Urinary Tract Infection, Upper (Pyelonephritis)

CHAPTER 86

Urinary Tract Infection, Upper

(Pyelonephritis)

Presentation

The patient (usually a woman between 18 and 40 years of age) has some combination of urinary frequency, urgency, dysuria, malaise, flank pain, nausea, vomiting, fever (>102° F), and chills that have been progressive over several days.

On physical examination, the patient is febrile and may be ill appearing and tachycardic. There is tenderness elicited by percussing the costovertebral angle over one or both of the kidneys and mild to moderate lateral abdominal and suprapubic tenderness without rebound. The urinalysis may help establish the diagnosis with pyuria, bacteriuria, and possibly tubular casts of white blood cells (WBCs).

What To Do:

Examine the urine using a Gram stain to look for gram-positive cocci (presumably enterococci) or the more usual gram-negative rods, and send for urinalysis culture and sensitivity (urine cultures should be obtained before initiation of antibiotic therapy).

Obtain blood cultures before beginning therapy, if blood cultures are thought to be necessary (see Discussion later). Other blood tests that may be helpful include a complete blood count, serum electrolytes, serum creatinine, and blood urea nitrogen (BUN).

If the patient appears toxic, with a high fever, high white count, nausea, or vomiting (preventing adequate oral medication and hydration); is immunocompromised (i.e., diabetes mellitus, cancer, sickle cell disease, human immunodeficiency virus (HIV), transplant patients); is pregnant; or shows signs of urinary obstruction or underlying anatomic urinary tract abnormality, she should be admitted to the hospital for IV antibiotics. Other indications for inpatient management include failed outpatient management, progression of uncomplicated UTI, renal failure, suspected urosepsis, age older than 60 years of age, poor social situation, and inadequate access to follow-up. After cultures are obtained, begin ceftriaxone (Rocephin), 1 g IV, ciprofloxacin (Cipro), 400 mg IV, or levofloxacin (Levaquin), 500 mg IV.

For stable, otherwise healthy patients with pyuria of greater than 15 WBCs/hpf, start with a first dose of oral antibiotics in the emergency department or clinic. Prescribe ciprofloxacin 500 mg PO bid or ciprofloxacin extended release (Cipro XR), 1000 mg qd × 7 to 14 days. Alternatively, prescribe levofloxacin (Levaquin), 500 mg qd × 7 to 14 days, gatifloxacin (Tequin), 400 mg qd × 7-14 days, or, if the local resistance of uropathogens to trimethoprim-sulfamethoxazole (TMP/SMX) is less than 20%, TMP/SMX [160/800 mg] (Bactrim DS), one bid × 14 days.

Instruct outpatients to return for reevaluation in 24 to 48 hours or sooner if symptoms worsen. Most patients improve on this regimen, but others will require hospital admission if they do not improve in 2 days.

All pregnant patients with pyelonephritis should be hospitalized for at least 24 hours and given IV antibiotics and hydration. Ceftriaxone, 1 g IV, can be started after blood cultures are drawn.

Treatment of pyelonephritis in patients with urinary catheters requires replacement of the catheter as well as the initiation of ampicillin, 1000 mg, plus gentamicin, 1.5 mg IV q8 hours, or levofloxacin (Levaquin), 750 mg IV qd, and hospitalization.

What Not To Do:

Do not forget a pregnancy test in women of childbearing age, and do not give aminoglycosides or fluoroquinolones in pregnancy.

Do not lose the patient to follow-up. Although lower urinary tract infections (UTIs) often resolve without treatment, upper UTIs that are inadequately treated can lead to renal damage or sepsis.

Do not miss a diagnosis of pyelonephritis in the absence of fever when other signs and symptoms are present. An elderly person may have few signs or symptoms other than increased confusion and/or lethargy.

Do not miss an infection above a ureteral stone or obstruction. Cramps, colicky pain, or hematuria with the symptoms listed earlier calls for sonography or unenhanced spiral computed tomography. Antibiotics and hydration alone may not cure an infected obstruction.

Discussion

Most renal parenchymal infections occur secondary to bacterial ascent through the urethra and urinary bladder. In men, prostatitis and prostatic hypertrophy, causing urethral obstruction, predispose to bacteriuria. Hematogenous acute pyelonephritis occurs most often in debilitated chronically ill patients and those receiving immunosuppressive therapy. In more than 80% of cases of acute pyelonephritis, the etiologic agent is Escherichia coli. Other etiologic organisms include aerobic gram-negative bacteria, Staphylococcus saprophyticus, and enterococci. In elderly patients, E. coli is a less common (60%) cause of acute pyelonephritis. The increased use of catheters and instruments among those patients predisposes them to infections with other gram-negative organisms such as Proteus, Klebsiella, Serratia, or Pseudomonas.

Patients who have diabetes mellitus tend to have infections caused by Klebsiella, Enterobacter, Clostridium, or Candida. They also are at an increased risk for developing emphysematous pyelonephritis and papillary necrosis, leading to shock and renal failure.

Although oral antibiotics are usually sufficient treatment for upper UTIs, there is a significant incidence of renal damage and sepsis as sequelae, mandating good follow-up or admission for IV therapy when necessary. By the same token, lower UTIs can ascend into upper UTIs, or it can be difficult to decide the level of a given UTI, in which case it should be treated as an upper UTI.

In general, the diagnosis of acute pyelonephritis should not be made if flank pain and fever are not present. One should be alert for alternative diagnoses, including pelvic inflammatory disease, lower lobe pneumonia, perforated viscus, the prodrome of herpes zoster, cholecystitis, acute appendicitis, and diverticulitis. However, up to one third of elderly patients with acute pyelonephritis have no fever; in 20% of elderly patients, the predominant symptoms are gastrointestinal or pulmonary.

Hospitalization is generally recommended for pregnant patients with pyelonephritis because of the risk for serious complications to the mother and fetus; however, outpatient therapy may be appropriate for select patients at less than 24 weeks of gestation.

Because urine culture frequently identifies the responsible organism, it is unclear whether blood cultures alter therapy in the management of pyelonephritis. Therefore some authorities believe that not obtaining blood cultures in immunocompetent, nonpregnant adults with apparently uncomplicated pyelonephritis is within the standard of care. Some say the use of blood cultures should be reserved for patients with an uncertain diagnosis, those who are immunocompromised, and those who are suspected of having hematogenous infection.