Women who suffer recurrent UTIs frequently have the bacteria in the periurethra prior to infection.


TORONTO—By examining temporal patterns of Escherichia coli colonization of the periurethra and urine, it may soon be possible to intervene and prevent recurrent UTIs in an unprecedented way.

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“If we can understand the pathogenesis and the steps involved in recurrent urinary tract infections, we may be able to intervene with antibiotics or another type of targeted intervention that could stop the process,” said Christopher Czaja, MD, an infectious disease fellow at the University of Washington in Seattle. ”We could even lower the use of antibiotics through better methods of prevention.”


At the 44th annual meeting here of the Infectious Diseases Society of America, Dr. Czaja presented data from an ongoing prospective study examining the patterns of E. coli colonization prior to recurrent UTIs in women. Mouse models suggest that uropathogenic E. coli can invade, persist in, and re-emerge from bladder epithelial cells to cause recurrent UTIs. The study will determine whether reemergence of bacteria from a bladder reservoir may be an important cause of recurrent UTIs in humans.


So far, Dr. Czaja and his colleagues have enrolled more than 100 healthy women with acute cystitis and a history of recurrent UTIs. The researchers analyze daily urine and periurethral specimens for culture over a three-month period. To date, at least one recurrent UTI developed in 34 of the first 100 women; E. coli was the causative organism in 76% of these cases. The researchers compared isolates using pulsed-field gel electrophoresis and they found that 65% of the recurrent UTI E. coli isolates were identical to the enrollment cystitis strain.


In 40% of cases, Dr. Czaja’s group found the causative strain in the peri-urethra; 10% of women had the identical E. coli in the urine as many as 14 days prior to recurrent UTI. All women had periurethral colonization with the identical strain at least one day prior to development of a recurrent UTI.


Additionally, 75% of the women had the identical E. coli strain in their feces an average of 16 days prior to recurrent UTI, suggesting an intestinal source, according to Dr. Czaja. A few subjects had colonization patterns compatible with a source of infection within the bladder. He pointed out, however, that the existence of a bladder reservoir in humans may be difficult to prove using colonization patterns alone.


The researchers found that the quantity of E. coli isolated from the urine increased in the days immediately prior to infection and 30%-40% of the women had more than 100,000 cfu/mL of the identical strain 24-48 hours prior to a recurrent UTI.