Rudy R P, Murray B E
J Infect Dis. 1984 Jul;150(1):25-9. doi: 10.1093/infdis/150.1.25.
A previous study revealed the emergence of high-level resistance to trimethoprim-sulfamethoxazole in strains of Escherichia coli isolated from 95% of students from the United States who were taking either trimethoprim alone or trimethoprim-sulfamethoxazole for prophylaxis of travelers' diarrhea while in Guadalajara, Mexico. Many of these strains were subsequently demonstrated to cotransfer resistance to trimethoprim along with that to streptomycin and ampicillin. The present study demonstrated that at least 12 (60%) of 20 transferable (tra+) trimethoprim-resistance plasmids studied possessed both an identical Hind III restriction pattern and type I dihydrofolate reductase genes. Donor strains were shown to be distinct; this finding suggested that a common tra+ trimethoprim-resistance plasmid was widely disseminated among E. coli strains in Guadalajara. These results may explain in part the surprising degree of resistance encountered in trimethoprim-consuming persons in that region.
先前的一项研究显示，从95%正在墨西哥瓜达拉哈拉的美国学生中分离出的大肠杆菌菌株中出现了对甲氧苄啶-磺胺甲恶唑的高水平耐药性，这些学生单独服用甲氧苄啶或服用甲氧苄啶-磺胺甲恶唑来预防旅行者腹泻。随后证明，其中许多菌株可将对甲氧苄啶的耐药性与对链霉素和氨苄西林的耐药性共同转移。本研究表明，在所研究的20个可转移（tra+）甲氧苄啶耐药质粒中，至少有12个（60%）具有相同的Hind III限制性内切酶图谱和I型二氢叶酸还原酶基因。供体菌株显示是不同的；这一发现表明，一种常见的tra+甲氧苄啶耐药质粒在瓜达拉哈拉的大肠杆菌菌株中广泛传播。这些结果可能部分解释了该地区服用甲氧苄啶的人群中出现的惊人耐药程度。
