Antimicrobial resistance trends among important clinical pathogens reported from the ARINCQ surveillance of bacterial resistance, 2012-2018: multi-center retrospective surveillance study in Chongqing
Authors: Sun Shan , Tian Xiaolang , Yan Li , Sun Jide , Zhang Chuanming , Xu Xiuyu , Jing Chunmei , Wang Yunying , Chen Wei , Xiong Zhongzheng , Yao Xin , Zhang Minjun , Qi Wen , Wang Renyan , You Shulin , Wu Yong , Zhang Mei , Yu Xiaofeng , Pei Guangde , Fang Juan , Huang Zhongxiu , Zhang Ji , Gao Yuan , Fu Gang , Xie Niqi , Ruan Zhen , Long Wenzhang , Xiong Yuan , Li Lijuan , Chen Lei , Deng Wenping , Ye Xiaoli , Shu Chengfeng , Shen Yan , Niu Siqiang , Huang Shifeng 
Published: April 2020

Background: Data on the Antimicrobial resistance (AMR) trends of the important clinical isolates in southwestern China is lacking. This study was conducted to monitor the temporal AMR trends of the most common pathogens contributing to the majority of human infections.Methods: A multi-center retrospective surveillance study was conducted from 2012 to 2018. Antimicrobial susceptibility testing was carried out according to unified protocols using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2018 definitions. Data from the China Antimicrobial Resistance Surveillance System (CARSS) in Chongqing (ARINCQ) was analyzed by WHONET 5.6 software. Results: The total number of bacterial isolates was between 49,636 and 128,460 annually. While the isolation rate of Acinetobacter baumannii (A. baumannii) presented decreasing trend, that of Staphylococcus aureus (S. aureus) showed increasing tendency. Escherichia coli (E. coli) showed decreasing susceptibility trends to most antibiotics except carbapenems. Resistance rates of Klebsiella pneumoniae (K. pneumonia) to ceftazidime (CAZ), ceftriaxone (CRO), and cefepime (FEP) are decreasing over time. Pseudomonas aeruginosa (P. aeruginosa) and S. aureus demonstrated obvious declining resistance trends to most of the antibiotics tested. Resistance of Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) to high-level gentamycin are decreasing continuously over time. The resistance rate of A. baumannii to meropenem increased from 48.3% to 57.7%. The isolation rate of carbapenem-resistant K. pneumonia (CRKPN) increased annually from 2.6% in 2012 to 6.1% in 2018. For CRKPN, consistent increasing trends in isolation rates were witnessed in both the children and the elderly groups, with its isolation rate in children being obviously higher than that in the elderly group from 2015 to 2018.Conclusions: The prevalence of CRKPN has been significantly increased in both the children and the elderly groups ever since 2012, which calls for continuous resistance surveillance, colonization screening and clearance, environmental monitoring, and effective antimicrobial strategies. While carbapenems are still active against K. pneumonia and E. coli, vancomycin or linezolid is still effective against S. aureus and Enterococcus spp. Notably, this is the first report of an CRKPN isolate co-harboring triple carbapenemase genes including blaKPC-2, blaNDM-1 and blaIMP-4 worldwide. Keywords: antimicrobial resistance, surveillance, multi-center, carbapenems, Southwestern China, carbapenem-resistant K. pneumonia