Urinary Tract Infection (Cystitis) Case File
Eugene C. Toy, MD, Patti Jayne Ross, MD, Benton Baker III, MD, John C. Jennings, MD
CASE 40
A 29-year-old woman complains of a 2-day history of dysuria, urgency, and urinary frequency. She denies the use of medications and has no significant past medical history. On examination, her blood pressure (BP) is 100/70 mm Hg, heart rate (HR) is 90 beats per minute, and temperature is 98°F (36.6°C). The thyroid is normal on palpation. The heart and lung examinations are normal. She does not have back tenderness. The abdomen is nontender and without masses. The pelvic examination reveals normal female genitalia. There is no adnexal tenderness or masses.
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ANSWER TO CASE 40:
Urinary Tract Infection (Cystitis)
Summary: A 29-year-old woman complains of a 2-day history of dysuria, urgency, and urinary frequency. Her temperature is 98°F (36.6°C). She does not have back tenderness. The abdomen is nontender and without masses. The pelvic examination is normal.
- Most likely diagnosis: Simple cystitis (bladder infection).
- Next step in the diagnosis: Urinalysis and/ or urine culture.
- Most likely etiology of the condition: Escherichia coli.
ANALYSIS
Objectives
- Recognize the symptoms of a urinary tract infection (cystitis).
- Recall that the most common bacteria causing cystitis is E. coli.
- Identify the evidence-based antibiotic therapies for cystitis.
Considerations
This 29-year-old woman has a 2-day history of urinary urgency, frequency, and dysuria, all of which are very typical symptoms of a lower urinary tract infection. Because she does not have fever or flank tenderness, she most likely has a bladder infection or simple cystitis. Other symptoms of cystitis may include hesitancy or hematuria (hemorrhagic cystitis). Urinalysis and/ or urine culture and sensitivity (if antimicrobial resistance/ complicated infection is suspected) would be the most appropriate test to confirm the diagnosis. Since E. coli is the most common etiologic agent, the empiric antibiotic treatment should be aimed at this organism. Current evidence suggests a 3-day course of trimethoprim/ sulfa (Bactrim) as the best agent for uncomplicated cystitis, unless bacteriology patterns in the community point to resistance; in that case, a quinolone such as ciprofloxacin twice daily for 3 days is effective. If the urine culture demonstrates no growth of organisms and the patient still has symptoms, urethritis is a possibility (often caused by Chlamydia trachomatis). In this setting, urethral swabbing for chlamydial testing is advisable. Another possibility is candidalvulvovaginitis. Finally, some women with symptoms of bladder discomfort with persistently negative urine and urethral culture may have a chronic condition of urethral syndrome.
APPROACH TO:
Urinary Tract Infections
DEFINITIONS
CYSTITIS: Bacterial infection of the bladder defined as having greater than 100 000 colony-forming units of a single pathogenic organism on a midstream-voided specimen.
URETHRITIS: Infection of the urethra commonly caused by C. trachomatis.
URETHRAL SYNDROME: Recurrent episodes of urgency and dysuria caused by urethral inflammation of unknown etiology; urine cultures are persistently negative.
CLINICAL APPROACH
Urinary tract infections (UTI) may involve the kidneys (pyelonephritis), bladder (cystitis), and urethra (urethritis). More than one half of all women will acquire a UTI in their lifetime. The most commonly stated reason for the increased incidence of UTIs in women is the shorter length of the female urethra and its increased proximity to the rectum. Pregnancy further predisposes women to UTIs due to incomplete emptying of the bladder (urinary stasis), ureteral obstruction by the gravid uterus, and immune suppression. Causative bacteria include E. coli (isolated 80% of the time) followed by Enterobacter, Klebsiella, Pseudomonas, Proteus, group B streptococcus, Staphylococcus saprophyticus, and Chlamydia.
The most common symptoms of lower tract infection (cystitis) are dysuria, urgency, and urinary frequency. Occasionally, the infection may induce a hemorrhagic cystitis and the patient will have gross hematuria. Nevertheless, gross hematuria should raise the suspicion of nephrolithiasis. Fever is uncommon unless there is upper urinary tract/ kidney involvement, which is usually reflected by flank tenderness. The diagnosis of cystitis hinges on identification of pathogenic bacteria in the urine; bacteriuria is defined as > 100 000 colony-forming units per milliliter of a single uropathogen obtained from a midstream-voided clean catch urine culture. In symptomatic patients, as few as 1000 colony-forming units per milliliter may be significant. On a catheterized specimen, 10 000 colony-forming units per milliliter is considered bacteriuria. The presence of leukocytes in the urine (pyuria) is presumptive evidence of infection in a patient with symptoms.
Simple cystitis is the most common form of UTI and is diagnosed by the lower urinary tract symptoms in the absence of fever or flank tenderness. Oral antimicrobial therapy is effective, and varies from one dose to 3 days, to 7 days, or even 10 days. Trimethoprim/ sulfa (Bactrim), nitrofurantoin, ciprofloxacin, norfloxacin, and fosfomycin are effective. Ampicillin and cephalosporins are generally not used as first-line agents due to the widespread resistance of common uropathogens. However, current evidence points to a 3-day course of trimethorprim/ sulfa as the treatment of choice for uncomplicated cystits. The utility of urine cultures in the first episode of simple cystitis is unclear. Some practitioners will routinely obtain cultures, whereas others will reserve these studies for recurrences, persistent symptoms, or in pregnancy. In the pregnant woman, asymptomatic bacteriuria (ASB) leads to acute infection in up to 25% of untreated women, and thus it should always be treated.
