Zhu Zhen, Shi Yuxiang, Zhou Xuzheng, Li Bing, Zhang Jiyu
Key Laboratory of New Animal Drug Project of Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of the Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS, Jiangouyan, Qilihe District, Lanzhou, 730050, China.
College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, Handan, 056038, China.
BMC Vet Res. 2018 Jun 7;14(1):177. doi: 10.1186/s12917-018-1500-6.
Members of the genus Shigella are intestinal pathogens and a major cause of seasonal outbreaks of bacterial diarrhea worldwide. Although humans are the conventional hosts of Shigella species, expansion of the Shigella host range to certain animals was recently reported. To investigate the prevalence of Shigella sonnei (S. sonnei) in yaks and perform molecular characterization, we analyzed 1132 fresh yak diarrheal stool samples and collected a total of 44 S. sonnei isolates.
We performed multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) with XbaI-digested DNA to study genetic relatedness among the 44 isolates, which were differentiated into 4 sequence types (STs) and 32 PFGE types (PTs). All isolates harbored virulence genes, and 87.36% tested positive for invasion plasmid antigen H (ipaH), invasion associated locus (ial) and the Shigella enterotoxin gene sen. According to the results of antimicrobial susceptibility tests, 45.45% (20/44) were resistant to fluoroquinolones and/or cephalosporin. By sequencing the quinolone resistance determining region (QRDR) genes, we identified double mutations in gyrA (Ser83-Leu and Asp87-Asn) and a single mutation in parC (Ser80-Ile). All 12 fluoroquinolone-resistant S. sonnei isolates tested positive for the aac(6')-Ib-cr gene but negative for qepA. Three isolates harbored qnr genes, including two with qnrS and one with qnrB. In addition, three types of β-lactamase genes, bla , bla and bla , were detected in cephalosporin-resistant isolates.
The findings of this study have enriched our knowledge of fluoroquinolone- and/or cephalosporin-resistant S. sonnei isolates from yaks, which has important public health significance.
志贺氏菌属成员是肠道病原体，是全球细菌性腹泻季节性暴发的主要原因。虽然人类是志贺氏菌属的常规宿主，但最近有报道称志贺氏菌的宿主范围已扩展到某些动物。为了调查牦牛中宋内志贺氏菌（S. sonnei）的流行情况并进行分子特征分析，我们分析了1132份新鲜的牦牛腹泻粪便样本，共收集到44株宋内志贺氏菌分离株。
我们对用XbaI消化的DNA进行多位点序列分型（MLST）和脉冲场凝胶电泳（PFGE），以研究44株分离株之间的遗传相关性，这些分离株被分为4种序列类型（STs）和32种PFGE类型（PTs）。所有分离株都携带毒力基因，87.36%的分离株对侵袭质粒抗原H（ipaH）、侵袭相关位点（ial）和志贺氏菌肠毒素基因sen检测呈阳性。根据抗菌药物敏感性试验结果，45.45%（20/44）对氟喹诺酮类和/或头孢菌素耐药。通过对喹诺酮耐药决定区（QRDR）基因进行测序，我们在gyrA中鉴定出双突变（Ser83-Leu和Asp87-Asn），在parC中鉴定出单突变（Ser80-Ile）。所有12株耐氟喹诺酮的宋内志贺氏菌分离株对aac(6')-Ib-cr基因检测呈阳性，但对qepA检测呈阴性。三株分离株携带qnr基因，其中两株携带qnrS，一株携带qnrB。此外，在耐头孢菌素的分离株中检测到三种β-内酰胺酶基因，bla 、bla 和bla 。
本研究结果丰富了我们对牦牛中耐氟喹诺酮和/或头孢菌素的宋内志贺氏菌分离株的认识，具有重要的公共卫生意义。
