福建省漳州市罗非鱼无乳链球菌分离鉴定及毒力基因和耐药性研究

doi:10.16431/j.cnki.1671-7236.2022.09.039

摘要/Abstract

摘要： 【目的】明确福建漳州地区罗非鱼无乳链球菌临床分离株的血清型、毒力基因携带情况与耐药特性，为鱼源无乳链球菌研究提供新的数据。【方法】于福建省漳州市部分罗非鱼养殖场采集疑似无乳链球菌感染的病鱼样品，通过分离培养、形态观察及生化试验初步分离鉴定病原菌。经由16S rDNA特异性片段引物、16S rDNA通用引物进行PCR鉴定及测序比对鉴定分离株。用PCR方法检测分离株血清型及4个主要毒力基因（cylE、sodA、gapC和scpB基因）分布情况。通过纸片扩散法对分离菌株进行11大类共29种抗菌药物的药敏试验，并进行多重耐药分析。【结果】分离株菌落呈白色圆形、边缘整齐、表面光滑湿润，呈β溶血；革兰染色阳性，菌体排列为长短不一的链状，单个或成对存在；VP试验、CAMP均为阳性，触酶试验阴性，能发酵海藻糖，均符合无乳链球菌的典型特征，经鉴定共分离获得14株鱼源无乳链球菌。14株分离菌株的血清型均为Ⅰa型。分离株毒力基因cylE、sodA、gapC的检出率均为100%，而毒力基因scpB均未检出。分离菌株对磺胺异噁唑、庆大霉素、卡那霉素耐药率均为100%，对链霉素、新霉素、甲氧胺嘧啶耐药率均>70%。分离株均为多重耐药菌株，6重及以上耐药的菌株占总分离菌株数的78.57%。【结论】本研究明确了当前福建漳州地区罗非鱼源无乳链球菌的血清型、毒力基因和耐药特性，为进一步研究鱼源无乳链球菌的致病机理和临床有效防控措施提供参考。

关键词: 无乳链球菌; 血清型; 毒力基因; 耐药性

Abstract: 【Objective】 The purpose of this study was to clarify the serotype, virulence gene carrier and drug resistance characteristics of clinical isolates of Streptococcus agalactiae (S.agalactiae) from tilapia in Zhangzhou, Fujian, and to provide new data for the study of S.agalactiae from fish.【Method】 Samples of diseased fish suspected of S.agalactiae infection were collected from some tilapia farms in Zhangzhou city, Fujian province.The isolates were identified by PCR identification and sequencing alignment through 16S rDNA-specific fragment primers and 16S rDNA universal primers.The serotypes of the isolates and the distribution of four major virulence genes (cylE, sodA, gapC and scpB genes) were detected by PCR.The susceptibility tests of 29 kinds of antibiotics in 11 categories was tested by disk diffusion method, and the multi drug resistance was analyzed.【Result】 The isolated colonies were white and round, with neat edges, smooth and wet surface, and showed β-hemolysis.Gram staining was positive, and the bacteria were arranged in chains of different lengths, single or in pairs.VP test and CAMP were positive, and enzyme contact test was negative, it could ferment trehalose, which accorded with the typical characteristics of S.agalactis.A total of 14 fish-derived S.agalactiae were isolated and identified.The serotypes of the 14 isolated strains were all type Ⅰa.The detection rates of virulence genes cylE, sodA and gapC were all 100%, but none of the virulence gene scpB was detected.The resistance rates of the isolated strains to sulfisoxazole, gentamicin and kanamycin were all 100%, and the resistance rates to streptomycin, neomycin and methotrexate were all more than 70%.The isolates were all multi-drug-resistant strains, and 78.57% of the strains were resistant to more than 6 kinds of drugs.【Conclusion】 This study clarified the serotype, virulence gene and drug resistance characteristics of tilapia S.agalactis in Zhangzhou, so as to provide reference for further study on the pathogenic mechanism and effective clinical prevention and control measures of S.agalactis in tilapia.

Key words: Streptococcus agalactiae; serotype; virulence gene; antibiotic resistance

中图分类号:

S852.61⁺1

袁橙, 陈怀君, 袁圣, 温华茂, 陈智怡, 董洪燕, 封琦, 郭长明. 福建省漳州市罗非鱼无乳链球菌分离鉴定及毒力基因和耐药性研究[J]. 中国畜牧兽医, 2022, 49(9): 3655-3664.

YUAN Cheng, CHEN Huaijun, YUAN Sheng, WEN Huamao, CHEN Zhiyi, DONG Hongyan, FENG Qi, GUO Changming. Isolation, Identification and Study on Virulence Gene and Drug Resistance of Streptococcus agalactiae from Tilapia in Zhangzhou City, Fujian Province[J]. China Animal Husbandry and Veterinary Medicine, 2022, 49(9): 3655-3664.

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