A patient with urethritis has similar complaints to one with cystitis (ie, urgency, frequency, and dysuria). Sometimes, the urethra may be tender on palpation and purulent drainage expressed on examination. The most commonly isolated organisms are Chlamydia, Gonococcus, and Trichomonas. Urethritis should be suspected in a woman with typical symptoms of UTI, yet with no growth in culture (sterile pyuria) and no response to the standard antibiotics. Gram stain and cultures of the urethra for Gonococcus and Chlamydia should be performed, with reflex confirmatory nucleic acid amplification testing (NAAT). Treatment may be initiated empirically for Chlamydia with doxycycline; if Neisseriagonorrhea is suspected, intramuscular ceftriaxone with oral doxycycline is usually curative. Azithromycin should be substituted for doxycycline in pregnant women.
Women with pyelonephritis usually present with fever, chills, flank pain, nausea, and vomiting. Mild cases in the nonpregnant female may be treated with oral trimethoprim/ sulfa or a fluoroquinolone for a 14-day course; these women should be re-examined within 48 to 72 hours. Sulfa agents are generally the most cost-effective. Those who do not begin clinically improving, are more toxic, unable to take oral medications, pregnant, or immunocompromised should be hospitalized and treated with intravenous antibiotics, such as ampicillin and gentamicin, 3rd gen cephalosporins such as ceftriaxone, intravenous fluroquinolones, a carbapenem, or piperacillin-tazobactam. Following resolution of fever and symptoms, pregnant women with acute pyelonephritis warrant suppressive antimicrobial therapy (such as nitrofurantoin macrocrystals 100 mg once daily) for the remainder of pregnancy.
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CASE CORRELATION
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COMPREHENSION QUESTIONS
40.1 A 29-year-old G1P0 at 19 weeks’ gestation is noted to have dysuria, urinary frequency, and urgency. A urine culture is performed, and growth is noted, which the microbiology laboratory notes as not E. coli. Which of the following is the most likely causative organism of cystitis?
A. Chlamydia trachomatisB. Klebsiella speciesC. PeptostreptococcusD. Bacteroides species
40.2 A 19-year-old G2P1 woman at 13 weeks’ gestation comes in for her first prenatal visit. Among other tests, a urine culture is performed showing 100 000 cfu/ mL of E. coli. The patient has no symptoms, and has not had pyelonephritis, dysuria, or fever. Which of the following is best next step for this patient?
A. Observation, as no therapy is neededB. No therapy needed unless the patient develops symptomsC. Initiation of antibiotic therapyD. No therapy needed at this time, but antibiotics should be given during labor
40.3 A 30-year-old G1P0 woman at 29 weeks’ gestation is noted to have a urinary tract infection with 100 000 cfu/mL of E. coli growing on culture. H er obstetrician notes that an upper urinary tract infection leads to increased complications. Which of the following is a common manifestation of upper urinary tract infection rather than simple cystitis?
A. FeverB. UrgencyC. HesitancyD. Dysuria
ANSWERS
40.1 B. The most common cause of UTIs in women is E. coli. Other causes include Enterobacter, Klebsiella, Pseudomonas, and Proteus. Chlamydia trachomatis is a common cause of urethritis along with Gonococcus and Trichomonas. Peptostreptococcus is a Gram-positive anaerobe that is a commensal organism with humans and usually does not cause pathology except in immunosuppressed individuals. Along with Peptostreptococcus, Bacteroides species live as gut flora in humans. Bacteroides is a Gram-negative anaerobe and, along with other anaerobes, rarely causes cystitis.
40.2 C. This patient has asymptomatic bacteriuria, which should be treated even without symptoms. If untreated, the patient has a 25% risk of developing pyelonephritis during the pregnancy. Asymptomatic bacteriuria (ASB) complicates approximately 8% to 10% of pregnant patients. Providing treatment of ASB at the first prenatal visit reduces the risk of pyelonephritis markedly.
40.3 A. Upper UTIs (including pyelonephritis) usually present with fever, costovertebral tenderness, chills, malaise, and often ill-appearing individual. They are at increased risk for septicemia, kidney dysfunction, or preterm labor. In severe cases, the patient should be hospitalized and started on intravenous antibiotics. Presenting symptoms of urgency, hesitancy, and dysuria are symptoms for a simple cystitis or urethritis. Urethritis can be differentiated from cystitis by a sterile culture and no response to antibiotics. Doxycycline (covers Chlamydia) with ceftriaxone (gonorrhea) is a good choice for suspected urethritis. Doxycycline should be avoided in pregnant women.
CLINICAL PEARLS
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» The most common cause of uncomplicated cystitis is E. coli. » For uncomplicated cystitis, a 3-day course of trimethoprim/sulfa is the treatment of choice. » Complicated UTI’s such as bladder retention, frequent infections, or indwelling catheters necessitate a longer course and perhaps a different antimicrobial agent. » Bacteriuria caused by group B streptococcus in pregnancy necessitates the use of intravenous penicillin or ampicillin in labor to decrease the risk of neonatal GBS sepsis. » Clinical features of pyelonephritis are flank tenderness and fever. » Urethritis, commonly caused by Chlamydia or N. gonorrhea, should be suspected with negative urine cultures and symptoms of UTI. » Asymptomatic bacteriuria has a high incidence in women with sickle cell trait. |
REFERENCES
American College of Obstetricians and Gynecologists. Treatment of urinary tract infections in nonpregnant women. ACOG Practice Bulletin 91. Washington, DC; 2012.
Gupta, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women. Clin Infect Dis. 2013;52(5):e103-e120.
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