[1] Yanan Univ, Affiliated Hosp, Clin Lab, Yanan 716000, Shaanxi, Peoples R China
[2] Xi An Jiao Tong Univ, Hosp 2, Dept Dermatol, Xian 710004, Shaanxi, Peoples R China
[3] Yanan Peoples Hosp, Infect Control Dept, Yanan 716000, Shaanxi, Peoples R China
[4] Yanan Univ, Affiliated Hosp, Dept Geriatr, Yanan 716000, Shaanxi, Peoples R China