氮磷营养盐对大肠杆菌四环素耐药性的影响

根据临床和实验室标准协会（clinical and laboratory standards institute， CLSI）推荐的微量肉汤稀释法检测泥样中大肠杆菌对四环素的敏感性，并应用PCR法检测四环素耐药基因tetA，tetB，探讨氮磷营养盐对大肠杆菌四环素耐药性影响的可能机制。结果表明：添加不同剂量氮磷营养盐能够导致大肠杆菌对四环素产生耐药性，但大肠杆菌的耐药率与剂量间无明显相关性。37株高耐药率大肠杆菌tetA基因的阳性率为100%，66株低耐药率大肠杆菌tetA基因的阳性率为16.67%，而16株对药物敏感的大肠杆菌未检测到tetA基因；但供试大肠杆菌均未检测到tetB基因。这表明，氮磷营养盐诱导的大肠杆菌四环素耐药性与tetA基因有关。

Effect of nitrogen and phosphorous on tetracycline resistance of Escherichia coli

In the present study， sensitivity of Escherichia coli strains to tetracycline （TE） was detected by broth micro-dilution method， and tetA， tetB genes of E.coli strains were detected by PCR methods to explore the possible mechanisms. It was shown that addition of different concentrations of nitrogen and phosphorous induced resistance of E.coli to TE. But， there was no significant correction between TE resistance of E. coli and nitrogen or phosphorus dose. For 37 strains with high TE resistance， the detection rate of tetA gene was 100%; for 66 strains with lower TE resistance， the detection rate of tetA gene was 1667%; and no tetA gene was detected in the strains sensitive to TE. Interestingly， no tetB gene was detected in either TE resistant or sensitive E.coli strains， which indicated that tetA gene， other than tetB gene， might be involved in the nitrogen and phosphorus induced TE resistance of E.coli.