Patients with overactive bladder (OAB) symptoms and pyuria benefited from six to nine months of antibiotics, researchers reported in Glasgow, Scotland, at the 41st annual meeting of the International Continence Society.
"There is a growing body of evidence that identifies a group of patients who, despite presenting with negative routine urinalyses, appear to have an infection or an inflammatory process at the heart of the cause of their overactive bladder symptoms," Dr Kiren Gill, of University College London, UK, told Reuters Health. "We think about half of patients with OAB may have bacteria in their urine."
Dr Gill and his team conducted an observational study of 440 patients (380 females and 60 males; mean age, 54) with OAB between 2003- 2010.
They divided patients into three groups. Group 1, with 147 patients, had pyuria and were treated from the start with antibiotics, primarily nitrofurantoin (100 mg bid) or cephalexin (500 mg bid) for six to nine months, in addition to anti-muscarinics and bladder retraining.
Improvement in OAB symptoms
Group 2, with 212 patients, had no pyuria and received anti-muscarinics and bladder retraining.
Group 3, with 81 patients, did not manifest signs of pyuria until a follow-up exam, at which point they received antibiotics.
When they entered the study, 75% of the patients in group 1, 88% in group 2, and 85% in group 3 had negative mid-stream urine cultures, said Dr Gill.
All three treatment groups had significant improvement in OAB symptoms of urgency, 24 hour frequency episodes and incontinence, Dr Gill reported.
Antibiotic resistance low
Group 3 patients, who received antibiotics later, took significantly longer to recover (198 - 321 days) than patients who received antibiotics from the start (Group 1, 165 to 229 days; p < 0.001). Group 2 patients, who had no pyuria, recovered the fastest (138 to 180 days).
Dr Gill said the data provide strong justification for a large-scale, randomised placebo-controlled trial of antibiotics in patients with OAB pyuria but negative urine culture.
The danger of antibiotic resistance is low, he believes.
Bacteria dormant in OAB
"We have looked at over 65,000 culture samples and have not found any increased risk of antibiotic resistance," he said. "A Darwinian understanding of the underlying pathophysiology would lead us to expect very low levels of antibiotic resistance.
For resistance to occur, bacterial replication is required to allow for variation and the influence of selection pressure. But in OAB, there is evidence that the bacteria are relatively dormant, and replication is low, so the chances of developing resistance in the offending pathogens are very low and our data confirm this."
(Reuters Health, September 2011)