Extremely common: - Second most common CA infection - Most common health care associated infection (CMS no longer reimburses hospitals for costs due to UTIs because they are seen as preventable)

Brown: Clinical Aspects of Urinary Tract Infections Flashcards by Andrew Kumar

Significant Bacteriuria definition:

What concentration in symptomatic patients?

> 105 cfu/mL of urine (only needs to be 102 cfu/mL in symptomatic patients)

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Asymptomatic Bacteriuria:

Significant bacteriuria in the absence of any symptoms suggestive of UTI

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Cystitis (Lower UTI):

Infection confined to superficial bladder mucosa

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Pyelonephritis:

Infection that involves the renal parenchyma

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Uncomplicated UTI:

Cystits or pyelonephritis that occurs in an otherwise healthy, non-pregnant woman with no underlying structure or functional abnormality of the urinary tract

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Complicated UTI:

Full list, don’t memorize

Associated with any of the following

o Obstruction: of any site of the urinary tract (enlarged prostate, uterine/bladder prolapsed, stones, tumor)
o Foreign body: catheter or stent
o Incomplete voiding: detrusor muscle dysfunction (neurologic disease, medications)
o Vesicoureteral reflex: urine travels up the ureters instead of out the urethra (usually only in kids)
o Recent history of instrumentation/invasive urologic procedure
o Renal transplant recipient: always classified as complicated
o Male: always classify as potentially complicated
o Pregancy: always classified as complicated
o Diabetes
o Immunocompromise
o Health-care associated infection
o Multi-drug resistant infection

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Recurrence:

Relapse or reinfection (most often)

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Relapse:

Recurrence due to the same microorganism (not completely eradicated; within 2 weeks)

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Reinfection:

Recurrence due to a different microorganism (usually after 2 weeks)

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How common?

Extremely common:

Second most common CA infection
Most common health care associated infection (CMS no longer reimburses hospitals for costs due to UTIs because they are seen as preventable)

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Most common source of what type of bacteremia?

What can childhood UTIs cause?

Can cause bacteremia: most common source of Gram negative bacteremia

Can cause chronic renal failure: early childhood UTIs

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What is Vesicoureteral reflex and in what population is it found?

Vesicoureteral reflex: urine travels up the ureters instead of out the urethra (usually only in kids)

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Prevalence by Age Group

Infant:
1-15 years:

Infant: more common in males than females, although rare in general

1-15 years: more common in females (4-5%)

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Prevalence by Age Group

16-35 years:
36-65 years:

16-35 years: more common in females (increases to 20%- sexual activity)

36-65 years: more common in females, but males also increase (due to benign prostatic hypertrophy)

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Prevalence by Age Group

65+ years:

65+ years: still more common in females, but very high rates in both genders (again, mainly due to BPH)

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Natural History of UTI

In Pregnancies:
Resolve without treatment?

Asymptomatic bacteriuria occurs in some pregnancies and many of those will develop pyelonephritis during pregnancy if untreated

Symptomatic and asymptomatic UTIs will resolve without treatment, but antimicrobial therapy increases probability of cure and speeds symptom resolution.

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Bacteria originating in intestine normally colonize:

Bacteria originating in intestine normally colonize vaginal introitus, periurethra and distal urethral meatus

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What are uropathogenic E.coli members of?

Where do they typically reside?

How does UPEC compare to commensal E.coli?

exPEC group

Reside in the gut without consequences. Can disseminate to/colonize extra-intestinal sites

Compared to commensal E.coli UPEC are more likely to harbor genes linked to virulence

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Infection occurs by ascending route

Effect on men vs women:
What facilitates entry of organisms into the bladder?

This is why it is more common in women (shorter urethra); in addition, prostatic antibacterial secretions may also contribute to decreased incidence in men

Sexual intercourse facilitates entry of organisms into the bladder (dose-response relationship between frequency of intercourse and risk of UTI in young women)

Host Defenses

What are defensive urine characteristics?
Inhibitors of bacterial adherence:
Role of humoral immunity:

Urine characteristics (high osmolality, low pH, presence of organic acids)
- Flushing out of bladder urine during voiding

Inhibitors of bacterial adherence to uroepithelial cells (Tamm-Horsfall protein, bladder MPS, sIgA)

Role of humoral immunity poorly understood

What are Tamm-Horsfall protein, bladder MPS, sIgA?

Inhibitors of bacterial adherence to uroepithelial cells

What can happen once the bacteria is established in the bladder?

Once established in bladder, can ascend to kidney: kidney can also be infected via hematogenous route (rare)

Cystitis
Clinical Presentation

Mild infection:

Mild infection:
o Dysuria, urgency, frequency, possible hematuria
o Suprapubic or low back pain
o NO signs of systemic infection (fever, chills etc.)

