摘要
目的从污染海域筛选非临床氯霉素耐药株,研究耐药基因定位及耐药机制多样性。方法TCBS和EMB选择平板筛选,结合16SrDNA序列分析鉴定耐药株。MIC测定、基因组DNA-RAPD分型和质粒消除评估多样性。结果评估187株氯霉素耐药株的MIC值分布、属种分布、耐药基因定位及耐药机制。发现80株耐药MIC25～128μg/ml是CLSI/NCCLS(1995年)定义临床标准(MIC12.5μg/ml)的2～10倍,分布在弧菌科和肠杆菌科主要属种;58株MIC>25μg/ml基因组DNA-RAPD分型与菌落表型分组结果吻合,显示多样性丰富。采用多轮高温(～43℃)和高浓度(～1%)SDS双重处理和交替培养,77株MIC>25μg/ml分离株的质粒消除效率为28.6%;55株不能消除耐药表型,暗示染色体编码耐药基因;22株可消除氯霉素耐药表型,其中16株完全消除,暗示质粒独立编码耐药基因,6株部分消除,暗示质粒和染色体分别编码耐药基因。结论来自污染海域环境的非临床氯霉素耐药株可作为新模型,提供耐药基因定位及耐药机制多样性的新视野。
Objective To screen out non-clinical isolates with chloramphenicol resistance from polluted marine environment, and study on the diversities of resistance gene locations and resistance mechanisms. Methods The isolates were screened on TCBS and EMB plates containing 25 μg/ml chloramphenicol, and co-identified by 16S rDNA sequencing and analysis. The diversity of isolates for resistance to chloramphenicol was assayed by determination of MIC values, genomic DNA-RAPD typing, and plasmid elimination. Results The distributions of MIC values, genus and species, locations of chloramphenicol resistance gene and resistance mechanisms of 187 isolates were determined. 80 isolates of them possessed MIC 25 - 128μg/ml up to 2 - 10 times of the standard for clinical isolates of MIC 12.5μg/ml recommended by the CLSI/NCCLS（1995）. These isolates were belonged to typical genera within Vibrionaceae and Enterobacteriaceae. The 58 isolates of them possessing MIC〉25μg/ml had well consistence of genomic DNA-RAPD types with their colony phenotypes showing abundant diversities. By multiple round treatments with high temperature （ -43℃ ） and high concentration - 1% ） of SDS coupled with alternative culture procedures, the rate of plasmid elimination for 77 isolates of MIC〉25μg/ml was only 28.6%. The resistance phenotype of 55 isolates were not eliminated suggesting chromosomal locations of resistance genes. The resistance phenotype of 22 isolates were eliminated, among them, the resistance of 16 isolates were entirely eliminated, suggesting plasmid encoding resistance genes, whereas the other resistance eliminating partially 6 isolates indicated both plasmid and chromosome encoded resistance genes. Conclusion The non-clinical isolates from polluted marine environment with chloramphenicol resistance were unique models to provide new insights into the diversities of resistance gene locations and their resistance mechanisms.
出处
《中国抗生素杂志》
CAS
CSCD
北大核心
2006年第7期437-441,共5页
Chinese Journal of Antibiotics
基金
国家自然科学基金(No.39870579
No.30270064
No.40376046)
广东省自然科学基金(No.031624)
教育部回国留学人员科研启动基金
教育部高等学校骨干教师资助计划
广东省科技计划重点项目(No.2005B20501001)
中山大学测试科学基金
985-II期专项资助项目
关键词
海洋环境
病原细菌
氯霉素
耐药性
基因定位
质粒
消除
Marine environment
Pathogenic bacteria
Chloramphenicol
Antibiotic resistance
Gene location
Plasmid
Elimination
