Have you had a UTI test and received negative results, even though you have symptoms of a UTI?
Or you might get a positive result, followed by a negative result, even though your UTI symptoms haven’t really improved.
Well, rest assured, you’re not the only one who has experienced this. And even more reassuring, there’s a good chance your test results were wrong, and that you do indeed have a UTI.
Science supports your suspicions that the standard UTI test is inaccurate. It has been proven inaccurate, and this article will help explain why, and what you can do about it.
Article Quick Links
- How accurate are UTI test methods? Not very. >>>>
- Why you can’t trust UTI test strips. >>>>
- 7 Reasons your negative UTI test could be wrong. >>>>
- 5 Alternative UTI test methods you could try. >>>>
- Should You Try UTI Test Alternatives? >>>>
How Accurate Are UTI Test Methods?
There are two standard ways to conduct a UTI test:
- A rapid dipstick strip test, which is done on the spot by your medical practitioner (or at home)
- A urine culture, where your sample is sent to a lab and is tested over the course of 24-48 hours.
Despite being the global standards for UTI testing since the 1980s and 1950s respectively, both of these tests are extremely inaccurate.
Accuracy Of Standard UTI Tests
In reality, antibiotics are very often prescribed without any form of UTI test. Patients and doctors are very competent at recognizing the symptoms of a UTI, but there are issues with this approach.
Statistics show that 26-44% of females will experience a recurrence of their first UTI. In this 26-44% it is likely the initial treatment failed.
Evidence suggests that with each recurrence of UTI, another recurrence becomes more likely.
The more UTIs you have, the more likely you are to get another.
If your UTI treatment failed the first time, it is crucial to find out why as soon as possible, in order to break the cycle of recurrence before it escalates.
So why don’t the standard UTI test methods provide the answers you need?
First, let’s take a quick look at those urine test strips you can use at home or at the doctor’s office. Then we’ll explain some of the problems with urine culturing done at a lab.
Knowing the issues with both of these tests will arm you with the right questions to ask if you feel like your negative results are wrong.
Why You Can’t Trust UTI Test Strips
UTI test strips are commonly used as an initial indicator for UTI. Studies have shown these test strips are unreliable, and cannot be used to rule out infection.
You’ve probably seen a UTI test strip if you’ve ever been to a doctor for a suspected UTI, but you can also buy them online or over the counter, to use at home.
Home UTI test strips often contain only two of the indicators (the little colored boxes) listed below.
What UTI Strip Test Indicators Mean
|Indicator||Why It’s Used|
|pH Level||If your urine pH is outside the normal range of 5-7, there could be an issue.|
|Protein||Protein in the urine (proteinuria) can indicate kidney disease or other health issues, but it can also be caused by:|
- Urinary tract infection
- Stress or strenuous exercise
- Exposure to extreme cold
|Sugar||The most common cause of sugar in the urine is diabetes, but it can also indicate other rare health conditions.|
|Ketone||Ketones in the urine can also be caused by diabetes, but can also be a result of a state of ketosis, where the body burns fat instead of sugar for fuel.|
|Bilirubin||Bilirubin in the urine may be an early indicator of liver damage, however, this indicator is known to be highly inaccurate.|
|Urobilinogen||Urobilinogen is a by-product of Bilirubin production and may indicate issues with the liver, among other health issues.|
|Nitrite||Some bacteria that cause UTIs make an enzyme that changes urinary nitrates into nitrites. So if the strip is positive for nitrites, the conclusion is that you have a bacterial UTI. Note that many bacteria do not create nitrites in your urine.|
|Red blood cells (erythrocytes)||Blood can appear in urine due to strenuous exercise, but generally, blood in the urine is taken to be a sign of infection, inflammation, disease, or injury to the urinary tract.|
|White blood cells (leukocytes esterase)||A positive strip result for white blood cells in your urine indicates an infection in your urinary tract, or possibly, kidney disease.|
Studies show that UTI test strips may only be reliable about 30% of the time.
|“My urine was visibly cloudy and it burned when I went to pee. My doctor used a UTI test strip in my urine sample and said everything on the test strip was normal. I was told I didn’t have an infection even though I’ve had UTIs before and I know exactly what they feel like.”|
Some studies have bluntly concluded that UTI test strips should be abandoned as a tool for the diagnosis of UTIs in patients with lower urinary tract symptoms.
