Guoye Liu1, Huimin Qian2, Bo Tang3, Yin Chen1, Haiquan Kang4, Fei Jiang4, Ping Ma5, Bing Gu6, Xiang Huo7. 1. Medical Technology School, Xuzhou Medical University, Xuzhou 221004, China. 2. Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China. 3. Nanjing Vazyme Medical Technology Co. Ltd., Nanjing 210046, China. 4. Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221002, China. 5. Medical Technology School, Xuzhou Medical University, Xuzhou 221004, China; Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221002, China. 6. Medical Technology School, Xuzhou Medical University, Xuzhou 221004, China; Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221002, China. Electronic address: gb20031129@163.com. 7. Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China. Electronic address: huox@foxmail.com.
Abstract
OBJECTIVES: The aim of this study was to assess the prevalence of Shigella flexneri resistance to third-generation cephalosporins (3GCs) and to characterise the underlying resistance mechanisms. METHODS: A total of 282 S. flexneri strains isolated in 2013-2015 in Jiangsu Province, China, were identified, serotyped and analysed for their susceptibility to 3GCs. The blaTEM, blaSHV, blaOXA-1-like and blaCTX-M-type extended-spectrum β-lactamase (ESBL) genes were amplified and sequenced by PCR. RESULTS: Of the 282 S. flexneri strains, 97 (34.4%) were resistant to cefotaxime, from which 68 (24.1%) were also resistant to ceftazidime. ESBL genes were detected in 73/97 isolates (75.3%), of which 66/73 (90.4%) showed resistance to 3GCs. Of the 73 ESBL-positive isolates, 32 (43.8%) were positive for CTX-M-1 group (17 for CTX-M-55, 4 for CTX-M-3, 1 for CTX-M-15, 3 for CTX-M-79 and 7 for CTX-M-123), 31 (42.5%) were positive for CTX-M-9 group (29 for CTX-M-14, 1 for CTX-M-24 and 1 for CTX-M-27), 25 (34.2%) were positive for TEM-types (21 for TEM-1 and 4 for TEM-1b) and 1 (1.4%) was positive for SHV-type (SHV-12); none were positive for CTX-M-2 group, CTX-M-8 group and OXA-type. CONCLUSION: ESBLs play an important role in Shigella resistance to 3GCs. CTX-M-14 and CTX-M-55 appeared to be the dominant ESBLs in 13 cities of Jiangsu Province. Therefore, it is time to regularly monitor resistance of S. flexneri to 3GCs and to take appropriate measures to manage this problem.
OBJECTIVES: The aim of this study was to assess the prevalence of Shigella flexneri resistance to third-generation cephalosporins (3GCs) and to characterise the underlying resistance mechanisms. METHODS: A total of 282 S. flexneri strains isolated in 2013-2015 in Jiangsu Province, China, were identified, serotyped and analysed for their susceptibility to 3GCs. The blaTEM, blaSHV, blaOXA-1-like and blaCTX-M-type extended-spectrum β-lactamase (ESBL) genes were amplified and sequenced by PCR. RESULTS: Of the 282 S. flexneri strains, 97 (34.4%) were resistant to cefotaxime, from which 68 (24.1%) were also resistant to ceftazidime. ESBL genes were detected in 73/97 isolates (75.3%), of which 66/73 (90.4%) showed resistance to 3GCs. Of the 73 ESBL-positive isolates, 32 (43.8%) were positive for CTX-M-1 group (17 for CTX-M-55, 4 for CTX-M-3, 1 for CTX-M-15, 3 for CTX-M-79 and 7 for CTX-M-123), 31 (42.5%) were positive for CTX-M-9 group (29 for CTX-M-14, 1 for CTX-M-24 and 1 for CTX-M-27), 25 (34.2%) were positive for TEM-types (21 for TEM-1 and 4 for TEM-1b) and 1 (1.4%) was positive for SHV-type (SHV-12); none were positive for CTX-M-2 group, CTX-M-8 group and OXA-type. CONCLUSION: ESBLs play an important role in Shigella resistance to 3GCs. CTX-M-14 and CTX-M-55 appeared to be the dominant ESBLs in 13 cities of Jiangsu Province. Therefore, it is time to regularly monitor resistance of S. flexneri to 3GCs and to take appropriate measures to manage this problem.