Purple urine bag syndrome: a perplexing finding in a urethral catheter related urinary tract infection

Abstract

The appearance of purple coloured urine within the Urethral Catheter-Urine Bag system is often frightening to patients and their relatives and gets health care givers perplexed. The purple colour is said to be a by-product of chemical transformation of indole to indigo or indirubin, or a mixture of the two. Both Indigo and Indirubin are derivatives of colonic bacterial metabolism of dietary Tryptophan using either the Sulphatase or Phosphate enzymes or both. It is seen in chronically ill patients with chronic constipation and on long standing urethral catheterisation. The organisms commonly cultured from such purplish urine are Escherichia coli, proteus mirabilis, klebsiella pneumoniae and Enterobacter species. We reported such a case in a 98-year old paraplegic male patient with a histologically proven metastatic prostate adenocarcinoma and chronic constipation. The urine and catheter tip culture yielded klebsiella specie. We wrote to draw attention to its occurrence and highlight a simple method of its treatment.