Pyelonephritis

Background

Definitions

• UTI = significant bacteriuria in presence of symptoms
  • Described by location: urethritis, cystitis, or pyelonephritis

Genitourinary infection

(1) Human urinary system: (2) kidney; (3) renal pelvis; (4) ureter; (5) urinary bladder (6) urethra.
Additional structures: (7) adrenal gland; (8) renal artery and vein; (9) inferior vena cava; (10) abdominal aorta; (11) common iliac artery and vein; (12) liver; (13) large intestine; (14) pelvis.

"UTI" frequently refers specifically to acute cystitis, but may also be used as a general term for all urinary infections; use location-specific diagnosis.

• Renal/perirenal
  • Pyelonephritis
    • Emphysematous pyelonephritis
  • Renal abscess
  • Perinephric abscess
• Ureteral
  • Infected urolithiasis
• Bladder
  • Acute cystitis ("UTI")
  • Chronic cystitis
• Urethra/periurethra
  • Urethritis
  • Prostatitis

Clinical Features

Diagram showing the typical location of pain

• Pyelo = Cystitis symptoms AND fever/chills/nausea/vomiting
  • CVAT alone may be referred pain from cystitis
  • CVAT is only physical examination finding that increases likelihood of a UTI

Complications

• Acute bacterial nephritis
  • CT shows ill-defined focal areas of decreased density
• Renal/Perinephric abscesses
  • Sign/symptoms similar to pyelo (fever, CVAT, dysuria)
  • Occurs in setting of ascending infection with obstructed pyelo
  • Associated with DM and Renal Stones
  • Also occurs due to bacteremia with hematogenous seeding (Staph)
• Emphysematous pyelonephritis
  • Rare gas-forming infection nearly always occurring in patients with DM and obstruction
    • Patients appear toxic and septic; nephrectomy may be required

Differential Diagnosis

Major

• Acute cystitis
• Infected kidney stone

Flank Pain

• Vascular
  • Abdominal aortic aneurysm
  • Renal artery embolism
  • Renal vein thrombosis
  • Aortic dissection
  • Mesenteric ischemia
• Renal
  • Pyelonephritis
  • Papillary necrosis
  • Renal cell carcinoma
  • Obstructive uropathy
    • May or may not be due to nephrolithiasis
  • Renal infarction
  • Renal hemorrhage
• Ureter
  • Nephrolithiasis
  • Blood clot
  • Stricture
  • Tumor (primary or metastatic)
• Bladder
  • Tumor
  • Varicose vein
  • Cystitis
• GI
  • Biliary colic
  • Pancreatitis
  • Perforated peptic ulcer
  • Appendicitis (appendix may be pushed to RUQ in pregnancy)
  • Inguinal Hernia
  • Diverticulitis
  • Cancer
  • Bowel obstruction
• Gynecologic
  • Ectopic Pregnancy
  • PID/TOA
  • Ovarian cyst
  • Ovarian torsion
  • Endometriosis
• GU
  • Testicular torsion
  • Epididymitis
• Other
  • Shingles
  • Lower lobe pneumonia
  • Retroperitoneal hematoma/abscess/tumor
  • Epidural abscess
  • Epidural hematoma
  • Rib contusion/fracture

Dysuria

• Genitourinary infection
  • Acute cystitis ("UTI")
  • Pyelonephritis
  • Urethritis
  • Chronic cystitis
  • Infected nephrolithiasis
  • Prostatitis
  • Epididymitis
  • Renal abscess/perinephric abscess
  • Emphysematous pyelonephritis
• Nephrolithiasis
• Urethral issue
  • Urethritis
  • Urolithiasis
  • Urethral foreign body
  • Urethral diverticulum
  • Allergic reaction (contact dermatitis)
  • Chemical irritation
  • Urethral stricture or obstruction
  • Trauma to vagina, urethra, or bladder
• Gynecologic
  • Vaginitis/cervicitis
  • PID
  • Genital herpes
  • Pelvic organ prolapse
  • Fistula
  • Cystocele
• Other
  • Diverticulitis
  • Interstitial cystitis
  • Behavioral symptom without detectable pathology

Evaluation

Urine with pyuria.

Acute pyelonephritis with increased cortical echogenicity and blurred delineation of the upper pole.

Workup

• Urinalysis
• Urine culture
• Consider imaging (CT or ultrasound) if any of the following:
  • History of Renal Stone
  • Poor response to antibiotics
  • Male
  • Elderly
  • Diabetic
  • Severely ill

Blood cultures are NOT indicated (organisms in blood culture matched those in urine culture 97% of time)

Diagnosis

• Urinalysis
  • Clumps and/or high WBCs
  • Nitrite
    • Very high specificity (>90%) in confirming diagnosis of UTI
    • Low sensitivity (enterococcus, pseudomonas, acinetobacter are not detected)

Management

Antibiotics

Treatment is targeted at E. coli, Enterococcus, Klebsiella, Proteus mirabilis, S. saprophyticus.

Outpatient

Consider one dose of Ceftriaxone 1g IV or Gentamycin 7mg/kg IV if the regional susceptibility of TMP/SMX or Fluoroquinolones is <80%

• Ciprofloxacin 500mg PO BID x7 days OR
• Trimethoprim-Sulfamethoxazole DS 160/800mg PO BID x14 days OR
• Cephalexin 500mg QID PO x 10-14 days (OR consider 1000mg BID if difficulty with QID regimen) OR
• Cefdinir 300mg BID PO x 10-14 days OR
• Cefpodoxime 200mg PO BID x 10 days OR
• Cefixime 400mg PO daily x 10 days OR
• Levofloxacin 750mg PO QD x7 days

Adult Inpatient Options

• Ciprofloxacin 400mg IV q12hr OR
• Ceftriaxone 1gm IV QD (Preferred in pregnancy) OR
• Cefotaxime 1-2gm IV q8hr OR
• Gentamicin 3mg/kg/day divided q8hr +/- ampicillin 1–2 gm q4hr OR
• Piperacillin/Tazobactam 3.375 gm IV q6hr OR
• Cefepime 2gm IV q8hr OR
• Imipenem 500mg IV q8hr

Pediatric Inpatient Options

• Ceftriaxone 75mg/kg IV QD OR
• Cefotaxime 50mg/kg IV q8hrs OR
• Ampicillin 25mg/kg IV q6hrs + Gentamicin 2.5mg/kg IV q8hrs

Disposition

• Discharge
  • Consider if young, otherwise healthy, tolerating PO
• Consider admission if:
  • Elderly (>60)
  • Renal Calculi
  • Obstruction
  • Recent hospitalization/instrumentation
  • DM
  • Immunocompromised
  • Unable to tolerate PO
  • Pregnancy
  • Solitary kidney or other anatomic abnormality

Disposition

• Admit all second trimester pregnant patients with OBGYN consult
• Urology consult during the inpatient admission for pediatric patients due to the risk for urologic scarring
• Consider advanced imaging to rule out abscess of urolithiasis if patient has failed 3 days of therapy

Special Populations

Elderly

• Elderly patients with pyelonephritis: 20% present with primary respiratory or GI symptoms. Also 33% are afebrile.

See Also

• Urinary tract infections
• Dysuria