Definition
A.Pyelonephritis is an acute infection and inflammatory disease of the upper urinary tract (renal pelvis, tubules, and interstitial tissue) of one or both kidneys. Acute pyelonephritis is an ascending urinary tract infection (UTI) that has progressed from the lower urinary tract.
B.Fever has been strongly correlated with the diagnosis of acute pyelonephritis; therefore, patients with clinical symptoms of pyelonephritis in the absence of fever should be evaluated for alternative diagnoses.
C.Acute pyelonephritis characteristically causes some scarring to the kidney and may lead to significant damage, kidney failure, abscess formation, and sepsis. Antibiotic therapy is essential to prevent the progression of pyelonephritis.
Incidence
A.Thirty percent of the female population has at least one UTI in their lifetime. Males demonstrate a gradual increase at age 35 and peak at 85 years old.
B.Annual rates of pyelonephritis in women are 15 to 17 cases per 10,000 and three to four cases per 10,000 for men.
C.The incidence of acute pyelonephritis in pregnancy is 20% to 30%. Most cases develop as a consequence of undiagnosed or inadequately treated lower UTI.
D.Upper UTIs are less common and more serious than lower tract infections. After puberty, the prevalence of UTIs increases slightly in females but remains low in males.
E.After age 65, UTIs are more common, with an equal incidence in both sexes.
F.Rates of bacteremia vary widely. Rates depend on host factors and are higher among patients who are severely ill, who are immunocompromised, who have an urinary tract obstruction, and who are 65 years of age or older.
Pathogenesis
A.Pyelonephritis is caused by ascending infection from the bladder usually caused by Escherichia coli (75%–95%) and other gram-negative bacteria including Proteus mirabilis (1%–2%), Klebsiella pneumoniae (1%–2%), Enterobacter (< 1%), and Group B Streptococcus (GBS: <1%). Grampositive causative agents are less common; 10% to 15% of cases are caused by Staphylococcus saprophyticus.
B.Bacteria can also reach the kidneys through the bloodstream from IV drug abuse and endocarditis.
C.In women, the short urethra in close proximity to the perirectal area makes colonization possible. In pregnancy, the increased glycosuria, increase in urinary amino acids, urinary stasis, and the presence of vesicoureteral reflux facilitate bacterial growth.
D.In men, benign prostatic hyperplasia (BPH) causing bladder obstruction is a common pathology.
E.Indwelling catheters increase ascending infections and pyelonephritis.
Predisposing Factors
A.Previous UTI, cystitis, and pyelonephritis.
B.Sickle cell disease.
C.Diabetes.
D.Urinary catheterization.
E.Obstruction: Calculi, tumors, and urethral strictures.
F.Neurogenic bladder disease: Strokes, multiple sclerosis (MS), and spinal cord injuries.
G.Urinary reflux.
H.HIV.
I.Trauma.
J.Chronic constipation/fecal impaction.
K.Incomplete bladder emptying related to medications (e.g., anticholinergics).
L.Gender:
1.Females:
a.Increased sexual activity, failure to void after intercourse, diaphragms, and nonoxynol-9 spermicide.
b.Pregnancy.
c.Atrophic vaginal mucosa predisposes to the colonization of pathogens and UTIs.
d.Cystocele.
2.Males:
a.Homosexuality.
b.Sexual partner with colonization.
c.Obstruction: Prostatic hyperplasia.
d.Age 50 years or older.
e.Acute or chronic bacterial prostatitis.
Common Complaints
A.Shaking, chills, and fever (fever is not always present).
B.Flank pain or tenderness.
C.Urinary frequency or urgency.
D.costovertebral angle (CVA) tenderness (may be mild, moderate, or severe).
E.Guarding.
F.Urinary frequency, nocturia, hematuria, and dysuria (up to 20% of patients do have bladder present in upper tract infections).
G.Gross hematuria (hemorrhagic cystitis) occurs in 30% to 40% of females; however, gross hematuria is unusual in males with pyelonephritis.
H.Malaise.
Other Signs and Symptoms
A.Adults (particularly the elderly) may be asymptomatic with cystitis.
B.Abdominal pain and suprapubic heaviness.
C.Pregnancy: Uterine contractions.
D.Shortness of breath (SOB).
E.Anorexia.
F.Elderly:
1.Fever.
2.Mental status change.
3.Generalized deterioration.
4.Decompensation in another organ system.
Subjective Data
A.Review the onset, course, and duration of symptoms.
B.Are there any problems with voiding, such as frequency, urgency, and dysuria?
C.Review the patient’s history of fever and any treatment.
D.Are there any other symptoms, odor, or nausea?
E.Have the patient point to the area of the backache. Is it unilateral or bilateral? What makes the backache better?
F.In women, rule out pregnancy; review first day of last menses.
G.Rule out sickle cell disease, diabetes, and MS.
H.Review the patient’s previous history of genitourinary (GU) tract problems, stones, UTIs, previous pyelonephritis, any previous testing, and any previous anomalies.
I.Review the strength and character of the urinary stream, especially in older men. Ask if the man has ever been diagnosed with BPH.
J.Review the patient’s history for active herpes lesion. Does urine flow hurt when urine stream begins? Or is the pain noted when urine passes over the lesion?
K.Review drug allergies.
