Correlation of plasma procalcitonin and C-reactive protein levels with disease severity in critically ill patients with mixed-pathogen bloodstream infections of both Enterococcus spp. and Candida spp.

Background: Antibiotic overuse and increase of rates of invasive treatments, the incidence of bloodstream infections (BSIs) caused by mixed-pathogens (fungi and bacteria) has been on the rise. This retrospective observational study investigated the clinical significance of inflammatory biomarkers in predicting prognosis of critically ill patients with mixed-BSIs due to Enterococcus spp. and Candida spp. Methods: : Patients who were admitted to intensive care unit (ICU) from January 2018 to December 2020 were included. Of the total 66 enrolled patients, 35 and 31 patients were assigned to mixed- (fungi and bacteria) and single- (bacteria only) pathogen BSI groups, respectively. On the one hand, we compared the diffferences in plasma procalcitonin (PCT) and C-reactive protein (CRP) levels and disease severity (including Acute Physiology and Chronic Health Evaluation [APACHE] II scores, ICU stay duration, and 30-day mortality) between these two groups. On the other hand, their correlations with disease severity were also analysed. Results: : The plasma CRP levels in the mixed-pathogen BSI group was higher than that in the single-pathogen BSI group; the same trend was observed for the disease severity. In the Spearman’s rank correlation analysis, plasma CRP levels were positively correlated with disease severity in the mixed-pathogen BSI group. Further, plasma PCT levels were also positively correlated with APACHE II scores and ICU stay duration. In contrast, in the single-pathogen BSI group, plasma PCT levels were positively correlated with APACHE II scores only, whereas plasma CRP levels did not correlate positively with 30-day mortality. Conclusions: : In summary, mixed-pathogen BSIs caused by Enterococcus spp. and Candida spp. lead to higher plasma PCT and CRP levels in comparison to BSI caused by Enterococcus spp. only, thereby resulting in a higher disease severity in critically ill ICU admitted patients.