 2023). Patients with BSI other than MSSA, hospitalization within 30 days, transferred from other facilities, immunosuppression, and incomplete data were excluded. The Whitney Mann U test and chi-square test were used for the analysis.

Material and Methods

The study included 101 patients with MSSA-BSI: 48 in the pre-group, and 53 in the post-group. More than half of the patients were Caucasian males with a median age of 70 and 67 years in the pre-and post-group, respectively. The primary source of MSSA-BSI was skin and soft tissue, followed by respiratory, osteoarticular, and intravascular line-related infections.

Results

The post-group had a higher percentage who delayed seeking medical attention and higher scores on the Charlson Comorbidity Index and Pitt bacteremia score upon presentation. The post-group had a longer median hospital stay compared to the pre-group (10 vs. 7 days), p=0.022. The ICU admission rate and 30-day mortality rate of pre- and post-group were 12.5% vs. 28% and 14.5% vs. 22.6%, respectively. However, neither of these measures were statistically significantly different, p=0.051 and p=0.301 respectively.

Conclusion

Although the number of community-onset MSSA-BSI was similar, the post-group was more likely to delay seeking medical attention and have longer hospital stays. The COVID-19 pandemic has impacted clinical care, leading to delayed medical attention and increasing disease severity. Our study highlights the importance of clinician awareness and patient education on early recognition of MSSA-BSI.