Acute pyelonephritis case file

Acute pyelonephritis case file

Eugene C. Toy, MD, Barry C. Simon, MD, Terrence H. Liu, MD, MHP, Katrin Y. Takenaka, MD, Adam J. Rosh, MD, MS

Case 53

A 24-year-old woman presents to the emergency department (ED) with complaints of flank pain and fever for the last 1 to 2 days. She describes feeling pain with urination over the previous week. She is currently feeling febrile and nauseated, but has not vomited. The pain in her right flank is a dull, constant, nonradiating ache that she rates as 5/10 for pain. She took 600 mg of ibuprofen last night to help her sleep, but this morning the pain persisted so she came into the ED for evaluation. She reports that she is sexually active and her last menstrual period was 1 week ago. She denies any vaginal discharge or abdominal pain. Her vital signs include a temperature of 38.3°C (101°F), heart rate of 112 beats per minute, respiratory rate of 15 breaths per minute, and blood pressure of 119/68 mm Hg. Her examination is significant for tenderness to palpation on her right costovertebral angle (CVA).

⯈ What is the most likely diagnosis?

⯈ What is the best treatment?

ANSWER TO CASE 53:

Acute Pyelonephritis

Summary: This otherwise healthy young woman presents with dysuria, flank pain, fever, and nausea. She is febrile, tachycardic, and has CVA tenderness.

• Most likely diagnosis: Urinary tract infection (UTI) complicated by pyelonephritis.
• Treatment: Antibiotics, hydration, analgesia, antipyretics, exclusion of other pathology.

ANALYSIS

Objectives

1. Recognize the clinical signs and symptoms of UT Is.
2. Understand the diagnosis and treatment of UTIs.
3. Understand the spectrum of UTIs and their variable treatment.

Considerations

Urinary tract infections are a spectrum of diseases that can affect any part of the urinary system. They are second only to respiratory tract infections as a problem encountered by physicians. Individuals who present to the ED with genitourinary complaints often warrant a rapid but thorough history and physical examination. This patient presentation (ie, dysuria, flank pain, nausea, and fever) is consistent with acute pyelonephritis; an infection of the renal parenchyma. Generally, the clinical features of acute pyelonephritis include fever, chills, dysuria, and flank and costovertebral angle pain. Patients may feel nauseated and vomit. The initial workup includes assessing the patient stability and immediately addressing any life threats. As the workup proceeds, the patient should receive an antipyretic (eg, acetaminophen), and intravenous fluids for hydration.

The differential diagnosis for patients with urinary complaints is broad and includes cystitis, pyelonephritis, urethritis, and vaginitis. In addition, patients who exhibit signs of systemic involvement (eg, fever) should be evaluated for other pathologies including ectopic pregnancy, perforated viscous, infected kidney stone, appendicitis, pancreatitis, colitis, and pneumonia. A good history and physical examination will help the physician narrow down these possibilities.

Laboratory studies are helpful in confirming the diagnosis. A urinalysis typically reveals leukocytes, red blood cells, and bacteria. A urine culture is essential to guide antibiotic therapy. Blood cultures should be obtained if the patient has a fever. A complete blood count, electrolytes, and renal function studies are also recommended. Patients with suspected pyelonephritis typically do not require imaging studies. However, patients who clinically exhibit pyelonephritis, but whose urinalysis is negative, and patients with a suspected urinary obstruction, should undergo imaging. In the ED, this is usually an ultrasound or contrast-enhanced CT scan. Supportive care consists of IV hydration, analgesia, antipyretics, and anti-emetics. In uncomplicated acute pyelonephritis, patients can receive a 10 to 14 day course of oral antibiotics (eg, fluoroquinolone) and be discharged home. In more severe cases, patients should be admitted to the hospital and receive intravenous antibiotics.

Approach To:

Urinary Tract Infections

DEFINITIONS

DYSURIA: Painful urination

CYSTITIS: Inflammation of the urinary bladder that generally results in dysuria, urinary frequency, urgency, and suprapubic pain.

ACUTE PYELONEPHRITIS: Inflammation of the kidney secondary to a UTI of the renal parenchyma and collecting system. It typically presents as the clinical syndrome of fever, chills, and flank pain.

BACTERIURIA: Presence of bacteria in the urine

HEMATURIA: Blood in the urine, may be micro- or macroscopic.

PYURIA: Pus in the urine

UNCOMPLICATED UTI: An infection of a structurally and functionally normal urinary tract that is generally eradicated by a 3- to 5-day course of antibiotics.

