CHAPTER 85
Urinary Tract Infection, Lower (Cystitis), Uncomplicated
Presentation
The patient (usually female) complains of urinary frequency and urgency, internal dysuria, and suprapubic pain or discomfort. The onset of symptoms is generally abrupt, often causing her to seek care within 24 hours. There may have been some antecedent trauma (sexual intercourse) to inoculate the bladder, and there may be blood in the urine (hemorrhagic cystitis). Usually, there is no labial irritation, external dysuria, or vaginal discharge (which would suggest vaginitis or cervicitis), and no fever, chills, nausea, flank pain, or costovertebral angle tenderness (which would suggest an upper urinary tract infection or pyelonephritis).
What To Do:
Examine a clean-catch urine specimen. Instruct the patient to wipe the introitus from front to back and begin urinating into the toilet before filling the sample cup. In women of childbearing age, send a urine pregnancy test—this will influence choice of antibiotic and follow-up. Use a dipstick test for leukocyte esterase, send for a urinalysis, or Gram stain a sample of urine. Epithelial cells on the microscopic examination are evidence of contamination from the vagina. The presence of any white blood cells (WBCs) or bacteria in a clean sample confirms the infection. A positive nitrite on dipstick is helpful, but a negative test does not rule out infection, because many bacteria do not produce nitrites. Menses or vaginal discharge makes a clean catch difficult. One technique is to insert a tampon before giving the sample. A better technique is urinary catheterization.
If the clinical picture is clearly of an uncomplicated lower urinary tract infection (UTI) in a nonpregnant patient and local Escherichia coli resistance to trimethoprimsulfamethoxazole (TMP/SMX) is less than 20%, give trimethoprim, 160 mg, plus sulfamethoxazole, 800 mg (Bactrim DS or Septra DS), one tablet PO bid for 3 days. Otherwise, give fosfomycin (Monurol), 3 g PO × 1, or a 3-day regimen of a quinolone, such as ciprofloxacin (Cipro), 500 mg PO bid, or Cipro XR, 500 mg qd; levofloxacin (Levaquin), 250 mg PO qd; or gatifloxacin (Tequin), 200 to 400 mg PO qd, or nitrofurantoin extended release (Macrobid), 100 mg PO bid × 7 days. Single-dose treatment with two TMP/SMX DS tablets is also effective in the young healthy female but is associated with a higher early recurrence rate. In pregnancy, give a 7-day course of nitrofurantoin (Macrodantin), 100 mg PO qid, or nitrofurantoin extended release (Macrobid), 100 mg PO bid. Cephalosporins (i.e., cephalexin [Keflex], 250 to 500 mg qid × 7 days) are alternatives in pregnancy, but not quinolones (or sulfas 2 weeks before delivery because of the potential increased risk for kernicterus). Trimethoprim is contraindicated during the first trimester because of its antifolate properties.
Instruct the patient to drink plenty of liquids (such as cranberry juice) and remain hydrated, but there is no need to drink excessively.
If the dysuria is severe, also prescribe phenazopyridine (Pyridium), 200 mg tid for 2 days only, to act as a surface anesthetic in the bladder. Warn the patient that it will stain her urine (and perhaps clothes) orange.
Extend antimicrobial therapy to 7 days and obtain cultures when treating a patient who is unreliable, diabetic, symptomatic more than 5 days, older than 50 years of age, or younger than 16 years of age. Also, extend treatment and obtain cultures for all male patients and for those with an indwelling urinary catheter, renal disease, obstructive urinary tract lesions, recurrent infection, or other significant medical problems. It should be noted that one small double-blind Canadian study of 183 immunocompetent, nondiabetic women aged 65 and older with culture-documented uncomplicated UTI had similarly effective treatment with a 3-day course of ciprofloxacin as they did with a 7-day course (with fewer antibiotic-related side effects).
If there are no bacteria or few WBCs, no hematuria or suprapubic pain, gradual onset over 7 to 10 days, and a new sexual partner, with a history of vaginal discharge and/or vaginal irritation, the dysuria may be caused by a chlamydial or ureaplasmal urethritis (see Chapter 83). Perform a pelvic examination and obtain samples for nucleic acid amplification testing, culture, and microscopic examination. Ask the patient about the use of spermicides or douches, which may irritate the periurethral tissue and cause dysuria. Adolescent females who are screened for both Chlamydia trachomatis and urinary tract infection have high rates of concurrent disease. Urinary or vaginal symptoms do not differentiate well between these infections. Clinical diagnosis is imprecise, suggesting that sexually active adolescent females with vaginal or urinary symptoms should be tested for both C. trachomatis and UTI.
When there is a history of lower UTI symptoms with negative urinalysis, cultures, and workups for sexually transmitted diseases, consider a paraurethral gland infection (sometimes referred to as “female prostatitis”) as the cause of this female urethral syndrome. This is usually associated with tenderness at either side of the distal two thirds of the urethra, adjacent to the urethral meatus (Skene paraurethral glands). During the pelvic examination, press firmly against the posterior and the lateral vaginal walls as a “control” maneuver to demonstrate the lack of pain with firm palpation. Then, bend your examining index finger forward to compress the paraurethral tissue firmly against the flat backside of the pubic bone. An affected patient will have an abrupt pain response, whereas an unaffected patient may only respond with the sensation of having to void. Treat presumed Chlamydia with doxycycline, 100 mg bid for an extended 2 to 4 weeks. After an initial treatment failure, older and younger women should be given a quinolone for at least 1 month. Hot sitz baths may provide comfort.
