RESUMO
The effect of different concentrations of some selected salts, namely, sodium chloride, potassium chloride, ammonium chloride, monosodium dihydrogen phosphate, calcium chloride, dibasic sodium phosphate, sodium sulphate, aluminium chloride and sodium citrate on the antimicrobial activity of nalidixic acid was investigated. It was found that all the salts tested, except aluminium chloride and sodium citrate, exert no antimicrobial activity. The effect of 10% non-ionic surface active agents, namely, Myrj 51, 52, 59, Brij 35, 58, 98, Tween 20, 40, 60, and 80 on the antimicrobial activity of nalidixic acid was studied. The results indicated that the activity of nalidixic acid was decreased in the presence of these surfactants. Furthermore, the effect of different concentrations of sodium chloride on the antimicrobial activity of nalidixic acid-surfactants systems was reported.