Dear Editor,

As a result of routine surveillance in our intensive care unit (ICU), we have noticed an increase over time in the incidence of central line-associated bloodstream infection (CLABSI) in patients with coronavirus disease 2019 (COVID-19). As dexamethasone and interleukin antagonists were later introduced as routine treatment of COVID-19, we performed a retrospective cohort study to explore whether these might be possible risk factors. All patients COVID-19 or non-COVID-19, admitted between January 1st, 2019 and January 1st, 2022 who were treated in our ICU and had at least one central venous line ≥ 48 h, were included. CLABSI was defined according to Centers for Disease Control and Prevention (CDC) guidelines as clinical signs of a central line infection with positive blood culture and positive culture of the catheter tip with more than 15 colony-forming units (CFUs) with the same microorganism in the absence of an alternative diagnosis [1]. Dexamethasone dose was 6 mg daily for 10 days or less if discharged earlier. Patients on long-term steroid treatment were not excluded. Interleukin antagonists (tocilizumab 400 mg or sarilumab 400 mg or anakinra 300 mg) were given within 24 h of admission. Central lines were always inserted using full sterile technique. The need for ethical approval or informed consent was waived.

672 patients were included in this study; 226 had COVID-19. The non-COVID-19 patients had higher Acute Physiology and Chronic Health Evaluation (APACHE) IV scores as compared to COVID-19 patients; hospital mortality was similar (27% vs 30%) (Table 1). The incidence of CLABSI was 1.99/1000 line days in non-COVID-19 patients compared to 6.25/1000 line days in COVID-19 patients. In COVID-19 patients, the incidence of CLABSI was 7.65/1000 line days in patients treated with dexamethasone versus 2.07/1000 without dexamethasone treatment; the latter being comparable to non-COVID-19 patients. At patient level, 4% of COVID-19 patients not treated with dexamethasone developed CLABSI compared to 2% in non-COVID-19 patients. This is most likely attributable to a longer period of ICU stay and central line use in COVID-19 patients. The risk of CLABSI was 13% in the dexamethasone-treated COVID-19 patients. We finally compared COVID-19 patients who only received dexamethasone to patients who received dexamethasone plus an interleukin antagonist with a CLABSI incidence of 7.47/1000 and 7.75/1000 line days and cumulative CLABSI incidence of 13% versus 12% per patient, respectively. Multivariate analysis confirmed dexamethasone treatment and COVID-19 as independent risk factors for CLABSI (Supplementary Table 2).

Table 1 Patient characteristics and results on central line-associated bloodstream infection (CLABSI) in 672 ICU patients with and without COVID-19
Full size table

It is generally accepted that the incidence of nosocomial infections is higher in patients with COVID-19 [2, 3]. Adding interleukin antagonists which have become the mainstay of the treatment of COVID-19 have further raised these concerns [4, 5]. In this study, we found that COVID-19 patients not treated with dexamethasone had a similar incidence of CLABSI compared to non-COVID-19 patients. We found that the risk of CLABSI was significantly increased among COVID-19 patients treated with dexamethasone with or without interleukin antagonists. Our results should be interpreted with caution as this is a small retrospective study, and we were unable to adjust for all potential confounders, like antibiotic use or ventilator-associated pneumonia among others. Nevertheless, we would like to suggest an exploration of the relationship between immunosuppressive drugs and risk of CLABSI in COVID-19 patients in future studies. Possibly, a post hoc analysis could be performed of the randomized controlled trials done with dexamethasone and interleukin antagonists for treatment of COVID-19 patients at ICU.