What is Urinary Tract Infection (UTI)?

UTI is an infection that occurs in the urinary tract; often caused by bacteria such as Escherichia coli.

UTI Epidemiology

About 60% of women suffer a UTI in their life. Symptomatic infection is more common in young women after the onset of sexual activity (20 to 50 years old).  And it is uncommon in males < 50 years old. The incidence of urinary tract infection increases in both sexes over 50 years, but the female: male ratio decreases due to the increased frequency of prostate disease in males. Why do women have a greater incidence of urinary tract infections than men? 

Women’s urethras are shorter, which makes it easier for bacteria to make their way into the body and cause infections. Women’s urethras are also located closer to their rectums which makes it easier for bacteria to travel to the urethra and gain entry into the body. In addition, urine is stagnant in women; forming a good medium for the growth of microorganisms. This is more significant with pregnant women due to the weak peristaltic movement of the urethra in pregnancy, which means more urine stagnation.

What causes Urinary Tract Infection?

Causative Organisms include:

Common organisms causing Uncomplicated UTI: Escherichia coli is responsible for 85% of UTI. 
Staph. saprophyticus 5-15%. klebsiella, proteus, pseudomonas 5-10%.

Pathophysiology of Urinary Tract Infection

Bacterial entry into the urinary tract can occur through one or more of the following routes:

  • Ascending from the urethra (mainly from the GIT; the easiest in treatment)
  • Through blood stream
  • Through the lymphatic system
  • During bladder catheterization

UTI Risk Factors include:

– Obstruction of the urinary tract (e.g. presence of kidney stones)
– Female gender
– Pregnancy
– Sexual intercourse
– Bladder catheterization (the longer it’s used, the more infection
– Diabetes mellitus
– Genitourinary malformation
– Prostatic hypertrophy in males

What are the Types of Urinary Tract Infection (UTI)?

UTI can be classified according to the section of urinary tract affected into:
Lower UTI: Cystitis (bladder) – Urethritis (urethra) – Epididymitis (epididymis)
Upper UTI: Pyelonephritis (kidney & renal pelvis), more serious

UTI is also classified into:
Uncomplicated UTI: affects mainly healthy females of age 15-45 yr
Complicated UTI:
Defined as: UTIs that are associated with metabolic disorders and anatomic or functional abnormalities that impair urinary tract drainage.
Complicating Factors include:
Immunosuppression – Urologic Structural – Functional Abnormality – Nephrolithiasis present – Recent Hospitalization – Nursing home – Catheter – Symptoms for > 7 days.Examples: Prostatitis – Renal abscesses – Pyonephrosis – Pyelonephritis – Urethritis.

Diagnosis of UTI

A-     Signs and Symptoms

Lower UTI: Dysuria, urgency, frequency, nocturia, suprapubic heaviness, gross hematuria.
Upper UTI: Flank pain, fever, nausea, vomiting, malaise.

B-      Lab Tests for UTI, including:

1-  Urinalysis, which is done through dipstick tests or microscopic examination of urine. Tests’ results and indications are stated in the map.
2-  Urine Culture & Sensitivity, which is a quantitative test that is not recommended to diagnose or verify uncomplicated UTI.

Special Conditions

A-      Asymptomatic Bacteruria (ASB)

A condition in which 2 consecutive urine cultures grow more than 100,000 colony-forming units (CFU) of bacteria/ml urine in a patient lacking symptoms of a UTI. It is common in the elderly, pregnant women, diabetic patients, and cathetarized patients. To know how to manage Asymptomatic Bacteruria, see the map above. Just click the image to enlarge it.

B-      Symptomatic cystitis in pregnancy

Should be treated and followed up similarly to ASB.

C-      UTI & Sexual Intercourse

How to prevent urinary tract infections caused by sexual intercourse?!

Nondrug therapy includes:
– Voiding immediately after sexual intercourse and before taking the prophylactic antibiotic.
– Drinking cranberry juice reduces pyuria and bacteriuria.
– Increasing total fluid intake.

Drug therapy is revealed in the map.

How to Treat Urinary Tract Infection?

Treatment Goals of UTI:

1-      Eradication of the invading microorganism
2-      Prevent recurrence of infection
3-      Resolve symptoms
4-      Avoid permanent kidney damage
5-      Avoid side effects from treatment

Antibiotics for urinary tract infection:

Uncomplicated UTI
First-line therapy for uncomplicated UTI is Trimethoprim/sulfamethoxazole 1 double strength (DS) tablet (160/800 mg) twice daily for 3 days.
Second line therapy includes:
Quinolones as Ciprofloxacin 250mg twice daily for 3 days, or
– Nitrofurantoin, amoxicillin, first-generation cephalosporin for 7 days

The treatment regimen for different types of urinary tract infections are represented in the map through the following table:

Urinary Tract Infections – Antibiotic Regimens

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