耐氟喹诺酮类药物的大肠埃希菌gyr A 基因点突变检测

目的：研究大肠埃希菌对氟喹诺酮类药物的耐药机制。方法：对大肠埃希菌标准菌４４３０２和临床收集的３株对氟喹诺酮类药物高度耐药的大肠埃希菌及１株敏感菌，用ＰＣＲ方法扩增ＤＮＡ旋转酶ｇｙｒＡ基因的Ｎ末端编码区，并进行克隆和序列测定。结果：对氟喹诺酮类药物高度耐药的大肠埃希菌的ｇｙｒＡ基因的序列分析，发现３个导致氨基酸改变的基因点突变：丝氨酸－８３→亮氨酸；丙氨酸－８４→脯氨酸；天冬氨酸－８７→天冬酰氨。结论：对氟喹诺酮类药物高度耐药的大肠埃希菌的ＤＮＡ旋转酶Ａ亚单位存在着基因点突变。

结核分枝杆菌耐氟喹诺酮类药物的严重性及其特点

上世纪80年代发现氟喹诺酮类药物（FQs）具有抗结核分枝杆菌活性以来，FQs被逐渐用于结核病的治疗之中，今天FQs已不仅仅是治疗耐多药结核病（MDR-TB）的主选化疗药物，多耐药结核病（PDR—TB）和单耐药结核病也在使用FQs，国际上甚至研究将FQs用于新发或初治肺结核患者的治疗，以期缩短疗程，增加患者的依从性，提高治愈率，从根源上控制或减少耐药结核病的发生。

Study of isolation of fluoroquinolone-resistant Ureaplasma urealyticum and identification of mutant sites

OBJECTIVE: To study the resistance mechanism of clinical isolates of Ureaplasma urealyticum resistant to fluoroquinolones. METHODS: Thirteen isolates of Ureaplasma urealyticum resistant to six fluoroquinolones were selected out of 184 clinical isolates and their QRDRs (quinolone resistance-determining region) gyrA, gyrB, parC and parE were amplified by PCR. Sequencing results were compared to those susceptible reference strains and a comparison of deduced amino acid sequences were performed. RESULTS: Sequence comparison revealed a C to A change at 87nt of gyrA QRDR leading to the substitution of Asp95 with glutamic acid and a C to T change at 50nt of parC QRDR leading to the substitution of Ser80 with leucine. CONCLUSION: These results suggest that a C to A change at 87nt of gyrA QRDR and a C to T change at 50nt of parC QRDR are associated with fluoroquinolone resistance of Ureaplasma urealyticum.