Cystitis
Clinical Presentation

Physical Exam:
Differential:

Physical Exam: suprapubic tenderness

Differential: perhaps vaginitis or urethrisis, but the urgency and frequency are pretty characteristic of cystitis

Pyelonephritis Clinical Presentation Symptoms Symptoms of cystitis present? Pain/tenderness where? Signs of systemic toxicity present:

Symptoms of cystitis may or may not be present May have flank pain/tenderness Signs of systemic toxicity present: fevers, chills, N/V/D, hypotension

Pyelonephritis Clinical Presentation Physical Exam:

Fever and costovertebral angle tenderness

Pyelonephritis Clinical Presentation Presentation in the elderly: May present as: (3)

Presentation in the elderly is a diagnosis of exclusion: presence of bacteriuria high in elderly to begin with; need to thoroughly asses and may present as one of the following: o Unexplained fever o New onset incontinence o Change in mental status

UTIs in Pediatric Population Infants Presentation: (4)

``` Non-specific presentation o Poor feeding o Failure to gain weight o GI symptoms o Unexplained fever (including febrile seizures) ```

UTIs in Pediatric Population Toddlers/Preschoolers Presentation: (3)

o Lower tract symptoms o Recurrence of daytime/nocturnal enuresis o Fever

UTIs in Pediatric Population | School-Aged:

Same as adults

EVALUATION What type of "catch" urine specimen is requried? Method for infants and toddlers: What may be used?

Urine specimen required: - Midstream “clean catch” - Stick on bags for infants and toddlers - Catheterization may be used to obtain specimen

EVALUATION Dipstick detects: What is pyuria?

Dipstick: to detect presence of RBCs, WBCs and bacteria WBCs in urine (pyuria) is supportive of UTI

Patients with Pyuria Spin Specimen What WBC count is considered significant?

Spin Specimen: 5-10 leukocytes per high-power field considered significant

Before Knowing Presence of Pyruria What is considered significant? What does it represent? Gram stain is an easy way to detect:

Gram Stain of Unspun Specimen: 1 or more bacteria per high-power field considered significant - Represents growth of greater than 105 cfu/mL in urine culture - Easy way to detect pyuria, bacteriuria and morphology of infecting agent all at once

Managing Uncomplicated Cystitis How do you treat a healthy, non-pregnant woman who presents with classic signs of cystitis? Urine culture: Use what to confirm diagnosis?

Treat empirically: healthy, non-pregnant woman who presents with classic signs of cystitis Culture of urine is not recommended: results would not be available in clinically meaningful time frame - Microbiology is predictable - May use urine dipstick to confirm diagnostic impression

What requires a urine culture?

Patients with complicated cystitis and pyelonephritis

Differentiating Lower UTIs (Cystitis) from Upper UTIs (Pyelonephritis) Usually based on what grounds? ~30% of women with symptoms of cystitis may have:

Usually based on clinical grounds: Issue is that ~30% of women with symptoms of cystitis may have subclinical pyelonephritis

Differentiating Lower UTIs (Cystitis) from Upper UTIs (Pyelonephritis) What do laboratory tests attempt to do? What are WBC casts specific for? Sensitivity:

Laboratory tests attempt to localize infection more accurately WBC Casts: specific for pyelonephritis (ie. if present, its pyelonephritis) but not sensitive because they are not present in all cases of pyelonephritis

Smell and appearance of urine:

Smell and appearance of urine is not evidence of a UTI: rather, evidence of hydration and recent dietary intake

Microbiology | Cystitis:

E.coli: 80% S.saprophyticus: 10-20% Rarely: Proteus, Klebsiella, Enterococcus

Microbiology | Pyelonephritis:

E.coli: Mainly | Rarely: Proteus, Klebsiella, Enterococcus

Microbiology | Complicated Infections and Healthy Care-Associated UTIs

E.coli: still an important cause | Others: Proteus, Klebsiella, Enterobacter, Serratia, Citrobacter, Pseudomonas, Enterococcus

Microbiology | Pediatric Population:

E.coli: mainly Klebsiella, Proteus Rarely: coagulase-negative staph (epidermidis, albus)

When do you treat asymptomatic bacteriuria?

Asymptomatic Bacteriuria: only treated in certain circumstances - Pregnancy - Prior to invasive instrumentation of urinary tract or urologic surgery - Renal transplant patient (during first 6 months post-transplant)

Who is imaging reserved for? (3)

Reserved for only some patients: - Complicated infections - Recurrent pyelonephritis - Pyelonephritis that does not respond to appropriate antibiotic therapy (in 72-96 hours)

What disease is looked for in children? | What imaging is used?

CAT scans, ultrasounds, and specialized procedures in children looking for vesicoureteral reflux