鱼类病原菌中R^+质粒的检出及其特性

DETECTION AND PROPERTIES OF TRANSFERABLE R^+ PLASMID IN FISH-PATHOGENIC BACTERIA

本文研究了5个属的15株鱼类病原菌对17种抗菌药物的耐药性。其中，对β-内酰胺类和红霉素的耐药率最高，对妥布霉素最敏感。以E．coliK-12RC85为受体菌，鱼类病原菌为供体菌，采用细菌接合试验，从耐氨苄青霉素、四环素和磺胺的嗜水气单胞菌CJ26株中检测到一株耐四环素和磺胺的可自身传递的R质粒pWH9601。它对四环素的抗性可被四环素类药物所诱导。pWH9601上的耐药基因在供体菌和受体菌中的表达水平有所不同。该质粒可在37℃下，15min内通过接合方式，转移到E．coliK－12RC85中，而且这种转移在12℃的条件下也可进行。

Fifteen strains of fish pathogens were tested for their sensitivity to 17different antibacterial agents and the detected drug resistant strains were investigated todetermine if they possessed R plasmids.These pathogens included A. hydrophila ,Vibrio , E.tarda, Yersinia and Pseudomonas. Most of them were resistant to β-Lactamsand erythromycin. All of tested strains were sensitive to tobramycin. The transferableR plasmid pWH9601 was detected from a strain of A. hydrophila CJ26.The detectedR plasmid showed resistance to tetracycline and sulfonamides. Resistance totetracycline conferred by pWH9601 was inducible in E. coli K-12 after exposure to1.0ug of tetracycline Per ml. This plasmid can transfer tO E. coli K-12 RC85 from A.hydrophila CJ26 within 0.25h at 37℃ by bacterial mating . This transfer can occur at12℃.