Stokes A, Lacey R W
J Clin Pathol. 1978 Feb;31(2):165-71. doi: 10.1136/jcp.31.2.165.
Thymidine at levels as low as 0.05 mg/1 reduces the activities of sulphamethoxazole and trimethoprim and their combination in vitro. Using a biological assay procedure, levels of thymidine greater than this were interpreted as being present in urine. The addition of sulphamethoxazole and trimethoprim, singly or in combination, to urine obtained from patients with urinary tract infections showed that all the antibacterial effect towards sensitive organisms was due to the trimethoprim component. It is suggested that trimethoprim should replace the combination co-trimoxazole for the treatment of some lower urinary tract infections, and that laboratory media, if they are to resemble the clinical environment, should contain thymidine.
低至0.05毫克/升的胸苷会降低磺胺甲恶唑和甲氧苄啶及其组合在体外的活性。使用生物测定程序，高于此水平的胸苷被解释为存在于尿液中。将磺胺甲恶唑和甲氧苄啶单独或联合添加到从尿路感染患者获得的尿液中，结果表明对敏感菌的所有抗菌作用均归因于甲氧苄啶成分。建议在治疗某些下尿路感染时，甲氧苄啶应取代复方新诺明，并且如果实验室培养基要模拟临床环境，则应含有胸苷。
