Low-count bacteriuria in refractory idiopathic detrusor overactivity versus controls

Background. Previous studies suggest an association between idiopathic detrusor overactivity (IDO) and high-count bacteriuria (>105 CFU/mL). Recently, the importance of low-count bacteriuria (103–105 CFU/mL) in dysuric women with has been recognised. However, the optimal microbiological threshold for women with overactive bladder (OAB) symptoms remains unclear. Design and Methods A 2-year prospective cohort study, to examine the incidence of low-count and high-count bacteriuria in women with refractory IDO (RIDO) versus a control group without OAB symptoms. Women with dysuria, voiding dysfunction or recent urethral instrumentation were excluded. Mid-stream urine (MSU) specimens were collected during acute symptomatic exacerbation in the IDO group and cultured at the 103 CFU/mL threshold. Statistical analysis was performed using Statsdirect statistical package 2.7.2. Results. Between November 2007 and November 2009, 218 study MSU specimens were collected. Both the overall incidence of any significant bacteriuria ≥103 CFU/mL (P<0.0001) and the incidence of low-count bacteriuria (P=0.0091) were significantly higher in the RIDO women than the controls. There were no baseline differences in age, menopausal status or prior continence surgery between the groups. In the RIDO group, specimens positive for low-count bacteriuria only were less likely to be associated with significant pyuria P<0.0001) and were cultured from younger women (P=0.0009), than specimens positive for high-count bacteriuria. Conclusions The prevalence of bacteriuria in women with RIDO during symptomatic exacerbation is 40%, which is significantly higher than the incidence in similarly-aged women without OAB. One-third of positive cultures show low-count bacteriuria only. The management of women with RIDO should include a search for bacteriuria, including low-count bacteriuria.