Urinary Tract Infection: Symptoms, Causes & Treatment

Urinary tract infections (UTIs) are among the most prevalent bacterial infections worldwide, second only to respiratory tract infections in community settings. Women are disproportionately affected — short urethra and its proximity to the rectum facilitate bacterial colonization — with 50–60% experiencing at least one UTI in their lifetime and 25–30% having recurrent infections. UTIs are anatomically classified as lower (cystitis, urethritis) or upper (pyelonephritis), and clinically as uncomplicated (healthy, non-pregnant women with normal urinary tracts) or complicated (men, pregnancy, structural abnormalities, immunocompromise, catheterization).

Most uncomplicated UTIs arise from ascending colonization by intestinal flora, predominantly Escherichia coli (80%), followed by Klebsiella pneumoniae, Enterococcus faecalis, and Staphylococcus saprophyticus (especially in young women). Uropathogenic E. coli express virulence factors — type 1 and P fimbriae — enabling adherence to uroepithelial cells and intracellular biofilm formation, explaining recurrence despite antibiotic therapy.

While antibiotics remain the cornerstone of treatment, rising antimicrobial resistance — including fluoroquinolone resistance and ESBL-producing E. coli — mandates culture-guided therapy and stewardship principles. For uncomplicated cystitis, nitrofurantoin and trimethoprim-sulfamethoxazole remain first-line in most regions.

• Dysuria: burning or pain during urination
• Urinary frequency and urgency with small volumes passed
• Suprapubic pain or pressure
• Cloudy, malodorous, or haematuria-stained urine
• Pyelonephritis: fever >38°C, rigors, flank pain, nausea, and vomiting (upper tract involvement)

• E. coli ascending from the perineum — responsible for ~80% of uncomplicated UTIs
• Short female urethra facilitating bacterial migration to the bladder
• Sexual intercourse displacing periurethral bacteria (honeymoon cystitis)
• Urinary catheterization (catheter-associated UTI — CAUTI)
• Postmenopausal urogenital atrophy reducing mucosal defenses
• Urolithiasis, obstruction, or benign prostatic hyperplasia trapping bacteria

• Female sex: Women are 10 times more likely to develop UTIs compared to men due to the short urethra anatomy.
• Menopause: Decreased estrogen reduces local immune response in the urinary tract.
• Pregnancy: Physiological and hormonal changes during pregnancy increase infection risk.
• Diabetes: High blood sugar in urine provides an ideal environment for bacterial growth.
• Weakened immunity: Patients with HIV or taking immunosuppressive medications are at higher risk.
• Chronic kidney disease: Kidney failure and urinary stones increase infection risk.
• Long-term catheter use: Both men and women using long-term urinary catheters face significant risk.
• Urinary incontinence: Inability to control urination may lead to urine retention in the bladder.
• Family history: There may be genetic factors increasing susceptibility.
• Chronic constipation: May affect bladder and urethral function.

Urinalysis showing pyuria (leukocyte esterase or >5 WBC/hpf) and bacteriuria confirms the diagnosis in the right clinical context. Urine culture (midstream clean catch) is essential before treatment in complicated UTIs, recurrent infections, or suspected pyelonephritis to identify the pathogen and antibiotic sensitivities. Ultrasound or CT urography is indicated for upper tract disease or suspected structural abnormalities.

Uncomplicated cystitis: 5–7 days nitrofurantoin or 3-day trimethoprim-sulfamethoxazole guided by local resistance patterns. Fosfomycin single dose is an alternative. Pyelonephritis: 7–14 days oral fluoroquinolone (if susceptible) or IV cephalosporins for severe/hospitalized cases. Recurrent UTIs (≥3/year): low-dose prophylactic antibiotics, post-coital prophylaxis, or intravaginal estrogen in postmenopausal women. D-mannose and cranberry prophylaxis have modest evidence.

• Ascending pyelonephritis from untreated or undertreated cystitis
• Urosepsis — bacteraemia and septic shock in severe upper tract infection
• Renal scarring and chronic kidney disease from recurrent pyelonephritis
• Preterm labor and low birth weight in untreated bacteriuria during pregnancy

• Adequate daily fluid intake (≥1.5–2 L) to maintain urinary flush
• Void promptly and completely; void after sexual intercourse
• Wipe front-to-back after urination and defecation
• Avoid spermicides and irritating genital hygiene products
• Postmenopausal women: consider topical vaginal estrogen