鸭疫里默氏杆菌耐药基因传播方式的鉴定及分布

Transmission ways and distribution of antibiotic resistance genes in Riemerella anatipestifer

摘要:

【目的】 鸭疫里默氏杆菌(Riemerella anatipestifer, RA)是一种感染鸭、鹅等禽类的革兰氏阴性病原菌。该菌的临床分离株具有多重耐药性，且其耐药性呈现逐年增加的趋势，但关于这些耐药基因在该菌的传播方式尚未被明确鉴定。本研究旨在鉴定耐药基因在鸭疫里默氏杆菌的传播方式，以及这些耐药基因在该菌临床分离株中的分布情况。【方法】 测定参考菌株RA ATCC 11845、临床分离株RA CH-1、RA CH-2对10类28种药物的耐药表型；通过基因组分析和基因缺失株的构建鉴定耐药基因；自然转化实验鉴定其耐药基因传播方式；通过PCR检测这些耐药基因在不同临床菌株的分布情况。【结果】 耐药检测结果表明，鸭疫里默氏杆菌RA CH-1株、RA CH-2株对β-内酰胺类、四环素类、大环内酯类、林可胺类及酰胺醇类等药物均具有耐药性，而RA ATCC 11845株对以上药物敏感；13个耐药基因分别缺失后对相关药物变得敏感，表明其参与耐药；以上耐药基因均可通过自然转化方式转移至敏感菌株RA ATCC 11845；相关耐药基因在2017-2023年分离的100株临床株的检出率最低为3%，最高为89%。【结论】 耐药基因在鸭疫里默氏杆菌可通过自然转化的形式进行传播，不同耐药基因在该菌临床分离株中的分布不同，其中tet(X) (B739_0030)耐药基因携带率最高，bla_OXA (G148_1768)耐药基因携带率最低。

Abstract:

[Objective] Riemerella anatipestifer (RA) is a Gram-negative bacterium that mainly infects domesticated birds such as ducks and geese. The clinical isolates of RA are multi-drug resistant and increasing year by year. However, the transmission ways of antibiotic resistance genes in RA have not been identified. This study aims to identify the transmission ways and distribution of antibiotic resistance genes in the clinical isolates of RA. [Methods] The drug resistance phenotypes of the reference strain RA ATCC 11845 and the clinical isolates RA CH-1 and RA CH-2 to 28 antibiotics belonging to 10 categories were determined. The antibiotic resistance genes were identified by genome analysis and construction of gene deletion strains. The transmission ways of antibiotic resistance genes were identified by natural transformation. The distribution of these resistance genes in different clinical isolates was detected by PCR. [Results] RA CH-1 and RA CH-2 were resistant to β-lactams, tetracyclines, macrolides, lincosamides, and amide alcohols, while RA ATCC 11845 was sensitive to the above antibiotics. The resistant strains became sensitive to the corresponding antibiotics after the deletion of 13 resistance genes, respectively, indicating that these genes were involved in antibiotic resistance. All the resistant genes can be transferred to the sensitive strain RA ATCC 11845 by natural transformation. The detection rates of resistance genes in 100 clinical isolates from 2017 to 2023 varied within the range of 3% to 89%. [Conclusion] Antibiotic resistance genes can be transmitted in RA through natural transformation, and different antibiotic resistance genes presented varied distribution in clinical isolates, among which tetX (B739_0030) and bla_OXA (G148_1768) were carried by the most and fewest strains, respectively.