UTI basic definitions:
Upper Tract Infection v Lower Tract Infection?
Upper Tract Infection: infection above the bladder, including kidneys
Lower Tract Infection: infection involving bladder and lower (urethra, prostate)
Pyelonephritis: kidney infection
Cystitis: bladder infection
Prostatitis: prostate infection
Urethritis: urethral infection
Ascending route of infection v hematogenous route?
Ascending: infection enters the urinary tract through the urethra
Hematogenous: infection is brought to the kidneys via bloodstream; enters urinary tract that way
Urine contamination v urine colonization?
Urine is normally sterile
Contamination: organisms in culture that were introduced from anatomy (foreskin, vulva) or environment -- not present in bladder
Colonization: organisms present in urine but not causing sx
symptomatic v asymptomatic UTI
There may or may not be symptoms with UTI.
Both will have significant growth of bacteria in urine.
symptoms of lower UTI?
dysuria, urgency, frequency, suprapubic pain
symptoms of upper UTI?
fever, flank pain (aka costo-vertebral angle pain), nausea, vomiting, sepsis
what is meant by complicated UTI?
-obstruction of the urinary tract due to anatomic abnormality or presence of foreign body (stone, catheter)
-functional disruption of flow due to neuromuscular issue
-abnormalities of immune function lowering host depenses, allowing establishment of infection in the urinary tract.
acute UTI v chronic UTI? how will they present?
Acute: onset of sx will be a few days prior to pt presentation
Chronic: may be sx or asx, but will have significant #s of bacteria on culture.
Recurrent UTIs: re-infection v relapsing infection?
Re-infection: repeated bouts of sx, associated wtih significant bacterial growth from urine. new species of bacteria present with each episode (more common than relapsing infections)
Relapsing infection: repeated episodes, due to the same organism each time. Organism persists despite treatment.
Risk factors for ascending UTI in women?
maternal history of UTIs
first UTI prior to age 15
new sex partner w increased activity
diaphragm, condom or spermacide usage
catheters or other instrumentation
what usually causes hematogenous seeding of the urinary tract?
usually caused by a bacteremia
a urine culture that grows Staph aureus should raise suspicion for what?
presence of staph bacteremia, or other intravascular staph infection such as infective endocarditis
what are 2 genetic characteristics that can promote or discourage UTIs?
why are women more predisposed to UTIs?
genetic characteristics: HLA types, blood types. seem to alter the adherence of bacteria within the urinary tract
women: short urethral length seems to encourage UTIs
what mechanical effects of urine or urodynamics can cause UTIs?
mechanical: urine flow can be altered by congenital abnormalities
over-distension may lead to inadequate drainage, pooling of urine in bladder, ascension of bacteria into the upper tract
a UTI in an infant should prompt what thought?
school age children through middle age: M or F more prone to UTIs?
geriatrics: M or F more prone to UTI?
-Infant UTI: consider congenital abnormality or urinary tract
-childhood thru middle age: women >> men
-geriatrics: men >> women (due to enlarged prostates)
what organism causes 95% of UTIs?
What causes a significant % of cystitis in young women?
UTIs: E Coli (bacteria)
cystitis: Staphylococcus saprophyticus
name 5 tests used to diagnose a UTI
-leukocyte esterase reaction
-urine gram stain
First step in lab analysis of a UTI
-more than 5-10 WBCs per high powered field indicates infection, as does presence of bacteria in urine sediment.
what is a leukocyte esterase reaction?
Dip stick test for UTI
what is a nitrite test?
dip stick test for UTI
based on the reduction of nitrate by bacteria in the urine. less useful than the leukocyte esterase reaction (also a dipstick test) due to false neg results
describe a urine gram stain
diagnostic test for UTI
seeing 1 organism per HPF of un-spun urine --> 10^5 organisms per cc --> significant bacteriuria.
may also provide info on gram pos v gram neg organisms
describe a urine culture
diagnostic test for UTI
determines presence of significant organisms in the urine
impt to have a clean sample (clean catch, mid stream) to avoid contamination with periurethral flora.
what number of organisms is diagnostic for a symptomatic patient?
what about for an asymptomatic patient?
symptomatic: greater than 10^2 organisms is diagnostic
asymptomatic: greater than 10^5 on two separate days (have to confirm due to potential contamination of sample)
what is an indication for imaging of the urinary tract?
Presence of complicated infection, anatomic differences, urodynamic conditions --> imaging (US, CT, MRI).
Can also observe the urinary tract directly via cytoscopy.
How might a UTI present in infants/children?
what should I consider?
Might present as failure to thrive, unexplained fever, vomiting.
consider congenital abnormalities
Treatment of UTI in women of childbearing age?
Treatment when it is a re-infection?
treatment when it is a relapse?
If re-infection (repeat w different orgs), short course therapy (3d) is indicated. These women may benefit from prophylactic therapy (daily) or self-administration at first symptoms.
If relapse (same org), long course therapy (2-6 weeks) is indicated.
Management of UTIs during pregnancy?
Pregnancy: dilatation and altered peristalsis of the ureter. Predisposes -> bacterial ascent.
Screen all preggo women for bacteriuria, even if no symptoms.
Repeat cultures to ensure absence of bacteria.
UTIs in young men - what is the usual cause?
usually indicate an STD.
rarely, due to a congenital abnormality.
UTIs in the elderly: what is the prevalence?
when do we treat?
what will predispose an elderly patient to UTIs?
relatively high prevalence of UTIs in elderly
We only treat if it is symptomatic: there is no increased morbidity/mortality with asx UTIs in this group.
Foley catheters predispose the elderly to UTIs. remove all catheters as soon as possible.
Prostatitis: when should I suspect this?
when should I treat this?
Suspect prostatitis in elderly men with recurrent UTIs and presence of prostatic enlargement.
Treat acute prostatitis, 2 or more weeks of antibiotics (they penetrate poorly into the prostate).
Drugs: Trimethoprim-sulfamethoxazole (TMP-SMX) and quinolones are best.
Drug to treat Lower Tract UTI in an outpatient?
as long as incidence of E Coli resistance to this is < 20% in local region.
Antibiotic for Upper Tract UTI in an outpatient?
ensure that blood levels obtained following oral ingestion are equiv to levels following IV administration
Antibiotics for UTI prophylaxis?
Antibiotic for Upper Tract UTI in an inpatient?
amino-glycoside + ampicillin
this combo will cover gram neg organisms and enterococci.