Given the low accuracy of UTI test strips, if the results are negative but you have UTI symptoms, it would generally be recommended that you have a urine culture test done in a lab.
Which brings us to the next problem…
7 Reasons Your Negative UTI Test Could Be Wrong
Let’s just put it out there that if you have received negative results for a urine culture, but you still have symptoms, it is very possible you have a UTI.
This happens very frequently, and we can help explain why below. It’s also a good idea to have an understanding of how a standard urine culture works, so we’ve explained that here.
#1. It Turns Out Urine Is Not Sterile
It has become common knowledge that urine is sterile – it’s even become ingrained in ‘first aid’ advice, like “urinating on a wound is better than using non-sterile water.” But it turns out it’s not.
The bladder has its own unique microbiome, and an ideal balance of microbes that your body does its best to maintain.
Studies have found hundreds of different bacteria in healthy bladders. And in patients with UTIs, they have found even more. That’s a lot of different bacteria that were assumed not to exist in the bladder!
Because UTI test techniques have always assumed urine is sterile, they have always been flawed.
For many, the consequences of this are UTI test results that list ‘contamination’ which implies the bacteria came from a source other than the bladder – possibly skin, vagina, or elsewhere.
This ‘contamination’ may actually be bacteria from inside the bladder that should be considered as part of the puzzle. Results may also show insignificant levels of growth that are then often dismissed.
#2. The Pathogen/s Causing Your Symptoms May Not Be In Your Sample
Standard UTI test methods focus on free-floating pathogens (which is how UTIs start).
With every recurrence of UTI, there is an increased risk of an embedded, difficult-to-treat bladder infection. An infection embedded in or attached to the bladder wall is called a biofilm.
Biofilms aren’t always bad – many types of bacteria form these structures naturally and they’re an important part of the gut microbiome.
When bacteria form biofilms in the bladder, they are no longer free-floating. If the bacteria are not floating around in the urine, they will not be passed into your sample on urination.
If the bacteria are not in your sample, they will not be detected.
There are other reasons your sample may not contain detectable levels of bacteria, including over-hydration. If your bladder is frequently flushed and your urine is diluted, your sample may not contain enough of anything a urine culture can detect.
#3. The UTI Test Was Never Meant To Be Used For Everyday UTIs
In the 1950s a scientist named Kass conducted two small studies on two groups of females with acute kidney infections. One group of participants were pregnant females, the other non-pregnant females.
Kass discovered that a certain concentration of bacteria in a cultured urine sample was enough to indicate a kidney infection with 80% accuracy.
Kass suggested that a kidney infection was present when a certain amount of bacteria was found in the urine. This is called the Kass threshold, and you may have seen reference to it on your UTI test results.
|The Kass threshold means a concentration of 100,000 (105) colony forming units (CFU) of bacteria per milliliter of cultured urine must be present to indicate an infection. It is a very specific threshold without much room for interpretation.|
The key point here is that the Kass test was already only 80% accurate for acute kidney infections. It was never validated for use in lower urinary tract infections, like bladder or urethral infections.
Yet, this test was embraced by the medical community and has been the global standard UTI test for more than 60 years.
The Kass threshold has since been found to be far too high to detect many lower urinary tract infections. That is, much lower counts of bacteria in the urine can indicate a UTI.
|“If a urine dipstick or lab test comes back negative but the patient is clearly describing symptoms of a UTI, doctors must listen to them. Urine tests are far from perfect and it is vital to interpret them in the context of the patient’s symptoms.”|
Dr Jon Rees, Chair, Primary Care Urology Society, UK
Because modern urine culture tests are based on the Kass test, any bacteria count that is below the Kass threshold will not be considered an infection, and antibiotic susceptibility testing will not be done.
