杭州地区多重耐药沙门氏菌的耐药特征

Characteristics and molecular subtyping of multidrug resistant Salmonella in Hangzhou

摘要:

【背景】沙门氏菌是重要的食源性致病菌，其多重耐药现象不容忽视。【目的】分析杭州地区临床来源多重耐药沙门氏菌的耐药特征和感染状况。【方法】利用微量肉汤稀释法对339株沙门氏菌进行14类28种药物的最低抑菌浓度(Minimum Inhibitory Concentration，MIC)测定，对同时耐3类或3类以上药物的多种耐药株进行耐药特征、血清型分布等分析，并对其进行Xba I酶切及脉冲场凝胶电泳(Pulse Field Gel Electrophoresis，PFGE)。【结果】从339株沙门氏菌中检出234株多重耐药株，多重耐药率达69.03%，近3年数据比较结果显示差异无统计学意义(χ2=0.117，P=0.943)；以同时耐4?8类药物的菌株多见，合计占总菌株数的56.93% (193/339)；大部分多重耐药沙门氏菌(199/234，85.04%)同时耐5?13种药物；菌株的耐药模式较为分散，相对优势的耐药谱为AMP-AMS-NAl-STR-SUL (10株，4.27%)和AMP-STR-TET-MIN-DOX-SUL (7株，2.99%)；鼠伤寒单相变种和德尔卑血清型的多重耐药现象较为突出，其多重耐药率分别为97.06% (66/68)和100% (11/11)；234株多重耐药沙门氏菌分为162个PFGE带型，相似度为44.2%?100%，其带型呈散在多态性；PFGE带型相同的菌株，其耐药类别和耐药谱不一定相同，PFGE带型不同的菌株，其耐药类别和耐药谱也可能相同。【结论】杭州地区临床来源沙门氏菌多重耐药现象普遍，但耐药谱分散，耐药表型呈多样性，而且PFGE带型呈散在多态性，与耐药表型也不存在对应关系。其基因组特征和主要食物来源有待于进一步研究。

Abstract:

[Background] Salmonella is one of the most important food-borne pathogens. Its multidrug resistance has attracted more and more attention. [Objective] To analyze the antimicrobial-resistant characteristics and molecular subtyping of multidrug resistant (MDR) Salmonella from clinical sources in Hangzhou, the present study was performed. [Methods] A total of 339 Salmonella isolates from clinical sources were subjected to antimicrobial susceptibility testing and the minimum inhibitory concentration (MIC) was determined. The MDR isolates, which show reduced susceptibility to at least 3 of the 14 antimicrobial categories tested, were analyzed the drug-resistant characteristics, serotype distribution, and the molecular subtyping by pulsed field gel electrophoresis (PFGE). [Results] Among the 339 Salmonella isolates, 234 MDR isolates were found and the MDR rate reached 69.03%. No significant difference was observed in the MDR rate from 2017 to 2019 (χ2=0.117, P=0.943). Isolates resistant to 4?8 antimicrobial categories were most common, accounting for 56.93% (193/339) of the total number of Salmonella isolates. Most of the MDR isolates (199/234, 85.04%) showed resistance to 5?13 antimicrobial agents. The resistance patterns of the MDR isolates were quite diverse, and the relatively dominant patterns were AMP-AMS-NAL-STR-SUL (10, 4.27%) and AMP-STR-TET-MIN-DOX-SUL (7, 2.99%). The level of MDR in Salmonella Derby and monophasic Salmonella Typhimurium was prominent, which MDR rate was 100% (11/11) and 97.06% (66/68), respectively. The 234 MDR Salmonella isolates were subtyped into 162 molecular types by PFGE, with the similarity of 44.2%–100%. The PFGE profiles of the MDR isolates showed high polymorphism and no predominant PFGE profile was found, except for serotype Enteritidis and Typhimurium. For the isolates with identical PFGE profiles, their MDR patterns were either identical or different. For those with different PFGE profiles, the MDR patterns may also be identical. [Conclusion] High level of MDR was observed in Salmonella from clinical sources in Hangzhou, with the MDR patterns being quite diverse, and the PFGE profiles showed high polymorphism. The results showed that the infection of MDR Salmonella in Hangzhou was mainly sporadic. However, the genomic characteristics and the main food origin of MDR Salmonella in Hangzhou need to be further studied.