In the present study comparing the quality of care between 2019 and 2020, we observed a negative impact of the COVID-19 pandemic on the appropriate management of SAB in our tertiary care facility.
Importantly, we observed a four times higher number of deaths among SAB patients in 2020 than in 2019 (prepandemic). Although in-hospital mortality in 2020 was not significantly different from that in 2019, it returned to the same level as in the period before the introduction of any intervention in our hospital, 28% in 2015 and 27% in 2016 . In 2017 and 2018, we started to implement the principles of SAB management, with annual in-hospital mortality rates of 16% and 18%, respectively. However, in this period, ID consultations were mostly unsolicited and associated with low adherence. Similar differences in SAB-related mortality were reported before and after the introduction of proper management in several studies: Bai et al.  described a reduction in patient in-hospital mortality from 29 to 21%, López-Cortés et al.  from 18 to 11% (14-day mortality) and Vogel et al.  from 26 to 12% (30-day mortality). The more deaths from SAB observed in our facility in 2020 could have been related to the COVID-19 pandemic because ID specialists had heavy workloads that included providing consultations in all specialized COVID-19 wards (60 beds) and ICUs (22 beds) and directly taking care of oxygen-dependent COVID-19 patients in the ID department (27 beds). This is further supported by the fact that ID consultations were performed during the pandemic year in a significantly lower percentage of SAB patients than in 2019. It is probable that less frequent ID consultations could lead to poorer compliance with the SAB institutional guidelines because several studies have demonstrated that the ID consultation at the bedside is associated with better SAB management and a significant reduction in mortality [1, 3, 7]. In addition, the clinical characteristics of SAB patients were not found to significantly influence their outcomes. However, it is important to consider a potential role of some unmeasured confounding factors.
When we evaluated the overall quality of care in both years by evaluating the monitored QCIs, we found that the procedures were followed for all but two patients in 2019, compared with only 2/3 of the patients in 2020. Similar differences were reported by other authors who compared periods before and after the implementation of SAB institutional guidelines [2, 8, 10, 11]. However, to our knowledge, the direct impact of the COVID-19 pandemic on the quality of care of SAB patients has not been reported in the literature, and only a few studies have evaluated the impact of the COVID-19 pandemic on SAB. Weiner-Lastinger et al. described a higher incidence of MRSA-induced catheter bacteremia in 2020 than in 2019 , and Baker et al. reported increases in catheter-related infection of 60% and MRSA bacteremia of 44% . However, these reports are in contrast with the situation in our facility because the incidence of SAB did not differ between prepandemic and pandemic years.
It is also very important to choose the correct antibiotic therapy for SAB: the first drug of choice for MSSA infections is intravenous oxacillin/cloxacillin and vancomycin for MRSA infection . However, it is no less important to treat SAB with an appropriate duration of antibiotic therapy, which depends on whether the infection is complicated or uncomplicated. Complicated SAB must then be treated with antibiotics for at least 28 days (6 weeks in the case of infectious endocarditis), whereas uncomplicated infection is usually treated for 14 days [1, 8]. In the context of antimicrobial therapy for SAB, it is necessary to stress that 97% of all evaluated patients in both years were treated with appropriate antibiotics for an adequate duration, indicating that the factors related to antimicrobial therapy were not compromised in our facility during the COVID-19 pandemic. The reason is probably the fact that antibiotic therapy was always discussed with the antibiotic centre in collaboration with microbiologists and ID specialists. Moreover, the monitoring of antibiotic levels, including their toxicity, was performed by a clinical pharmacist, which is the standard of care in tertiary care hospitals in the Czech Republic.