# Clinical Cases: Urinary Tract Infections

## Case 1: Uncomplicated Cystitis

### Patient Presentation
**Demographics:** 28-year-old female

**Chief Complaint:** Painful urination and urinary frequency for 2 days

**History of Present Illness:**
The patient developed dysuria, urinary frequency, and urgency 2 days ago. She has mild suprapubic discomfort but denies flank pain, fever, nausea, or vaginal discharge. She is sexually active with a new partner and notes symptoms began shortly after intercourse. She has had one prior UTI 3 years ago.

**Past Medical History:**
- No significant medical history
- No allergies

**Physical Examination:**
- Blood pressure: 118/72 mmHg
- Temperature: 37.0C
- General: Well-appearing, no distress
- Abdomen: Mild suprapubic tenderness
- CVA: No tenderness bilaterally
- No vaginal discharge on external exam

### Workup and Results

**Urinalysis:**
- Leukocyte esterase: Positive
- Nitrite: Positive
- WBC: 50-100/hpf
- Bacteria: Many
- No hematuria

### Clinical Image

![Urinalysis](case_01_image.jpg)

*Urinalysis demonstrating pyuria with numerous white blood cells and bacteria, consistent with acute bacterial cystitis. The positive nitrite test suggests presence of gram-negative bacteria.*

### Diagnosis
**Uncomplicated Acute Bacterial Cystitis**

Criteria met:
- Healthy, non-pregnant woman
- Normal urinary tract anatomy
- Classic lower UTI symptoms
- No fever or flank pain (excluding upper tract involvement)

### Discussion
This case illustrates uncomplicated cystitis:

- **Definition**: The lecture defines uncomplicated UTI as occurring in a healthy, non-pregnant woman with normal urinary tract anatomy. This patient meets all criteria.

- **Pathogenesis**: The lecture describes the ascending route as the primary mechanism, with the shorter female urethra explaining the higher UTI incidence in women. Sexual activity increases risk by promoting bacterial colonization.

- **E. coli Predominance**: The lecture states that Escherichia coli causes 80-90% of uncomplicated community-acquired UTIs. The positive nitrite test supports gram-negative infection.

- **No Culture Needed**: For uncomplicated cystitis, empiric treatment without culture is appropriate. Cultures are reserved for complicated infections, treatment failure, or recurrence.

### Treatment Plan
1. **First-line Antibiotic Options:**
   - Nitrofurantoin 100 mg twice daily for 5 days (first-line)
   - OR Trimethoprim-sulfamethoxazole DS twice daily for 3 days
   - OR Fosfomycin 3 g single dose

2. **Avoid Fluoroquinolones:**
   - Reserve for complicated infections due to resistance concerns

3. **Symptomatic Relief:**
   - Phenazopyridine for dysuria (warn about orange urine)
   - Increased fluid intake

4. **Patient Education:**
   - Void after intercourse
   - Wipe front to back
   - Complete antibiotic course

### Teaching Points
1. Uncomplicated cystitis occurs in healthy, non-pregnant women with normal anatomy
2. E. coli causes 80-90% of uncomplicated UTIs
3. Culture is not required for uncomplicated cystitis
4. Nitrofurantoin or TMP-SMX are first-line treatments
5. Fluoroquinolones should be reserved for complicated infections

---

## Case 2: Acute Pyelonephritis

### Patient Presentation
**Demographics:** 35-year-old female

**Chief Complaint:** Fever, chills, and back pain for 1 day

**History of Present Illness:**
The patient developed dysuria and urinary frequency 4 days ago which she ignored. Yesterday she developed high fever (39.2C), severe rigors, nausea with vomiting, and right flank pain. She feels very ill and has been unable to tolerate oral intake.

**Past Medical History:**
- Recurrent UTIs (3 in past year)
- Otherwise healthy

**Physical Examination:**
- Blood pressure: 100/62 mmHg
- Heart rate: 112 bpm
- Temperature: 39.4C
- General: Ill-appearing, diaphoretic
- Abdomen: Mild diffuse tenderness
- CVA: Marked right costovertebral angle tenderness
- Skin: Warm, flushed

### Workup and Results

**Laboratory Studies:**
- WBC: 18,400/mcL with left shift
- Creatinine: 1.1 mg/dL
- Urinalysis: 3+ leukocyte esterase, positive nitrite, >100 WBC/hpf, WBC casts, bacteria
- Blood cultures: Pending
- Urine culture: E. coli >100,000 CFU/mL

**CT Abdomen/Pelvis:**
- Right kidney enlarged with perinephric stranding
- No abscess or obstruction
- No stones

### Clinical Image

![Pyelonephritis CT](case_01_image.jpg)

*CT scan demonstrating acute pyelonephritis with enlarged right kidney, perinephric fat stranding, and wedge-shaped areas of decreased enhancement representing areas of infection.*

### Diagnosis
**Acute Pyelonephritis (Upper Urinary Tract Infection)**

Features indicating upper tract involvement:
- Fever and systemic symptoms
- Flank pain and CVA tenderness
- WBC casts (pathognomonic for pyelonephritis)

### Discussion
This case demonstrates acute pyelonephritis:

- **Upper Tract Indicators**: The lecture emphasizes that fever distinguishes upper from lower UTI. WBC casts are pathognomonic for pyelonephritis, localizing infection to the kidney.

- **Bacteremia Risk**: The lecture notes that bacteremia occurs in 20-30% of pyelonephritis cases. Blood cultures are indicated when systemic symptoms are present.

- **Hospitalization Criteria**: This patient requires hospitalization due to inability to tolerate oral intake, severe systemic symptoms, and hemodynamic instability (tachycardia, borderline hypotension).

