# Urinary Tract Infections: Cystitis, Pyelonephritis, and When Antibiotics Are Needed

Urinary tract infections (UTIs) are among the most common bacterial infections. They affect 50–60% of women at least once, with 20–30% experiencing recurrences. In men, UTIs are much rarer before age 50, but frequency increases with age (prostatic hypertrophy). This guide covers diagnosis, treatment, and prevention, including the antibiotic resistance challenge.

By location: Lower UTI — cystitis (bladder), urethritis (urethra). Upper UTI — pyelonephritis (kidneys). By complexity: Uncomplicated — in healthy, non-pregnant women without urinary tract abnormalities. Complicated — in men, pregnant women, with diabetes, abnormalities, catheters, immunosuppression. Recurrent — ≥2 episodes in 6 months or ≥3 in a year.

E. coli — 75–95% of uncomplicated UTIs. Staphylococcus saprophyticus — 5–15% (young sexually active women). Klebsiella, Proteus, Enterococcus — more common in complicated UTIs. Knowledge of local resistance patterns is critical for antibiotic selection.

Burning on urination (dysuria); frequent urgency (pollakiuria); incomplete emptying sensation; suprapubic pain; cloudy urine, sometimes with blood. No fever or back pain (that's pyelonephritis).

[Nitrofurantoin](/search?q=nitrofurantoin) 100 mg twice daily × 5 days — first-line in many countries. Low E. coli resistance (<5%). Not suitable with eGFR <30.

[Fosfomycin](/search?q=fosfomycin) 3 g single dose — one-dose convenience. Good activity against ESBL producers.

[Trimethoprim](/search?q=trimethoprim) 200 mg twice daily × 3 days — if local E. coli resistance <20%. Not in first trimester.

[Pivmecillinam](/search?q=pivmecillinam) 400 mg three times daily × 3–5 days — widely used in Scandinavia. High efficacy, minimal resistance impact.

[Ciprofloxacin](/search?q=ciprofloxacin) and other fluoroquinolones — NOT first-line for cystitis (FDA/EMA warnings: tendinitis, tendon rupture, neuropathy, aortic aneurysm). Reserve for pyelonephritis. [Amoxicillin](/search?q=amoxicillin) — high E. coli resistance (30–40%). Not recommended empirically.

[Phenazopyridine](/search?q=phenazopyridine) 200 mg three times daily × 2 days — urinary analgesic. Colors urine orange. Relieves dysuria until antibiotic kicks in. Generous fluid intake — helps "flush" bacteria.

Fever (>38°C), chills, flank pain (costovertebral angle tenderness), nausea/vomiting. May have cystitis symptoms. Pyelonephritis is a serious infection. Untreated → urosepsis, renal abscess.

Outpatient (mild, no vomiting): [ciprofloxacin](/search?q=ciprofloxacin) 500 mg twice daily × 7 days — fluoroquinolones ARE justified here. Inpatient (severe, vomiting, sepsis): [ceftriaxone](/search?q=ceftriaxone) 1–2 g IV daily — until culture results. Switch to oral after 48–72 hours afebrile.

Asymptomatic bacteriuria screening is MANDATORY (urine culture at first visit). Treatment mandatory (20–40% pyelonephritis risk if untreated!). Safe antibiotics: nitrofurantoin (not in third trimester), [cephalexin](/search?q=cephalexin) 500 mg three times daily × 7 days, fosfomycin. Contraindicated: fluoroquinolones, trimethoprim (first trimester).

Non-pharmacological: generous fluid intake (≥1.5 L/day — study showed 50% recurrence reduction); post-coital voiding; avoid spermicides. Pharmacological: [cranberry extract](/search?q=cranberry%20extract) (proanthocyanidins) 36 mg/day — moderate recurrence reduction. D-mannose 2 g/day. Vaginal estrogens (postmenopausal). Antibiotic prophylaxis (last resort): nitrofurantoin 50–100 mg nightly × 6–12 months; or post-coitally; or patient-initiated treatment.

E. coli fluoroquinolone resistance exceeds 20–30% in many countries. ESBL-producing E. coli — resistant to most oral antibiotics. What helps: don't treat asymptomatic bacteriuria (except pregnant women); prefer narrow-spectrum agents (nitrofurantoin, fosfomycin); don't treat "bad urinalysis" without symptoms; complete the full course.

Fever >38.5°C + back pain; no improvement after 48 hours of antibiotics; hematuria + fever; UTI in pregnancy; UTI in men; acute urinary retention; sepsis signs.

*This article is for informational purposes only and does not replace medical advice. Consult a urologist or physician before starting or changing treatment.*