If there is external dysuria, vaginal discharge, odor, itching, and no frequency or urgency, evaluate for vaginitis (see Chapter 83) with a pelvic examination.
Arrange for follow-up in 2 days if the symptoms have not completely resolved. If necessary, urine culture and a longer course of antibiotics can be undertaken.
Pediatric UTIs differ from adult UTIs. Pediatric UTIs may indicate a significant genitourinary anomaly; their accurate diagnosis requires invasive collection methods, such as suprapubic aspiration or transurethral catheterization in infants and young children; and accurate diagnosis requires a urine culture rather than relying solely on a simple urinalysis. UTIs in children, especially young children, can manifest as nonspecific symptoms (therefore you must maintain a high index of suspicion). Children, especially those younger than 5 years of age, have increased risk for renal scarring after a single UTI. (Therefore it is important to diagnose quickly and to initiate appropriate broad-spectrum antibiotic therapy.)
Although a midstream, clean-catch void can be a reliable method of urine collection in adults and older children, it is usually impossible for preschool children. For older children, patients and parents should be instructed to cleanse the periurethral area well, spread labia or partially retract the foreskin, and allow the initial urine to be wasted before beginning collection in a sterile container. Having girls sit backward on the toilet may facilitate this.
In small children, transurethral bladder catheterization is the preferred method for obtaining urine by many practitioners and parents.
The clues to the diagnosis of UTI in children before culture results include urine nitrite, leukocyte esterase, bacteria, or white blood cells. Bacteria on Gram stain are another specific indicator of UTI. The combination of leukocyte esterase, nitrite, and bacteria on microscopy is a sensitive test (sensitivity 99.8%, specificity 70%). The absence of any of these findings on urinalysis and microscopic examination nearly (but not completely) eliminates the diagnosis of UTI. More than 5 to 10 WBCs per high-powered field on catheter specimen in the presence of a suggestive clinical picture should be presumed to represent a true UTI until proven otherwise by a negative culture.
For uncomplicated infections in the nontoxic child, prescribe 2 mg of TMP/10 mg of SMX/kg PO qd × 7 days (where local resistance of uropathogens to TMP/SMX is less than 20%); cefixime (Suprax), 8 mg/kg/day divided q12h PO × 7 days; cefprozil (Cefzil), 15 to 30 mg/kg/day divided q12h PO × 7 days; cephalexin (generic), 25 to 100 mg/kg/day divided qid PO × 7 days; or, if the patient is vomiting, ceftriaxone (Rocephin), 50 to 75 mg/kg qd IV or IM. Because it is difficult to rule out pyelonephritis in febrile infants with UTI, a full 14-day course of antibiotics is indicated.
Arrange follow-up for all children, because a UTI may be the first evidence of underlying urinary tract disease.
What Not To Do:
Do not forget to check for pregnancy.
Do not undertake expensive urine cultures for every lower UTI of recent onset in nonpregnant, normal, healthy women with no history of recent UTI or antibiotic use.
Do not use the single-dose or 3-day regimens for a possible upper UTI or pyelonephritis (see Chapter 86).
Do not rely on gross inspection of the urine sample. Cloudiness is usually caused by crystals, and odors can result from diet or medication.
Do not request a follow-up visit or culture after therapy unless symptoms persist or recur.
Discussion
Lower UTI or cystitis is a superficial bacterial infection of the bladder or urethra. Most of these infections involve Escherichia coli, Staphylococcus saprophyticus, or enterococci.
The urine dipstick is a reasonable screening measure that can direct therapy if results are positive. Under the microscope in a clean sediment (free of epithelial cells), one WBC per 400 field suggests significant pyuria, although clinicians accustomed to imperfect samples usually set a threshold of 3 to 5 WBCs per field. In addition, Trichomonas organisms may be appreciated swimming in the urinary sediment, indicating a different cause for urinary symptoms or associated vaginitis.
In a straightforward lower UTI, urine culture may be reserved for cases that fail to resolve with single-dose or 3-day therapy. In complicated or doubtful cases or with recurrences, a urine culture before initial treatment may be helpful.
Risk factors for UTI in women include pregnancy, sexual activity, use of diaphragms or spermicides, failure to void postcoitally, and history of previous UTI. Healthy women may be expected to suffer a few episodes of lower UTI in a lifetime without indicating any major structural problem or incurring any long-term medical sequelae, but recurrences at short intervals suggest inadequate treatment or underlying abnormalities.
Young men, however, have longer urethras and far fewer lower UTIs. They probably should be evaluated urologically after just one episode unless they have a risk factor such as an uncircumcised foreskin, HIV infection, or homosexual activity, and they respond successfully to initial treatment. In sexually active men, consider urethritis or prostatitis as the cause. In men who are older than 50 years of age, there is a rapid increase in UTI resulting from prostate hypertrophy, obstruction, and instrumentation.
UTIs among pediatric patients are associated with significantly greater morbidity and long-term sequelae than UTIs among adults, including impaired renal function and end-stage renal disease.
Trimethoprim-sulfamethoxazole has been the standard therapy for UTI; however, E. coli is becoming increasingly resistant to this medication. Many experts support using ciprofloxacin as an alternative and, in some cases, as the preferred first-line agent. However, others caution that widespread use of ciprofloxacin will promote increased resistance.
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