Pyelonephritis - Urinary Tract Infection

Pyelonephritis is a type of urinary tract infection (UTI) that may affect either one or both kidneys. A lot of people tend to confuse pyelonephritis and cystitis, but it is imperative to mention that two conditions are very distinct. While pyelonephritis mainly involves upper urinary tract, cystitis is a variant of urinary tract infection which is confined to urinary bladder only and does not disseminate to kidneys or other organs of urinary tract.

The Urinary Tract

Urinary tract is a natural drainage system that eliminates the waste substances and excess water from the human body. The urinary tract is comprised of a pair of kidneys, two ureters, a urethra and urinary bladder. Kidneys are bean shaped organs that are located along the posterior abdominal wall, below the rib cage, each on one side of the spine. This fist sized organ filters about 200 quarts of blood on daily basis; thus producing 1-2 quarts of urine. The volume of urine produced depends on the age of patient. At an average, children produce lower volume of urine as compared to adults. Ureters are a pair of tubes that carry urine from the kidneys to the bladder where it is stored until person has the urge to urinate. Another tube called ureter is located at bottom of bladder which is responsible to expel urine out of the bladder.

Pyelonephritis: Causative Factors

It is an infection that occurs due to bacterial or viral attack on the kidney(s). Though there are different microorganisms which may cause pyelonephritis but, bacterium Escherichia coli is the primarily pathogen. The microorganisms invade into the body through urinary bladder or from other body parts via blood stream.

Pyelonephritis: Symptoms

The symptoms of Pyelonephritis are age dependent. Children with pyelonephritis will have high grade fever without any urinary tract related symptoms. Following are few symptoms which can be experienced in adults:

• Pain in back, sides and groin
• Painful urination with increased frequency

• Fever
• Chills
• Vomiting
• Nausea

Some older people will experience symptoms such as hallucinations, confusion or disordered speech rather than urinary tract symptoms.

Pyelonephritis: Risk Factors

• Bladder infection
• Anatomical disorder in the urinary tract
• Prostate enlargement
• Bladder stones
• Weak immune system
• Diabetes
• pregnancy

Any obstruction in urinary tract leads to backward flow of urine towards the kidneys which causes pyelonephritis. Vesicoureteral reflux (VUR) is a disorder in which the valve that prevents backward urine flow does not work properly. VUR is mostly diagnosed during childhood.

Pyelonephritis: Complications

Usually pyelonephritis doesn’t cause any complications but recurrent infections or anatomical abnormalities may cause scarring of kidneys which leads to hypertension, chronic kidney disease and kidney failures. If left untreated, the infection may disseminate into blood stream i.e. sepsis.

Pyelonephritis: Diagnosis

The diagnostic tests depend upon the gender, age and how patient responds to the treatment. Pyelonephritis can be diagnosed through:

• Urine culture test
• Urine analysis - it determines presence of white blood cells and bacteria in urine.
• Ultrasound - to rule out any obstruction in urinary tract
• Computerized tomography (CT) scan - determines any obstruction and is conducted when patient does not respond to treatment within 72 hours
• Voiding cystourethrogram (VCUG) - an x ray of urethra and bladder which is mostly done to detect VUR in children.
• Digital rectal examination (DRE) - a physical examination of prostate gland to rule out the doubt of prostate enlargement being responsible for urinary obstruction.
• Dimercaptosuccinic acid (DMSA) scintigraphy – it is performed to determine the severity of kidney infections, scarring, or damage.

Pyelonephritis: Treatment

Urinary tract infections are treated via antibiotics, the course can be for several weeks. Initially doctor prescribes antibiotics that are effective against common bacteria, after the culture report prescription can be switched to antibiotic that is specific for the causative agent. Depending upon the severity, antibiotics can be given orally and/or intravenously. Some might require hospitalization.

After treatment, person should be retested to make sure pathogen has been eradicated. If retesting indicates infection, a 14 - day antibiotic course is prescribed and with numerous repeated infections, course can exceed up to 6 weeks.

References

• Wing, D. A., Fassett, M. J., & Getahun, D. (2014). Acute pyelonephritis in pregnancy: an 18-year retrospective analysis. American journal of obstetrics and gynecology, 210(3), 219-e1.
• Hooton, T. M., Gupta, K., Calderwood, S. B., & Bloom, A. (2015). Acute uncomplicated cystitis and pyelonephritis in women. UpToDate. Waltham, MA: Wolters Kluwer.
• Wagenlehner, F., Umeh, O., Huntington, J., Cloutier, D., Friedland, I., & Steenbergen, J. (2014, May). Efficacy and safety of ceftolozane/tazobactam versus levofloxacin in the treatment of complicated urinary tract infections (cUTI)/pyelonephritis in hospitalised adults: results from the phase 3 aspect-cUTI trial. In 24th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), May (pp. 10-13).