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目的初步探究我国非伤寒沙门菌对多粘菌素的耐药情况。方法利用微量肉汤稀释法,测定不同来源404株非伤寒沙门菌对多粘菌素B及多粘菌素E的最小抑菌浓度(MIC),计算耐药率,推测野生沙门菌株的耐药阈值。同时利用聚合酶链式反应(PCR)方法检测菌株携带mcr-1基因的情况。结果 404株沙门菌对多粘菌素B及E的MIC范围为≤0.125μg/ml至>16μg/ml,对多粘菌素B的MIC50、MIC90分别为1μg/ml和8μg/ml;对多粘菌素E的MIC50、MIC90分别为2μg/ml和8μg/ml。优势血清型鼠伤寒沙门菌、肠炎沙门菌及德尔卑沙门菌对多粘菌素B及E的MIC值分布不同。以8μg/ml为耐药阈值判定折点,实验菌株对多粘菌素B及E的耐药率分别为10.89%和15.84%;其中食源性沙门菌、人源性沙门菌及动物源性沙门菌对多粘菌素B的耐药率分别为12.50%、17.16%和0.00%(P<0.01);对多粘菌素E的耐药率分别为8.30%、27.94%和0.78%(P<0.01)。发现7株同时耐多粘菌素及三代头孢的菌株。发现1株人源鼠伤寒沙门菌携带可转移的mcr-1基因,且该菌株产ESBLs。结论发现我国人源产ESBLs的沙门菌携带mcr-1基因。根据体外药敏结果,非伤寒沙门菌对多粘菌素B及E的耐药折点设为8μg/ml较宜。沙门菌对多粘菌素的耐药率尚处于低水平,应加强不同来源沙门菌对多粘菌素的耐药监测。
Objective To investigate the resistance of non-typhoid salmonella to polymyxin in our country. Methods Minimal broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of 404 non-typhoid Salmonella isolates from polygalactin B and polymyxin E, and the drug resistance rate was calculated. Threshold. At the same time, polymerase chain reaction (PCR) method was used to detect the strain carrying mcr-1 gene. Results The MICs of 404 Salmonella strains on polymyxin B and E ranged from 0.125μg / ml to> 16μg / ml, and the MIC50 and MIC90 of polymyxin B were 1μg / ml and 8μg / ml respectively. The MIC50 and MIC90 of colistin E were 2 and 8 μg / ml, respectively. The predominant serotypes Salmonella typhimurium, Salmonella enteritidis and Salmonella delphi had different MIC values for polymyxin B and E. The drug-resistant threshold of 8μg / ml was determined as the breakpoint. The resistance rates of the tested strains to polymyxin B and E were 10.89% and 15.84%, respectively. Among them, foodborne Salmonella, human Salmonella and animal origin The resistance rates of Salmonella to polymyxin B were 12.50%, 17.16% and 0.00%, respectively (P <0.01). The rates of resistance to polymyxin E were 8.30%, 27.94% and 0.78%, respectively <0.01). Seven strains of polymyxin and third generation cephalosporins were found simultaneously. One human Salmonella typhimurium was found to carry the transferable mcr-1 gene, and the strain produced ESBLs. Conclusion It is found that human salmonella ESBLs carrying mcr-1 gene in China. According to in vitro susceptibility results, the non-typhoid Salmonella polymyxin B and E drug-resistant break point set to 8μg / ml is appropriate. Salmonella polymyxin resistance rate is still at a low level, should strengthen the different sources of Salmonella polymyxin resistance monitoring.