URINARY TRACT INFECTIONS (UTIs)

Urinary tract infections (UTIs) are commonly evaluated in the emergency department (ED). Most UTIs are caused by pathogens that normally inhabit the perineum and gastrointestinal tract.

— 80-90% to one hundred percent of UTIs are caused by Escherichia coli.

—Klebsiella, Proteus, Enterobacter, and Pseudomonas species account for 10% to 20% of cases.

—Group D Streptococcus, Chlamydia, and Staphylococcus are responsible in fewer than 5% of cases.

Predisposing factors:

Women are affected more often than men because the shorter female urethra facilitates bacterial access to the bladder.

a) Sexual intercourse and the use of nonoxynol-9–containing spermicides predispose to the development of UTIs.

b) A significant frequency of asymptomatic bacteriuria is linked to pregnancy.

c) Postmenopausal state

d) Immunosuppression

Men

a) Predisposing conditions (e.g., anatomic abnormalities, tumors, calculi, prostatitis, and enlarged prostate) are found in up to 80% of men with UTIs.

b) Many male UTI cases are caused by catheterization.

c) Uncircumcised men (and women who have intercourse with uncircumcised men) are more prone to UTIs.

d) Immunosuppression

Clinical features:

Symptoms: Presenting symptoms may include urinary urgency, frequency, nocturia, dysuria, a sensation of incomplete voiding, and suprapubic pain. Patients with upper tract involvement may also have fever, chills, nausea, and vomiting.

Physical examination findings: Flank pain, mild suprapubic midline tenderness, and costovertebral angle tenderness may be associated with pyelonephritis and cystitis.

Differential diagnoses:

—Vaginitis resulting from Candida albicans, Trichomonas vaginalis, or Gardnerella infection must be considered.

—When males appear with urethral discharge, urethritis is a crucial factor to take into account. Neisseria gonorrhoeae and Chlamydia trachomatis are the most prevalent pathogens.

—Prostatitis: The most common infecting organisms are E. coli (80% of cases), Pseudomonas, Klebsiella, Proteus, and Enterococcus. 

Evaluation:

1).Urinalysis should be performed on a midstream clean-catch specimen. Patients with certain clinical conditions (e.g., vaginal discharge, vaginal bleeding, obesity) may need to be catheterized to obtain a urine specimen.

a) Microscopic analysis: 

—Hematuria could be an indication of upper or lower tract involvement.

—Bacteriuria: More than 10 to 15 organisms per high-power field on a centrifuged specimen is suggestive of UTI. Finding any bacteria on an uncentrifuged specimen correlates with a positive urine culture.

—Pyuria is defined by the presence of more than 10 white blood cells (WBCs) per high-power field.

b) Dipstick analysis:

—Leukocyte esterase test: The leukocyte esterase test is a reliable screen for pyuria, although false-negative results may occur with low-level pyuria.

—The presence of nitrites is a sign of gram-negative bacterial infection.

2). Urine cultures:

a) Indications: Urine cultures are not routinely ordered on uncomplicated infections but may be indicated in some patients. Examples include immunosuppressed patients, suspected pyelonephritis, indwelling catheters, patients who fail to respond to therapy, patients requiring hospitalization, or a history of drug-resistant infections.

b) Interpretation: A positive culture is one where 105 colonies/mL of urine are growing.

3). Complete blood count (CBC): The CBC may reveal leukocytosis in patients with suspected pyelonephritis. The leukocyte count is not generally elevated or indicated in patients with only cystitis.

Therapy:

1). Cystitis:

—Uncomplicated cases: In patients without constitutional symptoms or complicating medical conditions and a short duration of symptoms, uncomplicated cystitis can be treated with a 5-day course of nitrofurantoin, or a 3-day course of oral trimethoprim–sulfamethoxazole.

—Complicated cases: In patients with complicating medical conditions, a longer duration of symptoms, or a relapse of infection, 7 to 10 days of therapy is required.

—Pregnant patients: Uncomplicated cystitis and asymptomatic bacteriuria in pregnant women can be treated with oral amoxicillin, nitrofurantoin, or cefpodoxime.

2). Pyelonephritis:

a) Outpatient treatment

—Parenteral antibiotics should be given before discharge. Ceftriaxone (1–2 g) or gentamicin (1.0 mg/kg) with ampicillin (1–2 g).

—Oral antibiotics: A 10- to 14-day course of trimethoprim–sulfamethoxazole (160/800 mg, twice daily by mouth) or a fluoroquinolone (e.g., ciprofloxacin, 500 mg twice daily) is required. Nitrofurantoin shouldn't be used to treat pyelonephritis.

b)Inpatient management entails the intravenous administration of the Parenteral antibiotics [Ceftriaxone (1–2 g) or gentamicin (1.0 mg/kg) with ampicillin (1–2 g)], or aztreonam (0.5–2 g two to four times daily), imipenem (600 mg three to four times daily), or ciprofloxacin (200–400 mg intravenously twice daily).

Disposition:

Patients who need to be admitted to the hospital include:

—Those with clinical toxicity (e.g., fever, vomiting, ill-appearing)

—Those who are unable to take oral fluids or drugs..

—Patients with pyelonephritis who are very young, pregnant, or elderly

Discharge: Most patients are treated as outpatients. Before discharge, patients should be advised regarding the prevention of UTIs. There are several widely used strategies for preventing UTIs:

—Practicing postcoital voiding

—Urinating frequently and completely;

—Increasing fluid intake 

—Observing regional hygiene (including wiping from front to back)