Evaluation of biomarkers in the early diagnosis of bloodstream infections

Bloodstream infection (BSI) is a serious clinical condition with high morbidity and mortality rates, requiring early diagnosis and treatment. The blood culture method, which is considered the gold standard for definitive diagnosis, has some limitations such as long turnaround time, contamination risk and false negativity. Therefore, there is a need for rapid, specific and easy-to-apply biomarkers that can aid in the diagnosis of BSI. In this study, it was aimed to investigate the diagnostic performances of inflammatory and cell surface markers such as PCT, CRP, IL-6, TREM-1, CALPR, CAR, NLR, CD11b, CD14, CD64, and CD69 in the prediction of BSI. The study included 180 patients with suspected BSI who underwent simultaneously routine PCT, CRP, albumin, and complete blood count analysis and blood culture sampling. Blood culture bottles were incubated in the Render BC128 automated system, and the isolated agents were identified using the BD Phoenix 100 and BioFire FilmArray multiplex PCR system. IL-6, TREM-1 and CALPR levels were determined using the ELISA method, and CD11b, CD14, CD64, and CD69 levels were determined using the BD FACSCanto II flow cytometry analyzer. Of the hemoculture positive patients (n=130), gram-negative bacteria were isolated in 50, gram-positive bacteria in 50, and yeast fungi in 30 patients. A statistically significant difference was found in terms of PCT, CRP, IL-6, TREM-1, CALPR, RDW, MPV, NLR, LMR, CAR, MHR, nCD11b %/MFI, mCD11b %/MFI, nCD14 %/MFI, mCD14 %/MFI, nCD64 %/MFI, mCD64 %/MFI, nCD69 MFI, mCD69 %/MFI levels between the hemoculture positive and hemoculture negative (n=50) patient groups (p<0.05). A statistically significant positive correlation was observed between PCT, CAR, CRP, NLR, nCD14 MFI, nCD64%, mCD69%, and nCD64 MFI and between IL-6 and CALPR (p<0.05). According to ROC analysis, PCT, CRP, IL-6, TREM-1, CALPR, CAR, NLR, nCD11b %/MFI, mCD11b MFI, nCD14 %/MFI, mCD14 MFI, nCD64 %/MFI, mCD64 %/MFI, mCD69 %/MFI were found to have high AUC values ​​(>0.700) (p<0.05). In conclusion, PCT, CRP, IL-6, TREM-1, CALPR, CAR, NLR together with nCD11b, mCD11b, nCD14, mCD14, nCD64, mCD64 and mCD69 levels can be used as additional tests to support blood culture results in the prediction of BSI.