Urinary Tract Infections, Adult, Emergency Medicine

Basics

Description

Colonization of urine with uropathogens and invasion of genitourinary (GU) tract
Defined as urinary symptoms with ≥102 to 105 CFU/mL of uropathogen and ≥10 WBC/mm3
Lifetime risk of UTI in women is >50%
Uncomplicated cystitis:
- Females aged 13 " 50
- Symptoms <2 " 3 days
- Not pregnant
- Afebrile (temperature <38 °C)
- No flank pain
- No costovertebral angle tenderness (CVAT)
- Fewer than 4 UTIs in past year
- No recent instrumentation or previous GU surgery
- No functional/structural GU abnormality
- Not immunocompromised
- Neurologically intact
Complicated cystitis:
- Do not meet above criteria
- Male gender
- Patients with anatomic, functional, or metabolic abnormalities of GU tract
- Postvoid residual urine
- Catheters
- Resistant pathogens
- Recent antimicrobial use
Uncomplicated pyelonephritis:
- Renal parenchymal infection
- Dysuria, frequency, urgency
- Fever, chills, myalgias, nausea, vomiting
- Flank, back, or abdominal pain
- CVA tenderness
- Leukocytosis (common)
Complicated pyelonephritis:
- Renal parenchymal infection
- Temperature >40 °C
- Urosepsis with septic shock
- Intractable nausea, vomiting
- Diabetes, other immunosuppression
- Pregnancy (especially latter half)
- Concomitant obstruction or stone
- Asymptomatic (occult)

Etiology

Mechanism:
- Organisms colonize periurethral area and subsequently infect the GU tract.
Risk factors:
- Population:
  - Newborn, prepubertal girls, young boys
  - Sexually active young woman
  - Postmenopausal woman, elderly males
- Behavior:
  - Sexual intercourse, spermicides, diaphragms
Elderly females/postmenopausal state
Less efficient bladder emptying, bladder prolapse, alteration of bladder defenses
Increased vaginal pH
Contamination due to urinary or fecal incontinence (Enterobacteriaceae)
Instrumentation:
- Elderly males due to prostatic hypertrophy and instrumentation
Organisms:
- Escherichia coli (80 " 85%)
- Staphylococcus saprophyticus (10%)
- Other (10%): Klebsiella, Proteus mirabilis, Enterobacter spp., Pseudomonas aeruginosa, group D streptococci

Diagnosis

Signs and Symptoms

Lower tract infection: Cystitis:
- Dysuria, frequency, urgency, hesitancy
- Suprapubic pain
- Hematuria
Upper tract infection: Pyelonephritis:
- Symptoms of cystitis:
  - Fever, chills
  - Flank pain and/or tenderness
  - Nausea, vomiting, anorexia
- Leukocytosis
- Up to 50% of patients with cystitis may actually have pyelonephritis:
  - Symptom duration >5 days, homelessness, and recent UTI are risk factors for upper tract infection
- Elderly or frail patients:
  - Altered mental status
  - Anorexia
  - Decreased social interaction
  - Abdominal pain
  - Nocturia, incontinence
  - Syncope or dizziness

Essential Workup

Urinalysis (dipstick test, microscopy)
Females: Rule out pregnancy, urethritis, vaginitis, pelvic inflammatory disease (PID)
Males: Rule out urethritis, epididymitis, prostatitis; inquire about anal intercourse/HIV.
Urologic evaluation in young healthy males with 1st UTI is not routinely recommended.

Diagnosis Tests & Interpretation

Lab

Rapid Urine Screen:
- Dipstick (leukocyte esterase + nitrite) most effective when urine contains 105 CFU/mL
- Lab specimen unnecessary if pyuria and bacteriuria confirmed by dipstick
- Leukocyte esterase: Positive likelihood ratio (LR+) ¢ ¼5, negative likelihood ratio (LR ¢ ) ¢ ¼0.3
- Nitrite: LR+ ¢ ¼30, LR ¢ ¢ ¼0.5
Urinalysis/microscopy:
- Obtain if rapid urine screen is unavailable or negative in patients with presumed UTI.
- 10 WBC/mm3 in clean catch midstream urine indicates infection.
- Bacteria detected in unspun urine indicates >105 CFU/mL. (LR+ ¢ ¼20, LR ¢ ¢ ¼0.1)
Indications for urine culture:
- Complicated UTIs
- Negative rapid urine screen or microscopy in patients with presumed UTI
- Persistent signs and symptoms after 2 " 3 days of treatment
- Recurrence (relapse vs. reinfection)
- Recently hospitalized patients
- Nosocomial infections
- Pyelonephritis

Asymptomatic bacteriuria (including positive cultures) occurs in 20% of women >65 yr, 50% of women >80 yr and generally should not be treated.
Consider treating symptomatic geriatric patients for 5 " 10 days to decrease risk of recurrent or persistent bacteriuria.
Fluoroquinolones may cause CNS side effects.

