The role of tumor necrosis factor- related apoptosis inducing ligand, interferon-gamma inducible protein and myxovirüs resistance protein in differentiation of acute community- acquired viral and bacterial lower respiratory tract infections.

Objective: Acute lower respiratory tract infection (LRTI) is a common disease in children which is one of the most important causes of morbidity and mortality in childhood. The aim of this study is to prevent unnecessary or inappropriate use of antibiotics, side effect and resistance thus reducing the development of cost by determining the location of TRAIL, IP-10 and MxA protein markers in the differentiation of viral and bacterial LRTIs in patients hospitalized for acute community-acquired LRTI. Material and Method: A total of 56 patients, aged between one month and 18 years, who were admitted to the pediatric services with the diagnosis of community-acquired LRTI between January 2019 and January 2020, were included in our prospective and single-center study, considering the exclusion criteria (immunodeficiency, malignancy, underlying disease, known chronic disease, malnutrition and obesity, history of antibiotic or antiviral therapy within the last month). The control group included 28 children who had no evidence of infection, no known chronic disease, malignancy or immune deficiency until two weeks prior to admission. The demographic and clinical characteristics of all patients included in the study were recorded in the patient follow-up form. When taking venous blood samples for hemogram, peripheral smear, biochemistry, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin and blood culture, additionally blood sample for TRAIL, IP-10 and MxA protein markers into a hemogram tube has been taken. Swab samples were taken from nasal and nasopharyngeal mucosa to determine viral etiology. The patients were divided into two groups as bacterial (28 patients) and viral LRTI (28 patients) according to their history, physical examination, laboratory and imaging findings. Levels of MxA, TRAIL and IP-10 markers were investigated in serum samples with Enzyme Linked Immunosorbent Assay (ELISA) method. Result: In our study, the agent was detected in 76.7% of the patients with viral and bacterial LRTI. While the causative agent was detected in whole viral LRTI group, it was found in 53.5% of the bacterial LRTI group. Streptococcus pneumoniae and Mycoplasma pneumoniae were the most common bacterial agents, whereas respiratory syncytial virüs (RSV) and rhinovirüs were the most common viral agents. High serum levels of MxA, TRAIL and IP-10 markers, which are among the laboratory markers that distinguish viral LRTI from bacterial LRTI, were found to have diagnostic value. Among these three biomarkers, it was observed that MxA had higher sensitivity and specificity than TRAIL and IP-10 markers in predicting viral LRTI. Neutrophil-lymphocyte ratio (NLR), CRP and sedimentation were found more significant in predicting bacterial infections. Among these, the best diagnostic test for bacterial LRTI was NLR. Conclusion: This is the first study in the literature evaluating MxA, TRAIL and IP-10 markers together in distinguishing viral LRTI from bacterial LRTI. MxA, TRAIL and IP-10 markers in the viral LRTI group were found statistically significant higher than the control group and the bacterial LRTI group. In the differentiation of viral and bacterial LRTIs, high MxA, TRAIL and IP-10 values and low CRP and NLO will make a significant contribution to the determination of viral LRTI. With the routine use of this markers for viral LRTIs, unnecessary or inappropriate antibiotic use can be prevented, side effect rate and resistance development can be reduced.