Kikuvi G M, Schwarz S, Ombui J N, Mitema E S, Kehrenberg C
Institute of Tropical Medicine and Infectious Diseases, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
Microb Drug Resist. 2007 Spring;13(1):62-8. doi: 10.1089/mdr.2006.9998.
The aims of this study were to determine the genetic basis of streptomycin and chloramphenicol resistance in 30 Escherichia coli isolates from food animals in Kenya and the role of plasmids in the spread of the resistance. Seven of the 29 streptomycin-resistant isolates harbored both the strA and strB genes. Twenty-one of isolates had the strA, strB, and aadA1 genes. The strA gene was disrupted by a functional trimethoprim gene, dfrA14 in 10 of the 21 isolates harboring the three streptomycin resistance genes. Physical linkage of intact strA and sul2 genes was found in two different plasmids from four isolates. Linkage of cassette-borne aadA1 and dfrA1 genes in class 1 integrons was found in two of the isolates. Chloramphenicol resistance was due to the gene catA1 in all the chloramphenicol resistant isolates. The strB, strA, and catA1 genes were transferable by conjugation and this points to the significance of conjugative resistance plasmids in the spread and persistence of streptomycin and chloramphenicol resistance in food animals in Kenya.
本研究的目的是确定肯尼亚从食用动物中分离出的30株大肠杆菌对链霉素和氯霉素耐药的遗传基础，以及质粒在耐药性传播中的作用。29株链霉素耐药菌株中有7株同时携带strA和strB基因。21株菌株含有strA、strB和aadA1基因。在携带三种链霉素耐药基因的21株菌株中的10株中，strA基因被功能性甲氧苄啶基因dfrA14破坏。在来自4株菌株的两种不同质粒中发现完整的strA和sul2基因存在物理连锁。在其中两株菌株中发现1类整合子中盒式携带的aadA1和dfrA1基因存在连锁。所有氯霉素耐药菌株的氯霉素耐药性均归因于catA1基因。strB、strA和catA1基因可通过接合转移，这表明接合耐药质粒在肯尼亚食用动物中链霉素和氯霉素耐药性的传播和持续存在具有重要意义。
