> Table of Contents > Urinary Tract Infection (UTI) in Females
Urinary Tract Infection (UTI) in Females
Akhil Das, MD, FACS
image BASICS
DESCRIPTION
  • Urinary tract infection (UTI) is the presence of pathogenic microorganisms within the urinary tract with concomitant symptoms.
  • This topic refers primarily to infectious cystitis; other complicated UTIs, such as pyelonephritis, are discussed elsewhere.
  • Uncomplicated UTI: occurs in patients who have a normal, unobstructed urinary tract, who have no history of recent instrumentation, and whose symptoms are confined to the lower urinary tract. Uncomplicated UTIs are most common in young, sexually active women.
  • Complicated UTI: an infection of the lower or upper urinary tract in the presence of an anatomic abnormality, a functional abnormality, or a urinary catheter
  • Recurrent UTI: symptomatic UTIs that follow resolution of an earlier episode, usually after appropriate treatment
    • No single definition of the frequency of recurrent UTI exists, but a pragmatic definition is ≥3 infections per year.
    • Most recurrences are thought to represent reinfection rather than relapse.
    • No evidence indicates that recurrent UTIs lead to health problems such as hypertension or renal disease in the absence of anatomic or functional abnormalities of the urinary tract (1)[A].
  • System(s) affected: renal/urologic
  • Synonym(s): cystitis; infectious cystitis
EPIDEMIOLOGY
Incidence
  • Accounts for 8 million doctor visits and 1 million emergency room visits, and contributes to >100,000 hospital admissions each year
  • 11% of women have UTIs in any given year.
  • Predominant age: young adults and older
  • Predominant sex: female > male
Prevalence
  • >50% of females have at least one UTI in their lifetime.
  • One in four women have recurrent UTIs.
ETIOLOGY AND PATHOPHYSIOLOGY
  • Bacteria and subsequent infection in the urinary tract arise chiefly via ascending bacterial movement and propagation (1).
  • Pathogenic organisms (Escherichia coli) possess adherence factors and toxins that allow initiation and propagation of genitourinary infections:
    • Type 1 and P. pili (pyelonephritis-associated pili)
    • Lipopolysaccharide
  • Most UTIs are caused by bacteria originating from bowel flora:
    • E. coli is the causative organism in 80% of cases of uncomplicated cystitis.
    • Staphylococcus saprophyticus accounts for 15% of infections.
    • Enterobacteriaceae (i.e., Klebsiella, Proteus, Enterobacter, and Pseudomonas) also contribute.
  • Candida is associated with nosocomial UTI (2).
Genetics
Women with human leukocyte antigen 3 (HLA-3) and nonsecretor Lewis antigen have an increased bacterial adherence, which may lead to an increased risk in UTI.
RISK FACTORS
  • Previous UTI
  • Diabetes mellitus (DM)
  • Pregnancy
  • Sexual activity
  • Use of spermicides or diaphragm
  • Underlying abnormalities of the urinary tract such as tumors, calculi, strictures, incomplete bladder emptying, urinary incontinence, neurogenic bladder
  • Catheterization
  • Recent antibiotic use
  • Poor hygiene
  • Estrogen deficiency
  • Inadequate fluid intake
GENERAL PREVENTION
  • Maintain good hydration.
  • Women with frequent or intercourse-related UTI should empty bladder immediately before and following intercourse; consider postcoital antibiotic.
  • Avoid feminine hygiene sprays and douches.
  • Wipe urethra from front to back.
  • Cranberry juice (not cranberry juice cocktail) consumption may prevent recurrent infections.
COMMONLY ASSOCIATED CONDITIONS
See “Risk Factors.”
Geriatric Considerations
  • Elderly patients are more likely to have underlying urinary tract abnormality.
  • Acute UTI may be associated with incontinence or mental status changes in the elderly.
image DIAGNOSIS
PHYSICAL EXAM
  • Suprapubic tenderness
  • Urethral and/or vaginal tenderness
  • Fever or costovertebral angle tenderness indicates upper UTI.
DIFFERENTIAL DIAGNOSIS
  • Vaginitis
  • Asymptomatic bacteriuria
  • STDs causing urethritis or pyuria
  • Hematuria from causes other than infection (e.g., neoplasia, calculi)
  • Interstitial cystitis
  • Psychological dysfunction
DIAGNOSTIC TESTS & INTERPRETATION
Initial Tests (lab, imaging)
  • No lab testing is necessary in women with high likelihood of lower UTI based on classic symptoms.
