Adam | Aug. 27, 2020, 3:11 p.m.

E. coli - The Bacteria that causes 80%-90% of UTI cases

Whenever a person comes to the doctor's office due to a suspected case of urinary tract infection; the doctor’s first instinct would be to look for signs of E. coli infection. This is standard protocol because, according to the National Kidney Foundation, 80 to 90 percent of urinary tract infections are caused by Escherichia coli.1 Under normal circumstances, this bacteria lives happily and peacefully in your gut. However, when they are accidentally brought to a sterile area such as your urethra, the E. coli causes what we call an opportunistic infection.6

What is Urinary Tract Infection?

Urinary Tract Infection is kind of self-explanatory; it is an infection of the urinary tract. The urinary tract is the structure in your excretory system where urine production occurs and where the urine passes through. It is made up of your kidneys, bladder, ureters, and urethra. The urethra is the tube that carries urine from the bladder to the outside of your body while the ureters are the tubes that carry urine from the kidney to the bladder.1

Urinary tract infection, whether it is caused by E. coli or some other bacteria, is quite common. In the United States alone, about 6 to 8 million cases are recorded each year. Women are more likely to get urinary tract infection, mostly due to the proximity of their urinary tract and anus. However, this does not mean that men are immune to urinary tract infections. It’s just that they are less likely to have urinary tract infection.1

Uropathogenic E. coli - an Opportunistic infection

As mentioned earlier, E. coli under normal circumstances is a harmless resident of your colon. This bacteria is a member of the ‘Enterobacteriaceae,’ a family of facultative anaerobic gram-negative rods.3

Those are a lot of fancy words, so we’ll have to tackle them one by one.

A facultative anaerobic bacteria can produce energy in the form of Adenosine Triphosphate or ATP by taking in oxygen if it is available. Otherwise, it is perfectly fine with producing energy, even though oxygen is not present, through fermentation.6

Gram-negative rods refers to the bacteria’s appearance under the microscope when they are stained with Gram’s stain. The bacteria’s cell wall doesn’t have a strong affinity to Crystal Violet, Gram staining’s violet-colored primary stain, so when the Gram staining process is completed they would take up safranin, the pink-colored secondary stain. Gram staining is done for identification purposes.6

Now that you're caught up. Other notable bacteria belonging to the Enterobacteriaceae include Salmonella, Shigella, and Yersinia, the causative agent of typhoid fever, dysentery, and the bubonic plague, respectively. Enterobacter and Klebsiella are other non-pathogenic bacteria belonging to the Enterobacteriaceae family but they are worth mentioning because they could also cause urinary tract infections.3 Klebsiella, in particular, is one of many causative agents of a kind of urinary tract infection wherein a person’s urine turns purple. This condition is called ‘purple urine bag syndrome.’6

E. coli, in itself, can cause UTI but the Uropathogenic strain of this bacteria contributes 80% of UTI cases. This strain of E. coli has some special bacterial structures that make it an expert in taking advantage of the bladder. Uropathogenic E. coli can reproduce and grow in numbers exponentially within a host’s bladder. Once they are present in abundant numbers they are shed off and urinated. They may be transmitted to other hosts this way. Furthermore, there is evidence that Uropathogenic E. coli is capable of entering host cells despite being an opportunistic extracellular pathogen. This makes it harder for the body to detect the presence of Uropathogenic E. coli as it transiently invades cells to avoid detection. Despite this, they still have to go out of the cell to replicate.3

E. coli enters the Urinary Tract

Urine is one bodily excrement made up of water, salt, chemicals, and other cellular waste. Urine is supposed to be sterile, so is the urinary tract. However, there are harmless bacteria living near the urethral orifice. When a bacteria, such as the E. coli, winds up in the sterile area of the urinary tract, this could lead to infection.1

But how does E. coli travel all the way from a person’s colon to the urethra? When a fecal matter that is carrying some E. coli bacteria reaches the urethra, the E. coli bacteria in that fecal matter may enter the urethra. This is the reason why women are more likely to have urinary tract infections than men. The close proximity between their urethral orifice and anus means that it's easier for the E. coli-carrying fecal matter to reach the urethra.1

There are specific ways for fecal matter to reach the urethra.1

● For females, wiping the anus from the back towards the front is essentially delivering E. coli to your urethra; please stop doing this.

