2011～2016年广西罗非鱼源无乳链球菌的耐药谱型分析

摘要：【目的】了解廣西罗非鱼源无乳链球菌耐药谱的变迁规律，为罗非鱼无乳链球菌病的有效防控和科学用药提供参考。【方法】采用K-B纸片扩散法对分离自广西南宁、玉林、柳州、河池、北海和百色等市养殖患病罗非鱼的48株无乳链球菌株进行抗生素耐药性分析；并以抗生素的抑菌圈直径为变量，采用SPSS 18.0对无乳链球菌株进行聚类分析，以平方Euclidean距离表示菌株间的耐药性同类关系。【结果】48株广西罗非鱼源无乳链球菌的耐药谱型共有19种，谱型丰富度为39.6%。所有耐药谱型均为多重耐药谱型，耐药种数至少有3种。从采样地点来看，南宁市、玉林市、柳州市、河池市、北海市和百色市的分离株分别包含5、9、8、2、1和2种耐药谱型。2011～2016年各年份的菌株耐药谱型为：2011年10种（A、B、F、J、K、N、O、P、Q和S耐药谱型），2012年4种（B、H、N和S耐药谱型），2013年2种（L和M耐药谱型），2014年3种（B、D和S耐药谱型），2015年9种（B、C、D、E、G、H、J、R和S耐药谱型），2016年3种（B、I和J耐药谱型）。聚类分析将48株广西罗非鱼源无乳链球菌分成2个组群（Group I和Group II）和6个亚群（i～vi），其中Group I和Group II组群均含有11种耐药谱型，耐药谱型丰富度分别为37.9%和57.9%；Group I和Group II两组群无乳链球菌株的抗生素敏感性差异主要取决于其对恩诺沙星、氟苯尼考和环丙沙星的敏感率或耐药率。【结论】2011～2016年广西罗非鱼源无乳链球菌的耐药谱型呈多样性，谱型丰富度较高，且因来源地不同和年际变化存在一定差异性。此外，通过聚类分析可根据无乳链球菌的耐药情况对其进行有效分型，建议作为无乳链球菌流行病学分型方法给予推广应用。

关键词： 罗非鱼；无乳链球菌；耐药谱；聚类分析；广西

中图分类号： S965.125 文献标志码：A 文章编号：2095-1191（2018）05-1023-09

Abstract：【Objective】The study investigated the laws of change of antibiogram types of tilapia Streptococcus agalactiae strains in Guangxi so as to offer reference for effective control and scientific medication of S. agalactiae disease in tilapia. 【Method】The antibiotic resistances of 48 strains of S. agalactiae isolated from diseased tilapia cultured in Nanning， Yulin， Liuzhou， Hechi， Beihai and Baise of Guangxi were tested by K-B disc diffusion method. Clustering of S. agalac-tiae was analysed by SPSS 18.0， using the inhibition zone diameter of antibiotics as a variable. Homogeneous relationship of antibiotics resistance among the strains was indicated by squared Euclidean distance. 【Result】Results showed that 48 strains of tilapia S. agalactiae formed 19 antibiogram types with an antibiogram abundance of 39.6%. All the antibiogram types were multi-resistant patterns and contained at least three kinds of antibiotics to which the strains were resistant. According to the sampling places， isolates from Nanning， Yulin， Liuzhou， Hechi， Beihai and Baise possessed five， nine， eight， two， one and two antibiogram types respectively. The antibiogram types in 2011-2016 were as follows：there were ten kinds of antibiogram types（A， B， F， J， K， N， O， P， Q and S） in 2011， four kinds（B， H， N and S） in 2012， two kinds（L and M） in 2013， three kinds（B， D and S） in 2014， nine kinds（B， C， D， E， G， H， J， R and S） in 2015， and three kinds（B， I and J） in 2016. Cluster analysis showed that 48 strains of tilapia S. agalactiae were clustered into two groups（Group I and Group II） and six subgroups（i-vi）. Groups I and II each contained 11 kinds of antibiogram types with possessed antibiogram abundances of 37.9% and 57.9% respectively. The difference of antibiotics sensitivity of S. agalac-tiae between Group I and Group II mainly depended on the rates of sensitivity or resistance of the strains against eofloxacin， florfenicol and ciprofloxacin. 【Conclusion】The S. agalactiae isolates from tilapia in Guangxi during 2011-2016 display polymorphic antibiogram types with moderately high abundance. The antibiogram types of strains are diverse because of different source places and interannual variation. Besides， the clustering analysis can effectively cluster the S. agalac-tiae strains according to the antibiotics resistances of the isolates. It is recommended that this clustering analysis can be extended and applied as a typing method for epidemiology of S. agalactiae.

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