Imaging

Indicated for complicated upper tract disease (see Pyelonephritis)
Helical CT, renal ultrasound, or IV pyelogram if concomitant stone or obstruction suspected

Diagnostic Procedures/Surgery
Patients with significant hematuria, recurrent UTI with same uropathogen, or symptoms of obstruction need urologic evaluation to identify structural or functional abnormality.

Differential Diagnosis

Appendicitis
Diverticulitis
Epididymitis
Nephrolithiasis
PID/cervicitis
Prostatitis
Pyelonephritis
Urethritis
Vulvovaginitis

Treatment

Initial Stabilization/Therapy

Urosepsis/septic shock:

Manage airway and resuscitate as indicated
IV crystalloid and vasopressors as needed
Early goal-directed therapy

Ed Treatment/Procedures

Stable Patients

For uncomplicated UTIs in women for most antibiotics, 3 days of therapy:
- More effective than single dose
- Clinically as effective as 5 " 10-day course with fewer side effects
Resistance varies by place and changes over time:
- In North America, 40 " 50% of E. coli are resistant to ampicillin; 3 " 17% to fluoroquinolones and is increasing.
- Resistance to trimethoprim " sulfamethoxazole (TMP/SMX) is increasing (up to 30%).
- Nitrofurantoin: In some studies, nitrofurantoin resistance is less than for other more widely used antibiotics.
- Culture resistance may not correlate with clinical effect because urine antibiotic concentrations are much higher than those used in laboratory testing. However, symptom resolution may be delayed a few days in patients with resistant bacteria.
Antibiotics of choice:
- Nitrofurantoin
- TMP/SMX
- Fluoroquinolones 2nd-line treatment in women:
  - Sulfonamide intolerance
  - All quinolones equally effective ( ¢ ¼95% susceptibility rates) but side effects vary
  - High frequency of antimicrobial resistance related to recent treatment
  - Live in areas with unknown or >20% resistance to TMP/SMX
- Oral cephalosporins may be reasonable alternatives in specific circumstances:
  - Require 7-day treatment regimens
- Amoxicillin " clavulanate not as effective as ciprofloxacin, probably due to failure to eradicate vaginal E. coli
- Diabetic women have increased risk of bacteriuria with Klebsiella spp.
- Treat dysuria with phenazopyridine.
- Treat pain with appropriate analgesics.
Cranberry juice or tablets/products:
- Prevents specific E. coli from adhering to uroepithelial cells but probably does not lower UTI recurrence rate in women with history of recurrent UTIs
- Evidence suggests ineffective for treatment
Treatment of upper tract disease " rule of 2s:
- 2 L of IV crystalloid
- 2 tablets of oxycodone/acetaminophen
- 2 g of ceftriaxone or 2 mg/kg of gentamicin
- If fever drops by 2 °C and patient can retain 2 glasses of water
- Discharge with fluoroquinolone for 2 wk.
- Follow up in 2 days.

Treat asymptomatic bacteriuria in pregnancy with 4 " 7-day course of antibiotics:
- Nitrofurantoin:
  - May cause birth defects if used in 1st trimester
  - Contraindicated in G6PD-deficiency
- Amoxicillin (not 1st-line treatment due to high rate of resistance)
- Fosfomycin (safe and effective)
- TMP/SMX:
  - SMX should be avoided late in pregnancy as kernicterus can result.
  - TMP should be avoided in 1st trimester (folic acid antagonist; possible birth defects).
- Quinolones should be avoided:
  - CNS reactions
  - Blood dyscrasias
  - Effects on collagen formation

