广东不同地区葡萄球菌cfr基因的流行性调查

Characterization of the prevalence and distribution of Cfr gene in Staphylococcus isolated from pig farms in Guangdong

编码23SrRNA甲基化酶的cfr是多重耐药基因,它不仅介导细菌对截短侧耳素类药物耐药,而且也影响其他作用于PTC的药物,包括氯霉素类、林可胺类、噁唑烷酮类、链阳菌素A。cfr基因多次在动物及人医临床中分离到的葡萄球菌中发现。为了了解2013年广东省不同地区猪场中葡萄球菌的耐药情况和cfr基因流行情况,探讨耐药菌株克隆传播的可能性。采用PCR检测cfr、gap基因以及16SrRNA基因测序来鉴定葡萄球菌,用琼脂稀释法测定36株cfr基因阳性葡萄球菌对12种抗菌药的敏感性,并经SmaⅠ酶切、PFGE技术来分析菌株之间的亲缘性。结果显示,2013年从猪场采集的样品中分离出1 049株菌株中有36株携带cfr基因的葡萄球菌,分别是2株来源于人的葡萄球菌和34株来源于猪的葡萄球菌,其中19株松鼠葡萄球菌、5株腐生葡萄球菌、4株科氏葡萄球菌、3株阿尔莱葡萄球菌、1株木糖葡萄球菌、1株金黄色葡萄球菌和3株葡萄球菌属,其中23株也携带fex(A)基因。36株cfr基因阳性菌对四环素、氨苄西林、克林霉素、头孢噻呋、氟苯尼考的耐药率分别是83.33%,77.78%,77.78%,75%,75%,对环丙沙星、利奈唑胺相对敏感。PFGE图谱完全相同的菌株有328和371,251和283(其中菌株328和371来自于同一养殖场,菌株328来源于猪的腐生葡萄球菌,菌株371来源于人的腐生葡萄球菌)。2013年广东省不同地区猪场cfr基因检出率为9.15%,36株cfr基因阳性菌对12种兽医临床常用药物耐药较严重,提示人与猪之间存在cfr基因阳性菌株的克隆传播。

The cfr gene encodes an RNA methyltransferase that methylates A2503 in the 23S rRNA and thereby confers combined resistance to phenicols, lineosamides, oxazolidinones, pleuromutilins and streptogramin A. The cfr has been isolated from Staphylococcus of animal and human. In order to investigate the resistance and the characterization of the prevalence and distribution of cfr in Staphylococcus isolated from pig farms in Guangdong and the clonal relateness of the isolates. The qfr,gap, 16S rRNA gene of isolates were tested by polymerase chain reaction （PCR） method and were Slaphylococcus isolates identified by PCR and sequencing. The 36 cfr positive Staphylococcus were characterized by pulsed-field gel electrophoresis（PFGE） after Sinai digestion and drug sus- ceptibility testing. In total,1 049 isolates were collected from samples at ten pig farms,36 cfr-posi- tive isolates were identified as Staphylococcus. In total, 36 cfr-positive Staphylococcus isolates （2 from people, 34 from pig）, of which 19 isolates were identified as Staphylococcus sciuri, 5 as Staphylococcus saprophyticus, 4 as Staphylococcus cohnii ,3 as Staphylococcus arlettae, 3 as un- certained Staphylococcus, 1 as Staphylococcus aureus and 1 as Staphylococcus xylosus, and twenty-three isolates harbour resistance gene rex（A）. There was a high frequency of tetracycline, ampicillin, elindamycin, ceftiofur, florfenicol in 36 tested strains, with the resistance rates of 83.33% ,77.78%, 77. 78%, 75%, 75% respectively, and relatively sensitive to ciprofloxacin, lin- ezolid. Very similar PFGE patterns were isolated from 328 and 371,251 and 283（328 and 371 iso- lates were from the same pig farm, 328 were Staphylococcus saprophyticus islated from pig, 371 were Staphylococcus saprophyticus islated from people ）. In 2013, the cfr-positive rate was 9.15 in pig farms in Guangdong province, the resistance to 12 antimicrobial agents in 36 cfr-positive Staphylococcus was serious, the existing of strains with the same PFGE profiles indicates the clon- al transmission of cfr-possive isolates between human and swines.