Changes of Klebsiella pneumoniae infection and carbapenem resistance in ICU elderly infected patients before and after the COVID-19 pandemic in Zhengzhou, China. Issue 3 (March 2023) - Ding, Xianfei; Liang, Huoyan; Qi, Xueyan; Sun, Guiying; Cheng, Ming; Feng, Min; Sun, Tongwen