Escherichia Urinary Tract Infection

Urinary tract infections caused by E. coli bacteria are among the most common infections people experience, affecting millions each year and often returning even after treatment.

Table of contents

• What is an Escherichia urinary tract infection?
• Parts of the urinary system that can be affected
• Symptoms
• Causes and how infection occurs
• Who is at risk?
• Diagnosis
• Treatment
• Prevention

What is an Escherichia urinary tract infection?

An Escherichia urinary tract infection is an infection of your urinary system caused by a bacteria called Escherichia coli (E. coli). This type of bacteria normally lives harmlessly in your digestive system, specifically in your gut or intestines^[1][3]. However, when E. coli enters your urinary system, it can cause an infection.

E. coli is responsible for about 80% to 90% of all urinary tract infections, making it the most common germ causing this type of illness^[6][8]. The infection happens when E. coli bacteria from your digestive system spread to the opening of your urinary tract and travel up into your bladder^[8].

These infections are very common, especially in females. About one in two females will have a urinary tract infection at some point in their lives, while about one in 20 males will experience one^[3]. Healthcare providers treat 8 to 10 million people each year for urinary tract infections^[15].

Parts of the urinary system that can be affected

Your urinary system makes and stores urine. It includes several parts that can become infected with E. coli bacteria^[15][17]:

• Kidneys: These are small, bean-shaped organs on the back of your body, above your hips. They filter waste products and excess water from your blood to make urine.
• Ureters: These are thin tubes that carry urine from your kidneys to your bladder.
• Bladder: This is a balloon-like organ that stores urine before it leaves your body.
• Urethra: This is a tube that carries urine from your bladder to the outside of your body.

Most infections involve the lower urinary tract, which includes the bladder and the urethra^[2]. When E. coli infects the bladder, the condition is called cystitis^[3]. If the infection reaches the kidneys, it becomes more serious and is called pyelonephritis^[3].

Symptoms

The symptoms of an E. coli urinary tract infection can vary depending on which part of your urinary system is affected. Common symptoms include^[1][3][15]:

• Pain or burning sensation when you urinate
• Needing to urinate more often and urgently, sometimes only a few drops
• A feeling that the bladder is still full after urinating
• Pain in your abdomen, pelvic area, or lower back
• Pressure in the lower part of your pelvis
• Cloudy, foul-smelling urine
• Blood in your urine
• Dark-colored urine

If the infection has spread to your kidneys, you may experience more serious symptoms^[3][13]:

• Fever
• Chills
• Back pain or pain in the side of your back (flank pain)
• Nausea and vomiting

If you experience fever, flank pain, nausea, or vomiting along with urinary symptoms, this could signal that the infection has reached your kidneys, and you should seek immediate medical attention^[8].

Causes and how infection occurs

E. coli bacteria normally live in your intestinal tract without causing any problems. In fact, they even help you digest your food^[1][5]. However, when these bacteria leave your digestive system and enter your urinary tract, they can cause an infection.

The infection typically occurs when E. coli from stool (feces) spreads to the opening of the urethra^[6][8]. This is why the trip from the anus to the urethra is particularly relevant for females, as the distance is shorter, making it easier for bacteria to reach the urinary tract^[8].

Once E. coli enters the urethra, the bacteria can travel up into the bladder. The bacteria have special structures called pili, which are like hairlike appendages on their surface that allow them to stick to the tissues in your urinary tract^[4]. These pili attach to a sugar called mannose that is found on the surface of the bladder, allowing the bacteria to avoid being swept away when you urinate^[22].

The urinary system is designed to minimize the risk of serious infection in the kidneys by preventing urine from flowing back up into the kidneys from the bladder^[3].

Who is at risk?

Anyone can get a urinary tract infection caused by E. coli, but certain groups of people are more likely to develop one^[2][3][15]:

• Females: They are much more likely to get urinary tract infections than males, mainly because their urethra is shorter and closer to the anus, where E. coli bacteria are common.
• Sexually active females: Sexual activity can increase the risk of bacteria entering the urinary tract.
• Pregnant females: Pregnancy increases the risk of urinary tract infections.
• Older adults: Age is a risk factor for developing urinary tract infections.
• People who have had a previous urinary tract infection: Having one infection makes you more likely to have another.
• People with structural problems in the urinary tract: Such as an enlarged prostate.
• People with changes in vaginal bacteria: For example, changes caused by menopause or the use of spermicides.

