The antimicrobial susceptibility and contribution of Staphylococcus aureus to surgical site infections in patients hospitalized in the West Pomeranian region (Poland) during the COVID-19 pandemic period – a 3-year follow-up

Abstract Introduction: Surgical site infections (SSIs) are at the fore-front of healthcare-associated infections and the second most common cause of hospital readmission. The etiology of these infections is generally monobacterial with a predominance of Staphylococcus aureus. Although it is a preventable infection it significantly increases the cost of hospitalization and doubles the mortality rate. The aim of the present study was to evaluate the prevalence of SSIs and antimicrobial susceptibility of S. aureus isolated from SSIs in patients hospitalized at the Clinical Hospital No. 1 of the Pomeranian Medical University in Szczecin (Poland) – CH-1 – during the period 2019–2021, in the course of the COVID-19 pandemic. Materials and methods: Analysed specimens were collected from patients with diagnosed skin and soft tissue infections (SSTIs) caused by S. aureus, collected in 2019–2021, and then examined during routine microbiological diagnostics. The collection included specimens from patients hospitalized at CH-1, as well as consulted at the Emergency Department (ED) of CH-1, patients from healthcare facility of the Ministry of Internal Affairs and Administration in Szczecin, and from detain-ees of the Szczecin Detention Centre (Poland). Out of the total of 1140 results, 232 were classified as SSIs caused by S. aureus and then analysed. All the data were systemically entered into a spreadsheet (Excel 2019) and later subjected to several statistical tests (using StatSoft Statistica 13 package). Results: From the collection of results, 20.4% (232/1140) were considered as SSIs of S. aureus etiology. In the following years 2019, 2020, and 2021, the SSIs of S. aureus etiology were 17.1% (72/421), 19.5% (66/339), and 24.7% (94/380), respectively. Methicillin-resistant S. aureus (MRSA) was the cause of 7% of analysed SSIs. The highest incidence of SSIs was observed mainly in patients admitted to the trauma and orthopaedic wards and in patients seen in the ED. The majority of SSIs were mono-etiologic, caused by S. aureus only (93%). Mixed etiology was determined in 7% of SSIs with a significant share of beta hemolytic streptococci, enterobacteria, and non-fermentative Gram-negative rods. A slight increase in the prevalence of SSIs was observed during the analysed period. The overall antimicrobial susceptibility of all examined strains was noted, with a low rate of MRSA. The obtained results demonstrate the good practice of both strategies of hospital infection control, as well as the coherent and rational antibiotic policy in the CH-1 in the West Pomeranian region in Poland. The 2017–2018 data on the incidence of SSTIs and the percentage of SSIs among patients hospitalized in CH-1 show that in 2017, SSIs represented 17.9% of all cases classified as SSTIs (57/318), followed by SSIs in 2018, which represented 19.5% of all SSTIs analysed in CH-1 (68/348). The percentage of SSIs among the total SSTIs confirmed during the 2-year pre-pandemic period did not indicate significant changes in the number of SSIs among CH-1 patients hospitalized during the period of analysis. Therefore, it can be concluded that pandemic restrictions did not significantly affect the trend in the predominant proportion of S. aureus among SSIs during the study period.