#4. UTIs Can Be Caused By Multiple Pathogens (The Bad Guys)
Another issue with the standard mid-stream urine culture, or Kass test, is that it looks for a single pathogen, and does not take into account the possibility of multiple infection-causing pathogens.
Instead, if multiple pathogens are found, it is generally assumed that the urine sample was contaminated.
This is a problem because some chronic infections have been found to be caused by multiple pathogens co-existing in the bladder. And each pathogen may require a different treatment approach.
|“Our biological studies reveal mixed microbial infections hiding inside the cells of the bladder. Located there, the microbes seem quiescent but cause low-grade inflammation that may cause various bladder symptoms...Cloistered, inside cells bacteria escape antibiotic and immune attack.”|
#5. The Standard UTI Test Cannot Grow Most Bacteria
The standard urine culture method does not mimic the environment in the bladder. As we described above, a urine culture uses a specific medium, and specific conditions over a short frame of time.
The vast majority of all known organisms will not grow in these conditions. And many organisms that may be perfectly happy residing and multiplying in the bladder, will not grow in the environment of a culture plate.
This means the standard urine culture methods are just not able to identify all UTI-causing pathogens.
#6. White Blood Cells In Urine Are Often Ignored
We mentioned white blood cells (leukocytes) in urine earlier, as one of the indicators on a UTI test strip. As much as we cringe at the word, white blood cells are commonly referred to as pus.
White blood cells are also looked for in a standard urine culture at a lab. If either test method detects white blood cells in your urine, it is likely you have a urinary tract infection.
Unfortunately, the presence of white blood cells in a urine culture is measured against a threshold that was established even earlier than the Kass threshold.
You can think of the white blood cell measurement as a backup to the Kass test. Ideally, you would get UTI test results that show a significant amount of bacteria present, PLUS a level of white blood cells that confirms your body is fighting an infection.
Lots of bacteria paired with pus – an immune system response – builds a solid case for a UTI.
There are three major issues with the measurement of white blood cells in a urine sample:
- Much like the Kass threshold, research suggests the threshold for white blood cells is also too high, and that lower levels of white blood cells can indicate a urinary tract infection.
- White blood cells die off quickly outside the body, and may have already significantly reduced by the time a test takes place.
- If your urine contains white blood cells but fails the Kass test, the raised white blood cell count may be considered an anomaly and dismissed as unimportant.
This third point is commonly referred to as ‘sterile pyuria’.
|Pyuria means pus in the urine, and sterile means the absence of bacteria. So ‘sterile pyuria’ basically means pus was found in the urine, but infection-causing bacteria was not.|
Many researchers believe sterile pyuria is often incorrectly reported due to the Kass threshold being too high, and that lower levels of bacteria may be present and significant.
“I had ongoing symptoms. Sometimes acute, sometimes minor, but always there. I bought UTI test strips to monitor my urine. Every single day it showed I had raised white blood cells, but when I sent my urine to a lab, it kept coming back negative for an infection. I had no idea what was going on.”
#7. Epithelial Cells As An Immune Response Are Overlooked
Epithelial cells are the delicate tissue that can be found lining most of the urinary tract, including the bladder. When you have a UTI, your body can shed these cells as part of its defence against pathogens that form biofilms or intracellular bacterial communities (IBCs).
The body is pretty amazing really. Pathogens invade and start to form communities on and inside the bladder lining cells, and your body starts sacrificing its own cells, in an attempt to foil the plan.
Historically, if these epithelial cells were found in urine that tested negative for bacteria, the cells were considered to be sample contamination. It is now clear that the presence of epithelial cells can actually be an indication of an underlying, embedded infection.
