Urinary tract infections or UTI: A UTI is an infection of any part of the urinary tract, including the kidneys, ureters, bladder, and/or urethra. It’s most common in young women.
Upper UTI involves infection of the kidneys and ureters. Lower UTI involves infection of the lower tract (bladder, prostate, and urethra).
A complicated UTI is associated with a structural or functional abnormality of the genitourinary tract, or with an underlying disease (e.g., diabetes, sickle cell anemia) that may lead to more severe infection. In the absence of such conditions, UTIs are usually milder, are called uncomplicated UTIs, and have a good prognosis.
Significant bacteriuria: This is defined as the presence of 100,000 or more colony forming units (CFU) per ml of urine (Kass criteria). The cutoff can be lowered in the presence of clinical symptoms, pyuria (>10 WBC/mm3), cystitis, and pyelonephritis.
Pregnant women with asymptomatic bacteriuria are at increased risk of pyelonephritis and premature delivery.
Clinical features:
Clinical features include dysuria, frequency, and urgency in lower UTIs. In pyelonephritis, symptoms include chills and fever, flank pain, and malaise.
Chlamydia trachomatis is a common cause of urethritis in women and men. Other causes include Neisseria gonorrhoeae and HSV type 2.
Acute bacterial prostatitis presents with acute onset of chills and fever, urinary frequency and urgency, dysuria, perineal and low back pain, and constitutional symptoms. Rectal examination is contraindicated in acute bacterial prostatitis due to the risk of precipitating sepsis.
Chronic bacterial prostatitis is milder and presents with relapsing UTIs with urinary frequency, dysuria, nocturia, and low back and perineal pain. Prostatic massage followed by urine culture gives a better yield in chronic prostatitis.
Nonbacterial prostatitis is a chronic form that presents similarly, but urine and prostatic secretion cultures are sterile.
Prostatodynia is chronic noninflammatory prostatitis: no inflammatory cells are present, and the culture is sterile.
Reinfection is a recurring infection due to a different or the same microorganism that is usually drug susceptible. Unlike relapse, reinfection does not represent failure to eradicate infection from the urinary tract; it occurs due to reinvasion of the system.
Relapse is a return of infection due to the same microorganism, which is often drug resistant. It typically occurs within 3 weeks of completing treatment.
The term treatment failure has been used to describe:
Pathogenesis:
Bacteria in the enteric flora periodically gain access to the genitourinary tract. In women, the close proximity of the anus to the peri-urethra is a likely contributing factor. Bacterial colonization of the periurethral area often precedes the onset of bladder bacteriuria.
P-fimbriated strains of Escherichia coli adhere to uroepithelial cells via glycolipid receptors. Acidic pH and commensal vaginal flora protect against colonization.
After periurethral colonization, uropathogens can spread:
Urine is a good growth medium for bacteria. Tamm-Horsfall protein helps prevent colonization by adhering to fimbriae.
Renal calculi, structural anomalies of the urinary tract, VUR, residual urine in the bladder, BPH, urethral stricture, instrumentation of the urinary tract, catheterization, etc. increase the risk of UTI.
Diagnosis:
A centrifuged urine sample should be examined microscopically and cultured. Pus cells are present, typically >10/mm3.
Treatment:
In asymptomatic patients, treatment should be considered only if colony counts are greater than or equal to 100,000 per ml on at least 2 occasions. Bacteriuria developing after urinary catheterization should be treated with antibiotics.
Uncomplicated cystitis is treated with nitrofurantoin, fosfomycin, cephalexin, or trimethoprim/sulfamethoxazole. Fluoroquinolones can be used if local resistance is low.
Patients with uncomplicated pyelonephritis (i.e., no DM, non-pregnant, mild symptoms) can be treated on an outpatient basis. Other cases are admitted.
Outpatient treatment of pyelonephritis is with oral fluoroquinolone (if resistance is low), such as ciprofloxacin or levofloxacin, or trimethoprim/sulfamethoxazole. An initial single dose of intravenous gentamicin plus ceftriaxone is given.
Inpatient treatment is with intravenous fluoroquinolone, an aminoglycoside with ampicillin, cephalosporins, or carbapenems.
Acute prostatitis is treated with oral Bactrim or ciprofloxacin for 4-6 weeks; severely ill patients need intravenous ampicillin plus gentamicin. Therapy should be guided by culture and sensitivity.
Chronic prostatitis is treated with oral fluoroquinolones. Second-line drugs are doxycycline, Bactrim, azithromycin, and clarithromycin. Treatment may be needed for up to one year.
Nonbacterial prostatitis is treated with doxycycline or azithromycin. Prostatic abscess needs drainage.
Catheter associated UTIs should be treated with antibiotics and removal of infected catheter.