Approach to the Diagnosis of an Adult with a Urinary Tract Infection

 

Bacteriuria:

(1) usually defined as significant with > 10^5 colony forming units (CFU) per mL urine

(2) may include counts of 10^2 to 10^5 if symptomatic

 

In an adult patient with bacteriuria:

(1) Is the patient symptomatic?

(1a) If no, then: asymptomatic bacteriuria.

(1b) If yes, then: go to (2).

(2) Does the patient have known or suspected complicating factor(s)?

(2a) If yes, then: complicated UTI.

(2b) If no, then: young female patient with uncomplicated UTI, and go to (3).

(3) Is this a recurrent episode?

(3a) If yes, then: recurrent UTI.

(3b) If no. then: go to (4).

(4) Does the patient have symptoms of an upper UTI (pyelonephritis)?

(4a) If yes, then: upper UTI in a young woman.

(4b) If no, then lower UTI in a young woman.

 

High risk UTIs:

(1) immunosuppression

(2) pregnancy

(3) diabetes mellitus

(4) sickle cell anemia

(5) UTI caused by a multi-antibiotic resistant organism

 

Asymptomatic bacteriuria: usually not treated UNLESS:

(1) pregnant woman

(2) before or after urologic instrumentation

(3) after definitive removal of a chronic, indwelling catheter

(4) in a renal transplant recipient

 

Factors associated with complicated UTI:

(1) male patient

(1a) risk of complicated UTI in a man < 40: low to moderate

(1b) risk of complicated UTI in a man 40-65 years: high

(1c) risk of complicated UTI in a man > 65 years: high

(2) older woman

(2a) risk of complicated UTI in a woman 40-65 years: moderate

(2b) risk of complicated UTI in a woman > 65 years: high

(3) obstruction or foreign body in urinary tract

(4) post-voiding urine volume > 100 mL

(5) vesicoureteral reflux

(6) recent urologic invasive procedure

(7) renal transplant recipient

(8) azotemia (rising BUN and/or creatinine)

(9) surgically created ileal loop

 

Complicated UTI:

(1) urine cultures recommended before and after treatment

(2) identification and treatment of risk factor(s) goal

(3) cystitis in a young, sexually active male is usually not complicated and imaging studies are often unnecessary

(4) if a 7 day regimen fails in the young, sexually active male, then evaluate and treat as a complicated UTI

 

Recurrent UTI:

(1) urine cultures should be done 1-2 times to document recurrence and look for resistance, but additional cultures usually unnecessary

(2) imaging studies in young women with recurrent cystitis usually are not indicated

(3) postmenopausal women with recurrent infections may benefit from prophylactic vaginal estrogens or antibiotics

 

Upper UTI in a young woman:

(1) need urine culture before and after treatment

(2) imaging studies usually not indicated unless the infection is severe or atypical

(3) imaging studies should be done if symptoms persist > 72 hours (3 days) in a person on appropriate antibiotic therapy

 

Lower UTI in a young woman:

(1) need to differentiate between cystitis, urethritis, and vaginitis

(2) urine culture is usually not necessary

Type of Infection	Patient Characteristics	Management
acute uncomplicated lower UTI (cystitis) in a woman	no complicating conditions	oral antibiotics for 3 days
	diabetes	consider 7 days regimen of oral antibiotics
	symptoms > 7 days	consider 7 days regimen of oral antibiotics
	recent	consider 7 days regimen of oral antibiotics
	use of diaphragm	consider 7 days regimen of oral antibiotics
	age > 65 years	consider 7 days regimen of oral antibiotics
	pregnancy	consider 7 days regimen of nonteratogenic oral antibiotics
acute uncomplicated upper UTI (pyelonephritis) in a woman	mild to moderate illness, no nausea or vomiting	oral antibiotics for 10-14 days
	severe illness, urosepsis	hospitalization recommended with parenteral antibiotics until fever gone, then switch to oral regimen to complete 2 week course
	pregnancy	hospitalization recommended with parenteral antibiotics until fever gone, then switch to oral regimen to complete 2 week course
complicated UTI	mild to moderate illness, no nausea or vomiting	outpatient with oral fluoroquinolone for 14 days
	severe illness, urosepsis	hospitalization recommended with parenteral antibiotics until fever gone, then switch to oral regimen to complete 2-3 week course

 

Recurrence of infection:

(1) reinfection: recurrent infection more than 2 weeks after completion of therapy for a previous episode, typically with a new organism

(2) relapse: recurrent infection with same organism within 2 weeks after completion of therapy for an initial episode