  • Urinalysis
    • Pyuria (>10 neutrophils/high-power field [HPF])
    • Bacteriuria (any amount on unspun urine, or 10 bacteria/HPF on centrifuged urine)
    • Hematuria (>5 RBCs/HPF)
  • Dipstick urinalysis
    • Leukocyte esterase (75-96% sensitivity, 94-98% specificity, when >100,000 colonyforming units [CFU])
    • Nitrite tests are useful with nitrite-reducing organisms (e.g., enterococci, S. saprophyticus, Acinetobacter).
  • Urine culture: only indicated if diagnosis is unclear or patient has recurrent infections and resistance is suspected. It is neither cost-effective nor usually helpful for lower-tract, uncomplicated UTI.
    • Presence of 100,000 CFU/mL of organism indicates infection.
    • Identification of a single organism at lower CFU per milliliter likely also represents infection in the presence of appropriate symptoms.
    • Suspect a contaminated specimen when culture shows multiple types of bacteria.
  • Imaging studies are often not required in most cases of UTI.
Follow-Up Tests & Special Considerations
  • In nonpregnant, premenopausal women with symptoms of UTI, positive urinalysis, and no risks for complicated infection, empirical treatment may be given without obtaining a urine culture.
  • Dipstick urinalysis may be helpful but not necessary in patients with characteristic symptoms (i.e., high pretest probability).
  • Imaging may be indicated for UTIs in men, infants, immunocompromised patients, febrile infection, signs or symptoms of obstruction, failure to respond to appropriate therapy, and in patients with recurrent infections.
  • CT scan and MRI provide the most complete anatomic data in adults.
Pediatric Considerations
For infants and children, obtain US; if ureteral dilatation is detected, obtain either voiding cystourethrogram or isotope cystogram to evaluate for reflux.
Diagnostic Procedures/Other
  • Urethral catheterization maybe necessary to obtain a urine specimen from children and adults if the voided urine is suspected of being contaminated.
  • Suprapubic bladder aspiration or urethral catheterization techniques can be used to obtain specimens from infants.
  • Cystourethroscopy can be used for patients with recurrent UTIs and previous anti-incontinence surgery or hematuria (3)[A].
image TREATMENT
GENERAL MEASURES
  • Maintain good hydration.
  • Maintain good hygiene.
  • 1/4 of women with uncomplicated UTI experience a second UTI within 6 months and 1/2 at some time during their lifetime.
P.1085

MEDICATION
First Line
  • The urinary tract topical analgesic phenazopyridine 100 to 200 mg TID produces rapid relief of symptoms and should be offered to patients with more than minor discomfort; it is available over the counter. This medication is not a substitute for definitive treatment. This medication also may alter urinalysis but not the urine culture.
  • Uncomplicated UTI (adolescents and adults who are nonpregnant, nondiabetic, afebrile, immunocompetent, and without genitourinary anatomic abnormalities)
    • Trimethoprim-sulfamethoxazole (TMP-SMZ; Bactrim): 160/800 mg PO BID for 3 days, best where resistance of E. coli strains <20%
    • 5-day course of nitrofurantoin or 3-day fluoroquinolone course should be used in patients with allergy to TMP-SMZ and in areas where E. coli resistance to TMP-SMZ >20% (3)[A].
    • Fosfomycin (Monurol): 3 g PO single dose (expensive)
  • Lower UTI in pregnancy
    • Nitrofurantoin (Macrobid): 100 mg PO BID for 7 days
    • Cephalexin (Keflex): 500 mg PO BID for 7 days
  • Postcoital UTI: single-dose TMP-SMX or cephalexin may reduce frequency of UTI in sexually active women.
  • Complicated UTI (pregnancy, diabetes, febrile, immunocompromised patient, recurrent UTIs): Extend course to 7 to 10 days of treatment with antibiotic chosen based on culture results; may begin with fluoroquinolone, TMP-SMX, or cephalosporin while awaiting results (avoid using nitrofurantoin for complicated UTI)
    • Fluoroquinolones are not safe during pregnancy and are usually avoided in treatment of children.
    • TMP-SMX use in pregnancy is not desirable (especially in 3rd trimester) but is appropriate in some circumstances (3)[A].
Second Line
  • Uncomplicated UTI
    • Ciprofloxacin: 250 mg PO BID for 3 days; should be reserved for complicated UTIs
    • &bgr;-Lactams (amoxicillin/clavulanate, cefdinir, cefpodoxime proxetil) for 3 to 7 days
  • Chronic UTIs
    • Women with recurrent symptomatic UTIs can be treated with continuous or postcoital prophylactic antibiotics. Treatment duration guided by the severity of patient symptoms and by physician and patient preference: Consider 6 months of therapy, followed by observation for reinfection after discontinuing prophylaxis.