5 Alternative UTI Test Methods You Could Try
We cannot reiterate enough… No evidence of infection is not the same thing as evidence of no infection.
Or, to put it in a less mind-bending phrase – just because your UTI test comes back negative, it does not mean you do not have an infection.
There ARE other testing options available, ranging from a modified urine culture test, right up to high tech genetic sequencing methods like those described below.
|“There’s an old expression, if it looks like a duck, walks like a duck, and quacks like a duck. It's gotta be a duck. And so to have somebody who has pain, urgency, frequency and burning, and yet they're told they don't have an infection because a urine culture was negative, who do you believe? Are you treating a lab result? Or are you treating a person?” |
If you feel you have exhausted your current options and you are still experiencing symptoms that impact your life, it could be time to learn more about how to move forward.
A number of researchers, specialists and doctors in various countries have developed more comprehensive approaches to conditions such as recurrent UTI, chronic cystitis and Interstitial Cystitis.
Thanks to their efforts, there are a few alternative testing options you may wish to consider.
1. MicroGenDX: Next Generation Sequencing For UTIs
MicroGenDX, a US based molecular laboratory, uses NGS testing and states that their tests identify 100% of the known bacteria, fungi and parasites in a urine sample from a database of >30,000 species, with 99.9% accuracy.
In addition to breaking down the percentages of all microbial species detected, predictions around antibiotic resistance genes are provided. The results report contains recommendations about which antibiotics are likely to be most effective.
|“We strongly believe MicroGenDX Laboratory can provide better diagnostic information to treat chronic UTIs by utilizing Next-Gen Sequencing. NGS takes the guesswork out of microbial detection allowing for targeted utilization of antimicrobials." |
You can order a kit directly from the MicroGenDX website, and ship your sample from within the USA, or internationally.
We’ve covered the UTI testing service offered by MicroGenDX in much more detail here.
2. Aperiomics: Deep Next Generation Sequencing Test For UTIs
Aperiomics uses deep metagenomic sequencing, an unbiased genetic sequencing technology that allows them to create a complete genetic fingerprint of all microorganisms in any sample you provide.
In short, this technology looks for all known bacteria, fungi, parasites and viruses, in a single test.
Aperiomics is currently the only provider of this type of testing, globally. Their database of microbes contains more than 37,000 microorganisms, making it the most comprehensive in the world.
|“The traditional health-care system has never had the right tools to see what’s going on. We have the tool, and our goal is to change everything about how infections are identified." |
You can order a kit directly from the Aperiomics website, and ship your sample from within the USA, or internationally.
We’ve covered the UTI testing service offered by Aperiomics in much more detail here.
A Caveat Regarding Next Generation Sequencing UTI Testing
Although scientists have used DNA to identify microbes for many years, the technology has been expensive and time consuming, and therefore considered inappropriate for everyday testing of chronic illnesses.
This is changing, however, and the latest technology is now being used to identify the unique DNA of microbes found in human test samples, including urine. DNA testing has already detected more than 1,200 different microbial species in urine samples – a number far higher than any other UTI testing method.
This category of testing is known as Next Generation Sequencing, and the two services above fall into this group.
Some chronic UTI literate practitioners are wary of NGS testing, as it has the ability to detect hundreds of organisms in a single urine sample, and the significance of these organisms is not yet known. How can we know which to treat?
To help address this question, NGS results typically show what percent each organism was found in – the idea being that any dominant pathogens will be identified, and that these should be looked at first when it comes to treatment.
This approach has proven very successful for many practitioners who embrace NGS testing in different areas of human health, including chronic urinary tract issues.
If conventional UTI testing methods have failed to provide you with answers, NGS testing could finally help you find them.
3. Expanded Quantitative Urine Culture (EQUC)
Expanded Quantitative Urine Culture (EQUC) is a UTI testing method that is relatively new, and has been used in many recent studies around the female urinary microbiome and recurrent UTI.
