Urine pH Value and Bacteriology in Purple Urine Bag Syndrome

Abstract

<b><i>Background:</i></b> Purple urine bag syndrome (PUBS) is an unusual phenomenon in patients with urinary tract infections. The urine of most of these patients has an alkaline pH. <b><i>Objective:</i></b> The goal of this study was to identify infectious bacteria and determine urinary pH in patients with PUBS and to evaluate their correlation. <b><i>Methods:</i></b> PubMed was searched using the term “Purple urine bag syndrome (PUBS)” for studies on this condition published from October 1980 to September 2019. Sixty-seven patients were identified and divided into those with urine cultures positive for Gram-positive bacteria (GPB; <i>n</i> = 3), Gram-negative bacteria (GNB; <i>n</i> = 45), and mixed Gram-positive and Gram-negative bacteria (MGPNB; <i>n</i> = 19). Age, gender, urinary pH, comorbidities (diabetes and uremia), fever, shock, and mortality were compared in the 3 groups. The correlation between urinary pH and type of bacteria in urine cultures was assessed by regression analysis. <b><i>Results:</i></b> Presentation of fever in PUBS accounted for 66.7, 11.1, and 5.3%, <i>p</i> &#x3c; 0.05, in GPB, GNB, and MGPNB. Regression analyses showed that <i>Pseudomonas aeruginosa</i> was associated with less alkaline urine (regression coefficient −0.936, <i>p</i> &#x3c; 0.05), whereas <i>Proteus</i> spp. was associated with more alkaline urine (regression coefficient 0.489, <i>p</i> = 0.04). GNB were the most predominant pathogens in patients with PUBS. <b><i>Conclusion:</i></b> In PUBS, urine pH and symptom presentation are different by variable bacteria. Fever is associated with urinary GPB. <i>Proteus</i> spp. correlates with more alkaline urine, whereas <i>Pseudomonas</i> spp. correlates significantly with less alkaline urine.