Urinary tract infections (UTI) is one of the most common infectious diseases worldwide and targets women exponentially more often than men – due to a shorter urethra. One in 5 women experiences a UTI at least once in their lifetime and many have several recurrences every year. If left untreated, there may be serious implications such as kidney damage.
Now, research led by the University of Queensland has found that bacteria can reside in the intestine for very long periods, despite antibiotic treatments, and cause recurring UTIs.
This discovery means that UTI sufferers could expect more effective, tailored treatment in the future to eliminate the bacteria.
The study, published in Nature Communications, was performed in collaboration with researchers from the University of Utah and followed a long-term recurrent UTI sufferer. The researchers used genetic analysis to find out the source of the infection in a woman who had been suffering from UTIs for 45 years.
The problem of antibiotic resistance
The study was based on just one 82-year-old patient who had been suffering from chronic UTIs for 45 years after undergoing vaginal hysterectomy in 1971. The longest period she could recall being UTI-free was a short nine months, said Professor Mark Schembri from UQ's School of Chemistry and Molecular Biosciences.
During that time her doctors prescribed stronger and stronger antibiotics, but the bacteria had been able to survive the treatment.
Chronic UTIs are a major burden on global healthcare, said Schembri, and the problem is magnified by an increase in antibiotic resistance. “Antibiotic treatments can sometimes just stop working on these patients, with dire results."
‘Infections originated from a common reservoir’
The bacteria – E. coli – were isolated from the patient's urine during her repeat infections so that researchers could determine the DNA sequence. E. coli is a type of bacteria that normally live in our intestines, but sometimes get into the urinary tract. They are the cause behind up to 90% of UTIs.
After tests were done, researchers found that exactly the same E. coli bacteria were present in her intestine and urinary tract, causing the recurring UTIs.
According to UQ’s Dr Brian Forde, who is also the study’s first author, a faecal sample from a patient suffering from a UTI can determine if the infecting strain also resides in the intestine. This is done by combining bacterial culture with genome sequencing technology. The DNA of E. coli was therefore recovered from her faecal samples and sequenced.
It was found that the E. coli were the same as those that caused the recurrent UTI, meaning her intestine was the source of the infections.
"This was proof – her infections did indeed originate from a common reservoir," said UQ’s Associate Professor Scott Beatson.
Tailor-designed, more effective treatment
"We now know that bacteria can reside in the intestine for very long periods and cause recurring UTIs, despite antibiotic treatment,” said Beatson.
In light of the findings, future treatment should therefore consider not only using antibiotics that will solely treat the UTI in the bladder, but also eliminate the infection reservoir in the intestine that seeds the recurrent infection in the bladder, he added.
If the same strain keeps being identified, Forde explained that tailored treatment to eliminate the bacteria from not just the patient's urine, but also the intestinal reservoir, could be designed.
"We predict a treatment like this would lead to reduced incidences of recurring UTI in patients suffering from this debilitating, chronic disease for which there is currently no effective cure," added Schembri.