鸽源鼠伤寒沙门菌的分离鉴定及致病性分析

Isolation and Identification of Pigeon-derived Salmonella Typhimurium and Pathogenic Analysis

本研究旨在探究广东某地区鸽场沙门菌的系统进化分群、耐药性、耐药基因和毒力基因的携带情况及其致病性,为该地区沙门菌病的防控提供理论依据。试验将72份鸽病变组织样品进行分离纯化以及生化鉴定,通过16S rRNA测序、血清型鉴定、鼠伤寒沙门菌特异性引物PCR鉴定结果判断菌株类型,检测分离菌耐药性、耐药基因、毒力基因,并利用小鼠开展动物致病性试验。结果显示,12株分离菌镜检形态、生化指标、16S rRNA序列比对、血清型鉴定及特异性引物PCR结果均符合鼠伤寒沙门菌特性;耐药结果显示,12株菌对萘啶酸和利福平耐药,对甲氧苄啶、复方新诺明、恩诺沙星、氟苯尼考、氨苄西林、美罗培南高度敏感;15种耐药基因检测结果显示7株菌含有tetA、5株菌含有sul-11,其他耐药基因均未检测出;17种毒力基因检测结果显示,5株菌毒力基因携带率为100%,其余菌株毒力基因携带率也较高;在动物致病性试验中,试验组小鼠体重、采食量显著下降,HE染色观察肝脏枯否细胞数目增加,空肠杯状细胞数目减少,绒隐比下降。综上,本研究分离的12株菌均属于鼠伤寒沙门菌,均出现多重耐药,并且毒力基因携带率较高,动物试验观察到致病菌对动物体器官能够造成较强的炎性损伤,致病性强。建议当地使用甲氧苄啶等高敏感药物治疗鸽沙门菌病,或使用抗生素替代物治疗,定期检测细菌耐药性,及时调整治疗方案。

The aim of this study was to investigate the phylogenetic grouping,drug resistance,virulence and resistance gene carriage and pathogenicity of Salmonella spp.carried by diseased pigeons in a region of Guangdong,and to propose a basis for the prevention and control of Salmonella spp.diseases in the region.In this study,72 samples of diseased pigeon tissues were isolated,purified and identified.We determined the strain type by 16S rRNA sequencing,serotype identification,and PCR identification of Salmonella typhimurium-specific primers,and detected the drug resistance,resistance gene,and virulence genes of isolated bacteria,and carried out animal pathogenicity tests using mice.We found that the morphology,biochemical indexes,16S rRNA sequence ratio,serotype identification and specific primer PCR results of the 12 isolates were consistent with the characteristics of Salmonella typhimurium;Resistance results showed that 12 strains were resistant to nalidixic acid and rifampicin,and highly sensitive to trimethoprim,co-trimoxazole,enrofloxacin,florfenicol,ampicillin,and meropenem;We found that 15 drug resistance gene test results showed that 7 strains contained tetA,5 strains contained sul-11,and other resistance genes were not detected.The results of 17 virulence gene tests showed that the virulence gene carrier rate of 5 strains was 100%,and the virulence gene carrier rate of the remaining strains was also high;In addition,we found that in the animal pathogenicity test,the body weight and feed intake of mice in the experimental group decreased significantly,HE staining observed that the number of liver withered cells increased,the number of jejunal goblet cells decreased,and VH/CD decreased.The 12 strains isolated in this study all belonged to Salmonella typhimurium,all of which showed multi-drug resistance and high virulence gene carrier rate.Animal tests have observed that pathogenic bacteria can cause strong inflammatory damage to animal body organs and are highly pathogenic.We recommend the use of highly sensitive drugs such as trimethoprim for the treatment of salmonellosis in pigeons,or treatment with antibiotic substitutes,regular detection of bacterial resistance,and timely adjustment of treatment regimens.