Standard Test May Miss UTI in Some Women
By Labmedica International staff writers
Posted on 18 May 2017
Image: A scanning electron microscope (SEM) image of Escherichia coli (E. coli) (Photo courtesy of NIAID).
Urinary tract infection (UTI) is one of the most common infections that people experience. It arises when bacteria, most likely from the skin or rectum, enter the urethra and travel up to the bladder. UTIs affect several parts of the urinary tract, which includes the urethra, bladder, ureters, and kidneys. However, the most common type of UTI is a bladder infection, also known as cystitis.
The symptoms of UTI include experiencing a burning feeling during urination, or having frequent and intense urges to urinate, even when there is not much urine to pass. Females are more likely to be affected by UTIs than males because they have a shorter urethra that is closer to the anus, making it easier for bacteria to get into the urinary tract and cause infection.
Scientists at Ghent University Hospital and their colleagues compared urine samples from 220 women who went to see their doctor because they had symptoms of UTI, with those of 86 healthy women with no such symptoms. The urine samples underwent the standard culture test and were also tested with a more sensitive method called quantitative polymerase chain reaction (qPCR), which can detect minute amounts of bacterial DNA known to cause UTIs, including Escherichia coli and Staphylococcus saprophyticus.
The team found that in the symptomatic group, 178/220 (80.9%) of the urine cultures were positive for any uropathogen and 95.9% (211/220) were E. coli qPCR-positive. For the control group, cultures for E. coli and E. coli qPCR were positive in, respectively, 9/86 (10.5%) and 10/86 (11.6%). In the symptomatic group, qPCR yielded 19 positive samples for S. saprophyticus qPCR, one positive sample for Mycoplasma genitalium and one for Trichomonas vaginalis. However, the qPCR test detected E. coli in 95.9% of those samples, and S. saphrophyticus in 8.6%. When the two qPCR test results were combined, they showed that 98.2% of the symptomatic women had an infection.
Stefan Heytens, MD, the lead author of the study said, “This suggests that if a woman has these symptoms, she probably does have a UTI. Our findings support previous studies, which indicate that traditional testing may not be helpful in uncomplicated UTIs. However, traditional urine culture tests may still have a role to play if treatment fails or if there are signs and symptoms of a more complicated UTI.” The study was published on April 27, 2017, in the journal Clinical Microbiology and Infection.