EQUC uses a modified urine culture protocol, that builds on the standard concept of urine culture with some very important changes. These include using larger volumes of urine, varied atmospheric conditions for incubation and longer incubation times.
The result is that the conditions of EQUC are far superior to those of the standard urine culture.
In fact, one study that compared the two techniques found that EQUC grew bacterial species (were positive) in 80% of the samples tested. In comparison, 92% of these same samples were reported as no growth (negative) using standard urine culture.
EQUC has been adopted as a UTI test method by a selection of practitioners in the USA. We’re looking into where patients can access EQUC and will publish further information as we find it.
4. Fresh Sample Urine Microscopy Test
This test is exactly what it sounds like. Upon providing a urine sample, it is immediately analyzed under a microscope to count things such as bacteria, fungi, white and red blood cells, and bladder lining cells (epithelial cells). It’s a technique that was used in the 1920s and has since been revived.
Based on positive identification of infection using this technique, the study reported a treatment success rate of 84%, in patients with urinary tract conditions previously considered untreatable.
|"We do one test; immediate microscopy of a fresh specimen of urine; counting the white and red blood cells, bladder lining cells, bacteria and fungi. The symptoms and the microscopic data are interpreted...they force consideration of all the data particularly the patient's narrative."|
At present, we are unaware of US-based specialists using this same set of testing and assessment techniques. However, it is possible to replicate this technique with the help of a practitioner.
5. Modified Standard Urine Culture Test
Although we know standard UTI testing is inaccurate, some individuals do find an answer. You may be able to request changes to the standard urine culture to increase its accuracy. Possible enhancements include:
- Decrease the colony forming units (CFU) threshold from 105 to 103 or 102.
- Ensure a susceptibility test be completed if your test is positive for bacteria or yeast even at lower levels. This should be done automatically, and is essential to identify which antibiotic or anti-yeast treatment should be prescribed.
- Lengthen the incubation period, to encourage the growth of more types of pathogens.
These changes aren’t always possible, so you should ask your doctor about it, or request it directly at a lab if you test independently.
While we don’t usually recommend using techniques that have been shown to be so flawed, there are very few options for UTI testing in most regions, and we don’t want to dismiss it completely.
Why It’s Important To Find The Right Practitioner
While you may be able to request UTI testing independently, the results have limited usefulness without a practitioner who can interpret the information and prescribe an appropriate treatment regimen.
Because the types of UTI testing covered above are not widely available, many practitioners may not be aware of them at all. Or they may be aware of them but have no experience using them, or may believe them to be unhelpful.
Always find a practitioner to work with before ordering testing. We’ve covered recurrent UTI treatment approaches in a separate article, so dive in there for more insight.
|“With Microbiome testing, you don't often get one bacteria. Certainly, I have found the usual suspects like E. coli. I’ve even detected some STIs, and anaerobes that can’t be grown by culture. Sometimes, you get long lists of bacteria that we know very little about, and I'll do extensive literature searches and sometimes barely come up with one or two papers. And so what I generally do in that situation is to try and figure out which are likely to be pathogenic, and treat those. This is a really different way of prescribing antibiotics compared to when I was trained."|
Should You Try UTI Test Alternatives?
Only you can decide how important it is to pursue more effective testing and treatment.
Ask yourself a few questions first:
- Have you already submitted multiple urine samples for culturing in a lab?
- If so, were the results negative despite your symptoms? Did you actually receive your results?
- If your results were positive, do you feel the treatment was effective, or did you experience UTI symptoms again shortly after?
- Do you feel your recurrent or chronic symptoms are something you are happy to manage, or are you interested in investigating a possible long term solution?
- Have you gathered all your previous test results and gone through them with one practitioner to discuss any patterns or trends?
- Do you feel you understand the options available, or should you do some more research?
- Do you have a practitioner that you feel can help with alternative testing methods?
These are all questions we can’t answer for you. We understand this is an individual journey for each person.
You’re welcome to share any questions or comments below.