Serum β2-microglobulin may be a viral biomarker by analyzing children with upper respiratory tract infections and exanthem subitum: a retrospective study

Background Due to the lack of effective and feasible viral biomarkers to distinguish viral infection from bacterial infection, children often receive unnecessary antibiotic treatment. To identify serum β 2-microglobulin that distinguishes bacterial upper respiratory tract infection from viral upper respiratory tract infection and exanthem subitum in children. Methods This retrospective study was conducted from January 1, 2019 to September 30, 2020 in Yancheng Third People’s Hospital. Children with upper respiratory tract infection and exanthem subitum were recruited. The concentration of serum β 2-microglobulin in the viral and bacterial infection groups were statistically analyzed. Results A total of 291 children included 36 with bacterial upper respiratory tract infection (median age, 13 months; 44.4% female), 197 with viral upper respiratory tract infection (median age, 12 months; 43.7% female) and 58 with exanthem subitum (median age, 13 months; 37.9% female). When the concentration of β 2-microglobulin was 2.4mg/L, the sensitivity to distinguish viral from bacterial upper respiratory tract infection was 81.2% (95% CI [75.1–86.4%]), and the specificity was 80.6% (95% CI [64.0–91.8]%). When the cutoff was 2.91 mg/L, the sensitivity of β 2-microglobulin to distinguish exanthem subitum from bacterial upper respiratory tract infection was 94.8% (95% CI [85.6–98.9]%), and the specificity was 100% (95% CI [90.3–100]%). Conclusions Serum β 2-microglobulin may be a significant biological indicator in children with upper respiratory tract infection and exanthem subitum.