Pathogens in Urine from a Female Patient with Overactive Bladder Syndrome Detected by Culture-independent High Throughput Sequencing: A Case Report

Abstract

Introduction: Overactive bladder syndrome (OAB) is described as urgency, with or without urgency incontinence. A range of medical conditions shares the symptoms of OAB, however the diagnosis is contingent on the exclusion of urinary tract infection (UTI). Knowing that urine dipstick and routine culture of bacteria can miss UTI diagnosis caused by low-count bacteriuria or "difficult-to-culture" pathogens, we examined a case of OAB with a culture-independent approach.

Case presentation: A 61-year-old Norwegian female with a long history of urinary symptoms and a diagnosis of OAB was selected as a suitable subject for a culture-independent 16S rDNA analysis on the patient´s urine. The patient's medical records showed no history of recurrent UTI, however, when the urine specimen was sent to routine culture at the time of study it showed a significant bacteriuria caused by a single bacterium, and the patient was prescribed antibiotics. The 16S rDNA analysis revealed not one, but many different bacteria, including a considerable amount of fastidious bacteria, indicating a polymicrobial state. One year later, the subject was still experiencing severe symptoms, and a follow-up analysis was performed. This time the urine-culture was negative, however, the 16S rDNA profile was quite similar to that of the first sample, again displaying a complex bacterial profile.

Conclusion: The use of 16S rDNA pyrosequencing and sequence analysis to uncover "difficult-to-culture" bacteria should be considered when examining patients with chronic urinary symptoms. These methods may contribute to further elucidation of the etiology of overactive bladder syndrome and other urinary syndromes.

Keywords: 16S rDNA; amplicon; high throughput sequencing; microbiome; overactive bladder (OAB); urine..

Fig. (1)

Taxonomical classification of 16S rDNA found in reported samples. A and B: Tree view of 16S rDNA sequences from culture-positive urine (α-hemolytic Streptococcus >10⁵ CFU/ml), assigned at different taxonomy levels (family, genus and species) as computed by MEGAN 3.4 for V1V2 (A) and V6 (B) amplicons. Each circle represents a taxon and is labeled by its name and the number of sequenced reads assigned. Taxonomical assignment was done by comparing the sequences to a curated version of the SSUrdp database, then assigning the sequences to the taxon of the best-matched reference sequence (lowest common ancestor). The size of the circles is scaled logarithmically to the number of reads assigned to the taxon. C and D: Comparison of bacterial communities from culture-positive urine positive for α-hemolytic green Streptococcus (red bars) and culture-negative urine (blue bars) from a case subject diagnosed with overactive bladder syndrome. Sequence analysis is based on V1V2 (C) and V6 (D) amplicons. Only major genera with a sequence abundance ≥10 % for either V1V2 or V6 analysis are shown. The calculation of sequence abundance for each genus was relative to the total number of sequence assigned to Bacteria in each dataset.