NEXT time you succumb to a bladder infection, you might find that your doctor prescribes not only antibiotics but a daily drink of cranberry juice. A new study, reported in the Journal of the American Medical Association, has found that drinking a glass of cranberry juice a day prevents bacteria building up in the urine. The authors of the study have called for further research to see if cranberry juice can improve the outcome when added to antibiotic therapy for urinary tract infections.