COMPLICATED UTI: An infection in patients with underlying immunological, structural, or neurological disease that diminish the efficacy of standard antimicrobial therapy.

URETHRITIS: Inflammation of the urethra

CLINICAL APPROACH

UTIs are a common diagnosis in the ED. They can range from simple cystitis to pyelonephritis resulting in sepsis and shock. Urinary tract infections affect women more commonly than men. However, in children, boys are affected more commonly until 1 year of age. Urinary tract infections in children warrant further sonographic evaluation of the urinary tract to rule out congenital anomalies. The lifetime prevalence of UTIs is estimated to be 14,000 per 100,000 men and 53,000 per 100,000 women.

UTIs can be divided into lower tract (urethra and bladder) and upper tract (ureters and kidneys) infections. The symptoms of lower infections are localized and are commonly crampy suprapubic pain, dysuria, foul-smelling or dark-colored urine, hematuria, urinary frequency and urgency. Patients with upper tract infections usually appear more ill and are more likely to have abnormal vital signs and systemic symptoms (eg, fever, chills, nausea and vomiting). It is important to distinguish lower- from upper-tract infections as the treatments differ vastly, as will be discussed later.

Commonly, the infecting organism gains access to the urinary tract by direct entry from the urethra. The human body evolved many defenses against UTIs including frequent urinary flow, urine urea concentration and acidification, and urethral epithelial lining. The normal periurethral flora includes the bacteria lactobacillus that provides a symbiotic protective mechanism. The perirectal area and the vagina are both potential sites of bacterial colonization and are in much closer proximity to the urethral meatus in women. The female urethra is also much shorter than in males and brings the urethral meatus in closer proximity to the bladder, thus increasing the risk of infection by external organisms. A UTI in a man is usually the result of benign prostatic hypertrophy, kidney stones that become infected, urethral instrumentation (surgery or catheterization), or immunocompromised states.

Care should be taken to exclude other etiologies in patients who present with urinary complaints. Cervicitis, vulvovaginitis and pelvic inflammatory disease are important conditions to exclude in women and are more likely to present with discharge, lack of bacteria on urinalysis, and lack of urinary frequency and urgency. In considering these diagnoses, the patient should undergo a pelvic examination. Sampling with DNA probes for gonococcus and Chlamydia should be obtained, a wet mount slide examination performed, and treatment for these conditions considered. Pregnancy should also be considered and tested for in all women of reproductive age with any urinary symptoms. In men, urethritis and prostatitis should be excluded before the diagnosis of cystitis or pyelonephritis is confirmed.

UTIs are typically caused by a single bacterial species. Eighty percent of infections are caused by Escherichia coli, a gram-negative rod. Staphylococcus saprophyticus is the second most common cause of UTI and is common in young women. Other organisms include Proteus, Klebsiella, Enterococci, and Pseudomonas. The identification of an exact organism is rarely indicated in the ED. The “gold standard” of quantitative culture takes several days, but will significantly assist in treatment if the patient is being admitted to the hospital or failed outpatient therapy.

Major risk factors for women aged 16 to 35 years include sexual intercourse, pregnancy, bladder catheterization, and diaphragm usage. Later in life, additional risk factors include gynecologic surgery and bladder prolapse. In both sexes, conditions resulting in urinary stasis increase with age, as does the incidence of UTIs. Benign prostatic hypertrophy is a major risk factor in older men.

Laboratory Studies

The mainstay in the diagnosis of a UTI is urinalysis and culture. Collection of sterile urine is critical because a contaminated specimen can result in a false-positive urinalysis. Suprapubic aspiration and catheterization provides the best sample; however, both are invasive and uncomfortable to the patient. Clean catch urine samples, obtained by the patient collecting urine in midstream is standard and provides an adequate sample if done properly. In children, “bag” urine collection, by placing a bag over the perineum, should be avoided due to the high rates of contamination. Condom catheterization collection of urine is not acceptable for urinalysis due to the contact of the male glands to the collection vessel. Typically, contaminated urine will exhibit cellular elements (eg, epithelial cells) and should not be used to determine the presence of a UTI.

Abbreviations: LE = leukocyte esterase; N = nitrite; WBCs = white blood cells.

Urinalysis can include urine dipstick testing, urine microscopy, and urine culture with sensitivities. Table 53–1 lists the sensitivity and specificity of different components of the urinalysis.

Urine dipstick It tests urine for infection by measuring two specific entities: leukocyte esterase, a compound released by white blood cell breakdown in the urinary tract, and nitrite, a compound produced by the reduction of dietary nitrates by some gram-negative bacteria (eg, E coli).