- **P Fimbriae**: The lecture describes how E. coli P fimbriae enable ascending infection to the kidney by binding to renal epithelium.

### Treatment Plan
1. **Admission for IV Antibiotics:**
   - Ceftriaxone 1 g IV daily
   - OR Fluoroquinolone if ceftriaxone-resistant

2. **Supportive Care:**
   - IV fluid resuscitation
   - Antipyretics
   - Antiemetics

3. **Monitoring:**
   - Repeat cultures if no improvement in 48-72 hours
   - Watch for abscess formation

4. **Transition to Oral:**
   - After afebrile 24-48 hours
   - Complete 7-10 day total course

5. **Imaging Indication:**
   - CT if no improvement in 48-72 hours (rule out abscess/obstruction)

### Teaching Points
1. Fever indicates upper tract infection (pyelonephritis)
2. WBC casts are pathognomonic for pyelonephritis
3. Bacteremia occurs in 20-30% of pyelonephritis cases
4. Hospitalize for severe symptoms, inability to tolerate oral intake, or hemodynamic instability
5. Evaluate for abscess/obstruction if no improvement in 48-72 hours

---

## Case 3: Catheter-Associated UTI (CAUTI)

### Patient Presentation
**Demographics:** 72-year-old male

**Chief Complaint:** Confusion and fever in nursing home resident

**History of Present Illness:**
The patient is a nursing home resident with chronic indwelling Foley catheter for urinary retention due to BPH. Staff noticed he has been more confused than baseline over the past day. He developed fever this morning. He has no dysuria complaint (impaired sensation), but nursing staff note cloudy, foul-smelling urine.

**Past Medical History:**
- Benign prostatic hyperplasia with urinary retention
- Dementia (moderate)
- Diabetes mellitus type 2
- Hypertension

**Medications:**
- Metformin, lisinopril, donepezil

**Physical Examination:**
- Blood pressure: 128/78 mmHg
- Heart rate: 96 bpm
- Temperature: 38.6C
- General: Confused, oriented only to self
- Lungs: Clear
- Abdomen: Soft, mild suprapubic fullness
- Foley catheter in place with cloudy, malodorous urine

### Workup and Results

**Laboratory Studies:**
- WBC: 14,800/mcL
- Creatinine: 1.3 mg/dL (baseline 1.0)
- Urinalysis: Positive leukocyte esterase, many WBC, many bacteria
- Urine culture: Proteus mirabilis 100,000 CFU/mL

### Clinical Image

![CAUTI](case_01_image.jpg)

*Diagram illustrating catheter-associated urinary tract infection with biofilm formation on the catheter surface, creating a nidus for bacterial colonization and ascending infection.*

### Diagnosis
**Catheter-Associated Urinary Tract Infection (CAUTI)**

Criteria met:
- Catheter in place >48 hours (or removed within 48 hours)
- Signs/symptoms of infection (fever, confusion)
- Positive urine culture (>10^5 CFU/mL)

### Discussion
This case illustrates CAUTI:

- **Definition**: The lecture defines CAUTI as requiring symptoms plus catheter in place for at least 48 hours (or within 48 hours of removal). Bacteriuria alone is not CAUTI without symptoms.

- **Daily Risk**: The lecture notes that bacteriuria risk increases approximately 5% per day of catheterization. After 30 days, essentially all catheterized patients have bacteriuria.

- **Atypical Presentation in Elderly**: The lecture emphasizes that UTI may present atypically in elderly patients with confusion, falls, or functional decline rather than classic dysuria and frequency.

- **Proteus and Biofilm**: Proteus species are common CAUTI pathogens. Urease production alkalinizes urine and promotes struvite encrustation on catheters.

### Treatment Plan
1. **Catheter Management (Essential):**
   - Replace or remove catheter before starting antibiotics
   - Assess need for continued catheterization

2. **Antibiotics:**
   - Empiric broad-spectrum (ceftriaxone or fluoroquinolone)
   - Narrow based on culture results
   - Duration: 7 days (10-14 if slow response)

3. **Supportive Care:**
   - IV fluids if needed
   - Monitor mental status

4. **Prevention:**
   - Remove catheter as soon as possible
   - If catheter necessary, use closed drainage system
   - Daily assessment of catheter necessity

### Teaching Points
1. CAUTI requires symptoms plus catheter in place >48 hours
2. Bacteriuria risk increases ~5% per day of catheterization
3. Catheter removal/replacement is essential for treatment success
4. Elderly may present atypically (confusion, falls, functional decline)
5. Never treat asymptomatic bacteriuria in catheterized patients

---

## Image Reference

For visual reference of UTI concepts, see:
- Radiopaedia: [Pyelonephritis](https://radiopaedia.org/articles/pyelonephritis) - Imaging findings
- Wikimedia Commons: [Urinary tract infection](https://commons.wikimedia.org/wiki/Category:Urinary_tract_infections) - Pathology
- Radiopaedia: [CAUTI](https://radiopaedia.org/articles/catheter-associated-urinary-tract-infection) - Overview

---

## Learning Points

1. **Uncomplicated UTI**: Healthy, non-pregnant woman; empiric treatment without culture

2. **Fever = Upper Tract**: Fever distinguishes pyelonephritis from cystitis

3. **WBC Casts = Pyelonephritis**: Pathognomonic finding localizing infection to kidney

4. **CAUTI Definition**: Symptoms + catheter >48 hours; always remove/replace catheter

5. **Do Not Treat ASB**: Asymptomatic bacteriuria treatment indicated only in pregnancy and before urologic procedures