Problems with STANDARD Testing
Diagnostic lab tests for UTI have been widely discredited in peer-reviewed publications for at least 30 years. Both dipstick and MSU culture are known to miss at least 50% of genuine infections, yet published guidelines omit any mention of these failures.
Here’s why these tests are failing patients.
Pure Growth and Colony Counts
For a lab to determine a positive urinary tract infection via MSU culture there must be a pure growth of a known urinary pathogen. The growth must multiply to the point of reaching a set colony count, which was set by Edward Kass in the late 1950s at 10^5 colony forming units (cfu). The colony count was based on a study of 74 women with acute pyelonephritis (a kidney infection) and then backed by a second study of pregnant women with severe acute pyelonephritis—a very different condition to an uncomplicated, acute UTI, and from a most unrepresentative sample.
There are more reasons why the existing colony count is not reliable. The benchmarks used by labs to diagnose UTI through MSU culture are based on the assumption that healthy, uninfected urine should be sterile. Recent research however, has shown that this is not the case and that a healthy bladder has its own microbiota*, just like the gut. MSU culture also does not take into account the possibility of poly-microbial infections (infections that involve more than one pathogen, resulting in mixed growth that is currently discounted as contamination), or low bacterial counts due to slow growing bacteria, bacteria that does not grow well outside the body, or the concentration of the urine sample (i.e. how diluted the sample is due to an individual’s fluid intake).
This widely criticised diagnostic measure determined by Kass was never validated for diagnosing acute UTI, yet it has been in use in labs around the world for the past sixty years.
Another common UTI indicator ignored by labs is an elevated white blood cells (leukocytes) count that falls beneath the set threshold—usually referred to as sterile pyuria.
The white blood cell threshold was first set by Cuthbert Dukes almost 90 years ago after studying 300 asymptomatic males and females. He concluded that a count of 10 or more white blood cells/mm3 in urine was considered ‘abnormal’, and anything less than nine white blood cells was considered ‘normal’. This stark threshold has been repeatedly refuted by research teams who have criticised the technique used in this study and the defects in subsequent research which repeated Dukes’ critical mistake.
An important fact about white blood cells is their reduced survival rate outside the bladder. Studies have shown that white blood cells die off quickly, decreasing to 60 percent in the first two hours when stored at room temperature, and decreasing to 80 percent in the first two hours when refrigerated. Thus, by the time the average sample reaches the lab it no longer accurately reflects the true numbers of white blood cells when it was originally taken.
The epithelium is a thin tissue which lines the bladder and most of the urinary system. If someone has a confirmed urinary tract infection, elevated epithelial cells are expected and fit the diagnosis. If someone shows elevated epithelial cells without positive bacterial growth, the epithelial cells have historically been described as ‘sample contamination’.
Research in the UK and the US has demonstrated that epithelial cell exfoliation (also known as sloughing or shedding) is a defence mechanism/innate immune response to low-grade infection by intracellular bacterial communities. It is therefore wrong to assume that elevated epithelial cells in samples of those with lower urinary tract symptoms (LUTS) are due to ‘sample contamination’.
For many years researchers have repeatedly called for standard MSU culture to be abandoned as the gold standard for diagnosing UTI, but their concerns and evidence continue to be ignored.
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