      • Continuous antimicrobial prophylaxis involves daily administration of low-dose TMP-SMX 40/200 mg or nitrofurantoin 50 to 100 mg, among others.
  • Another treatment option is self-started antibiotics.
Pediatric Considerations
Long-term antibiotics appear to reduce the risk of recurrent symptomatic UTI in susceptible children, but the benefit is small and must be considered together with the increased risk of microbial resistance.
ISSUES FOR REFERRAL
Men with uncomplicated UTI and most other patients with complicated UTI should be referred to a urologist for evaluation.
Pediatric Considerations
UTI in children, especially <1 year of age, should prompt workup for urinary tract anomalies.
SURGERY/OTHER PROCEDURES
  • Urinary tract obstruction with urosepsis requires urgent drainage of the obstructed system.
  • Patients with emphysematous pyelonephritis or pyonephrosis may need immediate surgical intervention.
COMPLEMENTARY & ALTERNATIVE MEDICINE
  • Preliminary studies indicate that Vaccinium macrocarpon (cranberry) juice may help to prevent and treat UTIs by inhibiting bacterial adherence to the bladder epithelium.
  • Cranberry juice may decrease the number of symptomatic UTIs over a 1-year period, particularly for women with recurrent UTIs. The optimal dosage or method of administration (e.g., juice, tablets, or capsules) is still unclear.
INPATIENT CONSIDERATIONS
Inpatient evaluation is reserved for patients with complicated or upper tract UTIs. Majority of UTIs are managed in an outpatient setting.
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
  • First or rare UTI: Young or middle-aged, nonpregnant adult females require no follow up if UTI is clinically cured after 3-day therapy.
  • If symptoms persist after 2 to 3 days of therapy, obtain culture/sensitivity and change antibiotic accordingly.
Pregnancy Considerations
  • UTI during pregnancy always requires culture/sensitivity and usually requires a 7- to 14-day treatment.
  • Following the treatment of acute infection, pregnant women warrant surveillance urine cultures every trimester. They may receive prophylactic antibiotics for the remainder of pregnancy for recurrent or upper tract disease.
PATIENT EDUCATION
  • Although no controlled studies support this intervention, postcoital voiding is commonly advised.
  • FamilyDoctor Web site: http://familydoctor.org/familydoctor/en/diseases-conditions/urinary-tractinfections.html
PROGNOSIS
Symptoms resolve within 2 to 3 days of antibiotic treatment in almost all patients.
REFERENCES
1. Kodner CM, Thomas Gupton EK. Recurrent urinary tract infections in women: diagnosis and management. Am Fam Physician. 2010;82(6):638-643.
2. Hooton TM. Clinical practice. Uncomplicated urinary tract infection. N Engl J Med. 2012;366(11):1028-1037.
3. Zalmanovici Trestioreanu A, Green H, Paul M, et al. Antimicrobial agents for treating uncomplicated urinary tract infection in women. Cochrane Database Syst Rev. 2010;(10):CD007182.
Additional Reading
&NA;
  • Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011;52(5):e103-e120.
  • Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2008;(1):CD001321.
  • Litza JA, Brill JR. Urinary tract infections. Prim Care. 2010;37(3):491-507.
  • Mehnert-Kay SA. Diagnosis and management of uncomplicated urinary tract infections. Am Fam Physician. 2005;72(3):451-456.
  • Mody L, Juthani-Mehta M. Urinary tract infections in older women: a clinical review. JAMA. 2014;311(8): 844-854.
  • Stapleton A, Stamm WE. Prevention of urinary tract infection. Infect Dis Clin North Am. 1997;11(3): 719-733.
  • Williams G, Craig JC. Long-term antibiotics for preventing recurrent urinary tract infection in children. Cochrane Database Syst Rev. 2011;(3):CD001534.
See Also
&NA;
Algorithm: Dysuria
Codes
&NA;
ICD10
  • N39.0 Urinary tract infection, site not specified
  • N30.90 Cystitis, unspecified without hematuria
  • N30.91 Cystitis, unspecified with hematuria
Clinical Pearls
&NA;
  • Uncomplicated UTIs cause significant morbidity but generally do not cause renal damage.
  • Treatment of uncomplicated UTIs reduces morbidity, but the risk of recurrence stays the same.
  • Bacteria originating from intestinal tract cause most UTIs, especially E. coli.
  • Imaging studies are not required for most women with UTIs.
  • Uncomplicated UTIs should be treated for 3 days (TMP-SMX) or 5 days (nitrofurantoin). All pregnant women with bacteriuria should be treated.