Antimicrobial resistance in urinary tract infections.

In this investigation Gram negative bacilli resistant to two or more antibiotics were isolated from 120 individuals with urinary tract infection. Antibiotic sensitivity patterns were determined by the Kirby-Bauer paper disc method and by an agar-plate-dilution method capable of measuring the minimum inhibitory concentration at the level of antibiotic attainable in the renal interstitium and urine. The results have shown that with selected antibiotics up to 75 percent of the isolates resistant by standard disc procedures are sensitive at concentrations of antibiotic readily attainable in the urine. The implications of these results in relation to the therapy of urinary tract infection have been discussed and evidence presented that the determination of the minimum inhibitory concentration of selected antibiotics may be of considerable value in the management of urinary tract infections.