About a quarter of people who have a urinary tract infection develop another one within six months, even after antibiotic treatment^[22].

Diagnosis

If you have symptoms of a urinary tract infection, your healthcare provider will determine if you have one by^[19]:

• Asking about your symptoms
• Doing a physical exam
• Ordering urine tests, if needed

To test for E. coli in your urine, you will need to undergo a test called urinalysis^[6]. You may be asked to give a urine sample at your healthcare provider’s office. It’s important to collect the sample properly by first wiping your genital area with an antiseptic pad and then collecting the urine midstream (a second or two after you start passing urine). This helps prevent the sample from being contaminated^[11].

The urine sample can be tested rapidly for the presence of white blood cells (pus), bacterial residue (nitrites), and traces of blood^[8]. If the test is positive, your healthcare provider will discuss the appropriate treatment.

Your urine may also be sent for a test called a culture and sensitivities. A culture can identify the kind of bacteria growing in the bladder and urine and can help determine which antibiotics are most effective^[8]. Because this test can take one or two days, you will usually begin treatment right away with an antibiotic commonly used to treat urinary tract infections.

For recurrent infections, your healthcare provider might order additional tests, such as imaging tests like ultrasound, CT scan, or MRI, to check for structural problems in the urinary tract^[11].

Treatment

Because E. coli is a bacteria, treatment for urinary tract infections caused by this germ involves antibiotics^[6][13]. Antibiotics can kill the bacteria and prevent the spread of the infection.

The most commonly prescribed antibiotics for an E. coli urinary tract infection are^[6][10]:

• Trimethoprim/sulfamethoxazole (Bactrim, Sulfatrim)
• Nitrofurantoin (Macrobid)

Other oral antibiotics that may be prescribed include^[6][10]:

• Ciprofloxacin (Cipro)
• Ampicillin
• Fosfomycin (Monurol)
• Amoxicillin-clavulanate (Augmentin)
• Cephalexin (Keflex)
• Cefdinir
• Levofloxacin (Levaquin)

Based on local data, resistance patterns are changing. For example, one in three E. coli urinary tract infections are now resistant to ciprofloxacin, which was historically used to treat these infections^[12]. For bladder infections, nitrofurantoin and sulfamethoxazole/trimethoprim are now the recommended treatment options.

If you have recurrent infections (three or more times in one year), or if your infection is severe, you may need to take antibiotics for a few months or may need injected antibiotics^[6][10]. For pyelonephritis (kidney infection), ceftriaxone or gentamicin once daily may be recommended^[12].

Your healthcare provider might also recommend medicine to help lessen pain or discomfort, such as phenazopyridine (Pyridium), which can help reduce bladder pain^[13].

When taking antibiotics^[19]:

• Take antibiotics exactly as your healthcare provider tells you
• Do not share your antibiotics with others
• Do not save antibiotics for later
• Talk to your healthcare provider about safely discarding leftover antibiotics

Antibiotics can cause side effects, including rash, dizziness, nausea, diarrhea, and yeast infections. More serious side effects can include antibiotic-resistant infections. Call your healthcare provider if you develop any side effects while taking your antibiotic^[19].

People with recurrent urinary tract infections are at greater risk of developing antibiotic resistance^[13]. This happens when bacteria become less susceptible to the effects of antibiotics and can survive and cause problems. If you experience antibiotic resistance, your healthcare provider may recommend undergoing a urine culture test to determine which antibiotic will work best.

Prevention

There are several ways to help prevent urinary tract infections caused by E. coli^[13][19][20]:

• Wipe front to back: This technique after a bowel movement can help reduce the risk of E. coli coming into contact with the genitals and urethra. It is also important for females to wipe front to back after urinating.
• Urinate after sexual activity: This can help flush out bacteria that may have entered the urethra.
• Stay well hydrated: Drink plenty of water or other fluids.
• Take showers instead of baths: This may reduce the risk of bacteria entering the urinary tract.
• Minimize douching, sprays, or powders in the genital area: These products can disrupt the natural bacteria in the area.
• Teach girls proper hygiene when potty training: Show them how to wipe front to back.

Conventional wisdom holds that urinary tract infections recur frequently because bacterial populations from the gut are continually re-seeding the urinary tract with disease-causing bacteria^[22]. Researchers have found that reducing the number of E. coli in the gut could reduce the likelihood of developing a urinary tract infection and possibly prevent some recurrent infections.