A Retrospective Single-Centre Study on Healthcare-Associated Infections in Intensive Care Unit Patients with COVID-19, Central Italy, 2020 to 2022

The risk of healthcare associated infections (HAIs) among hospitalized patients increased with the severity of COVID-19 disease and duration of hospitalization, especially in intensive care units (ICUs). This study retrospectively investigated HAI trends between March 2020 and December 2022 in patients with a COVID-19 diagnosis admitted to the exclusive ICU for the management of severe COVID-19 patients in the Molise region, central Italy. The clinical records of patients were anonymously coded and examined for the number of HAIs and microbiological isolations. Only infections that occurred after 48 h of ICU admission were included for descriptive, univariate and multivariate statistical analysis. Over the three-year period, 185 patients with a COVID-19 diagnosis (69.7% male, mean age 66.1 ± 10.6 years) were admitted to the hospital ICU: 50 (27.0%) in 2020, 94 (50.8%) in 2021, and 41 (22.2%) in 2022. During ICU stays, a high proportion of patients required at least one invasive device and died (97.2% and 88.1%, respectively). Death outcome was significantly associated with pre-existing comorbidities and related treatment, sex, and devices. During ICU stays, 80% received antimicrobial therapy, which was further related to death. At least one microbiological HAI was detected in 103 (55.9%) patients (76.6% male, mean age 65.4 ± 9.6 years). HAI incidence differed by year (p < 0.001), occurring in 36 (35.0%) patients in 2020, 54 (52.4%) in 2021, and 13 (12.6%) in 2022, respectively, and 80.6%, 96.0%, and 92.3% of patients died. A total of 268 isolations were observed: 99 (36.9%), 139 (51.9%) and 30 (11.2) in 2020, 2021 and 2022, respectively, and were mostly fungi in 2020 and 2022 (46.5% and 36.7%, respectively), while Gram-negative bacteria predominated in 2021 (36.7%). The study revealed higher HAI rates among patients in 2021 according to the increasing number of COVID-19 cases and related hospitalizations due to the Alpha variant at the local level, but also reflected the national epidemiology, while the decline in 2022 could be likely associated with the pandemic evolution and improvements in the management of COVID-19 patients. These findings further underline a high rate of lethality, more likely attributed to severe COVID-19 in patients with advanced age and underlying diseases, to which HAI onset could have undoubtedly contributed. The study provides useful epidemiological data regarding HAIs among critically ill COVID-19 patients during different phases of the pandemic across three years.