大熊猫粪源大肠杆菌耐药性及整合子研究
Antimicrobial Resistance and Integrons of Escherichia coli Isolates from Giant Pandas Feces

中文摘要：为了解大熊猫粪源大肠杆菌的耐药性、整合子-基因盒的分布特性,分析整合子对细菌耐药性的影响,采用Kirby-Bauer(K-B)纸片法进行了50株大肠杆菌对13种抗菌药物的药物敏感性试验;PCR-测序法检测了1、2、3型整合酶基因,进一步对阳性菌株可变区的基因盒序列鉴定分析。结果显示,菌株对13种抗菌药物表现出不同的耐药性,其中对氨苄西林、头孢唑林、四环素和复方新诺明表现出较高耐药性(耐药率为30%~68%),对其余药物耐药性较低(耐药率低于14%);50株菌中有15株(30%)含有1型整合子,未发现2型和3型整合子;15株1型整合子阳性菌中,有6株(40%)扩增出1200~2000 bp的基因盒,主要介导氨基糖苷类和磺胺-甲氧苄啶耐药的 aadA和 dfrA基因家族。以 dfrA27+ aadA2为主(检出率83.33%),1株为 aacA4+ aadA1+ catB2。以上说明本次检测的大熊猫粪源大肠杆菌对多种抗菌药物呈低水平耐药;1型整合子在大肠杆菌中广泛分布,整合子-基因盒是造成整合子阳性菌株耐氨基糖苷类、磺胺-甲氧苄啶类、氯霉素的主要原因。
英文摘要：To investigate the antimicrobial resistance, distribution of integron-gene cassettes of Escherichia coli that isolated from the feces of giant pandas, as well as determine the correlation between resistance and integron-gene cassette, Kirby-Bauer method was used to test the susceptibility of 50 E. coli isolates against 13 antimicrobial agents. PCR-sequencing was established to detect the integrons (class 1, 2, 3) and gene cassettes that were harbored in E. coli isolates. The results showed that the isolates had different resistant levels to the 13 tested antimicrobials: high resistant level was observed in ampicillin, cefazolin, tetracycline and SMZ-TMP (resistant rates ranged from 30% to 68%); 30% of the isolates were found to harbor the class 1 integron, and no class 2 or class 3 integron was detected; gene cassettes with length of 1200-2000 bp were amplified from 40% of the 15 intI1-positive isolates, and the main resistant gens were identified as encoding aminoglycoside adenyltransferase ( aadA) and dihydrofolate reductase ( dfrA). The main arrays of gene cassettes were dfrA27+ aadA2 (detection rate was 83.33%), moreover, 1 isolate was found to harbor the gene cassettes aacA4+ aadA1+ catB2 discovered. In conclusion, the E. coli isolates from the feces of giant pandas were sensitive to majority of the tested antimicrobial agents. Class l integron was widely distributed in E. coli strains from giant pandas, and integron-gene cassettes were responsible for resistant to aminoglycosides, sulfonamides-TMP and chloramphenicol. 2015,34(4): 489-493 收稿日期：2014-11-22 DOI：10.11984/j.issn.1000-7083.2015.04.002 分类号：Q93 基金项目：国家科技支撑计划项目(2012BAC01B06) 作者简介：闫国栋(1988—),男,硕士研究生,主要从事细菌耐药性及耐药机制研究,E-mail:guodong0973@163.com *通讯作者：林居纯,教授,博士,硕士研究生导师,主要从事兽医药理及毒理学研究,E-mail:juchunlin@126.com 参考文献： 冯银, 陈体, 伍勇. 2013. 整合子介导细菌耐药调控机制的研究进展[J]. 国际检验医学杂志, 34(10): 1260-1263. 李蓓, 李旭林, 郭丽娟, 等. 2012. 大熊猫大肠杆菌的分离鉴定和耐药性分析[J]. 西南农业学报, 25(3): 1109-1113. 林居纯, 陈雅莉, 曹三杰, 等. 2011. 食品动物源大肠杆菌多重耐药菌株整合子-基因盒的分子特征[J]. 畜牧兽医学报, 42(1): 77-81. 林居纯, 舒刚, 张辉建, 等. 2014. 健康畜禽肠道大肠杆菌耐药性及整合子-基因盒检测[J]. 中国兽医学报, 34(1): 56-62.