Urinary Tract Infection

Symptoms and Causes

The urinary system is normally composed of two kidneys, two ureters, a single urinary bladder and a single urethra. Urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract. UTI is the second most common type of infection in the body.

What are the symptoms of a urinary tract infection?

The symptoms of urinary tract infections may vary with severity of infection, age and location of infection in the tract.

Most Common Symptoms of urinary tract infection

• Burning or pain during urination.
• Frequency of urination and persistent urge to urinate.
• Fever and malaise.
• Foul odor and cloudy urine.

Symptoms due to infection of the urinary bladder (Cystitis)

• Lower abdomen discomfort.
• Frequent, painful urination with small amounts of urine.
• Usually low-grade fever without flank pain.
• Blood in urine.

Symptoms due to infection of upper urinary tract (Pyelonephritis)

• Upper back and flank pain.
• High grade fever with chills.
• Nausea, vomiting, weakness, fatigue and general ill-feeling.
• Mental changes or confusion in elderly people.

This is the most serious symptom of urinary tract infection as it implies systemic involvement. Inadequate and delayed treatment can be life threatening.

What are the causes of recurrent urinary tract infection?

Important causes of frequent or recurrent urinary tract infections are:

1. Urinary tract obstruction:Various underlying causes which canlead to obstruction of urinary tract.

2. Female gender: Because of shorter urethra, women are more susceptible than men to UTI.

3. Intercourse:Women who are sexually active tend to have more urinary tract infections than women who aren’t sexually active.

4. Urinary stones: Kidney, ureter or bladder stone can block the flow of urine and increases risk for UTI.

5. Urinary catheterization:People with indwelling catheters have an increased risk of UTI.

6. Congenital urinary tract anomalies:Children with congenital urinary tract anomalies such as vesicoureteral reflux (condition in which urine moves backward from the bladder up the ureters) and posterior urethral valve have an increased risk of UTI.

7. Benign prostatic hyperplasia:Men over 60 years are prone to UTI because of an enlarged prostate (benign prostatic hyperplasia - BPH).

8. Suppressed immune systems: Patients with diabetes, HIV or cancer are at higher risk for UTI.

9. Other causes: Narrowing of the urethra or ureters, tuberculosis of the genito-urinary tract, neurogenic bladder or bladder diverticulum.

Can recurrent urinary tract infection cause damage to the kidney?

Recurrent lower urinary tract infection usually does not cause damage to kidneys in adults.

UTI in adults can cause damage to the kidneys if predisposing factors such as stone, blockage or narrowing of flow of urine and tuberculosis of the genito-urinary tract are not corrected.

However, in young children, delayed or improper treatment of recurrent urinary tract infection can cause irreversible damage to the growing kidney especially in those with vesicoureteral reflux. This damage may lead to reduction of kidney function and high blood pressure later in life. So the problem of urinary tract infection is more serious in children compared to adults.

Diagnosis

Diagnosis of Urinary Tract Infection

Investigations are performed to establish diagnosis and severity of urinary tract infection. In a person with complicated or recurrent urinary tract infection different tests are performed to establish the presence of predisposing or risk factors.

Basic Investigations for Urine Tract Infection
1. Urine test

Most important screening test for UTI is routine urinalysis. Early morning urine sample is preferable for this test. In microscopic examination of urine, presence of significant white blood cells is suggestive of UTI.

Presence of white blood cells in urine suggests inflammation of the urinary tract but its absence does not exclude UTI.

Special urine dipstick (leukocyte esterase and nitrite) tests are useful screening tests for UTI that can be done at the office or home. A positive urine dipstick test suggests UTI and such patients need further evaluation. The intensity of color change is proportional to the number of bacteria in the urine.

2. Urine culture and sensitivity test

The gold standard for the diagnosis of UTI is a urine culture test and it should be done before starting antibiotic therapy. A urine culture is recommended in complicated or resistant UTI and, in a few cases, for the confirmation of the clinical diagnosis of urinary tract infection. Urine culture test results are available after 48-72 hours. The significant time delay between collection of sample and availability of the report is a major drawback of this test. Urine culture identifies the specific bacteria causing infection based on the nature of growth of the organism and the number of colony forming units that grow in the Petri dish in the laboratory. The urine culture result also includes the type of antibiotics that the organism grown may be sensitive or resistant to. This guides the doctor in the appropriate choice of antibiotic.

