Comprehensive Medical Lecture Notes: Urinary Tract Infection (UTI)

 

🔬 Comprehensive Medical Lecture Notes: Urinary Tract Infection (UTI)

A complete, well-explained, medical-student friendly guide

 

📌 Introduction

Urinary Tract Infection (UTI) is one of the most common bacterial infections encountered in clinical practice. It affects the urinary system including urethra, bladder, ureters, and kidneys. UTI is seen in all age groups, but particularly common in women due to anatomical factors.

This lecture note explains UTI in a clear, step-by-step teaching style—covering definitions, causes, mechanisms, clinical features, investigation, complications, and evidence-based learning pearls. Designed for medical students to understand, remember, and apply easily.

 

🧠 Quick Anatomy Recap

Understanding UTI starts with knowing how the urinary system works:

• Kidneys → filter blood & produce urine
• Ureters → carry urine to bladder
• Bladder → stores urine
• Urethra → passage for urine to exit

Most UTIs begin at the urethra and ascend upward (ascending infection).

 

🔍 Classification of UTI

UTI can be classified based on anatomical location:

• Urethritis → infection of urethra
• Cystitis → infection of bladder (most common form)
• Pyelonephritis → infection of kidney (serious)

Based on complication risk:

• Uncomplicated UTI → healthy, non-pregnant female
• Complicated UTI → pregnancy, diabetes, male, stones, obstruction, catheter

 

🦠 Causative Organisms

• E. coli → 75–90% (most common)
• Klebsiella
• Proteus (stone-forming)
• Pseudomonas (catheter-related)
• Enterococcus

E. coli dominates because it has fimbriae that help it adhere to uroepithelium.

 

⚠ Risk Factors for UTI

• Poor perineal hygiene
• Sexual intercourse
• Use of diaphragm/spermicides
• Pregnancy
• Diabetes mellitus
• Urinary obstruction (stone, BPH)
• Catherization
• Low fluid intake
• Post-menopausal changes

 

🔬 Pathophysiology (Easy Explanation)

Most UTIs occur through the ascending route:

1. Bacteria enter urethra
2. Move up to bladder → causes cystitis
3. If untreated → ascend to kidneys → pyelonephritis

Why women get more UTIs?

• Shorter urethra
• Closer to anus → E. coli proximity
• Sexual activity introduces bacteria

 

🩺 Clinical Features

🔸 Symptoms of Lower UTI (Cystitis):

• Dysuria (pain during urination)
• Frequency
• Urgency
• Suprapubic pain
• Cloudy or foul-smelling urine

🔸 Symptoms of Upper UTI (Pyelonephritis):

• Fever (>38°C)
• Flank pain
• Nausea/vomiting
• CVA tenderness
• Malaise

 

🔎 Investigations

✔ Urinalysis (R/M/E)

• WBC ↑ (pyuria)
• Nitrite positive → gram-negative bacteria
• Leukocyte esterase positive
• Bacteria visible on microscopy

✔ Urine Culture (GOLD STANDARD)

Indicated for:

• Pregnancy
• Recurrent UTI
• Complicated UTI
• Pyelonephritis

✔ Imaging

• USG KUB → obstruction, stones
• CT → complicated cases

 

⚠ Complications

• Pyelonephritis
• Sepsis
• Renal abscess
• Preterm labor (in pregnancy)
• Recurrent UTI

 

💡 Prevention Tips (High Yield)

• Increase hydration
• Urinate after intercourse
• Avoid tight undergarments
• Proper perineal hygiene
• Avoid holding urine for long time

 

📚 Summary Table

Topic	Key Points
Common organism	E. coli (75–90%)
Lower UTI features	Dysuria, frequency, urgency
Upper UTI features	Fever, CVA tenderness
Gold standard test	Urine culture

 

✨ UTI Lecture Completed — Designed for Medical Students

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