● Sexual intercourse may also bring E. coli to the urethra. Sometimes the penis may rub against the anal orifice and then touch the urethral orifice. Those who practice heterosexual-anal-sex are more at risk.

● Spermicidal birth control devices such as spermicidal condoms may kill the natural bacterial residents of your urethra. This makes you more vulnerable to infection with a pathogenic bacteria. Hormonal changes that comes with pregnancy may also affect the bacteria in your urethra.

Symptoms of UTI that are caused by E. coli

Urinary tract infection that is caused by E. coli would give off some distinct symptoms.1,6

● Urgency and frequent urination is a common sign for UTI be it caused by E. coli or any other bacteria.

● A persistent fullness in the bladder is also another common symptom of UTI

● So is burning urination

● Pelvic pain

● and Cloudy urine that is sometimes brownish, pinkish, or tinged with blood

● Not all UTI’s will have foul-smelling urine, only those that are caused by bacteria which are capable of converting urea to ammonia will have this symptom. Bacteria from the Enterobacteriaceae family, such as E. coli, have the ability to convert urea to ammonia. So if these bacteria infect the urinary tract, your urine would smell more ammonia-like.


Microscopic urinalysis or the analysis of the urine’s content through the use of a microscope would reveal hematuria, presence of red blood cells, pyuria, presence of white blood cells, and bacteriuria, presence of bacteria, in the urine of a person who has UTI. The degree of hematuria, pyuria, and bacteriuria does not really reveal anything else besides the fact that the person has urinary tract infection.2

Chemical urinalysis, or the utilization of chemicals to analyze the contents of the urine, would also reveal results that are distinct to UTI that is caused by E. coli. The pH of the urine would turn alkaline because E. coli will turn urea to alkaline ammonia. Other findings uncovered through Chemical Urinalysis includes; protein in the urine as the lower urinary tract produces exudates in response to the infection, presence of hemoglobin from red blood cells, presence of leukocyte esterases from white blood cells, and presence of nitrite since E. coli has an enzyme that converts the urine’s nitrate to nitrite.5

The most definitive evidence that would reveal that a person has UTI that is caused by E. coli would be the recovery of the bacteria from the urine of the patient.2


There are certain practices that would reduce your likelihood of acquiring urinary tract infections:4

● If you increase your urine output, this will help flush away the bacteria in your urinary tract. Also, reducing the concentration of the dissolved-substances of your urine that the bacteria would utilize as food would starve the bacteria and help reduce their numbers. Drinking a lot of water would do both.

● Several studies have shown that cranberry juice prevents or even hastens recovery from UTI. This juice is harmless in general so it is a good idea to drink this frequently when you have UTI.

● As mentioned, females who wipe their anus from back to front are at risk of acquiring UTI. So doing the opposite, wiping from front to back would reduce the risk significantly.

● Sexual intercourse may increase your risk of acquiring UTI. However, if you and your partner would bathe before you would have sex; you’ll reduce your risk significantly. Aside from this, both male and female must drink lots of water after intercourse to encourage frequent urination. Frequent urination helps by flushing out any harmful bacteria that reached your urethra.

● There are a lot of feminine products that are advertised to make your feminine area feel and smell fresh and clean. News flash, using these products is not good for your reproductive health. The vagina has its own distinct smell because there are bacteria that reside there naturally. Using these products could kill these bacteria and make you more susceptible to infection.

● We mentioned previously that spermicidal birth control methods may also make you susceptible to UTI. By avoiding products that contain spermicides then you’re less likely to have UTI.

UTI can progress to Acute Cystitis

When you have an infection in the lower urinary tract, please seek medical attention immediately. Since UTIs are often caused by bacteria, this disease is not self-limiting and may worsen progressively. Acute cystitis, or the infection of the bladder, could occur if an infection of the lower urinary tract is left alone.2

Symptoms of Acute Cystitis

Acute cystitis may present with symptoms similar to lower urinary tract infection such as difficulty voiding urine, painful urination, and discomfort in the bladder area. A physical examination would reveal that the bladder area of the person affected would exhibit tenderness. In other words, when the doctor would apply light-pressure in the bladder area, the patient would experience pain when normally they should not.2