Thymidine and the Assessment of Co-Trimoxazole Action in Liquid Media

Summary

Thymidine and thymine contents in human blood and urine seem to be too low to interfere with the bactericidal activity of co-trimoxazole, (sulphamethoxazole/trimethoprim), observed in vitro in thymidine-free media. Most of the commercially available liquid media contain high thymidine concentrations which prevent a bactericidal action and are not suitable for testing purposes. Although the addition of 5% lysed blood converts the thymidine in those media very effectively into thymine, many media remain unsatisfactory since the relatively high thymine concentrations generated also antagonize a bactericidal action.