L.Review all medications including over-the-counter (OTC) and herbal products. Review medications for a recent history of an incomplete course of antibiotics and current use of anticholinergics.
Physical Examination
Clinical presentations and disease severity vary widely, from mild flank pain with low-grade or no fever to septic shock.
A.Check temperature, pulse, and blood pressure (BP); note orthostatic hypotension. Tachycardia may or may not be present, depending on associated fever, dehydration, and sepsis.
B.Inspect:
1.Note general appearance for respiratory distress and dehydration.
2.Inspect the male external genitalia for redness, edema, lesions, and discharge.
3.Inspect the female genitalia for discharge, lesions, and fissures; inspect cervix for cervicitis.
C.Palpate:
1.Palpate the back; check CVA tenderness (usually unilateral over the involved kidney).
2.Palpate the abdomen for suprapubic tenderness, rebound masses, or pain.
3.Perform a pelvic examination to rule out other infections and pelvic inflammatory disease (PID; tenderness of the cervix, uterus, and adnexal should be absent).
D.Auscultate:
1.The lungs and heart.
E.Pregnancy:
1.Check fetal heart rate; fetal tachycardia may be present with fever.
2.Palpate for uterine tenderness and contractions.
3.Pelvic examination for cervical dilation, if indicated for increased risk of preterm labor.
F.Males: Complete palpation of external genitalia, prostate, and rectal exam.
Diagnostic Tests
A.The urine culture is the cardinal confirmatory diagnostic test. Urine culture and sensitivity should always be performed before initial empiric treatment with antibiotics.
B.Urinalysis:
1.Dipstick leukocyte esterase test (LET) screens for pyuria. Pyuria is present in almost all women with acute cystitis and pyelonephritis; its absence strongly suggests an alternative diagnosis.
a.Significant pyuria is greater than two to five leukocytes per high-power microscope field (HPF).
2.Nitrite production test (NPT) screens for bacteriuria.
3.Examination for hematuria (gross and microscopic) and proteinuria.
4.Urine may need to be obtained from straight in-and-out catheterization or suprapubic needle aspiration if the patient is incontinent or has dementia.
C.Complete blood count (CBC) with differential or white blood cell (WBC), especially with systemic symptoms.
D.Blood culture, if indicated.
E.Arterial blood gases (ABGs), if indicated.
F.Consider sedimentation rate, especially with severe illness and in the elderly.
G.Culture for gonorrhea and chlamydia, if symptoms are associated with sexually transmitted infection (STI).
H.Wet prep, if symptoms are associated with STI.
I.Imaging studies are not routinely required for the diagnosis of acute pyelonephritis but can be helpful. Indications for initial and subsequent imaging (i.e., baseline risk factors and clinical worsening or lack or improvement after 24 to 48 hours of therapy) to assess for obstruction, abscess, or necrotizing infection:
1.CT scan to identify altered parenchymal perfusion, hemorrhage, nonrenal disease, inflammatory masses/abscessing, and obstruction. Contrast is contraindicated in patients with renal dysfunction.
CT with contrast medium is considered the imaging modality of choice for nonpregnant women.
2.MRI to detect renal infections or masses or obstruction.
3.Renal ultrasonography with Doppler study.
4.Scintigraphy to detect focal renal abnormalities.
5.Voiding cystourethrogram.
6.Intravenous pyelography (IVP), if indicated.
7.CT and magnetic resonance (MR) urography used in the evaluation of hematuria.
Differential Diagnoses
A.Pyelonephritis.
B.Appendicitis/acute abdomen.
C.Acute cholecystitis.
D.Pancreatitis.
E.Diverticulitis.
F.Pneumonia.
G.Prostatitis.
H.Epididymitis.
I.PID.
J.Nephrolithiasis.
Plan
A.General interventions:
1.Optimal therapy for acute uncomplicated nephritis depends on the severity of the illness at presentation.
2.Many severe infections (increased WBC, dehydration or vomiting, high fever) may need hospital admission for IV therapy. Risk factors include older adult, coexisting illness, pregnancy, and uncontrolled vomiting.
B.
See Section III: Patient Teaching Guide Urinary Tract Infection (UTI)
:
C.Dietary management:
1.Increase fluids; have the patient drink at least one large glass of water every hour while awake (unless contraindicated).
2.Encourage the patient to drink cranberry juice to help fight and prevent UTIs. If the taste is objectionable, he or she may mix cranberry juice 1:1 with another juice such as grape juice.
3.There are no dietary restrictions with pyelonephritis.
D.Pharmaceutical therapy:
1.Acetaminophen (Tylenol) for fever.
2.Urinary analgesic as needed to relieve dysuria. Dysuria is usually diminished fairly quickly after the start of antibiotics.
3.Antiemetics as needed; however, if the patient is not able to tolerate oral fluids, he or she should be hospitalized.
4.Antibiotics: Empiric antibiotic selection should be guided by local antibiotics resistance patterns, allergies, and culture results. Patients with delayed response to therapy should also receive a longer course of antibiotics of 14 to 21 days.
a.Adults:
i.First-line therapy: Ciprofloxacin (Cipro) 500 mg twice daily for 5 to 7 days, or ER Cipro XR 1,000 mg once a day for 5 to 7 days.
•Recommended treatment in pregnancy of standard or high-dose extended-release ciprofloxacin is 7 days.