Unexpectedly High Frequency of Enterococcal Bloodstream Infections in Coronavirus Disease 2019 Patients Admitted to an Italian ICU: An Observational Study

Abstract

Objectives: We aimed to assess the frequency of ICU-acquired bloodstream infections in coronavirus disease 2019 patients.

Design: Retrospective observational study.

Setting: The emergency expansion of an ICU from eight general beds to 30 coronavirus disease 2019 beds.

Participants: Patients with coronavirus disease 2019 admitted to the ICU of Luigi Sacco Hospital (Milan, Italy) for greater than or equal to 48 hours between February 21, 2020, and April 30, 2020.

Interventions: None.

Measurements and main results: The frequency of bloodstream infections per 1,000 days of ICU stay was calculated in 89 coronavirus disease 2019 patients, and the cumulative probability of bloodstream infection was estimated using death and ICU discharge as competing events. Sixty patients (67.4%) experienced at least one of the 93 recorded episodes of bloodstream infection, a frequency of 87 per 1,000 days of ICU stay (95% CI, 67-112).The patients who experienced a bloodstream infection had a higher Sequential Organ Failure Assessment score upon ICU admission (9.5; interquartile range, 8-12 vs 8, interquartile range, 5-10; p = 0.042), a longer median ICU stay (15 d; interquartile range, 11-23 vs 8, interquartile range, 5-12; p < 0.001), and more frequently required invasive mechanical ventilation (98.3% vs 82.8%; p = 0.013) than those who did not. The median time from ICU admission to the first bloodstream infection episode was 10 days. Gram-positive bacteria accounted for 74 episodes (79.6%), with Enterococcus species being the most prevalent (53 episodes, 55.8%). Thirty-two isolates (27.3%) showed multidrug resistance.

Conclusions: Coronavirus disease 2019 seemed to increase the frequency of bloodstream infections (particularly Enterococcus-related bloodstream infection) after ICU admission. This may have been due to enteric involvement in patients with severe coronavirus disease 2019 and/or limitations in controlling the patient-to-patient transmission of infectious agents in extremely challenging circumstances.

Figure 1.

Cumulative frequency of bloodstream infections (BSIs) in critically ill coronavirus disease 2019 patients admitted to the ICU. The continuous line represents the estimated cumulative frequency and the dashed lines the upper and lower 95% CI.

Figure 2.

A, Comparison of the frequency of bloodstream infections (BSIs) between February 21 and April 30 in 2018, 2019, and 2020. B, Comparison of the proportion of first BSI episodes attributable to Enterococcus species in each patient between February 21 and April 30 in 2018, 2019, and 2020. 1000 PDS = 1,000 patient-days of ICU stay, Feb = February, Apr = April. *Frequencies were compared using Poisson regression model. **The proportions of Enterococcus species were compared using the χ² test.

Figure 3.

Molecular characterization of the five vancomycin-resistant Enterococcus faecium strains collected from blood cultures in 2020. The analysis showed a strict genotypic relation between two strains.