Effect of Combined Therapy on Emergence of Drug Resistant Bacteria in Urinary Tract Infections: Observations on Origin of Resistant Strains

Abstract

A previous study revealed that in vitro the emergence of resistance to streptomycin could be inhibited by the combined use of streptomycin, penicillin and sulfadiazine. The clinical and bacteriological effects of these drugs were detd. on 37 patients with urinary tract infections. Following therapy, sterile urine cultures were obtained in 16 cases, 14 of which were uncomplicated urinary tract infections. Therapy was bacteriologically unsuccessful in 21 cases, 19 of which were characterized by some complication. In these 19 cases, bacteria resistant to all 3 drugs regularly emerged. A study of resistant strains in the urine and feces of 7 patients strongly indicated that many of the resistant strains in the urine had their origins in the fecal flora of the patient. Good clinical response was obtained in virtually all of the cases in spite of persistent bacillurias. Patients under therapy showed no evidence of toxicity due to the combined use of the 3 drugs. Efforts to remove the source of obstruction or complication must be made in order for combined therapy to be of any permanent value.