Lin Yumeng, Wang Fang, Ma Dexing, Wen Shanshan, Wang Xiaoyan, Yang Jiamei, Guan Zhenhong, Chen Hongyan, Ge Junwei, Zhao Lili
State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun, 130062, China.
College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China.
BMC Vet Res. 2025 May 27;21(1):378. doi: 10.1186/s12917-025-04817-6.
In recent years, rapid fatal hemorrhagic pneumonia (HP) has been increasingly reported in mink. In several studies, the virulence factors of strains isolated from diseased tissues have been identified as extraintestinal pathogenic Escherichia coli (ExPEC). The molecular characteristics of the strains were also analyzed, but whether ExPEC is the etiological agent of HP has not been confirmed in an animal challenge model. In this study, we characterized the antibiotic resistance, virulence characteristics, and pathogenicity of a bacterial strain isolated from a typical case of mink HP, and designated it L1. Our study revealed that isolate L1 has high levels of antibiotic resistance, to multiple antibiotics, including ampicillin, tylosin, kanamycin, and so on. Numerous virulence genes were detected in isolate L1, including those encoding adhesins (focG, afa/draB, mat, crl), invasins (ibeA, einv), and toxin (cnf1). ExPEC isolate L1 belongs to the O121 serogroup and was classified in the B2 phylogroup and sequence type 131 (ST131). Animal experiments showed that L1 is highly pathogenic to mice, and induced fatal HP in mink. A mouse model of isolate L1 infection showed lethargy, depression, and then death. The sick minks showed similar clinical signs and died soon after nasal bleeding and hematemesis, with a large amount of congestion and consolidation in the lungs. Using animal challenge experiments based on Koch's postulates, we demonstrate for the first time that ExPEC is a causative agent of rapid fatal HP in minks. Our research provides important insights into the identification and control of rapid fatal HP in minks and effective antibiotic treatments for infected animals.
近年来，水貂中快速致死性出血性肺炎（HP）的报道日益增多。在多项研究中，从患病组织分离出的菌株的毒力因子已被鉴定为肠外致病性大肠杆菌（ExPEC）。还分析了这些菌株的分子特征，但ExPEC是否为HP的病原体尚未在动物攻毒模型中得到证实。在本研究中，我们对从一例典型水貂HP病例中分离出的一株细菌进行了抗生素耐药性、毒力特征和致病性的鉴定，并将其命名为L1。我们的研究表明，分离株L1对多种抗生素具有高水平的耐药性，包括氨苄青霉素、泰乐菌素、卡那霉素等。在分离株L1中检测到许多毒力基因，包括编码黏附素（focG、afa/draB、mat、crl）、侵袭素（ibeA、einv）和毒素（cnf1）的基因。ExPEC分离株L1属于O121血清群，归类于B2系统发育群和序列型131（ST131）。动物实验表明，L1对小鼠具有高度致病性，并可在水貂中诱发致死性HP。分离株L1感染的小鼠模型表现出嗜睡、抑郁，随后死亡。患病水貂表现出类似的临床症状，在鼻出血和吐血后不久死亡，肺部有大量充血和实变。通过基于科赫法则的动物攻毒实验，我们首次证明ExPEC是水貂快速致死性HP的病原体。我们的研究为水貂快速致死性HP的鉴定和控制以及感染动物的有效抗生素治疗提供了重要见解。
