[Purple urine bag syndrome (PUBS) associated with strong alkaline urine].

Mechanisms for purple discoloration of the plastic urine bag in purple urine bag syndrome (PUBS) were investigated. Activities of bacterial indoxyl sulfatase catalyzing the conversion of indoxyl sulfate to indigo (or indirubin) were detected in strong alkaline liquid media but not in normal ones. These enzyme activities were particularly high in simple and combined cultures of Proteus mirabilis and/or Klebsiella pneumoniae. These results suggest that occurrence of PUBS is associated with strong alkaline urine as well as urinary tract infections induced by some species of bacteria with indoxyl sulfatase.