Evaluation of changes in leukocyte surface markers in the early diagnosis of late neonatal sepsis through flow cytometry

Sepsis is a major cause of newborn morbidity and mortality; thus its diagnosis and treatment are urgent. The final diagnosis is established by demonstrating the growth of bacteria in the blood culture. However, the symptoms and findings of sepsis being nonspecific, the blood culture tests requiring at least 48-72 hours to complete and the possible false negative results, may lead to a difficult diagnosis. Efforts to develop various laboratory methods to establish a faster and definitive diagnosis, are ongoing. In this study, our objective is to evaluate the availability of the changes in leukocyte surface markers in the early diagnosis of late neonatal sepsis through flow cytometry. The study was conducted at Zonguldak Bülent Ecevit University Health Application and Research Center Neonatal Intensive Care Unit between March 2019 - February 2020. Newborns diagnosed with late onset neonatal sepsis cared for at the NICU were included in the study, as patient group. As a control group, inpatient infants monitored at the neonatal service, not showing any findings of infection were included. 22 infants with clinical sepsis as well as 22 infants as a control group were included in the study. Routine investigations required for sepsis investigations were conducted for every patient considered having a diagnosis of sepsis after the initial 72 hours of the life and blood samples were taken prior to starting antibiotic treatment in order to study the leukocyte surface markers. The average gestational week and birth weight in the sepsis group were 30,1±3,7 weeks and 1535±713,2 grams respectively, and the average age was 13,7±8,6 days. There was no significant difference between the two groups in terms of demographic characteristics of the patients. The expressions of leukocyte surface markers CD64, CD63, CD62L, CD16, CD11b from sepsis and control group, expressions of HLA-DR at the onset of sepsis on lymphocytes, monocytes and neutrophils according to the cells in which they were found were evaluated. No statistically significant difference in terms of CD63, CD62L, CD11b, HLA-DR between the sepsis and the control group was observed, but a significant difference in terms of CD16 and CD64 on monocyte and neutrophils was detected. In our study, cut-off, sensitivity, specificity, positive and negative predictive values were respectively; for neutrophil CD64 %53,9, 72%, 91%, 75%, 55%, for monocyte CD64 %73,2, %68, %73, %71, %69, for neutrophil CD16 %81,1, %77, %64, %68, %73, for monocyte CD16 %26,2, %68, %68, %69, %67 was determined. As a result of our study, it was concluded that CD64 and CD16, which are on leukocyte surface markers on neutrophils and monocytes, are useful tests in the early diagnosis of late neonatal sepsis.