Objective: To evaluate the antimicrobial resistance of non-O157 Shiga toxin-producing Escherichia coli (STEC) isolated from human cases. Methods: From 2011 to 2019, 33 non-O157 STEC strains recovered from diarrheal patients from 7 provinces/cities were collected, including Qinghai (1 isolate), Heilongjiang (1 isolate), Guangxi (2 isolates), Shandong (2 isolates), Guangdong (4 isolates), Henan (11 isolates), and Shanghai (12 isolates). Minimum inhibitory concentration (MIC) of 19 antimicrobials were tested by broth microdilution method; O∶H serotypes, Multi-locus sequence typing (MLST) and antimicrobial resistance genes were determined by whole genome sequencing. Results: A total of 33 non-O157 STEC strains were typed into 19 O∶H serotypes and 17 sequence types (STs), respectively. Ten strains were resistant to one or more antibiotics,of which five were multiple drug-resistant (MDR). The resistance rate of tetracycline was 30.3% (10 isolates), and azithromycin resistant strains were detected (12.12%, 4 isolates), but all strains were susceptible to carbapenems. All strains carried the blaEC gene, and the Extended-Spectrum β-Lactamase (ESBL) genotype blaCTX-M-15 were detected (3.0%, 1 isolates). The fosA7 gene was firstly detected in non-O157 STEC strains. Conclusion: MDR, azithromycin resistance, and multiple drug resistance genes were detected in human-derived non-O157 STECs in many regions in China, but they were all susceptible to carbapenems. Our results might guide the clinical treatment of STEC infections.
目的： 了解人源非O157产志贺毒素大肠埃希菌（STEC）抗生素耐药表型及耐药基因携带状况。 方法： 33株非O157 STEC菌株来自2011—2019年7个省份，包括青海、黑龙江（各1例），广西、山东（各2例），广东（4例），河南（11例），上海（12例），均分离自感染性腹泻患者粪便标本。采用改良微量肉汤法对非O157 STEC进行19种抗生素最小抑菌浓度（MIC）检测；通过全基因组测序进行O∶H血清分型、多位点序列分型（MLST）及耐药相关基因预测。 结果： 33株非O157 STEC分为19种O∶H血清型、17种MLST序列型；10株菌对1种或以上抗生素耐药，5株为多重耐药菌株，对四环素耐药率最高（30.3%，10株），并检出阿奇霉素耐药菌株（12.1%，4株），但所有菌株均对碳青霉烯类药物敏感；共检出22种耐药基因，全部菌株均携带blaEC基因，并检出超广谱β-内酰胺酶（ESBL）基因型blaCTX-M-15（3.0%，1株），首次检出fosA7基因。 结论： 中国7省份33株人源非O157 STEC中存在多重耐药和阿奇霉素耐药菌株，且携带多种耐药基因型，但均对碳青霉烯类药物敏感。.