URINARY TRACT INFECTIONS: ACUTE PYELONEPHRITIS

Pyelonephritis is an inflammation of the kidney that is almost always caused by urinary tract infection ascending from the bladder. As with uncomplicated cystitis, pyelonephritis can be classified as uncomplicated if it occurs in a young, healthy non-pregnant woman. Most cases of pyelonephritis occur in women with normal urinary tracts. The causative organisms in pyelonephritis are similar to those in cystitis except that S. saprophyticus is less common.

The distinction between cystitis and pyelonephritis is often indiscernible in the clinical setting. Investigational radiologic studies have shown that subclinical upper urinary tract infections occur in about one third of patients who otherwise seem to have uncomplicated cystitis.

Symptoms

It is important to remember that pyelonephritis can occur without symptoms of lower urinary tract infection. This may be a more common presentation in initial UTI, since patients may ignore mild dysuria.

Typical symptoms of pyelonephritis include the following:

• Unilateral back/flank/abdominal pain

• Fever

• Nausea

• Emesis

• Lower urinary tract symptoms (may not be present)

Urinalysis

Urinalysis in cases of pyelonephritis is similar to that in cystitis: pyuria, hematuria, bacteriuria, and nitrite. In cases of pyelonephritis, white blood cell casts may also be found.

Culture

Unlike for cystitis, urine culture with antibiotic susceptibility testing should always be performed in cases of pyelonephritis. Although complications are not common, they are more likely to occur if treatment is inadequate. Complications include renal scarring and, rarely, chronic renal failure. Typically, colony counts are higher (>100,000 CFU/ml) than those in cystitis. However, up to 20% of cases have counts less than 10,000.

Blood Testing

Most patients with pyelonephritis do not require blood testing, but in toxic-appearing patients or those who are hospitalized, complete blood cell count and two sets of blood cultures should be performed. Blood culture findings are positive in 12% to 20% of pyelonephritis cases. Bacteremia in pyelonephritis does not alter treatment or outcome, however.

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URINARY TRACT INFECTIONS: ACUTE PYELONEPHRITISPyelonephritis is an inflammation of the kidney that is almost always caused by urinary tract infection ascending from the bladder. As with uncomplicated cystitis, pyelonephritis can be classified as uncomplicated if it occurs in a young, healthy non-pregnant woman. Most cases of pyelonephritis occur in women with normal urinary tracts. The causative organisms in pyelonephritis are similar to those in cystitis except that S. saprophyticus is less common.The distinction between cystitis and pyelonephritis is often indiscernible in the clinical setting. Investigational radiologic studies have shown that subclinical upper urinary tract infections occur in about one third of patients who otherwise seem to have uncomplicated cystitis.
SymptomsIt is important to remember that pyelonephritis can occur without symptoms of lower urinary tract infection. This may be a more common presentation in initial UTI, since patients may ignore mild dysuria.Typical symptoms of pyelonephritis include the following:• Unilateral back/flank/abdominal pain• Fever• Nausea• Emesis• Lower urinary tract symptoms (may not be present)
UrinalysisUrinalysis in cases of pyelonephritis is similar to that in cystitis: pyuria, hematuria, bacteriuria, and nitrite. In cases of pyelonephritis, white blood cell casts may also be found.
CultureUnlike for cystitis, urine culture with antibiotic susceptibility testing should always be performed in cases of pyelonephritis. Although complications are not common, they are more likely to occur if treatment is inadequate. Complications include renal scarring and, rarely, chronic renal failure. Typically, colony counts are higher (>100,000 CFU/ml) than those in cystitis. However, up to 20% of cases have counts less than 10,000.
Blood TestingMost patients with pyelonephritis do not require blood testing, but in toxic-appearing patients or those who are hospitalized, complete blood cell count and two sets of blood cultures should be performed. Blood culture findings are positive in 12% to 20% of pyelonephritis cases. Bacteremia in pyelonephritis does not alter treatment or outcome, however.*144/348/5*

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