Medication

Amoxicillin: 500 or 875 mg PO q12h
Cefixime: 400 mg PO q24h
Cefpodoxime: 400 mg PO q12h
Ceftazidime: 1 " 2 g IV q8 " 12h
Ceftriaxone: 1 " 2 g IV/IM q24h
Cefuroxime: 250 " 500 mg PO q12h
Cephalexin: 250 " 500 mg PO q6h
Ciprofloxacin: 100 " 500 mg PO q12h
Doripenem: 500 mg IV q8h
Fosfomycin: 3 g single dose
Gentamicin: 2 mg/kg IV or IM q8h
Levofloxacin: 250 mg PO q24h
Nitrofurantoin macrocrystals 100 mg PO q12h
Norfloxacin: 400 mg PO q12
Ofloxacin: 200 mg PO q12h or 400 mg IV q12h
Phenazopyridine: 200 mg PO TID for 2 days:
- For symptomatic treatment of dysuria
- May turn urine and contact lenses orange
TMP/SMX: 160 mg/800 mg PO q12h or 10 mg/kg/d IV div. q6 " 8 " 12h

Follow-Up

Disposition

Admission Criteria

Inability to comply with oral therapy
Toxic appearing, unstable vital signs
Pyelonephritis:
- Intractable symptoms
- Extremes of age
- Immunosuppression
- Urinary obstruction
- Consider if coexisting urolithiasis
- Significant comorbid disease
- Outpatient treatment failure
- Late in pregnancy

Discharge Criteria

Well appearing, normal vital signs
Can comply with oral therapy
No significant comorbid disease
Adequate follow-up (48 " 72 hr) as needed
Healthy patients with uncomplicated pyelonephritis who respond to treatment in ED according to rule of 2s
Pyelonephritis in early pregnancy with good follow-up may be treated as outpatients

Issues for Referral
Recurrent UTIs require workup for underlying pathology.

Followup Recommendations

Follow-up for UTIs should start with primary care physician.

Pearls and Pitfalls

For women who have more than 2 episodes of acute cystitis in 6 mo or 3 episodes in 1 yr, consider long-term (6 " 12 mo) prophylactic antibiotics or postcoital prophylaxis
Pregnant women should be screened and treated for asymptomatic bacteriuria (ASB) because 20 " 40% of women with ASB progress to pyelonephritis.
ASB in pregnant women associated with increased risk of preterm birth, low birth weight, and perinatal mortality.
Treat ASB in renal transplant recipients, patients who have recently undergone a urologic procedure, and neutropenic patients.
Risk factors for acute cystitis in men: Increased age, uncircumsized, HIV infection (low CD4 counts), anatomic abnormalities (BPH or urethral strictures), and sexual activity (especially insertive anal intercourse).
25% of male GU complaints are attributable to prostatitis. TMP/SMX or fluoroquinolones are 1st-line treatment.
In patients with indwelling catheters, pyuria is less strongly correlated with UTI than in patients without catheters.

Additional Reading

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:e103 " e120.
Hooton TM. Clinical practice. Uncomplicated urinary tract infection. N Engl J Med. 2012;366(11):1028 " 1037.
Nicolle LE, Bradley S, Colgan R, et al. Infectious Diseases Society of America guidelines for the diagnosis and treatment of asymptomatic bacteriuria in adults. Clin Infect Dis. 2005;40:643 " 654.
St. John A, Boyd JC, Lowes AJ, et al. The use of urinary dipstick tests to exclude urinary tract infection. Am J Clin Pathol. 2006;126:428 " 436.

Codes

ICD9

590.80 Pyelonephritis, unspecified
595.9 Cystitis, unspecified
599.0 Urinary tract infection, site not specified
646.60 Infections of genitourinary tract in pregnancy, unspecified as to episode of care or not applicable
041.49 Other and unspecified Escherichia coli [E. coli]
996.76 Other complications due to genitourinary device, implant, and graft

ICD10

N12 Tubulo-interstitial nephritis, not spcf as acute or chronic
N30.90 Cystitis, unspecified without hematuria
N39.0 Urinary tract infection, site not specified
O23.40 Unsp infection of urinary tract in pregnancy, unsp trimester
B96.20 Unsp Escherichia coli as the cause of diseases classd elswhr
N30.91 Cystitis, unspecified with hematuria
T83.51XA Infect/inflm reaction due to indwell urinary catheter, init

SNOMED

68566005 urinary tract infectious disease (disorder)
38822007 Cystitis (disorder)
45816000 Pyelonephritis (disorder)
307534009 Urinary tract infection in pregnancy
301011002 Escherichia coli urinary tract infection (disorder)
371061003 infection of bladder catheter (disorder)

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