Different bacterial and fungal infections detected in SARS-CoV-2-positive and SARS-CoV-2-negative patients admitted to intensive care units

Background COVID-19 is a severe global health issue caused by SARS-CoV-2, which results in respiratory illness. Severe cases, that may cause death, often require intubation and mechanical ventilation. The use of these invasive methods leads in many cases to bacterial co-infection. This study compared the distribution of the bacterial and fungal infections detected from patients admitted to intensive care units (ICU) of a tertiarycare hospital located in the epidemic area of Northern Italy (Parma) during the first SARS-CoV-2 Italian pandemic wave (27 February to 10 May 2020), taking also into account SARS-CoV-2 detection, with that of the same period of 2019. Methods Three-hundred-one lower respiratory tract samples belonging to 154 patients with clinical suspicion of respiratory infections and examined for the detection of SARSCoV-2-RNA, bacteria and/or fungi, were included in the study. The data available from 107 lower respiratory samples belonging to 84 patients admitted to ICU in the same period of 2019 were used for comparison. Results During 2020, among the 154 patients, 90 (58.4%) were SARS-CoV-2-positive. Bacterial infection was more frequently detected among SARS-CoV-2 negatives (p=0.0001) and fungal infection among the SARS-CoV-2 positives (p=0.0053). Among SARS-CoV-2 positives, Candida albicans (36), Enterococcus faecalis (11) and Klebsiella pneumoniae (4) were the most frequently isolated agents, whereas among SARS-CoV-2 negatives, Candida albicans (17), Staphylococcus aureus (13) and Pseudomonas aeuginosa (7) were the most frequently isolated. In the same period of 2019, S. aureus (27), C. albicans (22), Escherichia coli (20), P. aeuginosa (15) and K. pneumoniae (14) were the most frequently isolated. Conclusions This study highlighted that, between the two patient categories admitted to ICU during the first SARS-CoV-2 pandemic wave, C. albicans was the most prevalent agent detected (36+17), mainly among SARS-CoV-2 positives, in comparison to 2019 (22). With regard to bacteria, E. faecalis was mainly involved in co-infection among SARS-CoV-2 positives and S. aureus among SARS-CoV-2 negatives. A bacterial distribution similar to that found in SARS-CoV-2 negatives was observed in the same period of 2019, when S. aureus (27) was the first agent detected. The different therapies in SARS-CoV2 positives could have influenced these different patterns of infectious agents.