Urine microscopy It examines the urine for white blood cells, bacteria, and other visible structures. Classically, the criteria for diagnosis of UTI on microscopy include the presence of more than fi ve leukocytes or red blood cells per high-powered field or 2+ bacteria. Microscopic criteria are highly debated and the presence of WBCs, RBCs, and bacteria should be used in conjunction with clinical presentation to confirm the diagnosis of a UTI.

Urine culture Diagnosis and treatment of a UTI based on the UA result is presumptive as the true diagnosis requires a culture with greater than (10 × 5)/mL colony count. ED urine cultures should be sent on high-risk populations including infants and children. Cultures are also obtained in the elderly, adult men, pregnant women, individuals with comorbid illness, or failing initial antimicrobial therapy. Gram staining of the urine can also be helpful, but is not routinely indicated.

Imaging

The majority of patients with urinary complaints do not require imaging in the ED. However, in certain clinical settings it is indicated. Patients who exhibit clinical signs or symptoms of a urinary infection, but have a negative urinalysis, those with a suspected urogenital obstruction, and complicated UTIs often require imaging studies. In addition, first episodes of UTIs in girls younger than 4 years and men, should undergo an imaging study.

Imaging of the urinary tract consists of ultrasound, computed tomography (CT) scans, intravenous pyelography (IVP), and radionucleotide scans. Ultrasound testing is an acceptable initial study in the ED because it is quick, noninvasive, and can detect many abnormalities including perinephric abscess, hydroureter, urinary tract stone, pyelonephritis, and congenital anomalies. CT scans are more sensitive at detecting these abnormalities, but expose the patient to higher levels of radiation and often require the administration of IV contrast. The use of IVP and radionucleotide scans are generally not performed during ED evaluation and reserved for inpatient or outpatient workups.

Treatment

The correct choice of antibiotic can be a difficult one for the emergency physician. There are many factors that affect this decision including patient drug allergies, bacterial susceptibility, community versus hospital flora, local antibiotic resistance rates, the presence of medical comorbidities, as well as the patient ability to pay for the prescription. Table 53–2 lists the most commonly used antibiotics for the treatment of UTIs.

Uncomplicated cystitis patients are treated as outpatients. Antibiotic choices must be effective against E coli and include trimethoprim-sulfamethoxazole (TMPSMX), amoxicillin/clavulanate, nitrofurantoin, ciprofloxacin, and levofloxacin. Typically, patients are treated for 3 to 5 days. Longer therapy generally offers no benefit. However, in patients with suspected subclinical upper-tract infection, communities with high resistance rates, extremes of age, and comorbidities, a longer course (ie, 7-10 days) is recommended. For symptomatic relief, physicians often prescribe phenazopyridine, a drug that concentrates in the urine and often relieves the pain and irritation of urination. The drug causes a distinct color change in the urine; typically to a dark orange to reddish color. Phenazopyridine is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency because it can lead to drug-induced hemolysis of red blood cells.

Uncomplicated pyelonephritis can be treated as an outpatient, provided the patient can tolerate oral medications, has mild symptoms, gets good follow-up, and is not pregnant. TMP-SMX, amoxicillin/clavulanate, or a fluoroquinolone antibiotic should be prescribed for 10 to 14 days. All pregnant patients with pyelonephritis require admission (see Table 53-3).

Complicated pyelonephritis requires admission and IV antibiotics. The antibiotic choices are TMP-SMX, ceftriaxone, gentamycin (with or without ampicillin), and fluoroquinolones. In more severe cases where urovsepsis or a resistant organism is suspected, cefepime, ampicillin plus tobramycin, piperacillintazobactam may be indicated.

Due to increasing resistance patterns, urine culture should be considered.

All children and men who are discharged with the diagnosis of UTI require urological follow-up to assess for underlying anatomical abnormalities. Adults with complicated UTIs also need follow-up and evaluation of the genitourinary system.

Pregnant patients require special attention. Simple, asymptomatic bacteriuria necessitates treatment due to the increased risk of preterm labor, perinatal mortality, and maternal pyelonephritis. It is important that the bacteriuria is eliminated despite the patient being clinically asymptomatic. First-line agents include penicillins (eg, amoxicillin, ampicillin), and cephalosporins. Fluoroquinolones and tetracyclines are contraindicated as they are known teratogens. Admission should be considered in patients in their third trimester, suspected pyelonephritis, or those who cannot tolerate fluids by mouth.

