[1] Qingdao Univ, Women & Childrens Hosp, Natl Drug Clin Trial Inst, 6 Tongfu Rd, Qingdao, Shandong, Peoples R China
[2] Qingdao Univ, Basic Med Coll, Dept Immunol, 308 Ningxia Rd, Qingdao, Shandong, Peoples R China
[3] Qingdao Municipal Hosp, Dept Hosp Infect Control, 5 Donghai Middle Rd, Qingdao, Shandong, Peoples R China
[4] Qingdao Municipal Hosp, 5 Donghai Middle Rd, Qingdao 266071, Shandong, Peoples R China