目的  调查分析目前国内常见养殖淡水鱼类肠道菌群对不同抗生素的耐药性现状。方法  选取两种常见养殖淡水鱼类的粪便标本，分别在添加了7种抗生素〔青霉素G、头孢呋辛钠、庆大霉素、环丙沙星、四环素、红霉素和复方新诺明（SMZ）﹞的琼脂平板上进行培养，通过PCR法分析所获得的耐药菌株的16S rRNA基因序列并对其种属进行鉴定。采用χ²检验作两种鱼之间的比较。结果  筛选后共得到2956株耐药菌，对青霉素G、头孢呋辛钠、四环素、SMZ、庆大霉素、红霉素和环丙沙星的平均耐药率分别为8.89%、1.57%、0.28%、0.06%、0.08%、0.07% 和0.11%。用单纯随机法挑选71株耐药菌，培养鉴定后其主要组成为：气单胞菌31株（43.66%）、不动杆菌8株（11.27%）、假单胞菌6株（8.45%）、金黄杆菌6株（8.45%）。两种鱼肠道菌群对青霉素G、头孢呋辛钠、SMZ、红霉素和四环素的耐药水平差异有统计学意义（χ²值为129.06、212.54、7.76、8.62 和35.40,P值均<0.05）。结论 通过获得两种常见养殖淡水鱼类肠道菌群对7种抗生素（青霉素G、头孢呋辛钠、庆大霉素、环丙沙星、四环素、红霉素和SMZ）的耐药率，为今后进一步研究和追踪常见淡水鱼肠道菌群耐药率的变化提供了基础。

 Objective  To study the different antibiotic resistance of the intestinal flora in domestic species of freshwater fish.  Methods  The fecal specimens were collected from two species of freshwater fish, and were cultured on agar-plate containing 7 kinds of antibiotics (penicilin G, cefuroxime sodium, gentamicin, ciprofloxacin, tetracycline, erythromycin and SMZ) for the antibiotic susceptibility test. PCR was applied on the results to analyse the 16S rRNA gene sequence of resistant strains and identify their species. Х² test was adopt in the comparison between the two fish.  Results  2956 drug-resistant isolates were screened from all of the samples. The rates of resistance to  penicilin G, cefuroxime sodium, gentamicin, ciprofloxacin, tetracycline, erythromycin and SMZ were 8.89%, 1.57%, 0.08% , 0.11% , 0.28% , 0.07% and 0.06%, respectively. The results of identification showed that the main components of the 71 strains selected by simple random method were 31 strains of Aeromonas （43.66%）, 8 strains of Acinetobacter （11.27%）, 6 strains of Pseudomonas（8.45%）and 6 strains of Chryseobacterium（8.45%）.There were statistically significant differences in the rates of resistance to  penicilin G, cefuroxime sodium, SMZ, erythromycin and tetracycline between the two kinds of fish (Х2=129.06,212.54,7.76,8.62 and 35.40,P<0.05).  Conclusions  The rates of resistance to penicilin G, cefuroxime sodium, gentamicin,  ciprofoxacin, tetracycline, erythromycin of the intestinal flora in domestic species of freshwater fish we obtained can provide foundation for us to do some research and pursue the changes of the antibiotic resistance rates of the intestinal flora in domestic species of freshwater fish in future.