Diagnosis and management of acute pyelonephritis in adults
Overview
Pyelonephritis is bacterial infection of the renal parenchyma. Affecting one or both kidneys. Also called acute infective tubulointerstitial nephritis.
Pathophysiology includes infection spreads from the bladder to the ureters to the kidneys, commonly through vesicoureteral reflux. Vesicoureteral reflux may result from congenital weakness at the junction of the ureter and bladder. Bacteria refluxed to intrarenal tissues may create colonies of infection within 24 to 48 hours. Female anatomy allows for higher incidence of infection. Causes are bacterial infection of the kidneys. Escherichia coli the most common colonized organism. Microorganisms the same as those that cause lower urinary tract infection (UTI).
Diagnosis
Laboratory
Urinalysis and culture and sensitivity testing reveal pyuria, significant bacteriuria, low specific gravity and osmolality, and slightly alkaline urine pH, or proteinuria, glycosuria, and ketonuria (less frequent). White blood cell count, neutrophil count, and erythrocyte sedimentation rate are increased.
Imaging
Kidney-ureter-bladder radiography reveals calculi, tumors, or cysts in the kidneys or urinary tract. Excretory urography shows asymmetrical kidneys, possibly indicating a high frequency of infection.
Management
General
Identification and correction of predisposing factors for infection, such as obstruction or calculi, short courses of therapy for uncomplicated infections, rest and increased fluid intake and 7 to 14-day course of antibiotics (I.V. or oral fluoroquinolone is drug of choice), urinary analgesics such as phenazopyridine (Urisept) and antipyretics as needed.
Oral agents for acute uncomplicated non-pregnant cases
Preferred agents are fluoroquinolones (if community E. coli resistance rate < 10%) such as ciprofloxacin 500 mg orally twice daily for 7 days or levofloxacin 750 mg orally daily for 7 days. Trimethoprim-Sulfamethoxazole (Septin DS) twice daily for 14 days. Alternative agents (higher resistance rates, accompany with initial dose of a broad-spectrum IV antibiotic) like amoxicillin-clavulanate (Augmentin) twice daily for 10-14 days, cefixime (Suprax) 400 mg orally daily for 10-14 days, cefpodoxime 200 mg orally twice daily for 10-14 days or cephalexin (Keflex) 500 mg orally twice daily for 10-14 days.
Consider a single initial dose of IV antibiotics if emesis or community antibiotic resistance > 10%, ceftriaxone 1-2 g IV or ertapenem (Invanz) 1 g IV or gentamicin 5 mg/kg IV. Treatment course for acute pyelonephritis cases is 7 days for uncomplicated pyelonephritis. Fluoroquinolones course is typically 7 days in all pyelonephritis cases. Course 10-14 days is usually for complicated pyelonephritis, urinary tract obstruction, male gender and immunosuppression. Beta-Lactams (Augmentin, Cephalosporins) course is typically 10-14 days. Trimethoprim-Sulfamethoxazole course is typically 14 days. Do NOT use nitrofurantoin (Uvamin) or fosfomycin (Monuril) due to inadequate renal penetration to treat pyelonephritis.
IV agents in non-pregnant cases
Convert from IV to oral in first 48-72 hours. Preferred agents for patients at low risk for bacterial resistance are ciprofloxacin (Ciprocin) 400 mg IV every 12 hours or levofloxacin (Tavanic) 750 mg IV every 24 hours or ceftriaxone (Rocephin) 1 to 2 g IV every 24 hours. For patients at high risk for multi-drug bacterial resistance are ertapenem 1 g IV every 24 hours or meropenem (Meronem) 1 g IV every 8 hours or piperacillin-tazobactam (Tazocin) 3.375 to 4.5 g IV every 6 hours or cefepime 2 g IV every 12 hours or imipenem/Cilastin (Tienam) 500 mg every 6 hours. Alternative regimen is gentamicin 5 mg/kg IV every 24 hours.
References
- National Institute of Diabetes & Digestive & Kidney Diseases: www.niddk.nih.gov.
- Am Fam Physician. 2005 Mar 1;71(5):933-942. Available at: https://www.aafp.org/afp/2005/0301/p933.html.
- American Association of Kidney Patients: www.aakp.org.
