Snapshot A 23-year-old woman presents to her primary care physician due to pain with urination and increased urinary frequency. She reports that her symptoms began approximately 3 days ago and has not noticed any abnormal smell, vaginal discomfort, or vaginal discharge. The patient is otherwise healthy and states that she has been having sexual intercourse more frequently with her partner. She infrequently uses condoms and is on oral contraception. Her vital signs and physical examination is unremarkable. She is started on oral nitrofurantoin for 5 days. (Acute uncomplicated cystitis) Introduction Clinical definitionurinary tract infections (UTI) can either be asymptomatic or symptomatic and encompasses asymptomatic bacturia (ASB) login to view 7 more bullets cystitis prostatitis pyelonephritis login to view 1 more bullet it is important to distinguish between uncomplicated versus complicated UTI uncomplicated UTI login to view 1 more bullet complicated UTI login to view 1 more bullet Epidemiology incidence 50-80% of women acquire at least 1 UTI 20-30% of women with 1 UTI have recurrent infections demographics more common in women, elderly, and infants location bladder prostate kidneys risk factors female benign prostatic hyperplasia frequent sexual intercourse history of UTI incontinence diabetes mellitus vasicoureteral reflux spermicide use prolonged catheterization (most important for catheter associated UTI) Pathogenesis in most cases bacteria ascends from the urethra to the bladder (cystitis) bacterial organisms can further ascend through the ureter and infect the kidney causing a renal parenchymal infection (pyelonephritis) note that infection and symptom development depends on the login to view 7 more bullets hematogenous spread to the urinary tract can also result in a UTI; however, this is rare login to view 1 more bullet Prognosis ASB in elderly or catheterized patients does not increase the risk of death recurrent UTI in children and adults does not result in chronic pyelonephritis or renal failure this is true when there are not anatomic abnormalities Microbiology of Urinary Tract Infections Microbe Findings Comments E. coli Green metallic sheen on EMB agar Most common cause of UTI S. saprophyticus - Second most common cause in sexually active women K. pneumoniae Large mucoid capsule and viscous colonies Third most common cause S. marcescens Red pigment production by select strains - Enterococcus - Typically a nosocomial infection that is drug-resistant P. mirabilis "Swarming" appearance on agar Urease positive Can result in struvite stone formation - P. aeruginosa Blue-green pigment Typically a nosocomial infection that is drug-resistant Presentation Symptoms/physical exam/findings ASB asymptomatic patient with an incidental finding of bacteruria on urine culture cystitis dysuria urinary frequency urgency nocturia suprapubic discomfort gross hematuria prostatitis dysuria frequency pain in the prostatic pelvic or perineal area bladder outlet obstruction fever and chills pyelonephritis fever login to view 1 more bullet costovertebral angle pain login to view 1 more bullet obstructive uropathy in patients with diabetes login to view 1 more bullet emphysematous pyelonephritis in patients with diabetes login to view 1 more bullet Studies Labs urine dipstick nitrite positivity suggests an E. coli infection or other infection of the Enterobacteriaceae family leukocyte esterase positive urease positivity suggests an S. saprophyticus, Proteus, or Klebsiella infection urinalysis > 10 white blood cells (WBCs)/mL > 1000 CFU/mL white blood cell casts login to view 1 more bullet urine culture gold standard for diagnosing UTI may appear sterile if caused by chlamydia login to view 1 more bullet Histology chronic pyelonephritis "thyroidization" of tubules due to eosinophilic casts contained in the tubules Differential Acute hemorrhagic cystitis can be caused by adenovirus Urethritis Nephrolithiasis Genitourinary malignancy Treatment Medical TMP-SMX or nitrofurantoin indications login to view 6 more bullets fluoroquinolones (e.g., ciprofloxacin) indication login to view 1 more bullet fluconazole indication login to view 1 more bullet Operative nephrectomy indications login to view 1 more bullet percutaneous drainage indications login to view 1 more bullet Complications Uncomplicated UTI complications are uncommon Complicated UTI bacteremia urosepsis systemic inflammatory response syndrome (SIRS) renal and perinephric abscess emphysematous pyelonephritis xanthogranulomatous pyelonephritis associated with long-term urinary tract obstruction and infection login to view 1 more bullet malakoplakia renal papillary necrosis UTI in pregnancy pyelonephritis sepsis chorioamnionitis preterm labor low birth weight hypertension and pre-eclampsia UTI in men acute or chronic prostatitis urethritis acute epididymitis orchitis