1. Department of General Surgery, Liaocheng People's Hospital, Liaocheng, Shandong 252000, P.R. China
2. Department of General Surgery, The Third People's Hospital of Liaocheng, Liaocheng, Shandong 252000, P.R. China
3. Department of Operating Rooms, Shayang People's Hospital, Shayang, Hubei 448200, P.R. China
4. Department of General Surgery, The Second People's Hospital of Jingmen, Jingmen, Hubei 448000, P.R. China
5. Department of Infectious Disease, Tai'an Central Hospital, Tai'an, Shandong 271000, P.R. China