Erythromycin and alkalinisation of the urine in the treatment of urinary tract infections due to gram negative bacilli.

In an alkaline medium, the in vitro antibacterial activity of erythromycin is increased and its spectrum expanded. In an attempt to determine whether this in vitro effect could be translated into a useful therapeutic effect in vivo, 37 patients with chronic bacteriuria were treated with erythromycin estolate and alkalinization of the urine. The infecting gram negative bacteria were eradicated in 732 of the patients during therapy, and urine cultures remained negative 3 wk after treatment in 17 patients. In further follow up, 14 of these 17 patients had negative urine cultures 2-6 mth after treatment. Erythromycin and alkalinization of the urine is suggested as an alternative therapy for selected patients with urinary tract infections.