Some patients require chronic placement of indwelling catheters, which serve as a nidus for infection. Treatment of asymptomatic bacteriuria in these patients is not indicated because frequent antibiotic administration results in increased microorganism resistance. Generally, removal of the catheter results in elimination of bacteria. Symptomatic patients, who cannot be without the catheter, should be treated with antibiotics, have the catheter replaced, and be considered for admission to the hospital due to the high risk for systemic infection.

COMPREHENSION QUESTIONS

53.1 A 64-year-old woman is brought to the ED by her family for mental status changes. She has multiple sclerosis and self-catheterizes for urine. The family reports that over the past several days she has not been feeling well. They state that the patient vomited that day and was behaving bizarrely. Her vital signs are blood pressure of 83/38 mm Hg, heart rate of 135 beats per minute, respirations of 26 breaths per minute, and rectal temperature 38.8°C (101.9°F). After a history and physical examination, which of the following is the most appropriate next step in management?

A. Obtain a urinalysis and culture.

B. Start broad-spectrum antibiotics.

C. Perform a lumbar puncture.

D. Establish IV access and place the patient on a cardiac monitor.

E. Discharge the patient after close follow-up is arranged.

53.2 A 34-year-old woman complains of mild crampy suprapubic abdominal pain, dysuria, and urinary frequency for the last 3 days. She has no fever. Her blood pressure is 125/70 mm Hg, heart rate is 88 beats per minute, respiratory rate is 16 breaths per minute, and temperature is 36.8°C (98.3°F). She has no significant past medical history and is able to drink oral fluids with difficulty. She has a clean-catch urinalysis that reveals 2+ leukocyte esterase, 1+ nitrite, 1+ blood, and 2+ bacteria. Her β-hCG is negative. Which of the following organisms is most likely responsible for her presentation?

A. Klebsiella spp

B. Escherichia coli

C. Pseudomonas aeruginosa

D. Proteus mirabilis

E. Enterobacter spp

53.3 A 24-year-old woman presents to the ED for painful urination over the last 2 days that is associated with urinary urgency. She states that she is pregnant and the fetus is at 12-week gestational age as measured by ultrasound. On examination, she is well appearing, and sitting comfortably in bed. Her blood pressure is 115/70 mm Hg, heart rate is 81 beats per minute, respiratory rate is 16 breaths

per minute, and temperature is 37.2°C (98.9°F). A urinalysis reveals 5 WBC/mm3, 1+ leukocyte esterase, and 1+ bacteria. The urine is negative for nitrite and blood. As you return to the patient bed to tell her the results, she states that her pain has resolved, she is urinating without difficulty, and wants to go home. Which of the following is the most appropriate course of management?

A. Admit the patient for intravenous antibiotics.

B. Discharge the patient with a prescription for antibiotics and tell her to fill

the prescription only if the culture results are positive.

C. Ask the patient to undergo another examination to evaluate for gonorrhea and Chlamydia.

D. Administer a dose of ciprofloxacin in the ED and have the patient call the hospital to find out her culture results.

E. Prescribe the patient nitrofurantoin for 5 to 7 days and have her follow-up with her obstetrician.

53.4 A 65-year-old man with hypertension and benign prostatic hyperplasia (BPH) presents to the ED with urinary retention and a UTI on a catheterized urine analysis. He was evaluated by the urologist and is being discharged home with an in-dwelling Foley catheter and follow-up in the urology clinic in 1 week. Which of the following is the most appropriate antibiotic for this patient?

A. TMP-SMX bid for 3 days

B. Nitrofurantoin 100 mg for 14 days

C. Amoxicillin 100 mg tid for 14 days

D. Ciprofloxacin 500 mg bid for 14 days

E. Levofloxacin 250 mg qd for 3 days

53.5 Which of the following patients with pyelonephritis can be safely discharged home with close follow-up?

A. A 23-year-old woman in her second trimester of pregnancy.

B. A 13-year-old woman who cannot tolerate her diet despite anti-emetics.

C. An 88-year-old man with urinary retention and dehydration.

D. A 67-year-old woman with 3+ bacteria, a sulfa allergy, and a history of lupus.

E. A 44-year-old woman with a kidney stone and hydroureter on CT scan.

ANSWERS

53.1 D. This woman may indeed have a urinary tract infection; however, her vital signs are unstable. The mainstay of treatment in emergency medicine is to first address the patient airway, breathing, and circulation (ABCs). This patient is hypotensive (eg, BP 83/38 mm Hg). The first step in her management is placing an IV line and administering fluids. She should also be placed on a cardiac monitor to monitor her blood pressure, heart rate, and rhythm. Once her ABCs are addressed, laboratory studies should be obtained, including a urinalysis and culture. She should also receive broad-spectrum antibiotics and an antipyretic. This patient may need a lumbar puncture, but not until her ABCs are addressed. This patient requires admission to the hospital.