To avoid potential contamination of the urine sample, the patient is asked first to clean the genital area and to collect midstream urine in a sterile container. Other methods used for sample collection for urine culture are supra-pubic aspiration, catheter-specimen urine and bag specimen urine.

3. Blood tests

Blood tests usually performed in a patient with UTI include a complete blood count (CBC), blood urea, serum creatinine, blood sugar and C reactive protein.

Investigations to Identify Predisposing or Risk Factors

If the infection does not respond to treatment or if there is repetition of infections, further investigations, as mentioned below, are required to detect underlying predisposing or risk factors:

1. Ultrasound and X-rays of the abdomen.
2. CT scan or MRI of the abdomen.
3. Voiding cystourethrogram - VCUG (Micturating cystourethrogram – MCU).
4. Intravenous urography (IVU).
5. Microscopic examination of urine for tuberculosis.
6. Cystoscopy - a procedure in which a urologist (kidney surgeon) looks inside the bladder using a special instrument called a cystoscope.
7. Examination by a gynecologist.
8. Urodynamics.
9. Blood Cultures.

Prevention and Treatment

Prevention of Urinary Tract Infection

1. Drink plenty (3-4 liters) of fluids daily. Fluids dilute urine and help in flushing bacteria out of the bladder and urinary tract.
2. Urinate every two to three hours. Do not postpone going to the bathroom. Holding urine in the bladder for a long period provides opportunity for bacteria to grow.
3. Consume food containing vitamin C, ascorbic acid or cranberry juice to make urine acidic eventually reducing bacterial growth.
4. Avoid constipation or treat it promptly.
5. Women and girls should wipe from front to back (not back to front) after using the toilet. This habit prevents bacteria in the anal region from spreading to the vagina and urethra.
6. Clean genital and anal areas before and after intercourse. Urinate before and after intercourse and drink a full glass of water soon after intercourse.
7. Women should wear only cotton undergarments, which allow air circulation. Avoid tight-fitting pants and nylon underwear.
8. Recurrent urinary tract infection in women after sexual activity can be effectively prevented by taking a single dose of an appropriate antibiotic after sexual contact.

Treatment of Urinary Tract Infection
General measures

Drink plenty of water. A person who is very ill, dehydrated or unable to take adequate oral fluids due to vomiting, will need hospitalization and administration of IV fluids.

Take medications to reduce fever and pain. Use of heating pad reduces pain. Avoid coffee, alcohol, smoking and spicy foods, all of which irritate the bladder. Follow all preventive measures of urinary tract infection.

Treatment of lower urinary tract infection (cystitis, mild infections)

In a healthy young female, short term antibiotics for three days is usually enough. Some drugs need to be given for seven days to complete a course. Occasionally, a single dose of an antibiotic such as Fosfomycin can be used. Except for a previously healthy adult male who develops a cystitis for the first time, adult males with UTI require 7 to 14 days of antibiotics because of underlying structural abnormalities of the urinary tract that make them prone to infection. Commonly used oral antibiotics are nitrofurantoin, trimethoprim, cephalosporins, or fluoroquinolones. The choice of antibiotic is best determined by the sensitivity and resistance patterns of commonly used drugs in your locality.

Treatment of severe kidney infection (Pyelonephritis)

Patients with moderate-to-severe acute kidney infection, those with severe symptoms or sick patients need hospitalization. Urine and blood cultures are obtained before initiating therapy to identify causative bacteria and proper selection of antibiotics. Patients are treated with intravenous fluids and antibiotics for several days, followed by 10-14 days of oral antibiotics. If response to IV antibiotics is poor (marked by persistent symptoms and fever, worsening kidney function) imaging is indicated. Follow up urine tests are necessary to assess response to therapy.

Treatment of recurrent urinary tract infection

In patients with recurrent UTI, proper identification of the underlying cause is essential. According to the underlying cause, specific medical or surgical treatment is planned. These patients need follow-up, strict adherence to preventive measures and long term preventive antibiotic therapy.

When should a patient with UTI consult a doctor?

All children with UTI should be evaluated by a doctor. Adult patients with UTI should immediately consult a doctor when there is:

• Decrease in urine volume or total absence of urine output.
• Persistent high fever, chills, back pain and cloudy urine or blood in the urine.
• No response to antibiotics after 2 to 3 days of treatment.
• Severe vomiting, severe weakness or fall of blood pressure.
• A single kidney.
• Previous history of stones.