53.2 B. E coli is the infecting organism in more than 80% of all UTIs. All of the other choices cause urinary tract infections, but are less common. S saprophyticus is a common organism in young, sexually active women. In hospitalized or nursing home patients, Pseudomonas spp and Staphylococcus spp are frequent pathogens. Lactobacilli are normal urethral flora and are not considered a causative organism. Complicated UTIs are more likely to be caused by other organisms.

53.3 E. The patient is pregnant and has evidence of a urinary tract infection on the urinalysis. Pregnant patients are at high risk for preterm labor and perinatal mortality if a urinary infection goes untreated. Therefore, this patient should receive a 5 to 7 days course of nitrofurantoin or a penicillin-based antibiotic and follow-up with her obstetrician. The patient does not need to be admitted to the hospital for intravenous antibiotics. This would likely be the case if she were diagnosed with pyelonephritis. The patient should not wait for culture results and delay receiving her antibiotics. It is important to eradicate the bacteriuria as quickly as possible. This patient does not report the symptoms of gonorrhea or Chlamydia (eg, vaginal discharge) at this time, and does not require further evaluation for these conditions. Fluoroquinolones (eg, ciprofloxacin) are contraindicated in pregnant patients due to the risk of fetal abnormalities (eg, tendon maldevelopment).

53.4 D. Men with urinary tract infections automatically fit into the “complicated” variety of UTIs. Therefore, the most appropriate therapy is ciprofloxacin for 14 days. With the exception of amoxicillin as monotherapy, all of the above choices are appropriate for treatment of certain types of UTIs. Complicated UTIs mandate 14 days of therapy with an appropriate antibiotic. The emergency physician should also consider sending urine cultures on this patient and provide good follow-up. Patients with benign prostatic hypertrophy or other lower urinary tract obstructions may be discharged with a Foley catheter if they have good follow-up, understand how to manage their catheter, and have to significant medical comorbidities.

53.5 D. Despite a chronic medical condition, this patient may be safely discharged home. Because this patient has a sulfa allergy, TMP-SMX should not be administered. Other treatment options include quinolones, amoxicillin/ clavulanate, and nitrofurantoin. All of the other patients should be admitted for treatment. All pregnant patients with pyelonephritis require admission. The 13-year-old and 88-year-old are not tolerating their diet and require intravenous hydration. The 44-year-old has a urinary obstruction with a UTI, which makes it a complicated UTI. These patients are at high risk for developing sepsis. For most admitted patients, urine cultures should be sent to guide antibiotic therapy.

CLINICAL PEARLS

⯈ All urinary tract infections in men are considered complicated.

⯈ The definitive diagnosis of a UTI is made on urine culture from a noncontaminated urine sample.

⯈ Care should be taken to exclude other etiologies, such as cervicitis, vulvovaginitis, and pelvic inflammatory disease, in female patients who present with urinary complaints.

⯈ All pregnant patients with bacteriuria require antibiotic treatment to prevent complications.

⯈ Patients with a UTI and an obstructed kidney stone are at high risk for morbidity and require urgent urologic consultation.

⯈ Antibiotic therapy should be tailored to the type of UTI, the community resistance rates, and the patient ability to tolerate the medications.

REFERENCES

Ban KM, Easter JS. Selected urologic problems. In: Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. Philadelphia, PA: Mosby Elsevier; 2009. 

Dielubanza EJ, Schaeffer AJ. Urinary tract infections in women. Med Clin N Am. 2011;95:27-41. 

Howes DS, Bogner MP. Urinary tract infections and hematuria. Tintinalli JE, Stapczynski JS, Cline DM, Ma OJ, Cydulka RK, Meckler GD, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, NY: McGraw-Hill; 2011. 

Lane DR, Takhar SS. Diagnosis and management of urinary tract infection and pyelonephritis. Emerg Med Clin N Am. 2011;29:539-552. 

Nicolle LE. Uncomplicated urinary tract infection in adults including uncomplicated pyelonephritis. Urol Clin N Am. 2008;35:1-12. 

Schrock JW, Reznikova S, Weller S. The effect of an observation unit on the rate of ED admission and discharge for pyelonephritis. Am J Emerg Med. 2010;26:682-688.

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